NOVELTY - Biologically treating wastewater with biomass and enhancing polyhydroxyalkanoate (PHA) accumulation potential of the biomass, comprises mixing the wastewater with the biomass and biologically treating the wastewater to remove contaminants from the wastewater, and enhancing the PHA accumulation potential of the biomass by (i) subjecting the biomass to a primary feast-famine process, and (ii) in addition to the primary feast-famine process, applying a secondary famine process by subjecting biomass to repeated cycles of primary feast and famine conditions, to the secondary famine process.    USE - The method is useful for biologically treating wastewater with biomass for enhancing poly hydroxyalkanoate accumulation potential of biomass (claimed).    ADVANTAGE - The method efficiently enhances the PHA accumulation potential of biomass with an improved physiological state, thus improving overall process economy of producing the PHA as a by-product of services in water quality management by biological treatment.    DETAILED DESCRIPTION - Biologically treating wastewater with biomass and enhancing polyhydroxyalkanoate (PHA) accumulation potential of the biomass, comprises either (a) mixing the wastewater with the biomass and biologically treating the wastewater to remove contaminants from the wastewater, and (b) enhancing the PHA accumulation potential of the biomass by (i) subjecting the biomass to a primary feast-famine process where the biomass is subjected to repeated cycles of primary feast and famine conditions, and (ii) in addition to the primary feast-famine process, applying a secondary famine process by subjecting biomass subjected to repeated cycles of primary feast and famine conditions, to the secondary famine process where the biomass or a fraction of the biomass at a given time is subjected to secondary famine conditions for a period of time that is substantially greater than the average time period of the primary famine conditions, or directing a wastewater stream containing readily biodegradable chemical oxygen demand (RBCOD) and nitrogen into a primary feast reactor, maintaining anoxic conditions in the primary feast reactor and subjecting the biomass to primary feast conditions while denitrifying the wastewater, directing the wastewater and biomass from the primary feast reactor to a downstream primary famine reactor, maintaining aerobic conditions in the primary famine reactor and subjecting the biomass to primary famine conditions while nitrifying the wastewater, recirculating the wastewater and biomass from the primary famine reactor to the primary feast reactor to give rise to a primary feast-famine process where the biomass is subjected to repeated cycles of primary feast and famine conditions, after at least a portion of the biomass is subjected to repeated cycles of primary feast and famine conditions in the primary feast reactor and the primary famine reactor, directing the wastewater and biomass from the primary famine reactor to a secondary famine reactor (B2), and subjecting the biomass in the secondary famine reactor to a secondary famine process.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic illustration of a method for treating semi-continuous flow biological wastewater.    SBR (B1)    Secondary famine reactor. (B2)