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subject: Westewater Treatment Plant [print this page]

From Shubham : www.shubhamindia.com
From Shubham : www.shubhamindia.com

In the industrialised countries the first wastewater treatment

techniques involved processes of a purely

physical and mechanical nature to reduce the solid

content. The limitations of both the results and the

applicability of these processes later led to the use of

treatments of a chemical nature. At the beginning of

the 20th century water hygiene problems were overcome

by adding chlorine. At the same time other

types of treatment were introduced, with specific

objectives, such as rendering the water softer or reducing

the iron content.

There has been a gradual progression fiom the haphazard

treatment of wastewater treatment by dilution in large

tanks to the use of spreading areas andt o creation of

centralised systems. Originally the initial stage in

these systems aimed at reducing substances in suspension

by using chemo-physical methods. As a result

of findings in England during the last twenty

years of the 19th century, which led to the activated

sludge process, a second stage in the process was introduced

by which organic matter was stabilised by

aeration.

As a consequence, the technological evolution of

these processes has led to widespread mechanisation

of the systems, especially in the initial treatment

stage. So far as the secondary treatment stage

is concerned, trickling filters, rotating biological

disks, different versions of activated sludge processes

and rapid filtration systems have been introduced

and perfected.

The quality of water supplies has gradually declined,

largely because of high and often excessive

consumption of natural water and the abuse of the

ground soil as a recipient of wastewater treatment.Pollution

has also contributed to this effect. The situation is

so bad that it is now necessary to process water for

certain uses for whicihn the past no processing was

ever considered necessary. Therefore, highly advanced

processes have been introduced to reclaimur -

ban effluent for agricultural and industrial purposes.

Fundamental studies in the fields of chemistry and

microbiology and findings fiom research into process

techniques provide the foundations on which

new methodologies for planning and laying out

wastewater treatment systems are currently built.

Today these technologies conorm with environmental

politics which ftohre near fiture foresees the

integration of systems and devices for reducing the

impact of anthropic processeosn the environment.

Waters that are used for drinking, manufacturing, farming, and other purposes by residences (toilets, baths, showers, kitchens, sinks), institutions, hospitals, commercial and industrial establishments are degraded in quality as a result of the introduction of contaminating constituents. Organic wastes, suspended solids, bacteria, nitrates, and phosphates are pollutants that commonly must be removed.

To make wastewater acceptable for reuse or for returning to the environment, the concentration of contaminants must be reduced to a non-harmful level, usually a standard prescribed by the Environmental Protection Agency.

Sewage can be treated close to where it is created (in septic tanks, bio-filters or aerobic treatment systems), or collected and transported via a network of pipes and pump stations to a municipal treatment plant.

Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff (effluents) and domestic. The task of designing and constructing facilities for treating wastewaters falls to environmental engineers. They employ a variety of engineered and natural systems to get the job done, using physical, chemical, biological, and sludge treatment methods. Its objective is to produce a waste stream (or treated effluent) and a solid waste or sludge suitable for discharge or reuse back into the environment. This material is often inadvertently contaminated with many toxic organic and inorganic compounds.

The features of wastewater treatment systems are determined by (1) the nature of the municipal and industrial wastes that are conveyed to them by sewers, and (2) the amount of treatment required to preserve and/or improve the quality of the receiving bodies of water. Discharges from treatment plants usually are disposed by dilution in rivers, lakes, or estuaries. They also may be used for certain types of irrigation (such as golf courses), transported to lagoons where they are evaporated, or discharged through submarine (underwater) outfalls into the ocean. However, outflows from treatment works must meet effluent standards set by the Environmental Protection Agency to avoid polluting the bodies of water that receive them.

Sewage Treatment Plant is basically characterized as below system based on usage of Oxygen / Air in Secondary Treatment Stage (Biological Decomposition of organic matter).

For more details : www.shubhamindia.com

by: Vinod malavia

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