Initial Environmental Review of NWC Sewage Treatment Facilities in by oum18845

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									Initial Environmental Review
 of NWC Sewage Treatment
    Facilities in Ocho Rios
Coastal Water Quality Improvement Project
             USAID Contract No. 532-C-00-98-00777-00




          Initial Environmental Review
           of NWC Sewage Treatment
              Facilities in Ocho Rios



                             January 2001




                           Prepared for the:

                      Government of Jamaica’s
             National Environment and Planning Agency

                               And the

         United States Agency for International Development




                                                                   Implemented by:

                                               Associates in Rural Development, Inc.
                                                                      P.O. Box 1397
                                                          Burlington, Vermont 05402

                                                                       Prepared by:

                                                                      Robert Wynter
                                                               Dr.-Ing. Johan Vernik
Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                     2
T ABLE OF CONTENT

Abbreviations                                                                                 5

Nomenclature                                                                                  6

1    Background To The Project                                                                7

2    Background On The Consultants                                                            8

3    Purpose Of The Study                                                                     9

4    Approach                                                                                 10

5    Field Investigations                                                                     12

      5.1   Data Collection                                                                   12

            5.1.1        Flow                                                                 12
            5.1.2        Sampling (Volume Proportional)                                       12
            5.1.3        Sampling (Grab)                                                      13
            5.1.4        Chemical Sample Analysis                                             13

     5.2    Data Elaboration                                                                  13

6    Overview of the Ocho Rios Sewage Treatment Plant                                         14

7    Influent Characteristics                                                                 17

     7.1    Flow                                                                              17
     7.2    Conductivity                                                                      18
     7.3    COD, N and P                                                                      20
     7.4    Settleable Solids                                                                 21
     7.5    Temperature                                                                       21
     7.6    SS                                                                                22
     7.7    Ph                                                                                22
     7.8    Redox                                                                             23
     7.9    Hydrogen-Sulphide                                                                 23
     7.10   Summary of Major Findings                                                         24

8    Treatment Plant Performance                                                              25

     8.1    COD and Nutrients                                                                 25
     8.2    Oxygen                                                                            25
     8.3    Level in Oxidation Ditch                                                          27
     8.4    Outflow Pattern Of Sedimentation Tank                                             28
     8.5    Current                                                                           29
     8.6    Relative Mlss in Oxidation Ditch                                                  31
     8.7    Mlss and Sludge Activity                                                          32
     8.8    Return Sludge                                                                     35
     8.9    Effluent: E. Coli and Settleable Solids                                           35
     8.10   Scum                                                                              36
     8.11   Microscopic Examination of Activated Sludge                                       36
     8.12   Final Effluent Quality                                                            37
     8.13   Summary of Major Findings                                                         37


               Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                    3
9    Existing Data                                                                          39

10   Environmental Aspects                                                                  40

11   Conclusions                                                                            41

Appendix

Pictures of Ocho Rios Sewage Treatment Plant                                                42

12   NWC Data                                                                               62

     12.1   BOD and Nitrate                                                                 62
     12.2   PO4 And SS in Influent                                                          62
     12.3   SS and MISS                                                                     63
     12.4   Faecal Coli                                                                     65




             Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                  4
ABBREVIATIONS

ASP          Activated Sludge Process
BOD          Biochemical Oxygen Demand
C            Degree Centigrade
COD          Chemical Oxygen Demand
COD-f        COD of the filtered sample
COD-m        COD of the completely mixed sample
CWIP         Coastal Water Quality Improvement Project
d            Day
EMS          Environmental Management Systems
FTU          Formazine Turbidity Units
GOJ          Government of Jamaica
h            Hour
HRT          Hydraulic Residence Time
InWaSia      In Waste water Systems interactive (iterative) approach
ISO          International Organisation for Standardisation
kg           Kilogram
L            Litre
  2
m            Square Metre
  3
m            Cubic Metre
MLSS         Mixed Liquor Suspended Solids (Parameter to describe biomass of activated
             sludge)
mS           Milli Siemens
mV           Milli Volt
N            Nitrogen
NEPA         National Environment and Planning Agency
NH4-N        Ammonia Nitrogen
NO2-N        Nitrite Nitrogen
NO3-N        Nitrate Nitrogen
NRCA         Natural Resources Conservation Authority
NWC          National Water Commission
o-P          Ortho-Phosphate
P            Phosphorous
PE           Population Equivalent
PS           Pump Sump/Sewage Relift Station
SRT          Solids Retention Time
STP          Sewage Treatment Plant
SVI          Sludge Volume Index
t            Tons (Metric)
TN           Total Nitrogen
TP           Total Phosphorous
UASB         Upflow Anaerobic Sludge Blanket Reactor
WC           Water Column




            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                 5
NOMENCLATURE

On-line is the continuous and interactive measuring by sensors of operating conditions which
provides information that facilitates immediate responses to changes

Environmental aspects are elements or part of an activity or product or service that interacts
with or has some relation to the environment

Environmental impact is a change in the environment which is adverse or beneficial, wholly or
partially, resulting from an organisation’s activity, product or service.

Clause 4.3.1 of ISO 14001 requires on organisation establishes and maintains procedures to
identify aspects which it can control, over which it expects to have an influence and determine
those aspects which have or can have significant impacts on the environment. The clause also
requires that aspects are considered in setting objectives and that information is kept up to date.

The redox potential is given by the formula below. The normal potential (Eo) has different value
for each oxidation reduction reaction. n is the number of participating ions. Ox/Red is the
concentration ratio of oxidising and reducing ions.

                    Redox Potential (E) = Eo + 0,66 / n x log (Ox/ Red )

The redox potential will increase when the concentration of oxidised ions increases in relation to
the concentration of reduced ions. Under anaerobic conditions the redox potential may drop to –
300 mV or more.

The redox potential can be used to follow redox reactions like denitrification, sulphate reduction,
sulphide oxidation, etc.

Free board is the difference between the water line and the maximum possible water level in a
reservoir.




               Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                    6
1    BACKGROUND TO THE PROJECT

The National Environment and Planning Agency / Natural Resources Conservation Authority
(NEPA/NRCA) through the Coastal Water Quality Improvement Project (CWIP) Contract Result 3
(CR 3) - Environmental Practices of Industries and Commercial Establishments Improved has
been working to promote the implementation of EMS in support of the development of a national
agenda that recognises the role of government, private sector and non-government organisations
in environmental management.

Environmental Management Systems (EMS), based on the ISO 14000 series, are being
increasingly accepted, adopted, and implemented by industry, the services sector, utilities, local
government, and commercial enterprises. It is generally agreed that an EMS is a powerful tool
for achieving environmental protection and improved business operation. In this regard, the EMS
policy and strategy is viewed by the GOJ/NEPA/NRCA as a step along the sustainable
development path which will assist the country’s ability to ‘grow capital’ – the natural, economic
and human.

