Identification of the risk factors in concentrated seawater from seawater desalination process

Abstract

Based on the whole desalination process, this paper reviewed the source and fate of risk factors in concentrated seawater including salinity, temperature, chemicals used for pretreatment, chemicals required in desalination process, by-products, corrosion products, and filter backwash. According to the hazard and toxicological thresholds combined with the no-effect concentration for marine species, the risk factors of brine discharge to seawater environment were further identified. The results showed that the risk factors contained ferric salt, aluminium salt, acrylamide, phosphates and total phosphorus, residual chlorine, total chlorine and disinfection by-products, isothiazolinone, sodium bisulfite, and heavy metals/metalloids such as copper, nickel, chromium, molybdenum, zinc, lead, titanium, cadmium, arsenic, selenium, mercury and barium. After the preliminary assessment, it was necessary to further monitor the risk factors in situ and know their actual concentration level in brine from seawater desalination, so as to provide a scientific basis for accurately assess the environmental influence of discharge brine in the seawater.

Keywords

• desalination
• concentrated seawater
• environmental impacts
• heavy metals
• disinfection by-product