Application of sequencing batch membrane bioreactors (SB-MBR) for the treatment of municipal wastewater

摘要

Sequencing batch membrane bioreactors can be a good option in up-grading small municipal plantnand for industrial applications, maintaining some of the advantages of both original technologiesn(effluent quality improvement, flexibility and simplicity of realization, operation and control). In thisnstudy, the effects of volumetric exchange ratio (VER) and aeration/filtration strategy have beennevaluated. Moreover, with the adoption of cycles shorter than 8 h, the opportunity of furthernsimplification of the membrane operation has been tested by choosing a continuous filtration modeninstead of the usual short cycle of permeation/relaxation. Two lab-scales MBR equipped with Zenonnhollow fiber modules were fed on real primary effluent. For all tests, hydraulic retention time of 10 hnand sludge retention time of 60 days have been adopted. Different cycles have been investigated,nlasting between 1 and 8 h and all comprising an anoxic phase to allow for denitrification. Operationnat low VER resulted in better effluent quality with no limitations to the denitrification phase. FornVER >33% a pre-aeration step was required before effluent withdrawal for optimal ammoniumnremoval. Moreover, VER appeared to have limited negative effect on sludge concentration and yield,nwhile the membrane cleaning frequency slightly increased for increasing VER.