Water pollution control involves two types of measures (i) Preventive measures and (ii) Curative measures. The preventive steps are ;
a. Volume reduction of wastewater
b. Strength reduction.
Volume reduction' can be achieved by
i. Classifications of wastes: Concentrated waste waters of manufacturing process are segregated from dilute wastes as cooling waters, thereby reducing the quantity to be treated.
ii. Improved process control, improved equipment design and use of different or better quality raw materials.
iii. Recycling both treated industrial and municipal effluents as raw water supplies.
iv. Elimination of batch or slug discharges of process wastes. If the waste is discharged into our atmosphere in a short period of time. it is usually referred to as an slug discharge.
This type of waste because of its concentrated contaminants surge in volume can be troublesome to both treatment plants and receiving streams.
Strength Reduction can be achieved by following:
i. Process changes: industry can modify manufacturing process so that fewer wastes are created.
ii. Equipment modifications: changes in equipment can affect a reduction in the strength of the waste usually by the reducing of the amounts of contaminants entering the waste stream.
iii Segregation of wastes reduces the strength that eliminating the difficulty of treating the final waste from an industrial plant. It usually results in two types of wastes by one strong but smaller in volume and the other weaker more in volume . The strong waste can then be handled easily with specific methods as their quantity is less.
iv. Equalization of wastes: Blending of cool and hot wastes and acids and alkalies and strong waste and dilute waste nullifies or minimizes their pollutional characteristics and renders them stable. Stable effluents are treated more easily and effectively, than unstable ones.
v. By-product recovery: Almost all the wastes contain by-products. Recovery and use of these by-products reduce the total pollutional strength of the waste.
