Equilibrium of Ammonia (NH3) and Ammonium (NH4+) during Microalgae Harvesting using Electrocoagulation

Abstract

Harvesting microalgae is an important process in gaining biomass while the remaining water is still rich in nutrients. These nutrients, mainly nitrogen and phosphorous, could cause eutrophication of water bodies (rivers, lakes, and oceans) and ecosystem degradation if discharged directly without proper treatment. Electrocoagulation (EC) is one of the harvesting methods and has several advantages: ease of operation, fast harvesting, adaptability, environmental friendliness, and low footprint. However, EC method for harvesting microalgae has the potential in producing ammonia, which is undesirable due to its threat to the environment. The purpose of this study is to establish the equilibrium of ammonium (NH4+) and ammonia (NH3) during Dunaliella salina harvesting. The harvesting was conducted using EC with a variation of 20 volts, 30 min, and 400 rpm. The result shows that the harvesting efficiency can reach 93.72% after 5 min of processing, decreasing the concentration of inorganic nitrogen compounds in total ammonia nitrogen (TAN) to 98.80%.