Patent ID: 6991931

Claim:
A method of maintaining a viable culture in an activated sludge environment in the absence of carbon influx comprising: a) providing an activated sludge environment comprising: (i) a carbon influx; (ii) cultures of autotrophic, heterotrophic and facultative microorganisms producing polyhydroxyalkanoates; (iii) a feed nutrient; and (iv) an end electron acceptor; b) removing the feed nutrient from the activated sludge environment while continuously monitoring the concentration of polyhydroxyalkanoates present in the activated sludge environment; c) removing the carbon influx from the activated sludge environment when the concentration of polyhydroxyalkanoates is greater than about 15 to about 20 dry weight percent of the activated sludge environment; d) adding a minimal concentration of nitrate to the activated sludge environment of step (c); wherein the cultures of autotrophic, heterotrophic and facultative microorganisms are maintained in a viable state in the absence of a carbon influx.