Performance of a pilot-scale high rate algal pond system treating abattoir wastewater in rural South Australia: nitrification and denitrification

As part of a study examining the efficacy of high-rate algal pond treatment of high-strength abattoir wastewater, the impact of pond configuration and loading rate on nitrification was determined. The extent of nitrification in all ponds was consistent with mass balance estimates of oxygen demand and availability. Deeper ponds were more stable nitrifying systems, with shallow ponds displaying greater variation in response to changes in nitrogen loading. In a separate experiment the pond system was modified by covering a part of an in-series HRAP to exclude light, providing conditions suitable for denitrification. Specific denitrification rates were often within the range typical for endogenous carbon sources, with mass balance calculations indicating removals of up to 95%.