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Sewage Treatment Plants - NCH Drains and BioAmp Intranet

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					Sewage Treatment Plants (STP) & Water
       Treatment Plants (WTP)
Agenda:


 • Flow of waste

 • What is Sewage treatment?

 • What is a Sewage Treatment Plant?

 • Why do we do treatment?

 • Types of waste treatment
Flow of Waste
              Waste sources : Dietary , Sanitary, Production
     Grease traps, drain lines, sump pits, septic tanks, lift stations




 Drainage Systems                                  Solids separation
 assist the flow of                                happens at above
 waste water to a                                  Systems so waste
 Sewage Treatment                                  water flows
 Plant for waste                                   unimpeded down the
 breakdown                                         line.
Sewage Treatment

                                  Sewage treatment or
                                  Wastewater treatment, is the
                                  process of removing contaminants
                                  from wastewater.




It includes physical, chemical and biological processes to remove physical,
     chemical and biological contaminants.
What is a Sewage Treatment Plant?


 • A facility that receives wastewater (and sometimes runoff) from
   domestic and/or industrial sources, and by a combination of physical,
   chemical, and biological processes reduces (treats) the wastewater to
   less harmful byproducts.

 Waste Water Treatment Plant (WWTP)
 Sewage Treatment Plant (STP)
 Waste Treatment Plant (WTP)
Why do we provide treatment?

• Sewage treatment is a multi-stage process to rehabilitate wastewater
  before it reenters nature: Returned to a natural body of water, is
  applied to the land or is reused.

• The treatment goal is to reduce or remove organic matter, solids,
  nutrients, disease-causing organisms, and other pollutants from
  wastewater to prevent degrading the receiving body of water or land.

• Each receiving body of water has limits to the amount of pollutants it
  can receive without degradation. Therefore, each sewage treatment
  plant must comply with the allowable levels of BOD5, suspended solids,
  coliform bacteria, and other pollutants to ensure this.
Types of Waste Treatment
• Mechanical
   – Influx (Influent)
   – Removal of large objects
   – Removal of sand
   – Pre-precipitation
• Biological
   – Oxidation bed (oxidizing bed) or Aerated systems
   – Post precipitation
   – Effluent
• Chemical
   – This step is usually combined with settling and other processes
      to remove solids, such as filtration. The combination is referred
      to in the US as physical-chemical treatment. It is rarely used
      along with biological treatment.
Types of Biological Systems
• Conventional Activated Sludge Process
  With this treatment process, a mixture of wastewater and activated
  sludge is agitated and aerated. The activated sludge is subsequently
  separated from the treated wastewater (mixed liquor) by settling, and
  then wasted or returned to the process as needed
Flow of typical Biological Treatment

                    Solids       Equalization   Neutralization
     INFUENT       separator        Tank            Tank




                   Clarifying      Settling       Aeration
                     Tank           Tank           Tank




                  Chlorination
                                 EFFLUENT
Types of Biological Systems

 Anaerobic Digestion

 • Bacterial process that is carried out in the absence of oxygen

 • It is generally applied to high BOD strength wastewater and organic
   sludge

 • Advantage: low energy consumption

 • Disadvantage: slow reaction rates & not applicable to Biohygenics
   treatment
Types of Biological Systems

 Sequential Batch Reactors (SBRs)
 • The process is termed a “fill-and-draw” treatment method because all
   steps from aeration to final clarification occur sequentially within the
   same tank.
               1.                    2.




          3.                          4.                        5.
Sequential Batch Reactors (SBRs)
Types of Biological Systems

 Trickling Filters

     • Attached growth or fixed film biological treatment

     • Microorganisms grows a slime on the media that consumes
       organic matter

     • Oxygen passes through the thin layer of flowing wastewater
Types of Biological Systems

Trickling Filters
Types of Biological Systems

Rotating Biological Contactors

   • Also uses attached growth or fixed film biological treatment

   • Media is disc-like in shape and rotates around a shaft

   • Alternately exposing the media to the wastewater and air
Types of Biological Systems

Rotating Biological Contactors
Types of Biological Systems

Conventional Activated Sludge Process

• With this treatment process, a mixture of wastewater and activated
  sludge is agitated and aerated.

