Nutrient recovery from foam with microwave treatment

Abstract

Phosphorus recovery and solids reduction potential from foam generated in the anoxic reactor of membrane-enhanced biological phosphorus removal system were studied using the microwave-enhanced advanced oxidation process (MW/H2O2-AOP). The MW/H2O2-AOP-treated foam at different experimental conditions showed significant improvement in solubilisation of orthophosphate, ammonia, volatile fatty acids and soluble chemical oxygen demand as well as settling and dewatering ability. The most significant factors maximising orthophosphate release in the order of most to least affecting were (i) microwave heating temperature, (ii) combined effect of microwave heating temperature and hydrogen peroxide addition and (iii) addition of sulfuric acid. At temperature 180°C, pH 3 and hydrogen peroxide dosage 0·5% v/v, nutrient solubilisation, settling, and dewatering properties were at their maximum with 67% of the total phosphate solubilised as orthophosphate.