Drivers

Globally, the EMS approach is being rapidly adopted as a tool to achieve improvements in
internal efficiencies within operations thereby helping to reduce costs and achieve a competitive
advantage. Bankers and insurance companies are requiring assessments of environment risks
before funding projects. Governments are moving towards green procurement and regulators are
using EMS adoption as a mechanism for regulatory flexibility. The drivers for EMS
implementation internationally are as follows:

>   Global competition
>   Market pressures
>   Improving efficiencies
>   Public image/Stakeholder demands
>   Enhanced competitive advantage
>   Environmental protection
>   Financial requirements

The guiding principles of the policy and strategy embrace a number of philosophies. These
include sustainable growth, implementation of EMS as a fundamental tool to help achieve
sustainable development, voluntary implementation of EMS and the full participation of and
provision of information to all citizens of Jamaica re the quality of the environment.
The GOJ has taken the stance that it must lead from the front with regards to the promotion of the
EMS policy and strategy. In regard, Goal 1 Strategy 1.5 Build capacity to plan, implement
monitor and evaluate sustainable communities using an EMS approach.

GOAL 1:         To establish the framework within which Environmental Management
                Systems will be adopted across all sectors of society.

One of the proposed actions is to ‘Implement EMS in a regional waste water division of the NWC’.
The leadership of the NWC endorse this approach and have requested that CWIP provide the
technical assistance to develop and implement an environmental management system for three
of its sewage treatment facilities, Negril; Montego Bay; and Ocho Rios.




               Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                    7
2   BACKGROUND ON THE CONSULTANTS

CWIP contracted two short-term experts to provide the technical assistance to conduct the initial
environmental review and to provide an overview of the performance of the Ocho Rios Systems.
A brief introduction to the two consultants is found below.

§   Robert Wynter is a Chemical Engineer and Management Consultant with wide experience in
    environmental audits and EMS’.

§   Johan Verink is an Environmental Engineer with commitment to the development, adaptation,
    transfer and implementation of know-how in the wastewater treatment sector.

This document is intended to present a detailed description and interpretation of the
investigations at the Ocho Rios sewage treatment facility.




              Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                   8
3    PURPOSE OF THE STUDY

The purposes of this study are to:

1.   Conduct an initial environment review of the NWC Ocho Rios sewage treatment facilities.

2.   Provide a performance review of the facilities.

3.   Prepare a report on the findings of the initial environmental review to provide data to support
     the implementation of an EMS.

Tasks

The proposed tasks for the consultant are as follows:

1.   Determine the flow and influent characteristics of the wastewater going to the sewage
     treatment facilities using proportional sampling and conductivity measurements;

2.   Determine plant performance and envi ronmental impact using on-line monitoring and
     sampling technology.

3.   Analyse treatment process performance including:

     §   Load distribution
     §   Load distribution
     §   Daily variations in oxygen concentration and suspended matter in effluent
     §   Effluent quality

4.   Review and analyse NWC records describing concentrations of water quality parameters
     found in the final effluent at the Ocho Rios plant since it commenced operation.

5.   Identify the significant environmental aspects.

6.   Liase with NWC’s operational staff at the Ocho Rios facilities re the provision of existing
     information to be incorporated into the report.

7.   Prepare the initial environment review reports.

Organisation of the Report

Investigations in Ocho Rios involved on-line monitoring of the influent at the main pumping station
3 and additional monitoring at the ponds.

This report firstly outlines the findings of the influent characteristics followed by am assessment of
the treatment plant performance.




                Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                     9
4           APPROACH

On-line monitoring and sampling technology was at the heart of the approach and was used to
provide immediate and valuable information on the operations. The system sampled both time
and volume proportionally, and monitored:

§        Waste water characteristics
§        Flow
§        Electricity consumption

An overview of the concept is shown in Fig. 1

Fig. 1 On-Line Monitoring and Sampling Technology Concept


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                                                                                                                                                                                                                       Sa mpling
                                                                                                     Avoid ance and                                                                                                    U nit

                                                                                                          Minim isatio n of
                                                                                                                Waste Water / T reatmen t
                                                                                                          and Pro du ct Lo sses

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                                                                                                                 Waste Water                                                                                                                                     Authorities +
    Industry                                                                                                     Characteristics                                                                                             (Stand ards)                        ISO-Standards


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    or/and

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                                                                                                                                                                                                                      Sam p le   Sa mp le

    Influent
                                                                               Effluent
                                                                                                                Op timisation of T reatmen t                                                                      Expected Resu lts:
                                                                                                         an d                                                                                                     Cro ss -check T reatmen t Plant Design Criteria
                                                                                                                                                                                                                                          with Presen t Lo adin grate
                                                                                               Saving En ergy                                                                                                     Avo id T reating Tap an d Rain Water
                                                                                                                                                                                                                  Optim ise Energy C onsu mp tion




The benefits of the approach are: avoidance and minimisation of environmental impacts;
reduction of product losses; optimisation of wastewater treatment; energy savings; data for
treatment plant design and/or upgrade; data for environmental compliance programmes and/or
upgrade and data for environmental compliance programmes.

Work Programme

For the Ocho Rios Sewage Treatment Facility the following approach was used:

§        Preliminary visit to the plant for familiarisation and an initial review of documentation

§        Transferred, installed and tested the equipment at the contact tank



                                                                               Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                                                                                                                           10
§   Commenced on-line measurements and sampling

§   Monitoring and sampling at Ocho Rios sewage treatment plant from December 22 - 30, 2000




              Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                  11
5     FIELD INVESTIGATIONS

A computer controlled unit was used for on-line data monitoring and sampling. The features of the
equipment enable one to take different types of samples: grab, continuous, time and volume
proportional samples.

The unit was equipped with sensors to monitor the following parameters on line:

§     pH
§     Temperature
§     Conductivity
§     Redox potential
§     Oxygen
§     Solids ( Sludge )
§     Level ( Pressure, height or flow )
§     Power Consumption


Fig. 2 Overview of the Monitoring and Control Unit




5.1     Data Collection

The following sections of the report outline our approach to measure flow and the various
sampling techniques.

5.1.1      Flow

At the Screen, a flow monitoring device was installed. The device was calibrated through backing
                                                  3
up water in the inflow chamber. This value, 329 m /h was very similar to the one read at the flow
meter of the treatment plant.

5.1.2      Sampling (Volume Proportional)

Influent

A hose with a screen was positioned in the inflow to the contact tank at around 30 cm below the
water level. Every time the inflow to the treatment plant started, waste water was pumped into



                  Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                      12
containers of the automatic sampler. In this way, the best possible sampling (volume proportional
sampling of the sewage) was ensured.

Effluent

For the sampling of the treatment plant effluent time-proportional samples were taken of the
outflow from the sedimentation tank (See Fig. 5 ).

5.1.3      Sampling (Grab)

Grab samples were taken from the activated sludge in the oxidation ditch and the return sludge to
determine the sludge volume and the sludge content.

5.1.4      Chemical Sample Analysis

In situ analyses of settleable solids, pH, redox, conductivity and suspended solids were done.
The samples for chemical analysis COD, ammonia, nitrate, total nitrogen, ortho-phosphate and
total phosphate were preserved for analysis. Faecal Coliforms was carried out in laboratories.
BOD measurements were not carried out since the COD of the mixed sample was already
extremely low, no settleable solids were found in the regular samples and the ammonia
concentration was also close to zero.

