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Basic Concepts of Reusing Industrial Wastewater

written by: Jayant R Row • edited by: Lamar Stonecypher • updated: 3/14/2011

Heightened public awareness and stricter application of effluent standards by the authorities has led to industrial wastewater reuse being given a lot of importance. Advanced technologies have also led to such reuse becoming feasible and economical.

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    The Potential for Industrial Wastewater Reuse

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    Depletion of water sources is the net result of the use of water for industrial purposes. In addition to this, the discharge of industrial wastewater, which is normally highly contaminated, does lead to pollution of groundwater. All this has necessitated the reuse of industrial wastewater after adequate treatment, and there has been a vast improvement in the methods of treating industrial wastewater so that it can be safely reused.

    The potential for wastewater reuse depends on the volume, the concentration of pollutants, and their characteristics. The various technologies developed for such treatment each have their own area of specialization and costs for setting up. Biomimcry is one of the latest advances that imitates the ecological system and transforms waste material in water into nutrients while the water can be reused for the industrial activity or other activities that require water. Technology has also led to the creation of portable units to treat industrial wastewater reducing the need for land and space required for treatment. Many civic authorities also separately treat wastewater and supply such treated water to industries.

    It is estimated that water consumption is cut down by at least 50 percent by industrial wastewater reuse and this figure can even go high as 95 percent. While the use of water used in boilers by cooling has been always prevalent, it is now becoming imperative for industries that use a lot of water to consider the reuse of wastewater because of the costs of looking for water sources and to reduce the consumption of it. This has also been vastly influenced by environmental concerns.

    Industries that have a very high potential for industrial wastewater reuse are those of glass, steel, cotton textiles, pulp, and paper. There are other industries like food processing, chemicals, fertilizers, dairies, petroleum refining, and distilleries that have a potential also for reuse of industrial wastewater. There are however industries like tanneries, rubber, pesticides, paint manufacturing and aluminum where the potential is very low because of the high concentration of pollutants in the wastewater and inadequate cheap technologies for treating such wastewater.

    Image Source: Wikipedia

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    Industrial Wastewater Reuse Technologies

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    Technologies that are used to treat industrial wastewater for reuse can include refinements of methods of precipitation and sedimentation, biological treatment, evaporation and crystallization, filtration through media or membranes, disinfection, reverse osmosis or ion exchange.

    Deciding on the right technology will depend on mechanical constraints like corrosion, biological growth, and scaling. The capital costs of setting up the treatment plants and the costs of chemicals or other inputs required to be constantly replaced can also determine the technology adopted by an industry. Finally environmental constraints can also make their presence felt, especially where the industries are very close to large cities or residential areas or even environmentally fragile surroundings.

    It is necessary to see that all the potential sources of wastewater in an industry are identified and the quantity and quality from each source correctly estimated. Treatment of industrial wastewater is reduced when the number of steps required for the treatment is the least. Quite often the retention of wastewater itself serves as a means of some treatment, though this may require large capital costs in the retaining tanks, which mainly act to create sediments of the waste that can then be separately treated.

    Image Source: Wikimedia