A　Sludge　reduction　in　a　conventional　activated　sludge　process　combined　with　a　membrane　biofilm　inoculated　with　T.Tubifex　was　investigated.　The　influence　of　microbial　extracellular　polymeric　substances　(EPS)　extracted　in　forms　of　LB-EPS　and　TB-EPS　respectively　on　the　surface　properties　of　biomass　was　studied.　Results　showed　that　variations　of　polysaccharides　and　protein　along　with　the　increasing　of　EPS　feeding　would　affect　the　existence　of　T.Tubifex.　When　the　amount　of　EPS　varied　from　10　to　50μg/mg,　the　specific　resistance　of　a　sludge　suspension　was　obtained　from　3.5×107　to　1.4×107　S2/g.　Meanwhile,　polysaccharides　content　in　EPS　was　to　be　positively　correlated　with　the　SSR　of　sludge　suspension　whereas　protein　content　would　be　not.　Anyway,　it　can　be　argued　that　an　increase　in　LB-EPS　not　TB-EPS　may　affect　the　performance　of　activated　sludge　reduction　with　efficiency　about　40.1%　to　31.6%.　©　Published　under　licence　by　IOP　Publishing　Ltd.