Vitamin addition: an option for sustainable activated sludge process effluent quality

The process performance and metabolic rates of samples of activated sludge dosed with vitamin supplements have been compared. After initial screening, four vitamins and two metals as single supplements and in pairs, were dose d continuously into the mixed liquor of an activated sludge simulation. Tox icity, oxygen demand removal, respiration rates and suspended solids were m easured to monitor the effect on process efficiency. It was confirmed exper imentally that an industrial wastewater stream did not contain a sufficient supply of micronutrients for efficient biological treatment. This was conc luded from the observation that Control sludge batches (receiving no supple ments) aver aged chemical oxygen demand removal efficiency of 58%. Dosing m icronutrients into the mixed liquor produced removal efficiencies of up to 69%. Some of the supplements increased the respiration rate of the sludge w hile some decreased it, indicating a range of stimulatory and inhibitory ef fects. Complex interactions between micronutrients that were dosed simultan eously were evident. Several positive effects led to the conclusion that mi cronutrients have the potential to optimise process performance of activate d sludge plants treating industrial wastewater. The addition of phosphorus/ niacin and molybdenum/lactoflavin removed wastewater components that were t oxic to nitrifiers as indicated through toxicity testing, thus protecting d ownstream nitrification/denitrification treatment processes.