Land-based mariculture operations often discharge seawater into the sea. proliferation of microorganisms in the farm potentially causes environmental harm. To mitigate these risks, stringent regulations mandate the disinfection of mariculture effluent, traditionally achieved through UV disinfection. However, UV disinfection entails high energy consumption and maintenance costs. In this study, we explored the feasibility of on-site electro-chlorination as a cost-effective and environmentally sustainable alternative to UV radiation for disinfecting mariculture effluent.
Effluents from the Israeli National Center for Mariculture, characterized by approximately 41 ppt salinity, were used in this study. Effluents were analyzed for nutrients, total organic carbon (TOC), and chlorine demand. Sand-filtered effluents were utilized for the experiment and circulated through an electro-chlorinator (Magen, Israel) to produce chlorine (hypochlorite) on-site. The chlorine solution generated was then applied to evaluate the disinfection efficacy of the effluents at various doses. Disinfection efficiency was evaluated using total plate counts, and water samples were further analyzed for trihalomethanes (THM) concentration using quadrupole gas chromatography-mass spectrometry (GC/MS).
Results indicated On-site electro-chlorination effectively reduced microbial loads in the effluent, and a chlorination dose of 5 min∙mg /L is satisfying. Total THM concentrations below 22 ppb (Fig 1) , much lower than drinking water standards. Notably, the use of on-site electro-chlorination substantially minimized the risk of chlorine leakage and operational costs compared to traditional UV disinfection methods. Based on these findings, a disinfection design incorporating sand filtration for parasite removal and electro-chlorination for bacterial and viral disinfection was proposed (Fig 2) and subsequently approved by Israeli regulators for mariculture effluent disinfection before discharge into the sea. This study underscores the potential of on-site electro-chlorination as a viable and sustainable disinfection method for mariculture effluent, offering significant cost savings and environmental benefits.