Chlorination and biofouling control in industrial cooling water systems

Abstract

Chlorine, a powerful oxidizing biocide, was first used in Europe and North America in the early 1900s for the disinfection of drinking water and resulted in a dramatic decline in typhoid and cholera cases. At the present time, it is largely used as for water treatment, such as taste and odour control, disinfection of drinking water and wastewater, in the food industry and for biofouling control. Of all the disinfectants, it is certainly the most extensively studied with regard to chemistry, toxicity and ecotoxicity. Due to its well-tried technology, its long-term worldwide industrial uses and its reasonable cost, chlorine remains the most common antifouling treatment in industrial cooling water systems. An ideal biocide is toxic to one particular organism or group of organisms, but has no harmful effects on non-target organisms. It is not consumed by reactions with substances in the water (i.e. there is no demand), and soon after it enters the environment, it breaks down into non-toxic forms. Chlorine is a long way from being an ideal biocide: it is non-specific and reacts with virtually all constituents of natural waters-including man-made pollutants-to yield products having varying degree of persistence and toxicity. Nevertheless, it continues to be used for biofouling control in power plant cooling water systems.