Enhancing removal efficiency of ammonia and nitrate in shrimp farm wastewater using biofloc technology and effective microorganism S4 (EM4)

Shrimp farms generate wastewater which contains high concentrations of ammonia and nitrate produced by feed residue and shrimp excretion. This study aims to analyze concentration changes in ammonia and nitrate in shrimp farm wastewater by applying biofloc technology combined with Effective Microorganisms 4 (EM4). It also aims to determine the optimum concentration of EM4 for reducing ammonia and nitrate concentrations. Laboratory-scale experiments were carried out for 30 days using three 40×25×30 cm³ treatment tanks. Each tank was equipped with a 7 l/min aerator, a 30-watt lamp, 15 liters of fresh water, 20 young shrimp, and EM4 concentrations of 3 ml/l, 5 ml/l, and 7 ml/l, respectively. At the end of the observation period, water parameters were recorded, such as dissolved oxygen (DO) range of 4.11 to 4.48 mg/L, pH range of 7.7-8.4, and temperature range of 29.1-30.7°C. Nutrient levels had declined, with the maximum removal of ammonia from the 3 ml/l, 5 ml/l, and 7 ml/l EM4 concentration tanks of 74.1%, 84.2%, and 88.9%, respectively and for nitrates of 68.4%, 72.6%, and 83.7%, respectively. Ammonia and nitrate concentrations were reduced to about 0.634 mg/l and 1.261 mg/l, respectively. Dosage of EM4 of 7 ml/l was considered to be the optimum concentration for reducing ammonia and nitrate concentration. It can be concluded that the combination of biofloc technology and EM4 is successful in removing ammonia and nitrate waste from shrimp farm wastewater and in maintaining nutrients and water quality at safe levels. This combination therefore has the potential to be used for water recycling in shrimp aquaculture.