Performance of a bioreactor with submerged membranes for aerobic treatment of municipal waste water.
Aerobic treatment of municipal waste water in a membrane bioreactor was studied for 535 d. Apart from sampling, sludge was retained completely by a submerged hollow fibre membrane with a pore-size of 0.2 microm. The pilot plant comprised an anoxic zone to enable denitrification. The maximum liquid hold-up of the plant was 3.9 m3. In this study the reactor performance and the stability of the process and the membrane capacity were investigated. A stable flux of 181 m(-2)h(-1) could be realised with a mean transmembrane pressure difference of 0.3bar with air-bubbling and backflushing the membrane and cleaning it in place every two months for one or two hours. For about 140d, a flux of 271 m(-2)h(-1) was achieved, but cleaning became necessary more often. The hydraulic retention time (HRT) varied between 10.4 and 15.6h. Accordingly the volumetric loading rate was between 1.1 and 1.7kg CODm(-3)d(-1). No inoculum was used. The mixed liquor suspended solids (MLSS) concentration gradually increased to 18-20g MLSSl(-1). The feed to microorganism (F/M) ratio varied according to the operation conditions but decreased against a value of 0.07 kg COD kg(-1) MLSSd(-1). Treatment performance was very stable and on a high level. The COD was reduced by 95%. Nitrification was complete and up to 82% of the total nitrogen could be denitrified.
Rosenberger
S
S
Department of Chemical Engineering, Technical University of Berlin, Germany.
Krüger
U
U
Witzig
R
R
Manz
W
W
Szewzyk
U
U
Kraume
M
M
D001420:Bacteria, Aerobic / Q000502:physiology*; D019149:Bioreactors; D008567:Membranes, Artificial; D009584:Nitrogen / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010316:Particle Size; D016062:Porosity; D012722:Sewage / Q000382:microbiology; D014865:Waste Disposal, Fluid / Q000379:methods*; D014872:Water Movements; D018508:Water Purification / Q000379:methods*
D008567:Membranes, Artificial; D012722:Sewage; D009584:Nitrogen; D010100:Oxygen