The impact of entrapment of algae on simultaneous nutrient removal
Kube, M.1, Spedding, B.2, Fan, L.1 and Roddick, F.1, 1RMIT University, Australia, 2South East Water Corporation, Australia
(free)
Abstract
Rapid removal of both nitrogen (N) and phosphorus (P) to low concentrations can be achieved by algae entrapped by alginate beads. The algae can be retrieved by simple settling of the beads for producing energy and nutrient recovery, adding value to the treatment process. The rates and mechanisms of nutrient removal by suspended (free growing) and entrapped systems were compared for treating several different municipal wastewaters and nutrient concentrations. Algal cells of both systems assimilated a similar amount of nutrients per unit mass and adjusted uptake in response to the proportion of N and P in each wastewater. This demonstrated that entrapment did not compromise simultaneous removal of N and P, and as a method to concentrate the algal biomass within a reactor, shorter treatment times can be achieved. When ammonium rather than nitrate predominated in the wastewater indirect (abiotic) removal pathways were reduced, allowing more nutrients to be assimilated by the algal cells for later recovery. Additional relationships found linking algal N and P uptake to the wastewater carbon (C), N and P content allowed the effect of wastewater selection on the efficiency of wastewater treatment with entrapped algae to be determined.
