Evaluation of a laboratory and full-scale microalgae pond for tertiary treatment of piggery wastes

Piggery wastes tertiary treatment in laboratory and full-scale microalgal ponds was evaluated. COD, BOD, inorganic nitrogen and orthophosphate removals of up to 57%, 69%, 79% and 74%, respectively, were obtained. The effect of the hydraulic retention time (HRT) on removal efficiencies followed an exponential relationship. COD, BOD and orthophosphate removal rate decreased with increased effluent concentration while the inorganic nitrogen removal rate increased with an increasing effluent substrate concentration at inorganic nitrogen concentration values lower than 0.07 g l(-1). Values of maximum substrate removal rate, half rate constant, cell yield coefficient, endogenous constant and maximum specific growth rate were 7.1 +/- 0.5 d(-1), 0.21 +/- 0.02 g l(-1), 0.26 +/- 0.01 g VSS g(-1) COD, 0.012 +/- 0.001 d(-1)and 1.9 +/- 0.9 d(-1), respectively. At full-scale, effluent COD, BOD, MPN, inorganic nitrogen and orthophosphate decreased while pH and Chlorophyll a increased with the operation time. It was found that the use of the final effluent as drinking water did not affect pigs growth.