Water Pollution Reduction

water pollution

Over the last several decades, water quality management in the India has focused on control of point sources of water pollution and the use of effluent- (discharge-) based water quality standards. Although the quality of water in india has generally improved, nonpoint sources of pollution have not been as successfully controlled.

To help confront this disparity, the Environmental Protection Agency (EPA) implements the Total Maximum Daily Load (TMDL) program the objective of which is attainment of ambient water quality standards through the control of both point and nonpoint sources of pollution.

Over the past 20 years, scientists, coastal managers, and government decision-makers have come to recognize that coastal ecosystems suffer a number of environmental problems that can, at times, be attributed to the introduction of excess nutrients from upstream watersheds.

Nutrient over-enrichment is the common thread linking such diverse coastal problems as fish kills, outbreaks of shellfish poisonings, coral reef destruction, and the Gulf of Mexico’s “dead zone.”

Nutrient sources include runoff from agricultural land, animal feeding operations, and urban areas as well as discharge from wastewater treatment plants and atmospheric deposition of compounds released during the burning of fossil fuels.

Clean Coastal Waters: Understanding and Reducing the Effects of Nutrient Pollution , produced jointly by the WSTB and the Ocean Studies Board of the NRC, concludes that the central government together with state and local agencies should develop a comprehensive national strategy to combat nitrogen and phosphorus pollution in coastal waters.

Success in addressing coastal nutrient problems depends on having a solid scientific understanding of the causes of the problem and the full range of possible management alternatives. To this end, the report describes a number of initiatives that could help address nutrient overabundance.

Integrating waste and water management

Economic growth in most of the world has been vigorous, especially in the so-called newly industrialising countries. Nearly all new development activity creates stress on the “pollution carrying capacity” of the environment. Many hydrological systems in developing regions are, or are getting close to, being stressed beyond repair.

Industrial pollution, uncontrolled domestic discharges from urban areas, diffuse pollution from agriculture and livestock rearing, and various alterations in land use or hydro infrastructure may all contribute to non-sustainable use of water resources, eventually leading to negative impacts on the economic development of many countries or even continents.

Lowering of groundwater tables (e.g. Middle East, Mexico), irreversible pollution of surface water and associated changes in public and environmental health are typical manifestations of this kind of development.

Technology, particularly in terms of performance and available waste-water treatment options, has developed in parallel with economic growth. However, technology cannot be expected to solve each pollution problem. Typically, a wastewater treatment plant transfers 1 m3 of wastewater into 1-2 litres of concentrated sludge.

Wastewater treatment systems are generally capital-intensive and require expensive, specialised operators. Therefore, before selecting and investing in wastewater treatment technology it is always preferable to investigate whether pollution can be minimised or prevented.

For any pollution control initiative an analysis of cost-effectiveness needs to be made and compared with all conceivable alternatives. This chapter aims to provide guidance in the technology selection process for urban planners and decision makers. From a planning perspective, a number of questions need to be addressed before any choice is made:

Is wastewater treatment a priority in protecting public or environmental health? Near Wuhan, China, an activated sludge plant for municipal sewage was not financed by the World Bank because the huge Yangtse River was able to absorb the present waste load.

The loan was used for energy conservation, air pollution mitigation measures (boilers, furnaces) and for industrial waste(water) management. In Wakayama, Japan, drainage was given a higher priority than sewerage because many urban areas were prone to periodic flooding. The human waste is collected by vacuum trucks and processed into dry fertiliser pellets. Public health is safeguarded just as effectively but the huge investment that would have been required for sewerage (two to three times the cost of the present approach) has been saved.

Can pollution be minimised by recovery technologies or public awareness? South Korea planned expansion of sewage treatment in Seoul and Pusan based on a linear growth of present tap water consumption (from 120 l cap-1 d-1 to beyond 250 l cap-1 d-1). Eventually, this extrapolation was found to be too costly. Funds were allocated for promoting water saving within households; this allowed the eventual design of sewers and treatment plants to be scaled down by half.

Is treatment most feasible at centralised or decentralised facilities? Centralised treatment is often devoted to the removal of common pollutants only and does not aim to remove specific individual waste components. However, economies of scale render centralised treatment cheap whereas decentralised treatment of separate waste streams can be more specialised but economies of scale are lost. By enforcing land-use and zoning regulations, or by separating or pre-treating industrial discharges before they enter the municipal sewer, the overall treatment becomes substantially more effective.

Can the intrinsic value of resources in domestic sewage be recovered by reuse? Wastewater is a poorly valued resource. In many arid regions of the world, domestic and industrial sewage only has to be “conditioned” and then it can be used in irrigation, in industries as cooling and process water, or in aqua- or pisciculture. Treatment costs are considerably reduced, pollution is minimised, and economic activity and labour are generated. Unfortunately, many of these potential alternatives are still poorly researched and insufficiently demonstrated as the most feasible.

Ultimately, for each pollution problem one strategy and technology are more appropriate in terms of technical acceptability, economic affordability and social attractiveness. This applies to developing, as well as to industrialising, countries. In developing countries, where capital is scarce and poorly-skilled workers are abundant, solutions to wastewater treatment should preferably be low-technology orientated.

This commonly means that the technology chosen is less mechanised and has a lower degree of automatic process control, and that construction, operation and maintenance aim to involve locally available personnel rather than imported mechanised components.

Such technologies are rather land and labour intensive, but capital and hardware extensive. However, the final selection of treatment technology may be governed by the origin of the wastewater and the treatment objectives.

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