Low Temperature Influence on Package Membrane Bioreactor(MBR) Operation in Remote Mountain Areas

This study investigated low temperature influence on package membrane bioreactor operation, applied in the remote mountain residential areas. During initiation, F/M ratio should be controlled above 0.05 kgCOD/kgMLSS-d by adjusting inoculated sludge concentration. Operation experienced three phases divided by temperature. Above 12degC, package MBR could keep excellent COD and NH₃-N removal rate, and trans-membrane flux could keep stable. At 4degC or below, COD and NH₃-N removal rate dropped to around 15% and 40%. Sludge in the reactor was in dormancy or disaggregation condition which could cause severe membrane fouling. Polysaccharides components in the soluble microbial products (SMP) ranging from 100 ku to 150 ku are regarded as the main fouling material. It is also suggested that all package MBR used as decentralization treatment in northern parts of China, especially in remote mountain areas, must be installed underground. Before the installation of package MBR local meteorologic and geologic data must be studied to make sure that all package MBR will be installed below the freezing level.