5.2     Data Elaboration

Data collection, elaboration and presentation have been carried out by the use of the following
software packages:

§     DASYLab, Company WAL, Oldenburg, Germany
§     XACT (similar to Excel), Company SciLab, Hamburg, Germany
§     Microsoft Word 97
§     Microsoft Excel 97




                 Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                     13
6    OVERVIEW OF THE OCHO RIOS SEW AGE T REATMENT PLANT

Location

                                                          Fig. 3 ), which conveys the waste
Several pumping stations feed to the main pumping station (
water to the automatic screen at the treatment facility

Type

                                                                             F
Two parallel operated oxidation ditches, followed by a sedimentation tank ( ig. 4 ). The two
systems cannot be completely operated separately. Effluent from the oxidation ditches joins,
which could be separated with minor efforts, however, the return sludge from the sedimentation
tank joins in the return sludge pump sump where there is no wall to separate the return sludge to
both oxidation ditches.

Surplus sludge is thickened and dried on drying beds.

Disposal

Dried sludge is stored at the treatment plant until disposal/use for land application is available.

The treatment plant effluent flows via a deep sea outlet with diffusers into the nearby sea, west of
Ocho Rios
.
Fig. 3     Schematic Display of Pump Sump Feeding to the Automatic Screen of
           Treatment Plant




                                     Main Pump 1     Drain Pump    Main Pump 2   Main Pump 3




                            Inflow




                                                                                      pH
                                                                                      Level
                                                                                      Conduc tiv ity
                                                                                      Sample Intake
                                                                                      Temperature
                                                                                      MLSS and/or SS
                                                                                      Redox
                          Air                      Incoming Main                      Level Switch
                                                                                      Curre nt




                Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                              14
                                                                                                                                                                                                             Schematic Flow Diagram

                                                                                                                                                                                  Ocho Rios Sewage Treatment Plant

                                                                                                                                                                                                                                                      Power Supply

                                                                                                                                                                                                                                                                                      Control Room



                                                                                                                                                                                                                      Contact Tank                                                                      Sedimentation Tank 1

                                                                                                                                                                                                                                      Oxidation Ditch 1


                                                                                                                                                                           Bar Screen
                                                                                                                                                                                                                                                                                                                                   Effluent

                                                                                                                                                                                                                                          Return Sludge




15
                                                                                                                                                                                                                                      Oxidation Ditch 2

                                                                                                                                                                                Flow Meter


                                                                                                                                                                                                                                                                                                        Sedimentation Tank 2

                                                                                                                                                                           Inflow
                                                                                                                                                                                                                                                                                         Filtrate


                                                                                                                                                                                                                                                                     Surplus Sludge




                                                                                                                                                                                                                                                                                                                   Storage / Maturation
                                                                                                                                                                 ai
                                                                                                                                                                M nPump1    ri
                                                                                                                                                                           D anPump   M nPum
                                                                                                                                                                                       ai   p2    ai
                                                                                                                                                                                                 M n Pump3




     Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios
                                                                                                                                                                                                                                                 Drying Beds
                                                                                                                                                         Iflw
                                                                                                                                                         n o

                                                                                                                                                                                                                Pump Sump 1
                                                                                                                                                                                                                                      1      2    3   4   5    6     7                              Dried Sludge




                                                                                    Fig. 4 Schematic Overview of Ocho Rios Waste Water Treatment Plant
                                                                                  3
The oxidation ditches each have a volume of 5104 m . The free board between 500 and 800 mm.
                                                    3
The sedimentation tanks each have a volume of 1846 m .
                                                                                                                             2
The contact tank has an effective area (water surface) of around 27,56 m and an effective
                                   3
volume between 95,6 and 87,3 m . This volume varies because the water level in the oxidation
ditch varies with the adjustments of the overflow weir to adjust the oxygen supply to the activated
sludge.
                                                                                                                 2
The return sludge tank has an effective area of approximately 18,8 m . The plant has 7 sludge
                                                             2
drying beds. They occupy an effective area of around 1600 m . Fig. 5 displays the monitoring
and sampling points for different parameters.


Fig. 5              On-Line Monitoring and Sampling Points



                                                                                 Current
                           Tem peratur e
                           pH
                           Redox                           Oxygen
                           SS                                                Power Supply    Control Room
                                                           pH
                           Conductivity                    Redox
                           Sampling        Level, MLSS     MLSS                                                                         Level
                                                                                            Level              Sludge Vol.

                                                                                                                     Sedimentation Tank 1

                                                             Oxidation Ditch 1
 Level            Sludge Vol.                                                                                                                   Sampling
                                                         Sludge Vol.                                                                            Settl.Solids
         Bar Screen


                                                              Return Sludge
                                                                                                                                                Effluent
                                                             Oxidation Ditch 2
          F lo w Meter
                                                                                                    Filtrate




         Inflow
                                                                                                                     Sedimentation Tank 2




                         Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                       16
7             INFLUENT CHARACTERISTICS

The following section of the report outlines the findings from the monitoring and measurements at
the automatic screen near the contact tank of the oxidation ditch.

7.1                Flow

The graphical determination of the 2-h average flow into the contact tank is shown in Fig. 6 . The
                        3                            3                            3
average flow is 2600 m /d with a minimum of 52 m /h and a maximum of 175 m /h. The normal
                                                             3
minimum and maximum values are between 80 and 150 m /h. The peak flow is during the day,
minimum flows at night.

Fig. 6                    Daily Inflow Variations to the Treatment Plant

             200



                                 Q (m3/h)


             150
 Q (m 3/h)




             100




                                     Sunday                 Tuesda y                Thursday               Saturday
             50
                     2           3            4         5              6        7              8       9
                                                               Time (d)
The pattern seen during the flow out of the chamber in front of the screen is retarded by the
reduction of the cross-section of the bars, but also by the screenings attached to the bars.
0shows the number of times the level is between 25 and 35 cm in front of the screen.




                            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                 17
Fig. 7                    Level in Front of the Screen

             250

                             n 2 5-35 cm   Number of Times the Level of the Screen is between 25 and 35 cm

             200




             150
n 25-35 cm




             100




             50




              0
                      2           3           4          5            6          7           8             9
                                                               Time (d)


At high flow the level in front of the screen ranges more frequent between 25 and 35 cm. This
means that the water is not readily flowing out of the influent chamber in front of the screen, in
other words, there is a clogging of the screen bars near the bottom of the screen. At night time,
when the time between two feedings increase, there is more time for the water to trickle out.
During the week of investigations the number of times the level is between 25 and 35 cm
continually increased. This can be observed for the peak and the minimum values. Observations
at the screen during low flow showed an accumulation of screenings at the backside near the
bottom. Such matter could, when entering the RS pumps, lead to problems. This indicates that
more frequent manual cleaning of the screen is required.

7.2                Conductivity

The following two figures show the conductivity over a short period (24 hours) and over the longer
sampling period. The values are predominantly just below 1 mS/cm, an expected range for
sewage. The occasional peaks were up to around 5 mS/cm and associated with batch loads of
salty water (brownish coloured) which, may be from water treatment plants or, less probable, a
contribution from a sump infrequently emptied, where salt water has infiltrated. Fig. 8 shows that
the salt peak coincides with an increase of pH.




