Water treatment is used to maximize most water-based industrial processes, such as heating, cooling, processing, cleaning, and rinsing, so that operating costs and risks are reduced. Poor water treatment lets water contact with the surfaces of pipes and vessels which contain it. Steam boilers can scale up or corrode, and these deposits will mean more fuel is needed to heat the same amount of water.
Cooling towers can also scale up and corrode, but left untreated the warm, dirty water they can contain will allow bacteria to grow, and Legionnaires ‘ disease can be the fatal. Also, water treatment is used to improve the quality of water contacting the manufactured product including semiconductors, and/or can be part of the product like beverages, medicines, etc. In these instances, bad water treatment can cause defective products. Domestic water can become unsafe to drink if proper hygienic measures are not taken.
In many cases, water from one process might be perfectly suitable for reuse in another process somewhere else on site. With the proper treatment, a proportion of industrial on-site wastewater might be reusable. This can be a money saver in three ways: lower charges for lower water consumption, lower charges for the smaller volume of water discharged and lower energy costs due to the recovery of heat in recycled wastewater.
Industrial water treatment seeks to manage four main problem areas: scaling, corrosion, microbiological activity and disposal of residual wastewater. Boilers do not have many problems with microbes as the high temperatures prevent their growth.
Scaling occurs when the chemistry and temperature conditions make it so that the dissolved mineral salts in the water are caused to precipitate and form solid deposits. These can be mobile, like fine silt, or can build up in layers on the metal surfaces of the systems. Scale is a problem because it insulates and heat exchange becomes worse as the scale thickens, which wastes energy. Scale also narrows pipe widths and therefore increases the energy used in pumping the water through the pipes.
Corrosion occurs when the parent metal oxidizes (as iron rusts) and gradually the integrity of the plant equipment is compromised. The corroded products can cause similar problems to scale, but corrosion can also lead to leaks, which in a pressurized system can lead to epic failures.
Microbes can live in untreated cooling water, which is warm and sometimes ripe with organic nutrients, as wet cooling towers are very efficient air scrubbers. Dust, flies, grass, fungal spores and so on collect in the water and creates a sort of "microbial soup" if not treated with biocides.
Most outbreaks of the deadly Legionnaires ‘ disease have been linked to unmanaged cooling towers, and the UK has had stringent Health & Safety guidelines concerning cooling tower operations for many years as have had governmental agencies in other countries.