BIO-P REMOVAL FROM A PHOSPHORUS RICH DAIRY PROCESSING WASTEWATER
P.O.Bickers¹ and R.Bhamidimarri²
1North Shore City Council, Auckland, New Zealand 2Faculty of Engineering, Science and the Built Environment, London South Bank University, UK
(free)
Enhanced biological phosphorus removal has been extensively applied for low phosphorus bearing effluents (10-15 mg/L) such as those emanating from domestic environment. However, there has been little success reported with dairy processing effluents containing high concentrations (eg. 100mg/L) of phosphorus.
Pre-fermented dairy effluent containing 98 mg/L of total phosphorus similar to that is generated from a milk powder plant was treated in an AAO reactor. With a three hour anaerobic retention time, a phosphorus removal of 41.5 mg/L was achieved. Simultaneously, an influent TKN of 115 mg/L was reduced to no detectable nitrates in the anoxic zone. The sludge phosphorus concentration was 7% mgP/mg VSS. Extension of the anaerobic phase from 3 to 6 hours resulted in increased VSS concentrations in the system with increased the volatile fatty acid (VFA) uptake in the anaerobic phase, yielding 47% greater VSS concentration. Although the cellular phosphorus concentration was less (5.6% mgP/mg) in this system, total greater phosphorus removal was achieved.
This study demonstrated that large quantities of phosphorus can be recovered from effluents containing high phosphorus concentrations.
KEY WORDS AAO reactor, enhanced biological phosphorus removal, dairy effluent, volatile fatty acids, polyhydroxyalkoanates