                            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                 18
Fig. 8                          Conductivity and pH during a Short Period of Time

                          8,0                                                                                                  4,5

                          7,8                            pH 1 Canal [-]                                                        4,0

                          7,6                            Conductivity 12 [V]
                                                                                                                               3,5
                          7,4
                                                                                                                               3,0




                                                                                                                                     Conductivity 12 [V]
         pH 1 Canal [-]




                          7,2
                                                                                                                               2,5
                          7,0
                                                                                                                               2,0
                          6,8
                                                                                                                               1,5
                          6,6

                          6,4                                                                                                  1,0

                          6,2                                                                                                  0,5

                          6,0                                                                                                  0,0
                                00:00:        03:00:            06:00:   09:00:      12:00:    15:00:   18:00:   21:00:   00:00:
                                                                             Time (hh.mm)
                                                                                Uhrzeit




Fig. 9                          Conductivity of the Incoming Sewage over the Sampling Period


                          5,0


                                         Con ductivity 12 [V]


                          4,0




                          3,0




                          2,0




                          1,0




                          0,0
                                  1,0              2,0            3 ,0     4,0          5 ,0     6,0      7,0     8 ,0
                                                                                  Time (d)




                                  Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                                         19
7.3   COD, N and P

The daily variations of the Chemical Oxygen Demand (COD) of the wastewater on 28, 29 and
30.12.00 w                                                       F
           ere sometimes relatively strong for sewage in Jamaica ( ig. 10 ). Values reached
600 to 700 mg/L. At night the values dropped to 200 - 300 mg/L.

Fig. 10                 Daily Variations of COD in Influent

                     1.000

                      900                COD (mg/L)

                      800

                      700

                      600
       COD (mg /L)




                      500

                      400

                      300

                      200

                      100

                        0
                             0,0   0,2    0,4   0,6    0,8    1,0     1,2     1,4     1,6   1,8   2,0   2,2   2,4
                                                             Time (d fro m 28.12.2 000)



The COD of day composite samples (see Tab. 1. ) varies between 110 and 460 mg/L. The low
COD was on 25.12.00, a public holiday. The Nitrate concentration in the influent is low as to be
expected. The wastewater contains significant amount of phosphorous, expressed as total
phosphorous, whose concentration varies between 7,6 and 12,2 mg/L.

Tab. 1.                 COD of Composite Influent Samples


                             COD (mg/L) TN (mg/L) NH4 -N (mg/L) NO3-N (mg/L) TP (mg/L)
      23.12                        214                27,5                  21,2                                    12,2
      24.12                        181                28,7                  23,5                                    9,5
      25.12                        110                29,5                  17,1                                    8,6
      26.12                        300                30,2                  17,2                  0,4               8,6
      27.12                        300                > 12                  18,4                                    7,6
      28.12                        345                                      15,9
      29.12                        459                                      12,2
      30.12                        400



                             Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                     20
                7.4                 Settleable Solids

                                                                         -16 mL/L. The pattern in the influent
                The settleable solids, not unusually, ranged widely from 1
                shows most values around 6 mL/L which suggests a rather regular discharge of settleable matter
                to the sewer.

                Fig. 11                      Settleable solids of 2-h Composite Influent Samples


                           20

                           18         Sat               Sun            Mon         Tue                 Wed         Thu             Fri             Sat
                           16
Settleable Solids (mL/L)




                           14                 Settleable Solids (mL/L)

                           12

                           10

                            8

                            6

                            4

                            2

                            0
                                1                2                3          4                   5            6                7               8         9
                                                                                           Time (d)


                7.5                 Temperature

                The wastewater temperature, as shown in the figure below, varies slightly around 28 C.

                Fig. 12                      Temperature of Influent and Air


                                50


                                               Temp 0 Air [C]
                                               Temp 1 Water [C]
                                45




                                40




                                35




                                30




                                25




                                20
                                       1,0              2,0           3,0        4,0             5,0         6,0         7,0             8,0
                                                                                         Time (d)




                                               Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                                            21
The air temperature, however, varied from around 23 and 37 C with peaks during sunshine of
over 40 C (Sensor was not subjected to direct sunlight).

7.6         Suspended Solids

On-line measurement of suspended solids varies slightly and less than expected (Fig. 13 ). The
FTU reaches very low values during day 2 (25.12.00).

Fig. 13           SS (FTU) in Influent
      500


      450          SS 8 []


      400


      350


      300


      250


      200


      150


      100


       50


        0
                    1,0                             2 ,0                                     3 ,0
                                                             T ime (d)



7.7         pH

The pH is shown in Fig. 14 . The variations in the inflow are between 6,5 and 8. Predominantly
the pH is around 7. In the oxidation ditch the pH shows a slight general falling tendency.

Fig. 14           pH in Influent and in Oxidation Ditch
            9,0


                             pH 1 Canal [-]

            8,5




            8,0




            7,5




            7,0

                                                                               Oxidation Ditch

            6,5




            6,0
                  1,0           2,0           3,0      4,0               5,0         6,0            7,0   8,0
                                                                Time (d)




                        Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                22
In general one can see, that the pH values are a bit higher during the day than during the night,
however the differences may not have a significant impact on the biological process. An increase
could mean that less nitrate has been formed or m      ore nitrate has been used, thus providing
information about the denitrification process. The increase during the day could be also caused
by an increased pH of the incoming wastewater which can be observed during the monitoring of
the inflow.

7.8       Redox

In the nomenclature a brief description is given of the redox potential. Fig. 15         shows an
increase from a negative redox potential to a positive one, indicating that the pollution load
decreased over the period. This coincides with the low COD of the composite sample on
25.12.00. Since the redox can provide valuable information about the denitrification in the
oxidation ditch, the probe was placed there. The typical changes of the redox potential, due to
denitrification, were not observed. During the night the redox potential increases, indicating that
the conditions for denitrification become less favourable.

Fig. 15       Redox Potential in Influent and Oxidation Ditch




7.9       Hydrogen-Sulphide

The incoming wastewater had normally the typical sewage smell. However observations during
the sampling period revealed that there w      ere on few occasions, particularly when wastewater
entered the screen and contact tank, an intensive smell of rotting eggs. It has to be noted, that
different people describe the smell differently.

7.10      Summary of Major Findings

The major findings of the investigation of the influent are summarised below:
                                                         3                                 3
§     The flow rate is normally between 80 - 150 m /h, with an average of 111 m /h or around 2700
       3
      m /d a significant environmental aspect

§     The Phosphorous concentrations in the inflow indicate for this type of treatment process a
      significant environmental aspect


                  Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                      23
§   The screen requires more frequent manual cleaning.

§   COD ranged from below 200 to 800 mg/L. This is usual for sewage.

§   Odour from the inflow to the plant represents sometimes a significant environmental aspect

§   The sump, from where the waste water is pumped into the plant, cannot be routinely emptied
    completely




               Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                   24
8      T REATMENT PLANT PERFORMANCE

The following section of the report outlines the findings from the monitoring and measurements of
the treatment plant performance in terms of effluent quality, sludge characteristics and energy
consumption.

8.1     COD and Nutrients

The Effluent COD and nutrient concentrations of the treatment plant are presented in Tab. 2.
The effluent quality in terms of COD and ammonia is excellent. Improvements with respect to
nitrate levels can be obtained through improved denitrification (control of oxygen levels in the
oxidation ditch). Whether biological P-removal can be enhanced through process optimisation is
not completely certain at this time. In order to reduce the P levels in the effluent, simultaneous P-
precipitation is an option.

