Agricultural fertiliser from brewery effluent – the recovery of nutrients from the biomass of activated sludge and high rate algal pond treatment systems

Abstract

The disposal of waste biomass generated from biological wastewater treatment plants is a costly process and poses environmental threats to the receiving environment. This study aimed to determine the suitability of algae and waste activated sludge (WAS) produced from a brewery effluent treatment system as a fertiliser in agriculture. The change in soil characteristics and the growth of a crop fertilised with algae or WAS was compared with a conventional inorganic fertiliser. Swiss chard plants (Beta vulgaris) fertilised with anaerobically digested (AD) algae or WAS had a significantly higher mean biweekly yield (5.08 ± 0.73 kg/m2) when compared with the inorganic fertiliser control (3.45 ± 0.89 kg/m2; p 0.05). The nitrogen applied to the soil from algae and WAS biomass appeared to leach out of the soil less than the nitrogen supplied by inorganic fertilisers. The application of WAS or algae on soil increased the soil's sodium concentration and sodium absorption ratio from 774.80 ± 13.66 mg/kg to 952.17 ± 34.89 mg/kg and 2.91 ± 0.04 to 3.53 ± 0.13, respectively. Regulations on the application of algae or WAS on agricultural soils should be altered to consider the limit values for sodium. HIGHLIGHTS Swiss chard production was similar when fertilised with fertiliser, waste activated sludge or algae.; Anaerobically digested waste activated sludge and algae can replace inorganic fertiliser.; Waste activated sludge and algae increased the soil's sodium absorption ratio.; Soil application rates of sludge should consider sodium limit values.;

Keywords

• agriculture
• anaerobic digestion
• biosolids
• brewery effluent
• high rate algal ponds
• waste activated sludge (was)