Presentation onWATER POLLUTION & WASTE WATER TREATMENT

INDIRA GANDHI CENTRE FOR HUMAN ECOLOGY, ENVIRONMENT & POPULATIONSTUDIES

Supervised By Submitted By

Dr. T.I. Khan AJAY KUMAR

PG DIPLOMA

Environmental studies

INTRODUCTION

•Water pollution is the contamination of water bodies (e.g. lakes,

rivers, oceans, and groundwater).

•Water pollution affects plants and organisms living in these bodies of

water; and, in almost all cases the effect is damaging either to

individual species and populations, but also to the natural biological

communities.

•Water pollution occurs when pollutants are discharged directly or

indirectly into water bodies without adequate treatment to remove

harmful compounds.

Water pollution categories

Surface water and groundwater have often been studied and

managed as separate resources, although they are interrelated.

Sources of surface water pollution are generally grouped into two

categories based on their origin.

Point source pollution

Non-point source pollution

Groundwater pollution

Causes of water pollution

The specific contaminants leading to pollution in water

include a wide spectrum of chemicals, pathogens, and

physical or sensory changes such as elevated temperature

and discoloration. While many of the chemicals and

substances that are regulated may be naturally occurring

(calcium, sodium, iron, manganese, etc.)

Pathogens

Coliform bacteriaare a commonly-used bacterial indicatorof water pollution,

although not an actual cause of disease. Other microorganismssometimes

found in surface waters which have caused human health problems include:

Burkholderia pseudomallei

Cryptosporidium parvum

Giardia lamblia

Salmonella

Novovirus and other viruses

Parasitic worms(helminths).

Chemical and other contaminants

1. Organic water pollutants

2. Inorganic water pollutants

Thermal pollution

Thermal pollution is the rise or fall in the temperature of a natural

body of water caused by human influence. A common cause of

thermal pollution is the use of water as a coolant by power plants

and industrial manufacturers. Elevated water temperatures

decreases oxygen levels (which can kill fish) and affects

ecosystem composition, such as invasion by new thermophilic

species. Urban runoff may also elevate temperature in surface

waters.

Measurement of water pollution

Sampling

Physical testing

Chemical testing

Biological testing

Sewage treatment

Sewage treatment, or domestic wastewater treatment, is the

process of removing contaminantsfrom wastewater and

household sewage, both runoff (effluents) and domestic. It

includes physical, chemical, and biological processes to remove

physical, chemical and biological contaminants. 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.

Process overview

Pre-treatment

Screening

Grit removal

Primary treatment

In the primary sedimentation stage, sewage flows through

large tanks, commonly called "primary clarifiers" or

"primary sedimentation tanks". The tanks are large enough

that sludge can settle and floating material such as grease

and oils can rise to the surface and be skimmed off.

Secondary treatment

Secondary treatment is designed to substantially degrade the biological content of the sewage which is derived from human waste, food waste, soaps and detergent. The majority of municipal plants treat the settled sewage liquor using aerobic biological processes.

Activated sludge

Surface-aerated basins

Filter beds (oxidizing beds)

Biological aerated filters

Membrane bioreactors

Secondary sedimentation

Rotating biological contactors

Tertiary treatment The purpose of tertiary treatment is to provide a final treatment stage to raise the effluent

quality before it is discharged to the receiving environment (sea, river, lake, ground, etc.). More than one tertiary treatment process may be used at any treatment plant. If disinfection is practiced, it is always the final process. It is also called "effluent polishing".

Filtration Lagooning Constructed wetlands Nutrient removal Nitrogen removal Phosphorus removal Disinfection Odour removal

Package plants and batch reactors

Sludge treatment and disposal

Anaerobic digestion

Aerobic digestion

Composting

Incineration

Sludge disposal

Treatment in the receiving environment

Many processes in a wastewater treatment plant are designed to mimic the natural treatment processes that occur in the environment, whether that environment is a natural water body or the ground. If not overloaded, bacteria in the environment will consume organic contaminants,

Sewage treatment in developing countries

Few reliable figures on the share of the wastewater collected in sewers that is being

treated in the world exist. In many developing countries the bulk of domestic and

industrial wastewater is discharged without any treatment or after primary

treatment only. In Latin America about 15% of collected wastewater passes

through treatment plants (with varying levels of actual treatment). In Venezuela, a

below average country in South America with respect to wastewater treatment, 97

percent of the country’s sewage is discharged raw into the environment. In a

relatively developed Middle Eastern country such as Iran, Tehran's majority of

population has totally untreated sewage injected to the city’s groundwater.

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