Tab. 2.       Effluent Characteristics

                  COD (mg/L) TN (mg/L) NH4-N (mg/L) NO3-N (mg/L) o-P (mg/L) TP (mg/L)
      23-25.12          < 25                16,2                    <1                       13,2      1,2   5,7
      26-29.12          < 25                19,0                    <1                       13,5      1,4   5,8
      12.01              55                                         <1                       10,6      1,3
      15.01                                                         <1                       12,0
      20.01                                                                                  13,6

Denitrification will also lead to significant energy savings and probably also to an improvement in
sludge characteristics (SVI).

8.2     Oxygen

One oxidation ditch and one sedimentation tank were in operation during the week of the
investigations. First oxygen measurements revealed oxygen presence over the entire length and
depth of the oxidation ditch. 0 shows paired oxygen measurements and confirms the findings
over the length of the ditch.

Fig. 16       Paired Oxygen Measurements in the Oxidation Ditch


                               5,6                2,9                1,2         4,4




                         1,6                             Oxidation Ditch 1
                               2,4                      3.3            3.7

              Oxygen RS = 0                     Same colour = Oxygen values taken at appr. same time


                         Ox. Ditch Surface = 1,6
                         Deeper            = 1,2
                         Deepest           = 1,0 mg/L



The oxygen profile in the oxidation ditch is measured on-line next to inlet of the contact tank. The
results are shown in Fig. 17. It is interesting to see that the high oxygen concentrations up to 5


                  Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                   25
mg/L no longer appeared after the second day. The oxygen concentration varies depending on
return sludge flow and the load of the influent. An interesting observation took place during the
week, which supports the case for denitrification. Every day at around 10:30 p.m. one aerator was
switched off. At the same time the level in the oxidation ditch was increased to near maximum
while the oxygen concentration decreased to around zero, creating the conditions for
denitrification.

Fig. 17     Oxygen Profile in the Oxidation Ditch

       6

                                    (mg/L)
                      Oxygen Züllig 14 []


       5




       4




       3




       2




       1




           1,0          2,0                  3,0   4,0         5,0   6,0     7,0        8,0
                                                         Time (d)



After this dip the oxygen concentration started to increase again and the conditions for
denitrification reduce. More detailed investigations and adjustments are required to determine
and operate at optimum operational conditions for denitrification. On-line monitoring of oxygen in
the activated sludge, on-site chemical analysis, together with an automatic adjustment of the
overflow weir is essential for process control and to induce denitrification. Careful thoughts are
also required with respect to switching off aerators during night time, if at all at what time and how
long. Intermittent aeration might have to be taken into consideration as well. Note that the
investigations revealed a reduction of the flow occurs after midnight (see Fig. 6 ).

The aeration at the treatment plant is frequently controlled through the power uptake of the
                                                                    nd
aerators. Since the load variations are significant during the day a over the week, this control
process methodology requires improvement.

The oxygen profile (Fig. 18 ) shows significant potential for energy savings of 20% to over 50%.
This can be achieved through on-line monitoring and proper control of the oxygen concentration.




                 Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                             26
  Fig. 18                                 Summarised Daily pattern of Oxygen Concentrations in the Oxidation Ditch

                                    5,0
                                                                                                  14 []
                                                                                   Oxygen Züllig (mg/L)



                                    4,0
            Oxygen Zü ll ig 14 []




                                    3,0




                                    2,0




                                    1,0




                                      0 0:00:        03 :00:     06:00:   09:00:       12:00:      15:00:   18:00:    21:00:   00:00:
                                                                                   Time (hh.mm)
                                                                                      Uhrzeit




8.3    Level in Oxidation Ditch

Fig. 19 show the level in the oxidation ditch over 2 days. The level varies around 4 cm in height.
This is due to the return sludge and the inflow being pumped batch-wise into the oxidation ditch.
At around 10:30 pm the level in the oxidation ditch is increased by around 15 cm due to an
adjustment of the overflow weir. At around 6  :00 a.m. the level is reduced by approximately the
same value.

Fig. 19                               Level in Oxidation Ditch

      120


                                                    [A]
                                           Level 7(cm)


      115




      110




      105




      100




      95
             2,0                                               2,5                        3,0                   3,5                     4,0
                                                                                      Time (d)


A detail of the above figure is shown in the figure below. This Fig. 20 shows that sludge is
returned 4 times in around 5 hours while the inflow takes place around 11 times during the same


                                          Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                                     27
period, thus describing that return sludge (bigger peak) and waste water inflow (smaller peaks) do
not necessarily coincide, one of the different requirements for the proper operation of the contact
tank. The measurement of settleable solids in the contact tank (sludge volume determination in
1000 mL cylinders) and on-line measurements with the solids sensor revealed strong variations in
the sludge content, indicating that no proper mixing of return sludge and influent takes places all
time in the contact tank.

Inflow and return sludge should jointly enter the contact tank to create the favourable conditions
for better sludge characteristics (SVI).

Fig. 20                                    Short Period of Level Changes in Oxidation Ditch

      105


                                                         (cm)
                                                  Level 7 [A]
      104
                                                                               RS                           RS                            RS


                                                        I nfl .                                             Infl.                         Infl.
                                                                                         Infl.
      103
                                         RS                                    In fl.
                                                                                                                      Infl.
                                                                                                   Infl.
                                                                                                                                                  Infl.
                                                                      In fl.
      102                                                                                                                     In fl.
                                         In fl.



      101




      100




       99




       98
                         2,6                                                                       2,7                                                        2,8
                                                                                                 Time (d)



The average residence time of sludge and wastewater in the contact tank is at present around 30
min, which is greater than the design value. However, when looking into detail of flow and mixing,
this contact is could be unsatisfactory.

8.4    Outflow pattern of Sedimentation Tank

The figure below shows the outflow pattern of the sedimentation tank.

Fig. 21                                    Level Variations in the Outflow Canal of the Sedimentation Tank
                                    15

                                                      Level Outflow ST [cm]
            Level Outflow ST [cm]




                                    10




                                     5




                                     0
                                     13:00:                       14:00:                15:00:               16:00:              17:00:              18:00:
                                                                                                  Uhrzeit




                                                  Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                                                 28
Fig. 21 show a similar pattern as the level in the oxidation ditch. The small peaks occur shortly
after influent enters the oxidation ditch. Additionally there is the pattern of return sludge, which
starts every hour and a half. During no inflow to the oxidation ditch there is hardly any outflow
from the sedimentation tank. Here, one observation has to be mentioned. The overflow weir of
the sedimentation tank in operation was not properly attached to the sedimentation tank wall so
that effluent flows below the V-notched effluent weir.
                                                                                  3
The average overflow rate of the weir is less than 1 m /(m.h). At this flow rates no suspended
matters, other than from cleaning the surface of the sedimentation tank, has been observed
leaving with the effluent.

8.5                   Current

Current has been monitored at three incoming lines to the treatment plant. These signals on the
three lines are different and cannot be explained by the power consumption of the aerators and
small equipment of the treatment plant. Fig. 22 shows during the nighttime strong variations in
current. Fig. 23 show this in more detail. This phenomenon was never observed during the day
time.

The power consumption increases sharply in the morning at the point where the second aerator is
started again. The power consumption more than doubles. After some time the increase
stabilises between 100 and 120 A. Taking the oxygen concentration into consideration, there is
still room for significant energy savings.

