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

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

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

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

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

6 For growth and maintenance of cell living organisms use matter and energy (life) Matter  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) Biological process

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

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

9 Phosphorus removing mechanism Facultative bacteria Energy Acetate plus fermentation Products like VFAs Substrate Anaerobic Aerobic PHB Energy New biomass + Poly-P CO 2 +H 2 O PO 4 3- BOD+O 2 PO 4 3- Poly-beta-Hydroxybutyrate (PHB) Polyhydroxyalkanoates (PHA)

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

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

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

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

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

15 Results

16 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

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

18 “Effect of Nitrate on Phosphorus Release in Biological Phosphorus Removal Systems” in “Water Science and Technology (1994)30(6) ; (T. Kuba, A. Wachtmeister, M.C.M. van Loosdrecht, and J.J. Heijnen) Experimental set-up  A 3.5-L bench anaerobic- anoxic reactor.  Denitrifying Phosphorus bacteria (DPB) sludge  Nitrate was added to the anoxic reactor

19 Results PHB VFA Pi Glycogen

20 Results (Contd..)

21 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