[Mechanisms of the improvement in dewaterability of alkaline fermented sludge by simultaneous ammonium and phosphate recovery].

Simultaneous ammonium and phosphate recovery could notably improve the dewaterability of alkaline fermented sludge, the mechanisms of which, however, remains unclear at present. The influence of zeta potential, divalent ions, extracellular polymeric substances (EPS), dissolved polymers and struvite were studied in batch experiments. Under the optimal ammonium and phosphate recovery condition [i.

Toxicity reduction of municipal wastewater by anaerobic-anoxic-oxic process.

Objective: This study was conducted to optimize the operational parameters of anaerobic-anoxic-oxic (A²/O) processes to reduce the toxicity of municipal wastewater and evaluate its ability to reduce toxicity.

Methods: A luminescent bacterium toxicity bioassay was employed to assess the toxicity of influent and effluent of each reactor in the A²/O system.

Results: The optimum operational parameters for toxicity reduction were as follows: anaerobic hydraulic retention time (HRT) = 2.

Determination of textile dyeing wastewater COD components by comparison with respirometry and full-scale data.

A Modified Activated Sludge Model No. 1 (M-ASM1), including six COD components (S1, S(S), X1, X(S), X(H), and S(O)) and three biochemical processes (aerobic growth of heterotrophs, aerobic decay of heterotrophs and hydrolysis of entrapped organics) was used to simulate the anaerobic hydrolysis-aeration-sedimentation treatment series in a full-scale textile dyeing wastewater treatment plant (WWTP) with an influent flow rate of 200,000 m3/d. Using a respirometry method, the influent COD components of the WWTP activated sludge system were estimated.

[Activated sludge model based COD fractionation in wastewater characterization].

The successful application of activated sludge model (ASM) in wastewater treatment plant mainly depends on the correctness of wastewater fractionation. Based on three batch oxygen uptake rate (OUR) tests, a COD fractionation protocol and the corresponding Matlab program were developed to aid the standardization of COD fractionation in wastewater. COD fractionation results of two wastewater treatment plants (WWTP) in Shanghai show that COD in wastewater of the Quyang WWTP is composed of 8.

[Relationship between typical organic matters in domestic wastewater and water characteristic parameters in activated sludge models].

The contribution of typical organic matters such as proteins, sugars, lipids and linear alkylbenzene sulfonate (LAS) to COD of the domestic wastewater was investigated. Nitrate utilization rate was used to determine wastewater characteristic parameters. Relationship between these typical organic matters and wastewater characteristic parameters (Ss, Xs, SI, XI) in activated sludge models were investigated.

[Fractionation of soluble COD in wastewater based on batch respirometric method].

A fractionation protocol of soluble COD (SCOD) was put forward by combining respirometric method with hydrolysis kinetics of soluble slowly biodegradable COD (S(H)). SCOD fractionation results of two wastewater treatment plants (WWTP) in Shanghai show that the SCOD in sand basin effluents (typical domestic wastewater) of WWTP A is composed of 43.5%-58.

[Characteristics of microbial biomass in subsurface constructed wetland treating eutrophic water].

A subsurface horizontal-flow constructed wetland planted with Phragmites australis was developed and used to treat eutrophic water for nearly two years at fixed hydraulic loading rate. Substrate samples were taken at different depths respectively in the front, middle and back sites of wetland in January, May, August and October in the second year. Microbial biomass (MB) content was measured using the chloroform fumigation incubation method.

[Sorption and degradation of 17beta-estradiol to anoxic activated sludge].

Batch experiments were conducted to investigate the sorption isotherms and degradation kinetics of 17beta-estradiol (E2) at a low levels (microg/L) by anoxic activated sludge. The effects of temperatures and the concentrations of electron acceptor on the sorption and degradation were also investigated. Results showed that, when the initial concentrations of E2 were 5-15 microg/L, E2 was completely degraded after 2 h under anoxic conditions.

[Biological nitrogen and phosphorus removal in the anaerobic-aerobic-anoxic-aerobic-anoxic-aerobic sequencing batch reactors].

The biological nitrogen and phosphorus removal was investigated in two anaerobic-anoxic-aerobic sequencing batch reactors (SBRs), which were fed with synthetic and municipal wastewater, respectively. The operating cycle of (AO)3 SBR was 1.5 h anaerobic --> 1 h aerobic --> 1 h anoxic -->20 min aerobic --> l h anoxic --> 20 min aerobic.

[Treatment of SBR after wet air oxidation of emulsification wastewater].

This article studied the change of possible biochemistry and toxicity of emulsification wastewater before and after wet air oxidation and also studied the treating effect of wet air oxidation on emulsification wastewater after SBR process. The experimental results indicate that the toxicity of emulsification wastewater is equivalent to that of 0.12 mg/L HgCl2, while initial COD 48,000 mg x L(-1) and BOD5/COD (B/C) 0.

