Biological Phosphorus Removal Sudan Raj Panthi Advanced Remediation

Biological Phosphorus Removal Sudan Raj Panthi Advanced Remediation and Treatment (ART), Lab

Outline of the presentation 1. 2. Introduction Phosphorus removal technologies Chemical Ø Biological Ø Combined Ø 3. 4. 5. Key issues in biological-P removal Review of research papers Conclusion 2

1. Introduction Nutrient-Pollution Nitrogen & phosphorus n Phosphorus - limiting nutrient n Eutrophication § § Oxygen depletion Low light penetration Loss of aquatic life Aesthetic problem Eutrophication 3

Introduction (Contd. . ) n Major sources of P- pollution Agriculture n Waste water (domestic , industrial) n Others n n Domestic waste water Raw water – 8 to 10 mg-P/L n Treatment (primary + secondary) – 20 % remove n Discharge limit – 1 mg-p/L or less n 4

2. Phosphorus Removal Technologies n Chemical process Ø Chemical precipitation (coagulation) using metal salts such as Al 2 (SO 4)3 , Fe. Cl 3 and Ca(OH)2 etc. Ø Produce excess sludge, more expensive, more p. H dependent and may need further treatment to adjust p. H or to remove Cl. 5

Biological process For growth and maintenance of cell living organisms use matter and energy (life) n Matter Ø Ø n C, O, N, P, S, K, Ca, Mg, etc (macronutrients) Fe, Mn, Zn, Co, Ni, Cu, (micronutrients) Energy § § Solar (phototrophs- plants, algae) Chemical reaction (chemiotrophs = animals, many bacteria) 6

Cell respiration process for energy Three steps of respiration (C 6 H 12 O 6=H 2 O+CO 2+energy) n Glycolysis 6 C=2*3 C (Pyruvate)+ ATP (energy) n Krebs Cycle (Pyruvate + Co. A=Acetyl-Co. A) = ATP (energy) + H n Electron Transport System H+NAD(Electron carrier Co. Enzyme)= ATP(energy) Adenosine triphosphate (ATP)↔ADP + Pi + energy C 6 H 12 O 6 + 6 O 2 6 CO 2 + 6 H 2 O + 36 ATP 7

Typical phosphorus removal plants Anaerobic basin Fermentation of acetate (VFAs) - Phosphate release Influent Aerobic basin - BOD oxidation - Phosphate uptake To waste Effluent Clarifier 8

Phosphorus removing mechanism PO 43 Facultative bacteria Acetate plus Substrate fermentation Products like VFAs Anaerobic Aerobic Energy BOD+O 2 Energy PHB Poly-P + PO 43 Poly-beta-Hydroxybutyrate (PHB) Polyhydroxyalkanoates (PHA) CO 2+H 2 O New biomass 9

Phosphorus removal (contd…) Return sludge Influent Anaerobic Aerobic To clarifier Biomass Conc. Phosphate (Pi) 1 -2 mg-P/L (Effluent) Sol. BOD Time 10

3. Key issues in BPR n Representative species of microorganism n Metabolism of microorganisms n Nitrogen removal combination and performance of system 11

Representative species of microorganism n Before • Only genus of acinetobactor n Now • Pseudomonas, arthrobactor, nocardia, beyerinkia, ozotobacter, aeromonas, Microlunatus and denitrifying phosphorus bacteria (DPB) too 12

Metabolism of microorganisms PHB Poly P Simple aerobic cell-respiration process Energy ? ? ATP=ADP + Pi + energy VHF Pi Anaerobic condition Aerobic condition 13

Metabolism of microorganisms n “Biological Mechanism of Acetate uptake mediated by carbohydrate consumption in excess Phosphorus removal systems” in “Water Research” (1988) 22(5): 565 -570; (V. Arun, T. Mino, and T. Matsuo) n “Biological Phosphate removal process” in “Applied microbiology and biotechnology” (1997) 48: 289 -296; (M. C. M. van Loosdrecht, C. M. Hooijamans, D. Brdjanovic and J. J. heijnen) n “Microbiology and biochemistry of the enhanced biological phosphate removal process” in “Water Research (1997)32(11) 31933207; (T Mino, M. C. M. van Loosdrecht, and J. J. Heijnen) 14

Results 15

Mino model The conversion of the acetate to PHB requires reducing power, because PHB is more reduced compound than acetate, and this is gain by anaerobic degradation of glycogen 16

Nitrogen removal combination and performance of system n Biological phosphorus removal processes are often combined with nitrogen removal systems (Nitri. / denitri. ) n This lead to introduction of nitrate in the anaerobic phase. n Is Nitrate affects P-removal ? ? ? 17

“Effect of Nitrate on Phosphorus Release in Biological Phosphorus Removal Systems” in “Water Science and Technology (1994)30(6) 263 -269; (T. Kuba, A. Wachtmeister, M. C. M. van Loosdrecht, and J. J. Heijnen) n Experimental set-up Ø A 3. 5 -L bench anaerobicanoxic reactor. Ø Denitrifying Phosphorus bacteria (DPB) sludge Ø Nitrate was added to the anoxic reactor 18

Results PHB Pi Glycogen VFA 19

Results (Contd. . ) 20

Conclusion Denitrifying Phosphorus Bacteria (DPB) have mechanism according to Mino model Nitrate doesn’t block phosphorus release in the DPB, but HAc uptake increase and the P/C ration decreases. A reduction of phosphorus release by nitrate is due to HAc utilization for denitrification. To Improve Performance BOD/TP should be>25 If BOD: TP >> 40 phosphorus limiting condition → the aerobic zone size should be enlarged. If BOD: TP <<20 Carbon limiting condition →the P removal will be limited and the desired effluent P concentration may not be achieved 21