Bacterial Decomposition any hydrolysis Nitrification Organic Nitrogen (proteins; urea) O Ammonia Nitrogen 2 Nitrate (NO - O 2 ) 2 Nitrate (NO- 3 ) Assimilation Organic Nitrogen (bacterial cells) Lysis and Autooxidation Organic Carbon Nitrogen Gas (N 2 ) Denitrification Organic Nitrogen (net growth) Figure by MIT OCW. Adapted from: G. Tchobanoglous, F. L. Burton, and H. D. Stensel. Wastewater Engineering: Treatment and Reuse. 4th ed. Metcalf & Eddy Inc., New York, NY: McGraw-Hill, 2003, p. 617.
O2 Facultative bacteria Phosphorus removing bacteria Energy PHB P Carbon storage PHB Energy Short-chain fatty acids + Fermentation Products Carbon storage CO2 + H 2 O P Cell wall Substrate Soluble COD New cell production ANAEROBIC AEROBIC Removal mechanisms for excess biological phosphorus (COD = chemical oxygen demand, PHB = poly-β-hydroxybutyrate). Figure by MIT OCW. Adapted from: Rittman, Bruce E., and Perry L. McCarty. Environmental Biotechnology: Principals and Applications. New York, NY: McGraw-Hill, 2001.
15 Ortho Phosphorus 50 Nominal ortho phosphorus concentration, mg/l as P 10 5 1 Soluble BOD Bacteria absorb BOD by releasing phosphorus ATP ADP + PO 4 + energy Bacteria store phosphorus during growth to compete for BOD when they get back to anaerobic zone Influent ortho phosphorus concentration Stored phosphorus in bacteria is removed in waste sludge ADP + PO 4 energy ATP 40 30 20 10 Soluble BOD, mg/l 0 0 5 10 15 20 Anaerobic First Anoxic Aerobic Second Anoxic Reaeration Nominal Hydraulic Retention Time, Hours (Based on Influent Flow only) Typical profile of soluble phosphorus concentrations in a biological nutrient removal process (ATP = adenosine triphosphate, ADP = adenosine diphosphate). Figure by MIT OCW. Adapted from: Rittman, Bruce E., and Perry L. McCarty. Environmental Biotechnology: Principals and Applications. New York, NY: McGraw-Hill, 2001.
Anaerobic Aerobic CONCENTRATION Orthophosphorus Soluble BOD TIME Fate of soluble BOD and phosphorus in nutrient removal reactor. Figure by MIT OCW. Adapted from: G. Tchobanoglous, F. L. Burton, and H. D. Stensel. Wastewater Engineering: Treatment and Reuse. 4th ed. Metcalf & Eddy Inc., New York, NY: McGraw-Hill, 2003, p. 626.
Inorganic Chemicals Used Most Commonly for Coagulation and Precipitation Processes in Wastewater Treatment AVAILABILITY Chemical Formula Molecular Weight Equivalent Weight Form Percent Alum Al 2 (SO 4 ) 3. 18H2 O # 666.5 Liquid 8.5 (Al 2 O 3 ) Lump 17 (Al 2 O 3 ) Al 2 (SO 4 ) 3. 14H2 O # 594.4 114 Liquid 8.5 (Al 2 O 3 ) Lump 17 (Al 2 O 3 ) Aluminum Chloride AlCl 3 133.3 44 Liquid Calcium Hydroxide (lime) Ca(OH) 2 56.1 as CaO 40 Lump Powder 63-73 as CaO 85-99 Slurry 15-20 Ferric Chloride FeCl 3 162.2 91 Liquid 20 (Fe) Lump 20 (Fe) Ferric Sulfate Fe 2 (SO 4 ) 3 400 51.5 Granular 18.5 (Fe) Ferrous Sulfate (copperas) FeSO 4. 7H2 O 278.1 139 Granular 20 (Fe) Sodium Aluminate Na 2 Al 2 O 4 163.9 100 Flake 46 (Al 2 O 3 ) # Number of bound water molecules will typically vary from 14 to 18 Figure by MIT OCW. Adapted from : Metcalf, and Eddy. 2003
North Budapest Wastewater Treatment Plant Comparison of Influent vs. Pre-aeration Raw Water 100 80 COD Influent Conc. = 515 mg/l COD Pre-aeration Conc. = 594 mg/l % COD Removal 60 40 20 Jar Test - Influent Jar Test - Pre-aeration Primary Effluent: Cin = 515 mg/l Primary Effluent: Cin = 594 mg/l 0 0 20 40 60 80 100 Ferric Chloride Sulfate Concentration (mg/l) (no polymer) Topolcany Wastewater Treatment Plant BOD and COD % Removal vs. Ferric Chloride Concentration 70 60 % Removal 50 40 30 20 BOD % Removal COD % Removal 10 0 0 20 40 30 40 50 60 Ferric Chloride Concentration (mg/l) (no polymer) Figure by MIT OCW. Adapted from: Murcott, and Hurleman. 1994, p. 24
Grit chamber Primary Clarifier a. Existing primary treatment plant Low dose Fe/Al Cationic Polymer Grit chamber Anionic Polyme r Primary Clarifier High dose Fe/Al Grit chamber Optional Mixer Possibly Anionic Polymer Primary Clarifier b. CEPT (left) and primary precipitation (right) Fe/Al Grit chamber Mixer Primary Clarifier AST Aeration Secondary Clarifier c. Preprecipitation (or CEPT) followed by ASP Fe/Al Carbon source Grit chamber Mixer Primary Clarifier AST Aeration Denitrification D Secondary Clarifier d. Preprecipitation with ASP and postdenitrification Multi-stage upgrading of an existing primary treatment plant
100 Without Chemical Addition 80 60 40 20 0 Suspended Solid Removal (%) 100 80 60 40 20 0 100 Ferric Chloride Addition Ferric Chloride Plus Polymer Addition 80 60 40 20 0 50 Overflow Rate 100 150 cu m/sq.m/d Overflow Rate Verses TSS Removal for Sarnia Treatment Plant Figure by MIT OCW.