[Adsorption characteristics of 17beta-estradiol to anaerobic and anoxic sludge].

Adsorption tests were performed to measure the adsorption capacity of anaerobic and anoxic inactivated sludge for 17beta-estradiol. The effects of pH and temperature were also investigated. The adsorption equilibrium was established in 30 min; no significant pH effect was observed in the pH range of 6-9 at 20 degrees C; when pH >9, the adsorptive capacities decreased with increasing pH value; the adsorptive capacities decreased with increasing temperature.

[Long-term and short-term effects of propionic/acetic acid ratios on metabolism of glycogen-accumulating organisms].

Three activated sludges enriched with glycogen accumulating organisms (GAO) were acclimatized respectively with different ratios of propionic to acetic acid (i.e. biomass SBR-A, C and E) .

[Effect of SRT on denitrifying phosphorus removal in A/A/O process].

Based on a laboratory-scale anaerobic-anoxic-oxic process acclimated with municipal wastewater, effect of SRT on denitrifying phosphorus removal occurred in the system was investigated. The results indicate that the contribution of anoxic denitrifying phosphorus removal to total phosphorus removal becomes larger with prolonging the sludge retention time. DNPAOs' denitrification and P uptake capacities per anoxic PHAs utilized are quickly increased, while PAOs' P uptake capacity per aerobic PHAs utilized is rarely influenced by SRT.

[Addition of propionic acid on simultaneous biological phosphorus and nitrogen removal in anaerobic-low dissolved oxygen system].

Two lab-scale sequencing batch reactors (SBRs) were operated under conditions of anaerobic-low dissolved oxygen (DO) (0.15 - 0.45 mg x L(-1)), and the influences of addition of propionic acid on simultaneous biological nitrogen and phosphorus removal system were investigated.

[Transformation of linear alkylbenzene sulphonate in the anaerobic-anoxic-oxic wastewater treatment process].

The removal characteristics of linear alkylbenzene sulphonate (LAS) was studied in anaerobic/anoxic/oxic (AAO) municipal wastewater treatment processes. A removal (biological degradation and sorption) model was formulated, and kinetic parameters were evaluated with batch experiments under anaerobic, anoxic, oxic conditions. The resulting model calculations were then compared with sampling campaigns performed on AAO process.

[Influence of wastewater initial pH on enhanced biological phosphorus removal in sequencing batch reactor (SBR)].

Two laboratory-scale sequencing batch reactors (SBRs) were operated continuously to investigate the influence of wastewater initial pH on enhanced biological phosphorus removal (SBR1: pH = 6.8; SBR2: pH = 7.6).

[Research on substrate transformation mechanism in A2/O process].

Based on a laboratory-scale anaerobic-anoxic-oxic process acclimated with real wastewater, substrate transformation mechanism and the effect of nitrate on substrate transformations occurred in the system were investigated. The results indicated that under the anaerobic condition without nitrate, phosphorus-accumulating organisms (PAOs) could take up 51% of COD consumed and store them to PHAs; anoxic and aerobic specific phosphorus uptake rates were 3.87 mg/(g x h) and 6.

Simultaneous nitrogen and phosphor removal in an aerobic submerged membrane bioreactor.

Simultaneous nitrification and denitrification (SND) effect and phosphor removal were investigated in a one-staged aerobic submerged membrane bioreactor on pilot-scale with mixed liquor suspended solids (MLSS) 19-20 g/L. The effects of DO concentration, sludge floc size distribution on SND were studied. Test results suggested that SND was successfully performed in the membrane bioreactor (MBR) and about 70% total nitrogen removal efficiency was achieved when DO concentration was set to 0.

[Experimental research on separate structure jet aerator].

A new type of jet aerator (separate structure jet aerator) was designed and developed, and an idea of separate design was put forth. This type of jet aerator was mainly applied to the treatment of small-scale wastewater and industrial wastewater of high density treatment projects. The experimental set-up was built to investigate the influences of the structural parameters (R1, R2 and R3) on the gas suction flowrate.

[Cometabolic biodegradation of nitrogenous heterocyclic compounds indole and pyridine under anoxic conditions].

Based on the traditional theory of denitrification under anoxic conditions, and with the addition of nitrate, experiments were conducted to investigate the cometabolic biodegradation of nitrogenous heterocyclic compounds-indole and pyridine. Results show that the optimum ratio of COD to nitrate (C/N) is 8.4 to approximately 8.

Biodegradation kinetic of organic compounds of acrylic fiber wastewater in biofilm.

A group function relation curve between flux (J) and bulk phase concentration of substrate (S) was set up. The biodegradation kinetic of organic compounds of acrylic fiber wastewater in biofilm is studied (the treatment technology is coagulation/sedimentation-anoxic/aerobic biofilm process), and the results showed that the concentration of non-degradation pollutants in effluent is 77 mg/L. In aerobic zone, the half-rate constant is 72.