Enhanced polyphosphate organism cultures in activated sludge systems - Part 1: Enhanced culture development

In UCT and Bardenpho systems, by starting with 100 per cent municipal waste water as influent, incrementally decreasing the waste-water fraction and increasing the acetate fraction, an enhanced culture of polyphosphate (polyP) organisms was developed. Aerobic cultures, using the API procedure, indicated greater than 90 per cent of the microorganisms as Acinetobacter spp. As the acetate fraction increased, macro and micro-nutrients and yeast extract addition was necessary to maintain polyP organism growth. Of the macro-nutrients, magnesium, potassium and calcium had to be available in adequate concentrations for P uptake magnesium and potassium form the principal counter-ions for stabilising the polyP chain and, to a lesser extent, calcium; calcium was probably involved in other functions. Acid addition was necessary in the aerobic zone to maintain the pH near neutrality. At sludge ages of 10 and 20 d with 100 per cent acetate feed (500 mgCOD/l removals of about 60 and 50 mgP/l respectively were attained, P/VSS (mgP/mgVSS) of about 0,38 and VSS/TSS (mgVSS/mgTSS) of 0,46 in the aerobic zone. This enhanced culture was used to obtain information on the stoichiometry and kinetics of the growth of polyP organisms in nutrient removal systems.