Industrial water re-use provides many benefits, including:

• reduced water and wastewater costs;
• savings in terms of heating and water treatment costs;
• increased reliability of existing systems;
• environmental benefits associated with reduced water usage;
• high independence from source water.

Re-use is a generic term that encompasses wastewater recycling into process and feed water and process water re-use in small loops.

Water re-use may be applied to internal wastewater (effluents produced by the industrial process), or to secondary municipal sewage (biologically treated). For large water users, secondary sewage re-use can be a more attractive source of process water than surface water. This technique is currently used on many sites in the power, refining, pulp & paper and microelectronics industries. Secondary sewage is always heat and drought proof.

On many industrial sites, zero liquid discharge (ZLD) is justified by cost benefit analysis. Such systems have been operating in the pulp & paper, power and automotive industries for many years.