Chlorination by-products in chlorinated cooling water of some European coastal power stations

Development of an Environmental Impact Assessment and Decision Support System for Seawater Desalination Plants

“…If the predicted environmental concentration (PEC) exceeds the PNEC, a need for limiting the risks is usually identified. Residual chlorine concentrations in seawater of 0.02 mg/l, as observed near power plants up to a distance of 600 m from the outlet [184], clearly exceed the PNEC value derived by the EU risk assessment by two orders of magnitude. It is difficult to understand the reasons underlying the conclusion of the EU risk assessment for the power plant cooling water scenario that there is "no need for ... risk reduction measures beyond those which are being applied already".…”

“…In one plant, TRO concentrations of 0.02 mg/l were observed in the vicinity of the outlet (up to a distance of 600 m) and dropped below the detection limit (<0.01 mg/l) beyond 1,575 m. In the other plant, TRO levels of 0.02 mg/l near the outlet decreased even faster with distance [184]. The European risk assessment report for sodium hypochlorite evaluates the environmental exposure and effects caused by cooling water discharges from coastal power plants.…”

“…The European risk assessment report for sodium hypochlorite evaluates the environmental exposure and effects caused by cooling water discharges from coastal power plants. Based on the measured value of 0.02 mg/l nearby the outfalls, which decreased to zero after mixing with the receiving water [184], it is concluded that there is no need for further risk reduction measures. Potential effects − if any − are only to be expected in the near vicinity of the outlet [191].…”

“…Chlorine use in desalination and coastal power plants Low-level chlorination of 0.5-1.0 mg/l with residual oxidant levels of 0.1-0.2 mg/l in the cooling water flow is routinely employed in coastal power plants [184]. This is generally similar to the practice in some distillation plants, where low chlorine doses are employed.…”

“…Hypobromite/hypobromous acid reacts with organic seawater constituents, especially N-containing compounds, forming bromamines, which are as toxic as hypobromite/hypobromous acid, e.g., to mussels. Total residual chlorine (TRC) refers to the sum of FAC and combined chlorine, while total residual oxidant (TRO) also includes other oxidants such as bromine species [183,184]. In accord with many publications, the terms chlorine or residual chlorine will mainly be used in the following, although TRC would be more precise.…”