Sh. Chuang et Cf. Ouyang, The biomass fractions of heterotrophs and phosphate-accumulating organismsin a nitrogen and phosphorus removal system, WATER RES, 34(8), 2000, pp. 2283-2290
In this study, the biomass fractions of heterotrophs (X-H) and phosphate-ac
cumulating organisms (X-PAO) were estimated through experimental results an
d theoretic:al calculation on the mass balance of organic matter, nitrogen
and phosphorus in a pilot scale biological nutrient removal process. The pr
ocess, comprised of conventional anaerobic-anoxic-aerobic activated sludge
and a rotating biological contactor in the aerobic stage, was controlled un
der steady state under conditions of a solid retention time of 10 days and
a dissolved oxygen concentration of 2.0 mg/l in the aerobic stage. For long
term operation, the process exhibited high performance in organic matter,
nitrogen and phosphorus removal. The removal efficiency was 96.5, 70 and 10
0% of organic matter, total nitrogen and total phosphorus, respectively. Ac
cording to the mass balance calculation, approximately 62.0% of organic mat
ter, 48.0% of nitrogen and 37.2% of phosphorus of influent were removed in
the form of carbon dioxide, nitrogen gas and polyphosphate, respectively. R
egarding X-H and X-PAO as the major organisms responsible for biomass produ
ction, the yield fractions of X-H growth in anoxic and aerobic conditions w
ere 48.4 and 39.4%, respectively. Moreover, the yield fraction of X-PAO gro
wth in aerobic conditions was 12.2%. These results showed that X-H was the
major community: moreover, only a minute amount of X-PAO was present in thi
s nitrogen and phosphorus removal system for municipal wastewater treatment
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