1. Seminar on Biological Wastewater Treatment Processes Past, Present and Future Dr. Ajit P. Annachhatre Environmental Engineering Program Asian Institute of Technology

2. Keywords + Wastewater + Biological Processes + Treatment Processes + Applications + Ongoing Research Activities

3. 1.Wastewater  Domestic Wastewater c Industrial Wastewater Present State of Wastewater

4. Domestic Wastewater  over 80 % - untreated in Asian mega cities b major components- COD = 250-1000 mg/L Total N = 20-90 mg/L Total P = 4-15 mg/L b effects of discharging into natural receiving bodies b oxygen demand by carbon and nitrogen

5. Industrial Wastewater... Eg: Starch industry wastewater major component- COD = 10,000-20,000 mg/L effects of discharging into natural receiving bodies - 20 m 3 /ton of starch - high COD - high suspended solids - cyanide exposure

6. Industrial Wastewater... Starch industry wastewater ‡ factory with 300 T/d of starch ‡ wastewater generation 6000m 3 /d ‡ COD 14,000 mg/L ‡ population equivalent 1000,000

7. Industrial Wastewater present treatment method: Anaerobic ponds typical loading rates: 800-1000kg COD /ha/d area requirement: 100 ha

8. 2.Biological Processes c aim: any form of life- ‘ survive & multiply ’ c need for energy & organic molecules as building blocks c made of C, H, O, N, S, P and trace elements

9. Biological Processes... c cell: derives energy from oxidation of reduced food sources (carbohydrate, protein & fats)

10. Microorganisms Classification: 4 Heterotrophic- obtain energy from oxidation of organic matter (organic Carbon) 4 Autotrophic- obtain energy from oxidation of inorganic matter (CO 2, NH 4, H + ) 4 Phototrophic- obtain energy from sunlight

11. Biochemical Pathways \ oxidation of organic molecules inside the cell can occur aerobic or anaerobic manner \ generalized pathways for aerobic & anaerobic fermentation

12. Biochemical Pathways Glucose EPM Pathway Pyruvic Acid ADP ATP Energy Lactic Acid TCA Cycle H + Respiration H 2 O CO 2 O 2

13. D aerobic pathways contains- EMP pathways, TCA cycle, respiration D anaerobic pathways contains- EMP pathways D released energy stored as ATP molecules D excess food is stored as Glycogen C 6 H 12 O 6 + 6O 2 +38 ADP + 38 P i 6 CO 2 +38 ATP + 44 H 2 O Biochemical Pathways

14. Biological growth - exponential growth (batch) - Monod kinetics - Haldane kinetics under toxic conditions

15. c exponential growth Biological growth... Log No. of Cells Time Lag phase Log growth phase Stationary phase Death phase

16. c Monod kinetics Biological growth... Substrate Concentration (S) Specific growth rate ( µ) Max. rate µmµm µ m /2 ksks

17. c Haldane kinetics (under toxic conditions) Biological growth... Substrate Concentration (S) Specific growth rate ( µ) i

18. 3.Applications 1. Carbonaceous removal - aerobic - anaerobic 2. Nitrogen removal- nitrification - denitrification 3. Sulfide removal- anaerobic SO 4 reduction - aerobic HS - oxidation

19. Biological Carbonaceous Removal D aerobic - oxidation bacteria CHONS + O 2 + Nutrients CO 2 + NH 3 + C 5 H 7 NO 2 (organic matter) (new bacterial cells) + other end products - endogenous respiration bacteria C 5 H 7 NO 2 + 5O 2 5CO 2 + 2H 2 O + NH 3 + energy (cells)

20. Biological Carbonaceous Removal D anaerobic Schematic of the Anaerobic Process

21. Biological Nitrogen Removal D nitrification -energy Nitrosomonas NH 4 + + 1.5 O 2 NO 2 - + H 2 O + 2 H + + (240-350 kJ) (1) Nitrobacter NO 2 - + 0.5 O 2 NO 3 - + (65-90 kJ)(2) -assimilation Nitrosomonas 15 CO 2 + 13 NH 4 + 10 NO 2 - + 3 C 5 H 7 NO 2 + 23 H + +4 H 2 O(3) Nitrobacter 5 CO 2 + NH 4 + +10 NO 2 - +2 H 2 O 10 NO 3 - + C 5 H 7 NO 2 + H + (4) - overall reaction NH 4 + +1.83 O 2 + 1.98 H CO 3 - 0.021 C 5 H 7 NO 2 + 0.98 NO 3 - + 1.04 1H 2 O + 1.88H 2 CO 3

22. Biological Nitrogen Removal D factors affecting nitrification * temperature * substrate concentration * dissolved oxygen * pH * toxic and inhibitory substances

