Development of wastewater reuse system to eliminate the risk of microbial infection and toxicity to fish

Abstract

The Recirculating Aquaculture Systems (RAS) with a biological filter is the most noticeable representative which treats internally the water polluted with dissolved organics and ammonia. It also decreases the amount of water use. This study showed lower microbial content and lesser toxic element in treated water than non-treated water. Among the treatment 1, 2 and 3, treatment 3 showed lower microbial content; Aeromonus, Pseudomonus (20 × 10-4 CFUml-1, 30 × 10-3 CFUml-1) with low toxic elements; total ammonia nitrogen concentration 0.69 ± 0.3 gm^(-3), Nitrite-N concentration 2.1±1.5 gm^(-3), Nitrate 0.69 mg/L, CO2 5-10 mg/L, pH 7.16 ± 0.14 than other treatments 1 (35 × 〖10〗^(-4) CFU ml-1, 45 × 10-3 CFUml-1) and treatment 2 (50 × 〖10〗^(-4) CFUml-1, 30 × 〖10〗^(-3) CFUml-1). Usually maximum microbial content; Aeromonus, Pseudomonus (250 × 〖10〗^(-4) CFUml-1, 190 × 〖10〗^(-3) CFUml-1) and maximum toxic effect (total ammonia nitrogen concentration 1.20 gm-3, Nitrite-N concentration 6.66 gm^(-3), Nitrate 5.0 mg/L, CO2 15 mg/L, pH 7.48) was observed in the control condition (Non-treated water). This study indicates that the wastewater treatment using biological filter in case of microbial infection and toxic elements. Contents difference has the potentiality to fish production in aquaculture industry.