Simultaneous recovery of nitrogen and phosphorus from sludge fermentation liquid by zeolite adsorption: Mechanism and application

Abstract This study firstly achieved effectively simultaneous recovery of nitrogen and phosphorus sources from fermentation liquid using natural zeolites, and the optimization and mechanisms were studied. Results showed that adding zeolites to fermentation liquid could result in three major processes at the same time: (1) substantially recovering nitrogen and phosphorus, (2) obviously removing protein and polysaccharide, (3) distinctive maintenance of short chain volatile fatty acids (SVFA), indicating practical potential of fermentation reutilization. The ammonium was adsorbed on zeolites and then released calcium ions, which further precipitated with phosphate. The operational factors were evaluated using response surface methodology, and fitted model predicted that maximum simultaneous recovery rate of ammonium and phosphate could reach 94.06% and 98.28%. Furthermore, zeolite adsorption technology had promising temperature stability in range of 15–35 °C. Taken together, zeolite adsorption could serve as an alternative for recovering nitrogen and phosphorus resources from fermentation liquid.