• The activated sludge is subsequently separated from the treated
  wastewater (mixed liquor) by settling, and then wasted or returned to
  the process as needed
Flow of typical Biological Treatment

                    Solids       Equalization   Neutralization
     INFUENT       separator        Tank            Tank




                   Clarifying      Settling       Aeration
                     Tank           Tank           Tank




                  Chlorination
                                 EFFLUENT
Stages of treatment: Primary treatment
  PRIMARY TREATMENT is to reduce oils, grease, fats, sand, grit, and
    coarse (settlable) solids. This stage is also defined as SOLID
    SEPARATION. This step is done entirely with machinery, hence the
    name mechanical treatment.


Influx (influent) and removal of large objects
• In the mechanical treatment, the influx (influent) of sewage water is
   strained to remove all large objects that are deposited in the sewer
   system, such as rags, sticks, cans, fruit, etc.

• This is most commonly done using a manual or
  automated mechanically raked screen. This
  type of waste is removed because it can
  damage the sensitive equipment in the sewage
  treatment plant.
Stages of treatment: Other types
Sand / grit removal
Sedimentation
• The tanks are large enough that fecal solids can settle and floating
  material such as grease and inorganics like plastic can rise to the
  surface and be skimmed off.
The main purpose of the primary stage is to produce
• A generally homogeneous liquid capable of being treated biologically
• A sludge that can be separately treated or processed.

• Primary settlement tanks are usually
  equipped with mechanically driven
  scrapers that continually drive the collected
  sludge towards a hopper in the base of the
  tank from where it can be pumped to
  further sludge treatment stages.
Stages of treatment: Primary treatment stage
Equalization / pH correction

• Stage where pH is corrected to acceptable levels
  Acceptable level is 7.

• Correction is important. High / Low pH will kill activated sludge

• Correction is done by operator via introduction of acids or caustics.
Aeration / Activated BIOMASS Secondary
Treatment Stage


• Aeration ponds is where aerobic digestion occurs is a bacterial
  process occurring in the presence of oxygen

• Under aerobic conditions, bacteria rapidly consume organic matter
  and convert it into carbon dioxide

• Solids reduction occurs in this phase. Aerobic digestion occurs much
  faster than anaerobic digestion, hence this is the most common form
  of biological process
Activated Sludge

• Naturally occurring bacteria cultured to consume waste = lower BOD
• Need constant aeration
• Sludge live-cycle affects its effectivity

SLUDGE AGE
   • Young : inconsistent consumption
   • Mature: most efficient, peak of consumption
   • Dying : Low consumption, leads to septicity
Activated Sludge

                   SLUDGE AGE
                    – Young : milky brown,
                      frothy bubbles



                   – Mature: chocolate
                     brown, minimal
                     bubbles



                   – Dying : gray to black,
                     filthy , wide bubbles
Effluent Polishing: Tertiary Treatment Stage

• Final stage to raise the effluent quality before it is discharged to the
  environment.

• Filtration removes much of the residual suspended matter.

• Disinfection reduces substantially the number of microorganisms in
  the effluent.

• Sludge disposal – although not part of the treatment stage, the
  sludge accumulated in the process must be treated and disposed in
  a safe effective manner.
Effluent Polishing: Tertiary Treatment Stage




                 Sludge treatment
Activated Sludge System



    Air Blower

Raw Wastewater                                                                      Treated Effluent



                  Aeration Tank
                                                                    Settling Tank



                 Return Activated Sludge              Sludge Pump



                                       Waste Activated sludge
Waste Treatment Plant Application


                     Solids        Equalization     Neutralization
    INFUENT         separator         Tank              Tank




                    Clarifying       Settling         Aeration
                      Tank            Tank             Tank




                  Chlorinization
                                    EFFLUENT




        If pH is corrected and you have enough retention time
Quiz Questions

1. Identify the different types of biological aerated systems: 4 answers




2. What’s the purpose of disinfecting the effluent?
Quiz Questions

3. Which of the following process is not part of a treatment stage but still
   plays an important role in STP treatment?

    a. Filtration        c. Sludge dewatering
    b. Ozonation         d. Bioaugmentation
Quiz Questions
4. In this diagram, identify the treatment stages of the STP. You may
    redraw the diagram.



    Air Blower

Raw Wastewater                                                                      Treated Effluent



                  Aeration Tank
                                                                    Settling Tank



                 Return Activated Sludge              Sludge Pump



                                       Waste Activated sludge
Quiz Questions

5. Is it possible to construct an STP using the following processes?
    Why or why not?

    -   Screen filter
    -   Primary clarifier
    -   Anaerobic digester
    -   Neutralization tank
    -   Aerobic sludge digester
    -   Trickling filter
    -   Clarifier
    -   Activated carbon filtration
    -   Ultraviolet radiation

				
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posted:12/24/2012
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