Waste water

RecyclingS.Vignesh, BTG-12-037

Dr.A.Valliammai,

Assistant Prof.,(WTC)

Waste Water

It is any water that has been adversely affected in

quality by naturally or anthropogenic influence.

Wastewater is water containing wastes from

residential, commercial, and industrial processes.

Municipal wastewater contains sewage, gray water.

Wastewater requires treatment to remove

pollutants prior to discharge.

Wastewater Recycling

Wastewater recycling is emerging as an integral part of

water demand management.

Promoting as it does the preservation of high-quality fresh

water supplies as well as potentially reducing the pollutant

in the environment and reducing overall costs.

Motivational Factors

Opportunities to augment limited primary water sources.

Prevention of excessive diversion of water from alternative

uses, including the natural environment.

Possibilities to manage in-situ water sources.

Reduction and elimination of discharges of wastewater

(treated or untreated) into receiving environment.

Scope to overcome political, community & institutional

constraints.

Reuse Potential reuses of wastewater depends on the hydrau.

and biochemical characteristics of wastewater, which

determine the methods and degree of treatment req.

It can be recycled/reused as a source of water

for a multitude of water-demanding activities such as

agriculture, aquifer recharge, aquaculture, fire fighting,

flushing of toilets, snow melting, industrial cooling,

parks and formation of wetlands for wildlife habitats,

recreational impoundments.

Quality of Wastewater

Wastewater, if treated appropriately, has the potential to be

recycled in a number of sectors. Recycled water can be

treated to a number of different standards using different

technologies depending on the quality req.

Broadly, wastewater is treated to three levels, namely

primary, secondary and tertiary levels. According to the

Environment Protection Agency (EPA), they are defined as

follows:

Methods

Wastewater treatment is closely related to

the standards and/or expectations set for the

effluent quality.

Suspended solids (physical particles that can clog

rivers or channels as they settle under gravity)

Biodegradable Organics

Microorganisms combine this matter with oxygen from the

water to yield the energy they need to thrive and multiply;

Unfortunately, this oxygen is also needed by fish and other

organisms in the river. Heavy organic pollution can lead to

“dead zones” where no fish can be found; sudden releases

of heavy organic loads can lead to dramatic “fish kills”.

Pathogenic Bacteria

These are most relevant where the receiving

water is used for drinking, or where people

would otherwise be in close contact with it.

Nutrients

These nutrients can lead to high concentrations

of unwanted algae, which can themselves become

heavy loads of biodegradable organic load

Treatment processes may also neutralize or removing

industrial wastes and toxic chemicals.

1.Primary treatment:

Treatment involving sedimentation (sometimes preceded by screening and grit

removal) to remove gross and settle able solids. The remaining settled solids,

referred to as sludge, are removed and treated separately.

2.Secondary treatment:

Generally, a level of treatment that removes 85% of Biological Oxygen Demand

[BOD] and suspended solids via biological or chemical treatment process.

Secondary treated reclaimed water usually has a BOD of <20 milligrams per liter

(mg/L) and suspended solids of <30 mg/L, but this may increase to >100 mg/L

due to algal solids in lagoon systems.

3.Tertiary treatment:

The treatment of reclaimed water beyond the secondary

biological stage. This normally implies the removal of a high

percentage of suspended solids and/or nutrients, followed

by disinfection. It may include processes such as coagulation,

flocculation and filtration.

Wastewater Sludge Reuse

Wastewater sludge is the solid/semi-solid substance,

concentrated form of mainly organic, and inorganic

impurities, generated as a result of treatment of

wastewater.

It can be reused to reclaim parched land by application

as soil conditioner, and also as a fertilizer in agriculture.

Deteriorated land areas, which cannot support the plant

vegetation due to lack of nutrients, soil organic matter,

low pH and low water holding capacity, be reclaimed

and improved by the application of sludge…Etc.

Economic Characters

Centralized wastewater treatment systems, the location of the

treatment plants, the availability of space in and around cities and the

topography – all of these factors restrict the use of wastewater to

certain areas and for specific purposes.

There are both positive and negative externalities associated with

wastewater recycling. The positive externality is: environmental

benefits from reduced discharge of saline wastewater into natural

water bodies. The negative externalities include potential groundwater

pollution and increase in soil salinity if used for irrigation and potential

unknown ill effects on human health if used for potable uses

Government / Institutions roles

I. Environmental Protection Agency

Responsible for the developing and applying of best practice

management guidelines for reclaimed water irrigation

II. Department of human services

Responsible for ensuring that, reuse schemes do not

pose a risk to public health

III. Council/Local Government

Councils control development zoning, minimum subdivision

size, infrastructure size, infrastructure provision, and land use

controls

Conclusion

Today, these methods are most widely used in

wastewater treatment process.

An economic and reliable way of using solar energy for

effluent treatment is a very attractive option for Indian

industries since the life of the catalyst is long.

Also many possible synergism of these techniques

promise a good pollutant destruction rate that helps in

maintaining the environment clean.

Reference

• ABS. 2005. Annual Report 2005-06.

http://www.ausstats.abs.gov.au/ausstats/subscriber.nsf

• am (Canberra Time) 28 November 2006. Australian Bureau of Statistics.

Commonwealth of Australia.

• http://www.tn.gov.in

• ACIL Tasman Pty Ltd. 2005. Economics Policy Strategy. Research into access to

recycled water and impediments.

• recycled water investment. Report prepared for the Australian Government

Department of Agriculture, Fisheries.

• and Forestry on behalf of the Natural Resource Policy and Programs

Committee. June 2005.

Thank You