Utility of integrated papyrus-bivalve for bioremediation of aquaculture wastewater

Aquaculture generates substantial amount of residual feeds and faecal matter that accumulate in the culture environment and pollute effluent-receiving water, diminishing its ecological functioning. To devise means of treating nutrient-rich aquaculture wastewater, the efficiency of integrated papyrus-bivalve mesocosms in removing nutrients was evaluated. The mesocosms were fed on water (6600 L) from one brood-stock pond and allowed to settle for 2 weeks. Physico-chemical parameters, including nutrient level in influent and effluent of mesocosms, were analysed fortnightly using standard methods. The integrated papyrus-bivalve mesocosms had the highest removal of 69.5, 52.9, and 70.5% for total nitrogen (TN), total phosphorus (TP), and total dissolved solids (TDS), respectively, from the aquaculture wastewater. The removal efficiency of TN and TDS by the mesocosms followed the order: integrated papyrus-bivalve ˃ papyrus ˃ bivalves ˃ control, and removal efficiency for TP followed a similar trend, albeit integrated papyrus-bivalve≈papyrus. The nutrient retention (g/DMm²) in papyrus biomass was 24.09 and 2.93 in integrated papyrus-bivalve mesocosm and 20.77 and 3.81 in papyrus mesocosms for nitrogen and phosphorus, respectively. Meanwhile, the nutrient retention in bivalve biomass was 3.06 and 0.44 in integrated papyrus-bivalve and 1.95 and 0.34 in bivalve mesocosm, for nitrogen and phosphorus, respectively. The study confirms the synergistic functionality of papyrus and bivalves in treating aquaculture wastewater. Papyrus and bivalves in the mesocosms contributed to the bioremediation of wastewater through physical and biochemical processes, including filtration, nutrient uptake, and attachment surfaces for microorganisms. Therefore, we recommend integrated papyrus-bivalve bioremediation technology to fish farmers and policy makers.