Impact of Brine Discharges from Reverse Osmosis Plants for Central Drinking Water Softening on River Water Quality

Abstract

Three model sites with full-scale reverse osmosis plants for central softening of drinking water with brine discharge into rivers were identified to monitor quality changes as a result of brine discharge. The model sites are characterized by a relatively high percentage of brine in the river water, indicating unfavorable conditions in terms of possible changes in water quality. Physical-chemical parameters showed that seasonal factors had a greater impact on river water quality compared to brine discharge. Scale inhibitors contained in concentrates, however, led to a significant increase of the concentrations of these substances in water. Macrozoobenthos and diatoms have not changed significantly in the three model sites both in quantitative and qualitative terms as a result of brine discharge. Under the conditions of the model sites, brine discharge into rivers was ecologically compatible; however it is questionable for reasons of minimizing brine discharge in rivers.