Investigating the Effect of Salinity on Biological Wastewater Treatment (A Review Study)

Freshwater salinization in the world occurs during man-made urban and industrial activities. These activities range from groundwater abstraction for drinking water in coastal areas to the level at which seawater overflows with fresh water to de-hardening processes in industrial use to prevent damage to facilities.

In this research, using the study of reference books as well as internet search, with google search engine, in databases of springer, science direct, online library wiley, iwap online, etc., articles related to biological treatment of saline wastewater, checked.

The results show that the performance of bacterial metabolism, among other factors, depends on the ambient osmotic pressure, which is closely related to the concentration of salt in the mineral liquid. High salt concentration has direct and indirect effects on bacterial activity and this will have a significant impact on the capacity to use biological processes in saline wastewater put.

The best way to treat this type of wastewater is to use halophilic bacteria that are less sensitive to salt additions. Phosphorus removal and nitrogen oxidation are more sensitive to the removal of organic matter in these wastewaters. In general, according to studies, the use of combined anaerobic-aerobic process can create a higher efficiency in the treatment of such wastewater, provided that if the amount of salt is added to more than 12% of halophilic bacteria is added to the system.