The World Indicators Report (WIR) indicated that
water for industrial use represents approximately 22
% of global fresh water use1
. In 1995, the water volume
used by industry was 752 litres/year and was estimated
to be 1170 litres/year in 2025
2
. Despite industries
requiring good quality water for manufacture, the
wastewater produced from industry is usually
contaminated with nutrients and heavy metals such as
Pb, Fe, Mn, Cu and Zn. As these pollutants are toxic to
humans and have impact on the environment,
treatment before discharging to a natural or storage
water body is essential. A study in 1989 showed that 18
major rivers in Thailand were contaminated with heavy
metals and a subsequent study in 1994 found that 25
of the total 43 rivers in Thailand were contaminated
3
.
According to preliminary estimates, water pollution is
estimated to cost between 0.6 and 1% of GDP, annually
4
.