SOURCES AND EFFECTS OF WATER POLLUTANTS ON HUMAN HEALTH,

QUALITY STANDARDS FOR DRINKING WATER AND WASTE WATER

TREATMENT

Presented By:-JYOTI DEVENDRA ADALA

MSC PART 1

WATER POLLUTION

Water pollution is defined as any adverse change in composition and condition of the water which tend to lower its quality and cause health hazard or makes it unfit for domestic use.

SOURCES AND EFFECTS OF WATER POLLUTION

1) Sewage and domestic waste

2) Industrial wastes and effluents

3) Insecticides and pesticides

4) Detergents and fertilizers5) Siltation6) Thermal pollution7) Radioactive materials

SEWAGE AND DOMESTIC WASTES

Nearly 75% of water pollution is due to sewage and domestic wastes. Biological oxygen demand (BOD)- The amount of oxygen consumed by microbiological action when 1000ml sample of water containing known amount of oxygen is incubated for 5 days. Water having DO content below 8.0 mg/l is considered as polluted. Heavily polluted water have DO content below 4.0 mg/l. Chemical oxygen demand (COD) - It is the oxygen required by organic substance in order to oxidise them by a strong chemical oxidant.

INDUSTRIAL WASTES AND EFFLUENTS

The industrial wastes and their effluents include poisonous materials like acids, alkalis, salts, phenols, cyanides, zinc, insecticides which makes water toxic and deoxygenated and eventually do not support aquatic life.

MERCURY- Minamata disease.

OILS- Oil reduce rate of oxygen uptake by water, retards light intensity by 90%.

BLACK FOOT DISEASE (Arsenic), ASBESTOSIS (Asbestos), BERYLLIOSIS (Beryllium), ITAI- ITAIdisease (Cadmium).

INSECTICIDES AND PESTICIDESThey are biologically active chemicals are used for pest control. These include DDT (dichlorodiphenyltrichloroeth-ane), aldrin etc.

Increased accumulation of these toxic substance in the food chain at high trophic level is called BIOLOGICAL

MAGNIFICATION.

DETERGENTS AND FERTILIZERSDetergents are used as cleaning agent and derived from surfactant (10% - 30%, alkyl benzene sulphonate), builder (10% to 15%, sodium phosphate ) and other ingredients. Fertilizers such as nitrates and phosphates are used to improve crop yield reach through irrigation, rainfall and drainage into rivers and ponds. They cause serious illness metheamoglobin. EUTROPHICATION

OTHER SOURCESSILTATION :- Seen in hilly streams and creates turbidities.THERMAL POLLUTION:- Heated waste water from power plants and industries which raises the temperature of water to a harmful level.RADIOACTIVE MATERIALS :- Radioactive pollutants get their way into water streams from various sources such as nuclear reactors, nuclear power plants and nuclear test.

WASTE WATER TREATMENTThe sewage treatment process are conveniently classified as

PRELIMINARY TREATMENT

This involves the removal of floating material, settle able inorganic solids, and greasy materials.SCREENERS - Device with opening and further classified as coarse (75-150mm), medium (20- 70mm) and fine (<20mm).

SHREDDER - Special device that cut and retain floating and suspended material.

GRIT CHAMBERS -Heavy inorganic material can be removed. Based on principle of sedimentation.

SKIMMING TANK -Greasy material can be removed using skimming tank which is divided into 3 compartments.

PRIMARY TREATMENTIt is aimed at removal of suspended organic solids that cannot be removed in preliminary treatment. It involves the process of sedimentation.Sedimentation is the separation from water by gravitational settling if suspended particles are heavier than waterSedimentation tank have inlet zone, settling zone, outlet zone, sludge zone.

Chemicals are added to aid sedimentation . Examples are alum, iron salts, lime etc.

SECONDARY/ BIOLOGICAL TREATMENTIt is required to remove dissolved and fine colloidal organic matter. This process involves the use of microorganisms that decompose the unstable organic matter to stable inorganic forms.

AEROBIC SUSPENDED GROWTH TREATMENT PROCESS

1) ACTIVATED SLUDGE PROCESS:- The sewage containing organic matter with microorganism is aerated in an aeration tank.

Advantage- cost effective, sludge has higher fertilizer value. organic matter + O2 CO2 + NH3 + H2O + new cells

2) AERATED LAGOONS :- They are also known as aerated ponds, are the facultative stabilization ponds wherein surface aerators are installed to overcome bad odors.

AEROBIC ATTACHED GROWTH TREATMENT PROCESS

1) TRICKLING FILTERS :- It has a bed of coarse, hard, porous material over which sewage is percolated or trickled and microorganisms attached to medium degrade the organic matter.

2) PACKED BED REACTORS:- A reactor is packed with a medium to which microorganism get attached and form biofilms.

ANAEROBIC SUSPENDED GROWTH TREATMENT PROCESSANAEROBIC DIGESTION :- Process is carried our in a air tight reactor.

It involves 3 stages namely hydrolysis, acidogenesis (clostridium sp. , cornybacterium ), methanogeneis (methanococci, methanobacillus).

ANAEROBIC ATTACHED GROWTH TREATMENT PROCESS ANAEROBIC FILTER PROCESS:- Consist of column fitted with solid media for treatment of organic matter in sewage.

Due to solid media bacterium is retained in the column.

POND PROCESS Pond process treatment is carried out in a specially designed and constructed ponds called stabilization ponds which are large and shallow.a) Aerobic :- They contain bacteria and algae in suspension and they show symbiotic

relationship.b) Anaerobic :- Useful for treatment of high strength organic matter and solid containing

sewage water.c) Facultative ponds :- Combination of both aerobic and anaerobic process.

FACULTATIVE PONDS

TERTIARY TREATMENTOnly 1-2 % domestic sewage receives tertiary treatment which is the most advance phase of sewage treatment. The tertiary treatment is needed under the following circumstances

When the quality if effluent to be discharged does not meet the standard requirement.

When there is necessity to remove dissolved solids by ION EXCHANGERS.

To remove nitrogen and phosphorus.

To remove pathogenic organisms through DISINFECTION.

ION EXCHANGE METHOD:- Involves displacement of one ion by another. The exchange occurs between the ions of insoluble exchange material and ions of the different species in water sample. Two types are cation and anion exchangers.

CARBON ADSROPTION :- The main purpose of this process is to remove dissolved

organism compound from the effluent.

REMOVAL OF NITROGEN: Through nitrification and denitrification.

REMOVAL OF POHSOPHORUS:- Waste water is mixed with lime. This lime reacts with phosphorus containing compounds in the effluent to form insoluble calcium phosphate which settles at the bottom.

Broadly refers to the selective destruction or inactivation of disease causing organisms. The very purpose of disinfection is to control the various water borne diseases.Characteristic of ideal disinfectantToxic to pathogen at low concentration.

Soluble and stable in water.

Non toxic to man and higher organisms.

Cheap and easily available.

Agents :- chemical and radiation.

DISINFECTION

QUICK RECAP

REFERENCES

ENVIRONMENTAL BIOCHEMISTRY BY A K DEENVIRONMENTAL SCIENCE BY DANIEL D CHIRAS FUNDAMENTAL CONCEPTS OF ENVIRONMENTAL CHEMISTRY BY SODHI

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