Fig. 22                    Current


                       160


                       140
      Current 6 [A]




                       120


                       100


                        80


                        60


                          00:00:                06:00:              12:00:             18:00:              00:00:
                                                                   Uhrzeit




                                Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                    29
Fig. 23                        Current Detail


                          120

                          110                                                          Leg 1

                          100
         Current 6 [A]




                               90

                               80

                               70

                               60
                                00:00:            01:00:              02:00:          03:00:        04:00:
                                                                          Uhrzeit
The current drawn on the different legs of the power lines shows different pattern. Leg 3 behaves
totally different, a behaviour which may require explanation.

Fig. 24                        Current Monitoring on Different Legs



                                Current 6 [A]
   150



   125



   100



   75



   50


                                    Leg 1
   25                                                                 Le g 2                                Leg 2
                                                                                       Le g 3

     0
                         1,0                2,0      3,0        4,0             5,0       6,0        7,0           8,0
                                                                         Time (d)




                                    Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                           30
Fig. 25            Current Detail in Relation to Inflow and RS




                   Current 6 [A]                    Inflow Starts
                                                         Inflow stops


      125




      100


                                                                    Return Sludgestarts

                                                                                             Return Sludgestops

            4,60   4,61               4,62   4,63          4,64           4,65        4,66         4,67      4,68         4,69   4 ,70
                                                                        T ime (d)



Details of power consumption which can be explained by aeration and operation of return sludge
pumps is displayed in Fig. 1 . The power uptake of the return sludge pump is around 15 A. Also
with respect to return sludge pumping some energy savings seem to be possible.

Current monitoring provides an excellent tool to continually observe and document some details
of the plant operation.

8.6          Relative MLSS in Oxidation Ditch

On-line monitoring of the MLSS, a relative value which describes the level of biomass, in the
oxidation ditch shows minor variations and a certain daily pattern. This is confirmed by the MLSS
measurements as presented in Fig. 27

Fig. 26            On-Line MLSS in the Oxidation Ditch

              60


              58          SS (Re l)
                              8 []


              56


              54


              52


              50


              48


              46


              44


              42


              40
                               5,0                         6,0                               7,0                    8,0
                                                                           Time (d)




                      Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                                 31
8.7   MLSS and Sludge Activity

The micro-organisms concentration, expressed as mixed liquor suspended Solids (       MLSS) of the
oxidation ditch, is fairly constant over the whole week, with exemption of the last day. The MLSS
of the return sludge varies a bit more, which could be explained by the variations in sludge
concentration of the return sludge as shown in Fig. 27 .

Fig. 27     MLSS in the Oxidation ditch and Return Sludge

            20


            18
                               MLSS Ox. Ditch (g/L)
                               MLSS RS (g/L)
            16


            14


            12


            10


             8


             6


             4


             2


             0

                       3           4           5            6         7           8
                                                      Day


The sludge volume readings were taken three times per day. The volume has been fairly constant
over the whole week and thus is not graphically presented. The values did not show a tendency
other than being fairly constant. An example of the settling behaviour of one sample is shown in
Fig. 28 . The 30-minute value is 860 mL/L. The volume reduces with time. After an hour the
volume stays nearly constant and drops after around 5 hours to 400 mL/L. From this point
onwards the compacting of the sludge starts.

The ratio of the MLSS of sludge from the oxidation ditch and the return sludge is a good
representation of the influent return sludge flow ratio which is around 30 %, a bit lower than the
value found based on the flow measurements. One of the reasons for this is that the return
sludge flow was measured at high water levels in the return sludge sump. Since the capacity of
pumps reduce at lower levels, this is one explanation for the lower values.

                                             50
Since the sludge volume is far more than 2 mL/L, a dilution with effluent is recommended
according to the methodology applied in Germany.

The slduge volume index (SVI) is the volume that is used by 1 g of activated slduge. This
provides a quick impression of settleability. Values of 100 mL/g and less indicate good setlting


                 Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                       32
sludge. The SVI of the undiluted sample was around 220 mL/g, which indicates strong bulking
sludge. Applying the dilution method, the sludge volume index drops to 150 mL/g, still indicating
bulking and very light sludge.

The sludge volume with the dilution method reached 400 mL/L, however not after 30 minutes, but
after 3 hours. This indicates, that the present practice, of routine determination of the sludge
volume over 30 minutes at the treatment facility, requires modifications.

Fig. 28     Activated Sludge Volume in the Oxidation Ditch



            Sludge Volume (mL/L)

           1.000


             900


             800


             700


             600


             500

                                  Wide Cylinder
             400                  Narrow Cylinder

             300
                   0               100                 200             300              400
                                     Time (min since 21.20 24.12)




              Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                  33
Fig. 29     Sludge Volume with Dilution


                                         11 h Sludge Volme RS (mL/L)
                                         18 h Sludge Volme RS (mL/L)

                    900


                    800


                    700


                    600


                    500


                    400
                          12,5    13,0      13,5        14,0     14,5       15,0
                                           Time (hh.mm)
                                             Time (27.12)


A series of return sludge samples has been taking over a short period of time (Fig. 30 ).

Fig. 30     Sequence of Sludge Volumes from Return Sludge

                1.500

                            Sludge Volume (mL/L)
                1.400

                1.300
                                                         mL Sludge/1000 mL
                1.200
                                                                  1000 mL
                1.100                                             500 mL
                                                                  400 mL
                1.000                                             300 mL
                                                                  200 mL
                 900

                 800

                 700

                 600

                 500

                 400

                 300
                        0         50         100         150        200        250
                                               Time (min)




               Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                   34
The values vary between 500 and 660 mL/L after 18 h settling. The settling time has been
extended since no significant settling occurred during the first hour. In some other analysis the
sludge sometimes started to float, indicating denitrification, a phenomenon which has never been
observed at the surface of the sedimentation tank.

8.8                     Return Sludge

The investigating team determined the return sludge flow based on the surface area of the return
sludge sump. Since the area reduction in the deeper part of the sump was not know, the values
vary strongly. The red lines indicate the approximate return sludge flow into the sump and out of
the sump. The latter has to be increased by the continual flowing return sludge to obtain the real
capacity of the return sludge pump.

Fig. 31                      RS Flow into and from the RS Pump Sump (Flow into Contact Tank )


                  60


                  40

                  20


                   0
RS Flow (m3/h)




                  -20           RS Flow (m3/h)

                  -40


                  -60


                  -80

                 -100


                 -120
                        1           2             3             4              5             6             7
                                                                    Time (d)


Return sludge flows over 22 – 26 minutes. The flow into the contact tank is at maximum 26/60 x
                    3
(40 + 100) = 60 m /h. In relation to the waste water flow into the contact tank, the average return
sludge ratio is 60/111 * 100 = 54 %, a value that is in an acceptable and expected range.

Observations of the return sludge quality showed on few occasions that the sludge content in the
return sludge seemed to decrease. This indicated that during this time the return sludge ratio
could have been reduced. Under no circumstances a sludge bed rise was observed in the
sedimentation tank. Both observations demonstrate that the solids residence time in the
sedimentation tank is most probably around the minimum.

