title: Batch production of polyhydroxyalkanoate by low-polyphosphate-content activated sludge at varying pH.
abstract: Polyhydroxyalkanoate (PHA), a biodegradable plastic, can be produced from excess activated sludge by utilizing intracellular glycogen and polyphosphate as energy sources under growth-limiting conditions. Activated sludge of 2%, 6%, and 8% polyphosphate with similar glycogen content of 33% was investigated for batch PHA production by varying the pH values from 6 to 8. Acetate applied at 1000 mg COD/L was almost exhausted within 80 min of anaerobic stage. The remaining glycogen in the sludge was higher at a lower pH because of less energy used for acetate uptake. Highest PHA content of 51% was obtained from sludge with an 8% polyphosphate content at pH 8. PHA production occurred rapidly within the first 20 min, with a productivity rate of 2.19 g PHA/L-h. The results in this study indicate that PHA production by using activated sludge is a promising alternative to a typical pure culture approach.
authors.affiliation: The Joint Graduate School of Energy and Environment, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand. k_charuvan@yahoo.com
authors.forename: Charuvan
authors.initials: C
authors.lastname: Kasemsap
authors.forename: Chalermraj
authors.initials: C
authors.lastname: Wantawin
mesh_terms: D001420:Bacteria, Aerobic / Q000378:metabolism; D001421:Bacteria, Anaerobic / Q000378:metabolism; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology; D006003:Glycogen / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D011091:Polyesters / Q000378:metabolism*; D011122:Polyphosphates / Q000032:analysis / Q000378:metabolism; D012037:Refuse Disposal; D012722:Sewage / Q000737:chemistry / Q000382:microbiology
chemical_list: D011091:Polyesters; D011122:Polyphosphates; D012722:Sewage; D006003:Glycogen