Using an extended activated sludge model to simulate nitrite and nitrate variations in TNCU2 process

Abstract

Keywords: TNCU2 Biological nutrient removal (BNR) Activated sludge model No. 2d (ASM2d) Ammonia oxidizing bacteria (AOB) Nitrite oxidizing bacteria (NOB) a b s t r a c t In this study, an extended activated sludge model was established to describe the transformation of nitrite ðS NO 2 Þ, nitrate (S NO 3 Þ and other components in TNCU2 process (National Central University of Taiwan No. 2) that consisted of anaerobic, oxic, anoxic, oxic zones in sequence. The significant differences between this extended model and other models were that two-stage nitrification, multi-stage denitrification, and phosphorus removal were taken into account simultaneously. The results indicated that the growth rate constants of X AOB and X NOB were 1.4 and 0.4 d À1 , respectively. Y AOB value was 0.14 and Y NOB value was 0.04. According to model simulation, the heterotrophic microorganism (X H ), phosphorus accumulating organism (X PAO ), X AOB and X NOB concentrations were 1160-1322, 182-226, 21-26 and 13-17 mg l À1 , respectively, in TNCU2 process. X H ; X PAO ; X AOB , and X NOB decreased in the anaerobic tanks because of the lysis reaction. Then X H ; X PAO ; X AOB , and X NOB increased in the aerobic tanks due to aerobic growth. X H ; X PAO ; X AOB , and X NOB increased in quantities by about 5%, 6%, 6% and 4% in the first aerobic tank and decreased in quantities by about 12%, 19%, 20% and 19% in the anoxic tank in which the step feeding influent flowed. The ratio of total nitrifying species to total active biomass was about 3% in each tank.

Two types of organophosphate pesticides and their combined effects on heterotrophic growth rates in activated sludge process

“…According to literature and our previous studies,4, 5, 9, 10, 18 oxygen consumed by X H with neither substrate nor oxygen limitation is where S O2 is the concentration of oxygen (mg L −1 ), OUR H ( t ) is the oxygen uptake rate at time t (mg O 2 L −1 h −1 ), Y H is the yield coefficient of heterotrophic biomass (mg COD mg COD −1 ), µ H is the growth rate constant for X H at any pesticide concentration (d −1 ), X H is the concentration of heterotrophic biomass (mg L −1 ) and b H is the lysis rate constant for X H at any pesticide concentration (d −1 ). The growth for X H with neither substrate nor oxygen limitation can be written as follows: Integration of Eqn (2) leads to Equation (3) can be introduced into Eqn (1).…”

“…In order to understand bacterial conversion in ASP, several mathematical models have been proposed, such as the activated sludge model (ASM)4 and the Taiwan extension activated sludge model no. 1 (TWEA1),5 and applied in our previous works 5–10. In the concept of these mathematical models, growth of microorganisms and consumption of substrate are predominated by growth rate.…”

“…Simple procedures to evaluate growth rate constant in sludge based on respirometry are currently available 5, 9, 10, 16–18. The measurement of oxygen uptake rate (OUR) reveals characteristic results for the active biomass due to the stoichiometric relation between biomass growth and dissolved oxygen (DO) consumed as electron acceptor.…”

Modeling the Effect of External Carbon Source Addition under Different Electron Acceptor Conditions in Biological Nutrient Removal Activated Sludge Systems

“…Different approaches have recently been proposed for modeling nitrification and denitrification as two-step processes. ,,, As a consequence, modeling the nitrite behavior becomes essential for the description of other processes, including P uptake . Several studies with PAOs have confirmed that elevated concentrations of nitrite would negatively affect the activities of PAOs under either anoxic or aerobic conditions, although the different threshold values of inhibition were reported. ,,, Extended activated sludge models, including two-stage nitrification, two-stage denitrification and EBPR were developed to successfully predict the behavior of nitrite and nitrate …”

Variation of biomass and kinetic parameters for nitrifying species in the TNCU3 process at different aerobic hydraulic retention times

“…Process rate equations(Pai 2007;Pai et al 2009b) j Process Process rate equationq i, q j C 0 [M 1 L -3 T -1 ] KNO X S KNO X S þSNO X Á XS=XH KXSþXS=XH Á X H Phosphorus accumulating organisms (PAO): X PAO SALK KALKPAOþSALK Á XPHA=XPAO KPHAþXPHA=XPAO Á XMAXÀXPP=XPAO KIPPþKMAXÀXPP=XPAO Á X PAO 13 Aerobic growth of X PAO l PAO Á SO 2 KO 2 PAO þSO 2 SNH 4 KNH 4 PAO þSNH 4 SALK KALKPAOþSALK Á XPHA=XPAO KPHAþXPHA=XPAO Á X PAO 14 Lysis of X PAO b PAO Á X PAO 15 Lysis of X PP b PP Á X PP 16Lysis of X PHA b PHA Á X PHA…”