Mitigation of eutrophication through phosphate removal by aluminium pillared bentonite from aquaculture discharge water

Abstract

Deterioration of aquatic ecosystem by accumulation of nutrients has increased due to anthropogenic activities, and adsorption is one of the efficient methods for removal of phosphate from discharge water. The present study investigated the efficiency of aluminum pillared bentonite in removing phosphate from aquaculture discharge water with high salinity. Adsorption capacity of pillared bentonite increased with increasing temperature from 11.85 (25 °C) to 13.81 (35 °C) and 15.85 (45 °C) mg/g. At 30 ppt salinity, there was 57.7% reduction in phosphate sorption capacity of the pillared bentonite from 0 ppt. The kinetic studies revealed that adsorption followed the pseudo second-order model. The free energy change of the phosphorous sorption by pillared bentonite was −4.19, −5.87 and −6.24 kJ mol−1 at 25 °C, 35 °C and 45 °C, respectively. The pillared bentonite reduced the phosphate level by 85.3–99.6% from eutrophic waters of shrimp farm, fish larval rearing tanks, algal culture system, discharge water treatment system, etc. The study revealed that aluminum pillared bentonite is efficient in reducing the phosphate level of aquaculture discharge water, and it could be used for the treatment of aquaculture discharge water before releasing into the environment.