Effects of nanosilica immobilised microbes on NH4+-N removal of aquaculture effluent

Experiments were conducted to evaluate the effects of microbe immobilisation and NH4+-N removal in effluent by combining nanosilica absorbent with effective microorganisms. The results revealed that the absorbent consisting of a small amount of nanosilica improved cell immobilisation considerably. Absorbents containing 10% nanosilica had the maximum immobilised biomass of 0.066 g w/w, which was 0.006 and 0.056 g w/w larger than those containing 10% activated carbon and 100% sediment carriers, respectively. Removal of NH4+-N by carriers was proportional to the immobilised effective microorganism amount within a certain initial NH4+-N concentration in wastewater. The experimental results suggested that 10 g biocarriers containing 10% nanosilica had the largest NH4+-N removal rate of 78.29% when the initial NH4+-N concentration in the effluent was 53.21 mg L-1. Moreover, it had the maximum NH4+-N removal amount of 110.7 mg L-1 when the initial NH4+-N concentration in wastewater was 400 mg L-1.