Importance of industrial wastetreatment:

• Industries use water that is obtained from the water treatment system for a variety of purpose such as for manufacturing goods, for heating, for cooling, as carrier of raw material, as carrier of waste matter, as a solvent etc.

• The resulting water is then classified as waste water.

• The indiscriminate discharge of these waste water streams into the environment can render soils sick, pollute the receiving bodies of water, and cause air pollution by generating obnoxious gases.

• Discharge untreated waste water into the domestic sewer system makes the tasks of treating domestic sewage a very difficult and costly exercise.

• To prevent any health hazards caused by discharging waste water into the environment and protect domestic sewage, the waste water must be treated before discharge.

• Important contaminants of concern in waste water treatment are: suspended solids, nutrients, priority pollutants, refractory organics, heavy metals, dissolved inorganic etc.

Strength reduction:

Waste strength reduction is the second major objective for the industrial plant. The following are the methods which help in reducing the strength which include:

• Process change

• Equipment modification

• Segregation of waste

• Equalization

• Proportioning of waste

• Monitoring of waste stream

• Deduction in accidental spills

• By-product recovery.

Process change The production engineer can be asked to change the manufacturing process by providing options either by change in manufacturing intermediate chemicals or change in certain raw materials or change in some equipment. In reducing the strength of waste through process changes, the wastes that are most troublesome from a pollutant point of view should be considered.

Equipment modification: The change in equipment can reduce the amount of contaminant entering the waste stream and thereby reducing the strength.

Segregation of waste Segregation of waste reduces the strength and a difficulty of treating the final waste in an industrial plant. It results into 2 waste:1) one is strong and small in volume 2) Another bigger and more in volume with almost the same volume as the original unsegregated waste.

Equalization: Description provided in same module.

Volume reduction:

Volume reduction is the primary treatment given to the waste and can be accomplished by the following methods:

• Classification of waste

• Conservation of waste water

• Changing production technique

• Reuse and recycling

• Elimination of Batch and plug discharge.