BACKGROUNDAlkaline　fermentation　of　waste　activated　sludge　(WAS)　is　feasible　to　recover　carbon　for　biological　nutrients　removal.　However,　it　is　difficult　to　abstract　the　soluble　organics　from　the　fermented　mixture　since　sludge　dewaterability　is　deteriorated　after　fermentation.　In　this　study,　a　novel　system　consisting　of　complete　mixing　fermentation,　water　elutriation　and　settling　reactor　was　developed　to　produce　and　abstract　short　chain　fatty　acids　(SCFAs)　from　waste　activated　sludge　through　an　alkaline　fermentation　process.　RESULTSFor　the　novel　system,　57%　of　sludge　solubilization　and　327mg　COD　g(-1)　VS　of　SCFAs　production　were　achieved　in　the　fermentation　zone,　resulting　in　a　sludge　reduction　of　54%.　In　the　elutriation　zone,　nearly　70%　of　soluble　organics　was　recovered　when　the　water　exchange　ratio　was　33.3%.　Moreover,　mass　balance　of　the　system　was　calculated　and　the　results　showed　that　C,　N,　and　P　element　were　converted　into　the　liquors　phase　in　the　fermentation　process　with　proportions　of　54%,　30%,　and　16%,　respectively.　CONCLUSIONThis　work　successfully　developed　a　novel　process　for　wasted　sludge　fermentation　and　soluble　organic　carbon　separation.　Effective　results　were　obtained　in　the　system,　indicating　it　is　favorable　for　pilot　and　full　scale　application.　(c)　2017　Society　of　Chemical　Industry