Detection of Reserve Oxygen Potential in the Present of Fine Bubbles and its Ammonia Removal for Aquaculture Effluent

Abstract

The availability of oxygen and the minimum amount of ammonia in the water media are crucial in catfish larvae hatchery performance. The condition with a balanced amount of required oxygen and the presence of ammonia resulting from the feces of striped catfish larvae is essential to maintain the health of the aquaculture media. This study aims to remove ammonia by introducing fine bubbles (FBs) into recirculating aquaculture media and investigating reserved dissolved oxygen inside the bubbles in the media. The water media for the striped catfish larvae hatchery was designed and set up with three containers in a recirculating system. Also, a separate container was utilized as bubble storage connected to FBs generator. The water treatment was conducted in three different scenarios using air and pure oxygen as the FBs generator sources. The generated FBs were investigated in terms of their size and zeta potential concerning the dissolved oxygen (DO). The media’s DO was measured using the titration method and digital DO meter. The difference in DO concentration received from titration and DO meter define as potential reserved oxygen. Furthermore, the removal of synthetic effluent (ammonia, NH4Cl) and effluent in the media with FBs resources were investigated and tested at a different duration of FBs applications. The results showed that bubbles size was 518.5 – 607.6 nm independent of gas resource, either pure oxygen or air. However, the gas resources affected the zeta potential value of suspended bubbles, air (-11.5 to -16.7 mV), and pure oxygen (-21.4 to -25.2 mV). When pure oxygen was used as a gas resource, the media reach the oxygen supersaturation DO condition (25.39 ppm) within 45 minutes with reserve oxygen potential (ROP) of 2.95 ppm. Thus, this condition allowed the synthetic effluent removal of 83.33% and effluent removal of 39.93%. It is emphasized that the ammonia removal due to the presence of reactive oxygen species when the FBs collapsed and the information of ROP due to FBs application is important to preserve the fitness of aquaculture media for catfish larvae hatchery.