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BNR PhD Thesis Summary Zeng, Oehmen, Vadivelu’s

BNR PhD Thesis Summary Zeng, Oehmen, Vadivelu’s. 2006. 10 Changwon Kim University of Queensland Pusan National University. Raymond Jianxiong Zeng, “The role of intracellular storage products in biological nutrients removal” (2002).

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BNR PhD Thesis Summary Zeng, Oehmen, Vadivelu’s

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  1. BNR PhD Thesis SummaryZeng, Oehmen, Vadivelu’s 2006. 10 Changwon Kim University of Queensland Pusan National University

  2. Raymond Jianxiong Zeng, “The role of intracellular storage products in biological nutrients removal” (2002). Adrian Oehmen, “ The competition between PAO and GAO in the EBPR process” (2004). Vel Murugan Vadivelu, “Kinetic and stoichiometric characterisation of enriched Nitrosomonas and Nitrobacter cultures by decoupling the growth and energy generation processes” (2006).

  3. SND & storage carbon • SND (Simultaneous nitrification & Denitrification) NH4+  NO2-  N2 O2 COD NO3- • Conventional N&D rate = 0.024~0.125 gN/gVSS-d • SND due to oxygen limitation inside of floc when floc dia.>150 μm, DO<0.5 mg/l, COD/N>4 organic C • SND at even at low COD/N. The C from where? • Maybe from storage in the cell.

  4. Zeng’s, COD storage by PAO & GAO • Anaerobic, PAO & GAO store PHA (PHB) from VFA (acetate> propionate) using energy from poly P. • Aerobic, PAO use stored PHA for growth & P uptake. • Aerobic, GAO use stored PHA but don’t uptake P. • PAO prefer pH>7.5, GAO prefer pH<7.2.

  5. Anoxic, DPAO (proved same to PAO, Accumulibacter) does same using NO3--N resulting lower rate, 32% less Puptake/PHAconsumed, 40% less energy production, 20% less cell yields. Inhibited @ >8 mgNO2--N/l, opt. temp. 20~30 oC. This is the C source for SND. • Anoxic, DGAO does same, but to produce N2O.

  6. Conclusions • PAO & DPAO are same, Accumulibacter phosphatis. • Complete GAO metabolic model was developed. • DGAO was enriched and produce N2O during denitrification. • PAO & GAO metabolic model based analysis was developed. • SNDP was possible with denitrification by DGAO.

  7. Recommendations for future study • DGAO & GAO same? • Metabolic model for other substrates? • DGAO anoxic model? • DPAO produce N2O? • PAO & GAO competition? • Nitrite conc. vs N2O production? • Nitrite accumulation inside the floc?

  8. Oehmen’s Competition between PAO & GAO • PAO (Comeau 1986, Wentzel 1986, Smolders 1994, Mino 1987, 1998, Maurer 1997) and GAO metabolic models (Mino 1995, Filipe 2001, Zeng 2003) were developed. • FISH probes were designed for PAO, Accumulibacter and GAO, Competibacter. • No. of GAO at full-scale EBPR plant correlated with anaerobic acetate uptake rate. Fewer GAO showed higher P release to acetate uptake, lower glycogen utilization, and lower PHV accumulation.

  9. GAO is incapable or slower than PAO to respond to change in acetate and propionate, where propionate could be more advantageous through the inhibition of Competibacter GAO. • In the long term propionate is a more effective carbon source for P removal than acetate, and provides PAO with competitive advantage over GAO. GAO reveals so far more specific preference for carbon source. • Propionate uptake by PAO was modeled considering selective condensation of propionyl-CoA into PHA and found out similar to acetate. This indicates PAO has equal preference.

  10. Propionate fed GAO is identified as Alphaproteobacteria and metabolic characterization and a metabolic model are done. • At higher pH (~8) PAO outgrowth over GAO and better with propionate fed than acetate fed system. • Among PHA, PHB and PHV are commonly analyzed by GC. PH2MV is key fraction of PHA in propionate fed GAO and PAO. Analytical method of PH2MV in addition to PHB and PHV was developed.

  11. Recommendations for future study • Effect of carbon source and pH on full-scale plants? How to implement? • Identify of Alphaproteobacteria GAO and FISH probes? • Other process factors on competition of PAO & GAO? Temp., DO, Chemical precipitants, sulfide, inhibitory compounds, starvation conditions or SRT? • Why high pH is favor for PAO over GAO? • Why propionate is favor for PAO over GAO? • Why Competibacter can’t metabolize propionate? • Why do GAO has more specific carbon preference than PAO?

  12. Vadivelu’s Kinetic & Stoichiometry of Nitosomonas & Nitrobacter • Maintenance energy requirements of Nitrobacter ; At maximum growth rate, for maintenance 0.042 mgN/mg CODbiomass-d used, 20% of total consumption At absence of growth the maintenance energy consumption rate is three times higher than that at max. growth rate. • Maintenance energy requirement of Nitrosomonas ; At max. growth rate, for maintenance 0.162 used, 68% of total consumption. At absence of growth, maintenance energy rate was not changed. • Above difference of two organism might be due to different biological activity or different enrichment conditions.

  13. In-situ lysis rates of Nirobactrer and Nitrosomonas; 0.069 /d (at 20 oC) and 0.26/d (at 30 oC), respectively, measured by starvation method under normal grow condition. Considerably lower than aerobic decay rates reported. • Max. specific growth rates and affinity constants of Nirobactrer and Nitrosomonas; 0.48/d and 1.03/d, respectively, using energy decoupling method. Affinity constants to nitrite and ammonia were 1.49 mgN/l and 0.36 mgN/l, respectively, not influenced by CO2.

  14. Impact of free nitrous acid (FNA, HNO2) on catabolic and anabolic activities of Natrobacter ; Energy generation is not inhibited up to 0.05 mgN/l Growth is inhibited from 0.01 mgN/l and ceased at 0.02 mgN/l. • Impact of free nitrous acid (FNA, HNO2) on catabolic and anabolic activities of Nitrosomonas ; Both activities were inhibited from 0.08~0,10 mgN/l. Growth is ceased at 0.4 mgN/l but energy generation is 50% inhibition. • Nitrosomonas has higher tolerance than Nitrobacter.

  15. Impact of free ammonia (FA, NH3) on catabolic and anabolic activities of Natrobacter ; Both activities are inhibited as soon as FA is added. At FA of 4~10 mgN/l energy production is inhibited by 12% , but growth is ceased completely at 6 mgN/l. • Impact of free ammonia (FA, NH3) on catabolic and anabolic activities of Nitrosomonas ; Both activity are not inhibited up to 16.0 mgN/l but are limited by ammonia concentration below 4 mgN/l.

  16. Recommendations for future work • Characterization of mixed culture of AOB an NOB will be useful. • Impact of FA and FNA may be inferred by manipulating CO2 supply and therfor growth rate rather than only absence and presence of CO2. • Effect of temp., pH and DO on maintenance consumption rate is need to study. • Mechanisms of FNA and FA inhibitions on catabolism and anabolism should ne studied further.

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