Performances of an activated sludge process for the treatment of fish processing saline wastewater

In recent years, there has been a rapid proliferation of fish industries across the world. The conditions in the fish industries are often squalid with the continual generation of liquid wastes. The generated wastewaters are rich in salts (NaCl) and nitrogen ammonia. In this work an industrial wastewater containing 1 to 6% salt (NaCl) was treated in an activated sludge unit operating in a continuous mode. Effects of important process parameters such as organic loading and O2 rates on COD, N-NH4+ and BOD5 removal rates were investigated. Increasing the aeration rate resulted in the improvement of the performance of the system. However, the pollution abatement rates decreased with increasing the COD loading rate and salt content. Inhibition process was found to be significant for salt concentrations higher than 4% NaCl. Experimental results demonstrate that the acclimatized consortium can be efficient for the treatment of saline wastewaters, even in the presence of high salt concentrations up to 4% and an organic loading rate reaching 855 mg COD/l.d. These experimental results may be used in the design of activated sludge units treating saline wastewaters.