23. Biological Nitrogen Removal D denitrification * assimilatory denitrification - reduction of nitrate to ammonium by microorganism for protein synthesis * dissimilatory denitrification - reduction of nitrate to gaseous nitrogen by microorganism - nitrate is used instead of oxygen as terminal electron acceptor - considered an anoxic process occurring in the presence of nitrate and the absence of molecular oxygen - the process proceeds through a series of four steps

24. Biological Nitrogen Removal D denitrification * heterotrophic denitrification - denitrifiers require reduced carbon source for energy and cell synthesis - denitrifiers can use variety of organic carbon source - methanol, ethanol and acetic acid

25. Biological Nitrogen Removal D factors affecting denitrification * temperature * dissolved oxygen * pH

26. Biological Sulfate Removal * Sulfate removal cycle anaerobic SO 4 -- HS - S 0 (O 2 deficient) (O 2 excess)

27. 4.Treatment Processes c pond treatment c activated sludge process c biofilm process

28. - no biomass recirculation - high HRT - high land area - O 2 transfer limitations - inadequate mixing - excess loading (anaerobic condition-H 2 S generation) Pond Treatment

29. Activated Sludge Process PSTATSST RASSW F E

30. Activated Sludge Process... - aerobic - suspended-growth - Design equations

31. Activated Sludge Process... typical values of cell residence time (  c ) -  c for C removal ~ 3-10 days -  c for N removal ~ 5-30 days - loading rates ~ 2-3 kg COD/m 3 /d - drawbacks: O 2 requirements, inlet conc.

32. Biofilm Processes advantages of biofilm processes: - higher process productivity (loading rates) - higher biomass holdup - higher mean cell residence time - no need for biomass recirculation - creates suitable environment for each type of bacteria - sustains toxic loads

33. Biofilm Processes... types of biofilms: aerobic, anaerobic, anoxic process of biofilm formation - formation of diffuse electrical double layer due to electrostatic forces and thermal motion - transfer of microorganism to surface - microbial adhesion - biofilm formation

34. Biofilm Processes... biofilm operation X Y BiofilmLiquid Film Bulk Liquid Support Material (a) Physical concept Fully Penetrated Partially Penetrated S SbSb Substrate Concentration X Y (b) Substrate concentration profile

35. Biofilm Processes... biofilm operation - diffusion resistance - inadequate supply of nutrients to inner portions of Biofilm - limitations on product out diffusion - attrition of reaction conditions

36. Biofilm Processes... biofilm operation as biofilm thickness increases effectiveness factor (  ) decreases

37. Anaerobic biofilm processes

38. Anaerobic biofilm processes... importance of H partial pressure loading rates 10-15 kg COD/m 3 /d against 2-5 kg COD/m 3 /d in suspended growth processes

39. Ongoing Research Activities Biological Processes aerobic anoxic anaerobic nitrificationdenitrification SO 4 2-- reduction HS - oxidation detoxification

40. Ongoing Research Activities aerobic nitrification HS - oxidation inhibition aniline modeling biofilm in ASP degradation processes in SBR Shabbir Jega Sunil & Keshab Savapak Shabbir & Shabbir

41. Ongoing Research Activities anaerobic SO 4 2-- reductiondetoxification& modeling Savapak Amara

42. Ongoing Research Activities anoxic denitrification toxic chemicalsmembrane as C sourcebio reactor Krongtong Tran membrane processes Piyaputr

43. qStudy of nitrification process inside a spherical biofloc particle based on biofilm kinetics. qdetermination of effectiveness factor for substrate consumption and thus the substrate removal rates.

44. qMathematical model consists of a system of second order differential equations based on steady state material balance and appropriate boundary conditions. qModel is solved numerically using a computer program developed in Macsyma 2.3, which uses 4 th order Runge-Kutta method for solving system of ODEs

45. R r dr Assumptions:  Spherical biofloc  Double substrate limited kinetics based on Michaelis - Menten equation  Steady State conditions.  Constant Kinetic and Diffusional parameters, and biomass density inside the floc. Evaluation of concentration profile for the substrates inside a spherical biofloc

46. Substrate : Oxygen and Ammonia-nitrogen  Material Balance Equation: Mass transfer limitations due to diffusional resistances and biochemical reactions taking place inside the biofloc are considered.

47.  Boundary Conditions: Depend on,  Degree of penetration Partial or Full  Limiting Substrate Substrate-1 (Oxygen) Substrate-2 (Ammonia ) Case : Full Penetration at r = 1.00, s 1 = 1.0, s 2 = 1.0 at r = 0, s 1 = s 1,0, s 2 = s 2,0, ds 1 /dr = 0, ds 2 /dr = 0 0 0 1 r s s 2,0 s 1,0 1

49. Ongoing Research Activities

50. Fludized Bed for Sulfide Oxidation Process UASB for Sulfide Removal

51. Ongoing Research Activities

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