Effect of Sole Nitrogen Sources and Temperature on Activated by ixl26840

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									Effect of Sole Nitrogen Sources
      and Temperature on
       Activated Sludge

   R. O. Mines, Jr.           J. H. Sherrard
   Mercer University        University of Nebraska
   Macon, GA                   Omaha, NE
   1999 ASCE CSCE Environmental Engineering Conference
           Introduction
Objectives
Literature Review
Modified Arrhenius Equation
Methodology
Results and Discussion
Summary and Conclusions
              Objectives
Evaluate the effects of temperature on
biokinetic coefficients used to design
aerobic biological systems treating
wastewaters with different nitrogen sources.
Examine the impact of temperature on
substrate removal, sludge production, and
oxygen requirements.
        Literature Review
Novak (1974) recommended that both k and
Ks be corrected for temperature variations in
aerobic treatment systems
Characklis and Gujer (1979) stated that
biomass yield is constant over a wide range
of temperature.
Characklis and Gujer (1979) indicated that
maximum growth rate (:max), k, Ks, and kd
were temperature dependent.
        Literature Review
Knowles et al. (1965) indicated that both k
and Ks for Nitrosomonas and Nitrobacter
increased as temperature increased.
Benefield et al. (1975) found that kd varied
between 15 and 25 ° C and suggested a θ
ranging between 1.02 and 1.06 for
correcting kd.
Benefield and Randall (1980) presented
data showing yield (Y) to be independent of
temperature in the range of 15 to 25 ° C.
        Arrhenius Equation

                          (T °C −20°C )
K (T °C) =K (20°C) (θ )

 K = Kinetic rate coefficien t
     Materials and Methods
Literature Search for Biokinetic
Coefficients

Example Problem to illustrate the effects of
temperature on substrate removal, biosolids
production, and oxygen requirements
    Temperature Corrections

Microbial yields for heterotrophs and
autotrophs were not corrected for
temperature changes.
A theta value (θ) of 1.04 was used to correct
the kd value for heterotrophs and autotrophs.
A theta value (θ) of 1.08 was used to correct
the k value for heterotrophs and autotrophs.
    Temperature Corrections

The heterotrohpic Ks value was not
corrected for temperature.

The autotrophic Ks value was corrected for
temperature variations with a theta value (θ)
value of 1.14 .
Biokinetic Coefficients with Ammonia as Nitrogen Source



  Temperature           5° C                     10° C
   Coefficient Heterotrophs Autotrophs   Heterotrophs    Autotrophs
   Y (mg/mg)        0.4         0.2           0.4            0.2
   K (days-1)      1.89        0.63          2.78           0.93
   Ks (mg/L)       120         0.28          120            0.54


  Kd (days-1)     0.039       0.028         0.047          0.034
  Temperature          20° C                    30° C
   Coefficient Heterotrophs Autotrophs   Heterotrophs    Autotrophs
   Y (mg/mg)       0.4         0.2           0.4             0.2
   K (days-1)       6           2           12.95           4.32
   Ks (mg/L)       120          2            120            7.41
  Kd (days-1)     0.07         0.05         0.104          0.074
Biokinetic Coefficients with Nitrate as Nitrogen Source


  Temperature      5° C        10° C        20° C        30° C
   Coefficient Heterotrophs Heterotrophs Heterotrophs Heterotrophs
   Y (mg/mg)       0.27         0.27         0.27         0.27
   K (days-1)      1.89         2.78          6          12.95

   Ks (mg/L)       120          120          120          120
   Kd (days-1)    0.028        0.034        0.05         0.074
        Example Problem

Completely-mixed activated sludge process
COD : N Ratio = 13.7 : 1
Initial Operating Temperature = 20 ° C
Influent Flowrate = 37, 850 m3/day (10
mgd)
Hydraulic Detention Time = 0.25 days
Temperatures varied at 5, 10, 20, and 30 ° C
    Results and Discussion

Effluent COD Concentration

Biosolids Production

Oxygen Requirements
Effluent COD vs MCRT with Ammonia as Nitrogen Source
                                        140.00


                                                                                         NH 4 + - N
                                        120.00        5° C
                                                                                         COD : TN = 13.7 : 1
     EFFLUENT COD CONCENTRATION, mg/L




                                        100.00



                                         80.00

                                                      10° C
                                         60.00



                                         40.00

                                                     20° C
                                         20.00
                                                      30° C


                                          0.00
                                                 0            5   10                15                 20      25
                                                                       MCRT, days
Effluent COD vs MCRT with Nitrate as Nitrogen Source
                                     250.00




                                                   5° C
  EFFLUENT COD CONCENTRATION, mg/L




                                     200.00
                                                                                 NO 3 - - N
                                                                                 COD : N = 13.7 : 1


                                     150.00

                                                  10° C


                                     100.00




                                      50.00       20° C


                                                  30° C

                                       0.00
                                              0           5   10                15               20   25
                                                                   MCRT, days
Biosolids Production vs MCRT with NH3 as Nitrogen Source
                                   2500




                                   2000
    BIOSOLIDS PRODUCTION, kg/day




                                                                                        5°C
                                   1500
                                                                                        10° C

                                                                                        20° C

                                   1000
                                                                                        30° C



                                   500                                   NH 4 + - N
                                                                         COD : N = 13.7 : 1



                                     0
                                          0   5   10                15             20           25
                                                       MCRT, days
Biosolids Production vs MCRT with Nitrate as Nitrogen Source
                                   1600


                                   1400
    BIOSOLIDS PRODUCTION, kg/day




                                   1200
                                                                                         5°C
                                                                                         10° C
                                   1000
                                                                                         20° C

                                   800                                                   30° C


                                   600


                                   400                                   NO 3 - -N
                                                                         COD : N = 13.7 : 1
                                   200


                                     0
                                          0   5   10                15              20           25
                                                       MCRT, days
Oxygen Required vs MCRT with NH3 as Nitrogen Source
                                8000
                                                                                          30° C
                                7000
                                                                                          20° C
                                                                                          10° C
                                6000
  OXYGEN REQUIREMENTS, kg/day




                                                                                          5° C


                                5000


                                4000


                                3000


                                2000                                  NH 4 + - N
                                                                      COD : N = 13.7 : 1

                                1000


                                  0
                                       0   5   10                15                  20           25

                                                    MCRT, days
Oxygen Required vs MCRT with Nitrate as Nitrogen Source
                                  6000

                                                                                   30° C

                                                                                   20° C
                                  5000

                                                                                   10° C
    OXYGEN REQUIREMENTS, kg/day




                                                                                   5° C
                                  4000



                                  3000



                                  2000
                                                                        NO 3 - -N
                                                                        COD : N = 13.7 :1

                                  1000



                                    0
                                         0   5   10                15         20            25
                                                      MCRT, days
         Conclusions
Lower effluent soluble CODs can be
achieved as wastewater temperature
increases and MCRT increases.

At similar MCRTs, the effluent COD
concentration will be lower when ammonia
rather than nitrate serves as the nitrogen
source.
     •Conclusions Continued

At similar MCRTs, less waste biosolids are
produced as the wastewater temperature
increases.

At similar MCRTs, biosolids production is
significantly larger when ammonia rather
than nitrate serves as the nitrogen source.
    •Conclusions Continued

Oxygen requirements are significantly
higher when ammonia rather than nitrate
serves as the nitrogen source since
nitrification will occur.

								
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