This study presented the performance of simultaneous nitrification and denitrification (SND) process using a new developed hybrid airlift reactor which integrated the activated sludge reaction process in the airlift reactor and the sludge settling separation process in the clarifier. The proposed reactor was started up successfully after 76 days within which the COD and total nitrogen removal r...

Apseudohomogeneous model of the nitrifying activated sludge process was developed to investigate the effects ofmass-transport resistance and heterotrophic/nitrifier competition on the apparent relationship between dissolved oxygen (DO) concentration and nitrification . The kinetics of both heterotrophic carbon oxidation and autotrophic ammonia oxidation within activated sludge flocs were descri...

In this paper a new model, tailor-made for nutrient deficient aerobic COD removal, is presented. The Activated Sludge Model No. 1 is chosen as a basis for model development. The original model is extended to include (1) phosphorus state variables; (2) phosphorus and nitrogen limited heterotrophic growth and (3) an additional active biomass component to model predation by higher-order organisms,...

The kinetics of sulfate reduction and cell densities of sulfate-reducing bacteria (SRB) were determined in activated sludge at Aalborg East wastewater treatment plant, a modern 100 000 person equivalent plant, where SRB are subjected to alternating cycles of oxic and anoxic conditions. The number of SRB was relatively constant over the year, ranging from 2.1x10(5) to 1.1x10(6) cells ml(-1) as d...

The objective of this study is to evaluate the occurrence of fungi in aerobic and anoxic activated sludge from membrane bioreactors (MBRs). Thirty-six samples of both aerobic and anoxic activated sludge were taken from 2 MBR treating domestic wastewater. Over a period of eight months 2 samples from each plant were taken per month. The samples were prepared for count and definition of fungi. The...

In biological wastewater treatment technologies the majority of systems are based on activated sludge technology. In these systems the population structure and dynamics of the activated sludge microbial community is largely governed by indirect regulatory mechanisms, such as aerated/nonaerated reactors, reactor configurations and sludge recycling ratios. The build-up of activated sludge flocs (...

MACLEOD, R. A., HOGENKAMP, H., AND ONOFREY, E. 1958 Nutrition and metabolism of marine bacteria. VII. Growth response of a marine Flavobacterium to surface active agents and nucleotides. J. Bacteriol., 75, 460-465. MICKINNEY, R. E. AND HORWOOD, M. P. 1952 Fundamental approach to the activated sludge process. I. Floc-producing bacteria. Sewage and Ind. Wastes, 24, 117-560. MCKINNEY, R. D. AND WE...

Anaerobic digestibility of the waste activated sludge (WAS) discharged from large-scale membrane bioreactors (MBRs) and conventional activated sludge processes (CASs) were compared using batch trials. Four wastewater treatment plants were sampled. Results showed that the sludge from MBRs had poor anaerobic digestibility as it had lower volatile solid (VS) reduction rate and lower maximum biogas...

polyhydroxyalkanoates (phas) are naturally occurring polyester that can be accumulated in bacterial cells as a carbon and energy storage compound. they are metabolized by many microorganisms. these biopolymers accumulate in microbial cells under stress conditions such as limitation of nitrogen, phosphate, sulfur, oxygen, and excess carbon source. currently, phas have attracted increasing intere...