Inorganic nitrogen removal of toilet wastewater with an airlift external circulation membrane bioreactor.

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).

[Dynamic membrane bioreactor with glass fiber tube covered with organic membrane].

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.

[Study of a new type of tubular self-forming dynamic membrane bioreactor and its application for treatment of landfill leachate].

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.