Cloth filters as alternative to the conventional membranes for solids removal from UASB effluents.

Anaerobic Membrane Bioreactors (anMBR) represent one of the most promising technology to achieve energy neutral or positive wastewater treatment with a high effluent quality. Despite this potential, its implementation is still restricted by the high costs of the ultrafiltration membrane. This thesis investigated the feasibility of using a cloth filter as an alternative to the conventional membranes for solids removal from an Upflow Anaerobic Sludge Blanket (UASB) effluent. The advantages of the cloth filter are the low cost of the material, simpler operation and maintenance procedures. However, solids removal efficiencies are lower than those of the ultrafiltration membrane. The removal efficiency depends on the pore size of the cloth and on the influent particle and solid profile load characterisation. The aim of this study is to assess the efficacy of cloth filters to treat UASB effluent. Effective solids separation was possible with the cloths tested with optimal performance achieved for the 1 and 10 µm non-woven cloths operated under low cross flow or dead end conditions. In these cases, solids removal efficiencies up to 67% were possible whilst maintaining a flux of 1000 LMH. In relation to the UASB operation, the sludge blanket height in the UASB was seen to correlate to the suspended solids removal and resulted in a progressively higher median particle size exiting the reactor. Further, incorporation of the separation in the recycle line deteriorated performance a little indicating that the cloth filters would be best configured post the recycle line.