BIOFILM PROCESS FOR TREATING WATER WITH CONTINUOUS OR SEMI-CONTINUOUS PRODUCTION OF BIOMASS WITH ENHANCED POLYHYDROXYALKANOATE CONTENT

摘要

A biofilm process is disclosed for treating wastewater containing readily biodegradable dissolved organic matter (measured as chemical oxygen demand or COD) and producing surplus biomass from the biofilm process that includes an enhanced polyhydroxyalkanoate (PHA) content. The process comprises directing a wastewater influent containing the readily biodegradable COD (RBCOD) into a biofilm unit process. The PHA content of surplus biomass is enhanced by controlling for a decreased biofilm process specific organic loading rate in combination with controlling phosphorus loading rates relative to the process RBCOD loading rates: (1) controlling the wastewater influent phosphorus loading rate to the biofilm unit process includes maintaining an average RBCOD/P ratio of the influent that is between 200 and 800 g/g; (2) decreasing the process specific organic loading rate includes producing a biofilm unit process effluent having readily separable mixed liquor volatile suspended solids (RS-MLVSS); and (3) separating a portion of the RS-MLVSS from the biofilm unit process effluent and recycling at least a portion of the separated RS-MLVSS back to the biofilm unit process. The combination of the RBCOD/P control and specific loading rate control maintains, on average, the surplus biomass with a PHA content that is greater than 30% gPHA/g VSS.