Algae bioreactor used to reduce the pollution load of outlet wastewaters from fish farms

Phytoplankton and algae are as the first level of the food chain and food producers for other organisms in the aquatic environment. These organisms acquire their nutrients in the process of photosynthesis (N and P) from the aquatic environment. In this study, the amount of purified fish wastewaters was studied by microalgae (Chlorella vulgaris) in a period of 18 days. The present study was conducted in a laboratory system and on the wastewater outlet of fish farms. For this purpose, a 5-liter semi-industrial reactor was designed with a mixer blade, a porous plate, and a compressor. The required algae stock on the basis of density was cultured in the laboratory environment and then was injected into the bioreactor compartment containing fish wastewater. The averages of nitrate, nitrite, phosphate, and ammonium, TDS, TSS and BOD were 1.94, 2.22, 0.39, 4.11, 2.2, 1.94, 2.39 mg L-1, respectively. Also, PH and electrical conductivity were 7.52 and 1315 µ mho cm-1. The results showed that algae films efficiently reduced the amount of contaminants in the reactor space. This decreasing trend has increased over the course of the encounter. At the end of the exposure period, all parameters except phosphate have been reduced by almost half. The algal reactor can effectively reduce the organic loading of fish farms, which will partially prevent environmental contamination.