A proper adjustment of the return sludge amount is required to avoid to much accumulation in the
sedimentation tank, but also the bring the influent into proper contact with the return sludge in the
contact tank and to maintain a sufficiently high micro-organisms in the oxidation ditch for proper
waste water treatment. When this level reaches the point that plant performance deteriorates,
surplus sludge must be removed from the system.

8.9                     Effluent: E. Coli and Settleable Solids

The Faecal Coliform concentration was 25000 MPN/100 mL which is in a similar range as the
NWC effluent analytical data (see appendix).




                                Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                      35
Settleable solids were determined (Imhoff Cone) of the composite effluent samples. Only on
Saturday that a grab sample taken after cleaning the scum collector area of the sedimentation
tank had some suspended solids. All the other effluent samples were crystal clear and contained
no settleable matter at all.

8.10 Scum

The oxidation ditch contained a scum layer which, appeared at first glance, to be mainly grease,
oil and suspended matter. This scum is removed on a daily basis from the surface of the contact
tank. Since there is no proper baffle at the overflow weir of the oxidation ditch at all times, the
scum is displaced to the sedimentation tank, where little scum is found on the surface. The scum
removal equipment of the sedimentation tank is insufficiently sized to remove the scum from the
surface. Also the scum outlet clogs from time to time.

The scum forms large bubbles which are more typical for certain types of bulking sludge. The
scum may cause optically problems, however it does not result in a reduced effluent quality,
unless the scum of the sedimentation tank is pushed into the effluent launder during cleaning. In
order to retain the sludge in the oxidation ditch a modification at the overflow weir is required.

8.11 Microscopic Examination of Activated Sludge

The activated sludge at the beginning and the end of the investigation week, but also a sample
taken in January 2001, was viewed under the microscope. Basically the sludge showed the same
pattern at all occasions: No dark clusters in flocs, but bacteria grown along the thread forming
bacteria (bulking), very few protozoa were seen. This is also unusual for a well-aerated sludge.
The heavy bulking sludge is at first glance unusual for a low loaded activated sludge process with
a contact tank. The sludge volume index (SVI (mL/g)) is a good indicator for bulking. The next
general figure shows a general view with respect to bulking. With respect to bulking, there are
many publications. During a conference in Japan, Mr. Henk Rensink, lecturer at Wageningen
University in the Netherlands, indicated findings which clearly show a high correlation of bulking
sludge with the feeding pattern (continual and batch wise). In around 75 % of the cases equalised
feeding is one of the causes for the existence of bulking sludge in the aerobic activated sludge
process.

Fig. 32     Schematic Diagram of Bulking Sludge



                   Bulking




                Sludge Loading Rate (kg COD/(kg MLSS.d)




               Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                   36
8.12 Final Effluent Quality

Tab. 3.    shows the NRCA standards, as listed in the Negril Wastewater Operations Protocol of
May 2000, compared to the Ocho Rios treatment plant performance.

Tab. 3.     NRCA Standards and Compliance November 2000


                                Unit      NRCA-Standard          Ocho Rios December 2000

      COD                      mg/L             < 100                          met

      BOD                      mg/L              < 20

      TSS                      mg/L              < 30                          met

      DO                       mg/L               >4                        partly met

      pH                         -               6-9                            ok

      Conductivity            mS/cm              < 0.4                       not met

      Total - Nitrate          mg/L              < 10                        not met

      Total - Phosphate        mg/L               <4                         not met

      Faecal Coliformes        MPN              < 1100                       not met

      Ammonia-N              mg N/L              none                      acceptable



8.13 Summary of Major Findings

The following summarise the major observations during the monitoring of the Ocho Rios sewage
treatment ponds:

§   The Flow meter provides reliable data about flow into the treatment plant, however the signal
    cannot be read and the control panel.
                                                           3
§   Flow into the treatment plant was around 2600 m /d.

§   The return sludge ratio was around 50 %

§   The oxidation ditch was predominantly aerobic

§   Nitrate content in the effluent was relatively high, indicating options to improve denitrification
    and energy savings.

§   Significant odours occurred sometimes at the inlet.




               Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                   37
§   Scum removal and aerosol could be one of the explanations for the fact that hardly surplus
    sludge is being produced.

§   Aerosol formation at the brush aerators is significant.

§   Average HRT of the wastewater in oxidation ditch is 2,0 d and in the sedimentation tank is
    0,7 d.
                                                                                 3
§   COD loading rates are low. They vary between 0,05 and 0,24 kg/(m .d) at MLSS of around 4
    g/L.

§   Surplus sludge production is less than expected. The sludge thickens and dewaters well.
    However, there is a need to slope the sludge drying beds different so that the sludge layer is
    equal all over the bed. A definition for dried sludge has to be established, supported by
    empirical measurements at the site.

§   Plant effluent does not meet all NRCA standards and would be considered a significant
    aspect for the EMS.




               Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                   38
9   EXISTING DATA

Existing data was received from NWC and reviewed by the consulting team. The details the
consultants review have been placed in the appendices for reference.




             Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                 39
10 ENVIRONMENTAL ASPECTS

This is intended as initial environmental review to identify environmental aspects, which should
form the basis for the development of an environmental management programme.

Tab. 4.       Summary of Environmental Aspects

                                                                                                                Ocho Rios Level
      Activity / Service                Aspects                    Impacts          Quantification of Aspects
                                                                                                                 of Significance


                             Inflow   Odour release     Air pollution               H2S                                -
                                                        Corrosion                   Observation                        o
                           Lighting   Use of energy     Resource depletion          Power consumption                  o
        Desludging Drying Beds         Solid waste      Landfill                    Volume, Solid content             --
                                                        Agricultural Applications   Volume, Solid content             +
                  Scum removal         Solid waste      Landfill                    Volume, Solid content              -
                      Treatment       Denitrification   Resource depletion          Nitrate Concentration             --
                                        Aeration        Resource depletion          Power consumption                 --
                                         Aerosol        Air pollution               Bacterial Counts                   -
                      Operation          Outflow        Water pollution             Organics (COD)                     o
                                         Outflow        Water pollution             Organics (BOD)                     o
                                         Outflow        Water pollution             Organics (SS)                      o
                                         Outflow        Water pollution             N                                  -
                                         Outflow        Water pollution             P                                 --
                                         Outflow        Water pollution             Pathogens (Faecal Coli)            -


§   - or +       = significant negative or positive
§   = very significant
§   = slight or moderate




                   Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                         40
11 CONCLUSIONS

The investigations of the treatment system indicate that there is no great variability in the overall
treatment performance. However there are significant improvements possible with respect to
energy saving and denitrification.

Without additional equipment and experience in on-site monitoring and process control, it will be
difficult to achieve the energy savings without endangering a deterioration of the effluent quality.
Given the presence simple process control modifications, a proper response is possible and
economically viable.

Surplus sludge production and drying requires attention. Equipment for determining the solids
content of the different sludge should be available on-site so that not only the bulking can be
documented, but also the sludge thickening and drying process is supported with empirical data
on a daily basis.

The introduction of environmental management systems supported by more effective data
collection and an interactive training approach (on the job) can result in improvements in plant
performance and a reduction in operational costs. Indeed these changes should be incorporated
in the management plan.

It is our recommendation therefore that for Ocho Rios the implementation of the EMS should
involve a consideration of this report as well as a full and detailed capacity assessment report.




               Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                   41
                    PICTURES OF OCHO RIOS SEW AGE T REATMENT PLANT


TREATMENT PLANT OVERVIEW




Pict. 1.   Aerial view showing location of the monitoring tent




Pict. 2.   Overview of the Treatment Plant showing Reynolds loading pier in background




             Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                 42
Pict. 3.   Outflow weir of the Oxidation Ponds




Pict. 4.   Secondary Sedimentation tank (not in operation)




             Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                 43
Pict. 5.   Scum layer on the sedimentation tank




Pict. 6.   Automatic screen for inflow




             Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                 44
Pict. 7.   Screen




Pict. 8.   Collection of screenings




             Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                 45
Pict. 9.    Screen




Pict. 10.      Screen



              Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                  46
Pict. 11.    Overflow weir at the Oxidation ditch




Pict. 12.    Sludge Drying Beds




            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                47
Pict. 13.    Sludge Drying Beds




Pict. 14.    Sludge Drying Bed recently filled




            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                48
Pict. 15.    Contact Tank




Pict. 16.    Aerators




            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                49
Pict. 17.    Influent to the Screen




Pict. 18.    Inflow




            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                50
Pict. 19.    Location of Monitoring Tent




Pict. 20.    Return Sludge and Inflow




            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                51
Pict. 21.    Monitoring Screen




Pict. 22.    Sample Measurement




            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                52
Pict. 23.    Monitoring Equipment




Pict. 24.    Return Sludge from Sedimentation Tank to Oxidation Tank




            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                53
Pict. 25.    Return Sludge from Sedimentation Tank to Oxidation Tank




Pict. 26.    Aerators at the outflow




            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                54
Pict. 27.    Details of Aerator at the Outflow




Pict. 28.    Outflow weir with baffle




            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                55
Pict. 29.    Details of Outflow weir with baffle




Pict. 30.    Sedimentation Tank


            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                56
Pict. 31.    Sedimentation Tank




Pict. 32.    Outflow weir of the Sedimentation Tank




            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                57
Pict. 33.    Outflow weir of the Sedimentation Tank




Pict. 34.    Outflow weir of the Sedimentation Tank




            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                58
Pict. 35.    Flowmeter at Influent




Pict. 36.    Driver of bridge on Sedimentation Tank




            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                59
Pict. 37.    Return sludge valves




Pict. 38.    Water in a cable shaft



            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                60
Pict. 39.    Corrosion on screen cover




            Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                61
12                                NW C DATA

12.1 BOD and Nitrate


Fig. 33                                        BOD and Nitrate in the Effluent

                                      30,0                                                                                                                               30,0

                                      27,5                                                                                                                               27,5
                                                               BOD Effl. (mg/L)
                                      25,0                                                                                                                               25,0
                                                               SS Effl. (mg/L)
                                      22,5                                                                                                                               22,5

                                      20,0                                                                                                                               20,0
                   BOD Effl. (mg/L)




                                                                                                                                                                                          SS Effl. (mg/L)
                                      17,5                                                                                                                               17,5

                                      15,0                                                                                                                               15,0

                                      12,5                                                                                                                               12,5

                                      10,0                                                                                                                               10,0

                                       7,5                                                                                                                               7,5

                                       5,0                                                                                                                               5,0

                                       2,5                                                                                                                               2,5

                                       0,0                                                                                                                               0,0
                                             200         250         300         350         400         450         500         550         600         650      700
                                                                                               Days since 1999


12.2 PO4 and SS in Influent



Fig. 34                                              PO4 and SS in the Influent

                   30,0                                                                                                                                          30,0

                   27,5                                                                                                                                          27,5
                                                         BOD Effl. (mg/L)
                   25,0                                                                                                                                          25,0
                                                         SS Effl. (mg/L)
                   22,5                                                                                                                                          22,5

                   20,0                                                                                                                                          20,0
BOD Effl. (mg/L)




                                                                                                                                                                        SS Effl. (mg/L)




                   17,5                                                                                                                                          17,5

                   15,0                                                                                                                                          15,0

                   12,5                                                                                                                                          12,5

                   10,0                                                                                                                                          10,0

                        7,5                                                                                                                                      7,5

                        5,0                                                                                                                                      5,0

                        2,5                                                                                                                                      2,5

                        0,0                                                                                                                                      0,0
                                      200          250         300         350         400         450         500         550         600         650     700
                                                                                         Days since 1999




                                                    Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                                                         62
       Fig. 35                        BOD in Influent and Effluent


                   300                                                                                                 50

                                                                                                                       45
                                       BOD Infl. (mg/L)
                   250                 BOD Effl. (mg/L)                                                                40

                                                                                                                       35
                   200




                                                                                                                            BOD Effl. (mg/L)
BOD Infl. (mg/L)




                                                                                                                       30

                   150                                                                                                 25

                                                                                                                       20
                   100
                                                                                                                       15

                                                                                                                       10
                    50
                                                                                                                       5

                    0                                                                                                  0
                         200    250       300       350    400        450        500      550   600     650      700
                                                                 Days since 1999


       12.3 SS and MLSS

       Fig. 36                        Phosphate in first Pond in Series and Effluent


                    20


                    18


                    16


                    14


                    12

                                                                                                      SS Effl. Composite (mg/L)
                    10
                                                                                                      SSEfffl. Grab (mg/L)

                     8


                     6


                     4


                     2


                     0
                         29,4   29,6     29,8     30,0    30,2      30,4    30,6       30,8
                                                    Time (d)




                                  Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                            63
      Tab. 5.                                        Suspended Solids in first Pond in Series and Effluent

                 5.000



                                                          SS MLSS (mg/L)
                 4.000
SS MLSS (mg/L)




                 3.000



                 2.000



                 1.000



                                    0
                                        200        250       300        350   400     450         500    550     600     650         700
                                                                                Days since 1999




      Tab. 6.                                        MLSS




                                    240                                                                                              240

                                    220                    SS infl. (mg/L)                                                           220

                                    200                    SS Effl. (mg/L)                                                           200

                                    180                                                                                              180

                                    160                                                                                              160
                                                                                                                                           SS Effl. (mg/L)
                  SS infl. (mg/L)




                                    140                                                                                              140

                                    120                                                                                              120

                                    100                                                                                              100

                                        80                                                                                           80

                                        60                                                                                           60

                                        40                                                                                           40

                                        20                                                                                           20

                                        0                                                                                            0
                                             200    250        300      350   400    450      500       550    600     650     700
                                                                                Days since 1999




                                                    Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                                                            64
12.4 Faecal Coli


Fig. 37              Faecal Coliforms

 10 9                                                                                              10 9




 10 8                                                                                              10 8




                                                                                                          Faecal Coli Effl. (MPN/100 mL)
 10 7                                                                                              10 7




 10 6                                                                                              10 6




 10 5                                                                                              10 5




 10 4                                                                                              10 4
        200   250       300      350       400       450    500      550      600      650   700
                                              Days since 1999

                    Faecal Coli Infl. (MPN/100 mL)          Faecal Coli Effl. (MPN/100 mL)
                    Total Coli in MLSS (MPN/100 mL)




                    Initial Environmental Review of NWC Sewage Treatment Facilities in Ocho Rios

                                                           65
Coastal Water Quality Improvement Project

								
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