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A novel grille form complex membrane module composed of glass fiber covered with organic membrane and the dynamic membrane bioreactor (DMBR) with this complex membrane were studied. The results showed that the flux of the dynamic membrane of glass fiber tube without covering with organic membrane solution was only 4 L/(m2 x h) at a trans-membrane pressure (TMP) of 0.02 MPa. After the modification of covering with the organic membrane solution, the complex dynamic membrane flux could reach to a level of 16 L/(m2 x h) at a TMP of 0.01 MPa in operation, and after a hydraulic and chemical cleaning, the membrane flux was up to 17.1 L/(m2 x h) at a lower TMP of 0.003 MPa. When the glass fiber tube was coated with a membrane solution with a concentration of 1:4 (membrane materials/solution in volume ratio), the flux of the complex membrane worked steadily at 14.29 L/(m2 x h) more than 51 days, and according to calculation by TMP rising, the flux could maintain for almost 275 d. The average removal rates of COD and NH4+ -N were 81.96% and 83.66% respectively by the DMBR, and that were 21.01% and 3.61% only by the complex dynamic membrane. Moreover, the cost of complex membrane was approximately 40-60 yuan/m2, which was lower than the traditional organic membrane.

A new type of fiberglass tubular self-forming dynamic membrane bioreactor (DMBR) and its application for treatment of landfill leachate on laboratory scale were studied. The results showed that the system worked with a average membrane flux 3.75 L/m2 x h) maintained by gravity filtration at a trans-membrane pressure (TMP) of 2 900 Pa for near 80 days. After the modification of membrane module, a higher membrane flux was achieved at a TMP of 1 450 Pa and the membrane flux could be maintained steadily at 6 L/(m2 x h) for a long time. At the same time, the formation and filtration performance of dynamic membrane (DM) was tested. The effluent turbidity was blow 1.0 NTU and the average removal of COD, BOD5 and NH4(+) -N in this system exceeded 71%, 96% and 98% respectively. Moreover, COD removal from the supernatant on an average of 19.34% was made only by the dynamic membrane.

Removal of inorganic nitrogen (inorganic-N) from toilet wastewater, using a pilot-scale airlift external circulation membrane bioreactor (AEC-MBR) was studied. The results showed that the use of AEC-MBR with limited addition of alkaline reagents and volumetric loading rates of inorganic-N of 0.19-0.40 kg inorganic-N/(m3 x d) helped achieve the desired nitrification and denitrification. Furthermore, the effects of pH and dissolved oxygen (DO) on inorganic-N removal were examined. Under the condition of MLSS at 1.56-2.35 g/L, BOD5/ammonia nitrogen (NH4+ -N) at 1.0, pH at 7.0-7.5, and DO at 1.0-2.0 mg/L, the removal efficiencies of NH4+ -N and inorganic-N were 91.5% and 70.0%, respectively, in the AEC-MBR. The cost of addition of alkaline reagent was approximately 0.5-1.5 RMB yuan/m3, and the energy consumption was approximately 0.72 kWh/m3 at the flux of 8 L/(m2 x h).

A water quality model for water reuse was made by mathematics induction. The relationship among the reuse rate of treated wastewater (R), pollutant concentration of reused water (Cs), pollutant concentration of influent (C0), removal efficiency of pollutant in wastewater (E), and the standard of reuse water were discussed in this study. According to the experiment result of a toilet wastewater treatment and reuse with membrane bioreactors, R would be set at less than 40%, on which all the concemed parameters could meet with the reuse water standards. To raise R of reuse water in the toilet, an important way was to improve color removal of the wastewater.

An enhanced mechanical-cleaning membrane module M1 and a mechanical-cleaning membrane module M2 were designed in this research. An orthogonal array design was adopted to investigate effects of operational parameters including aeration intensity, membrane flux, MLSS, ratio of suction time and non-suction time on membrane filtration of two membrane module of M1 and M2. The results showed that M1 could weaken the negative influence of disadvantage parameters including high MLSS, high membrane flux, and low aeration intensity on membrane flux. M1 and M2 module both maintained a high flux of 40 L/(h x m2) under the conditions of MLSS 6 g/L, aeration 0.5 m3/h, ratio of suction time and non-suction time of 12/1, which was selected by the study of orthogonal array. Resistance distribution showed that the mechanism of mechanical-cleaning help to remove the sludge cake pollution on membrane surface.

A pilot-scale (10 m3/d) anoxic/oxic membrane bioreactor (A/O MBR) was tested for dyeing wastewater treatment of woolen mill without wasting sludge in 125 days operation. Results showed that the effluent quality was excellent, i.e. effluent COD less than 25 mg/L, BOD5 under 5 mg/L, turbidity lower than 0.65 NTU, and colour less than 30 DT, and met with the reuse water standard of China. The removal rates of COD, BOD5, colour, and turbidity were 92.4%, 98.4%, 74% and 98.9%, respectively. Constant-flux operation mode was carried out in this study, and backwash was effective for reducing membrane fouling and maintaining constant flux. Membrane fouling had heavy impact on energy consumption. More attention should be paid on pipe selection and design for the sidestream MBR system, too.

Based on the microorganism kinetic model, the formula for computing hydraulic retention time in a membrane bioreactor system (MBR) is derived. With considering HRT as an evaluation index a combinational approach was used to discuss factors which have an effect on MBR. As a result, the influencing factors were listed in order from strength to weakness as: maximum specific removal rate K, saturation constant Ks, maintenance coefficient m, maximum specific growth rate mu m and observed yield coefficient Yobs. Moreover, the formula was simplified, whose parameters were experimentally determined in petrochemical wastewater treatment. The simplified formula is theta = 1.1(1/beta-1) (Ks + S)/KX0, for petrochemical wastewater treatment K and Ks equaled 0.185 and 154.2, respectively.

Abstract: An anaerobic/oxic membrane bioreactor (A/O MBR) was used for treatment of dyeing wastewater from a woolen mill. COD and color of the wastewater were 54-473 mg/L and 40-400 dilution time (DT) respectively. The ratio of BOD[sub 5]/COD was less than 0.13. By the A/O MBR process, the average removal of COD, BOD[sub 5], color and turbidity was 82%, 96%, 71% and 99%, respectively. The average COD, BOD[sub 5], color and turbidity of effluent was 37 mg/L, 0.8 mg/L, 40 DT and 0.44 NUT respectively. The effluent COD met the local standard of reuse water in Beijing, China. The average COD volume load of the anaerobic biological tank was 0.0483 kgCOD/(m[sup 3] x d) and that of the aeration tank of the MBR was 0.3589 kgCOD/(m[sup 3] x d). The sludge load of the MBR was 0.19 kgCOD/(kg x MLSS x d) on average and the maximum of that was 0.4 kgCOD/(kg x MLSS x d). The flux of the A/O membrane bioreactor could be remained at larger than 50 L/(h x m[sup 2] x 0.1MPa). The results indicated that A/O membrane bioreactor has technical feasibility for treatment of woolen mill wastewater. [ABSTRACT FROM AUTHOR]