SOURCES AND CLASSIFICATION OF WATER POLLUTANTS

Dr(Smt) Shanti Vaidya

Senior Research Officer, Chemistry Division,

CW&PRS, Khadakwasla R.S. PUNE, India 411024

WATER is essential for our existence. GOOD and ADEQUATE water is essential for the comfortable and happy living.

The national building code (NBC) as well as the Indian Standards (IS-1172)  assume the requirement of water per person per day to be 135 ltrs. (about 9 buckets) for hygienic living.  The NBC reckons a family to be made up of 5 members on an average. Of this total requirement of 135 ltrs., the quantum needed for cooking and drinking purposes is only about 10 – 15 ltrs.; a substantial portion (about 40 – 45 ltrs.)  goes for flushing the water closets. The rest goes for bathing (30 ltrs.), washing of clothes (15 – 20ltrs), vessels (10 – 15ltrs.), floors (5 ltrs), etc. The portion needed for cooking and drinking at least has to be absolutely free of any pollution.

Of the four Metropolitan cities, viz., New Delhi, Bombay, Calcutta and Madras, only the capital city is able to supply the requisite per captia quantity of treated water. Bombay falls a little short, whereas in Calcutta and Madras, the supply is woefully inadequate, with the Madras Metropolitan Water Supply & Sewerage Board (MMWSSB) itself admitting to a supply of only 78ltrs. per captia which is the smallest quantity supplied in any metropolitan town or city in India.

What is water pollution ?

To pollute is to “make unfit for or harmful to living things, especially by the addition of waste matter”.

1. a) Any Physical or Chemical change in water that can adversely affect humans and organisms.
2. b) Any departure from purity. Better expressed, any  departure from normalcy.
3. c) The addition to water of an excess of material or heat that is harmful to humans, animals, desirable aquatic life or otherwise causes significant  departure   from   normal activities  of various living communities in or near a  water body.

Ever-increasing population and the consequent urbanization and industrialization have mounted serious environmental pressures on these ecosystems and have affected them to such an extent that their benefits have declined significantly. This is particularly grave for water resources. e.g in Bangalore city, studies revealed a nearly 35% decrease in the number of bodies of water during 1973 to 1996. Thus, water the most precious natural resource is the most  USED  and ABUSED resource.

For a suitable restoration action plan, recycling, reuse, recharge are the key words. The knowledge about the characterization of the type and source of pollutants entering the ecosystem can help us device a good restoration plan.  Investigation of the physico-chemical and biological parameters in this regard helps in assessing the status, which is required for evolving appropriate restoration methods towards conservation and management.

Water pollution : How ?  From where i.e. Sources:

Many natural processes like sedimentation, growth of pathogenic organisms, leaching cause water pollution. An  excess of natural processes like tsunami left near-coast lands saline. But the most effective and continuous phenomenon are human activities that cause pollution of all types of waterbodies like  rivers,  lakes,  marshes,  ground  water  and  coastal waters. Pollution then becomes an issue of intensity, the quantity and quality of the pollutant being more important than whether it was generated by natural processes or industrial processes.  Discharging various  wastes in and near a waterbody  causes  pollution of  that waterbody. Wastes   from   following operations cause pollution.

• Domestic waste
• Sewage
• Mining
• Agriculture : This sector uses 70% of total water use in India.
• Stock Breeding
• Fisheries
• Forestry
• Urban human activities
• Construction works
• Industries : This sector uses 8% to 50% of total water use.

Which water is pure water ?

Varied beneficial uses of water require different levels  of  minimum  purity.  Water is suitable for  certain  designated use  if it complies certain crieteria.  Classes A to E are defined by Central Pollution Control Board (CPCB) in 1991.

Tolerance Limits For Inland Surface Water

Class A : For Domestic  Supply  After   Disinfection

Class  B : For Outdoor  Bathing

Class  C : For Domestic Supply After Conventional Treatment  And Disinfection

Class D : For Wild Life And Fisheries

Class  E : For Irrigation, Industrial Cooling,  Controlled  Waste  Disposal

Water Quality Parameters

Which substances can be called pollutant ?

As  per definitions above, any excess of material or heat,  thus  following are some such pollutants:

• Gases CO₂, O₂, N₂
• Dust suspension
• Metals
• Bacteria
• Heat
• Organic substances
• Inorganic substances

A report of CPCB study conducted in 1984 concluded that 75%  pollution  of  rivers is caused  by  discharge  of  UNTREATED  MUNICIPAL  WASTE/SEWAGE  from  large  and  medium towns.  Remaining 25% is due to discharge of partly treated  or untreated EFFLUENTS from INDUSTRY. This certainly is not very encouraging.

Classification of water pollutants

1) Depending on nature of polluting activity:

1. a) Natural surface water run off.
2. b) Dissolved chemical that percolates through soil, causes ground water pollution –
3. c) Human sources like agriculture,  mining,  construction, industry, homes and business – all cause water pollution –

2) Depending upon the pattern of entry :

1. a) Point source which is identifiable and hence comparatively easy to control. e.g. Sewage, storm-water, Industrial effluent, animal feed-lots.
2. b) Non-point source which is widely spread out, diffused and hence difficult to identify and to control. e.g. agricultural run-off, Sediment run offs from natural or human caused forest fire, construction, logging, drainage of acids, minerals, sediments from   active/abandoned mines, oil-spills or spills of other hazardous material.

3) Depending upon the degradability or reactivity:

1. a) Biodegradable: Degraded by microbes in reasonable time say up to 1 month. These pollutants become a problem when added to the environment faster than they can decompose.

Biodegradable pollutants are of two types, rapidly degradable and slowly degradable. Rapidly degradable pollutants are ‘natural’, we put them somewhere until they degrade to non-toxic levels. Slowly degradable pollutants are materials that either do not decompose or decompose slowly in the natural environment. Once contamination occurs, it is difficult or impossible to remove these pollutants from the environment. E.g. synthetic compounds which resemble nothing natural, such as dichloro diphenyl trichloro ethane (DDT), dioxins, polychlorinated biphenyls (PCBs), and radioactive materials. They can reach dangerous levels of accumulation as they are passed, up the food chain into the bodies of progressively larger animals, e.g., molecules of toxic compounds may collect on the surface of aquatic plants without doing much damage to the plants. A small fish that grazes on these plants accumulates a high concentration of the toxin. Larger fish or other carnivores that eat the small fish will accumulate even greater, and possibly life-threatening, concentrations of the compound. This process is known as bioaccumulation. Such very slowly degradable pollutants are more problematic; we try to put them some place forever, because they will not degrade to non-toxic levels in a reasonable period of time.  Ultimately they seep back into the environment and create much havoc. Some special measures like advance oxidation systems are required to remove slowly degradable pollutants from wastewater. They are often difficult and expensive.

1. b) Non degradable pollutants are bacteria, virus, salts of metals, sediment fractions, heavy metals and the last PLASTICS. They are conservative like heat, a form of energy but certainly a pollutant.

4) Depending upon the effect intensity:

1. a) Acute : Such pollutants have an immediate and intense effect on the consumer.
2. b) Chronic or Long term : Such pollutants have slow but long term effects on consumers.

5) To Systematise more, the water pollutants are classified into nine categories:

1. Oxygen-demanding wastes
2. Disease causing agents
3. Plant nutrients
4. Synthetic organic compounds.
5. Oil
6. Inorganic chemicals and mineral substances
7. Sediments
8. Radioactive material
9. Heat (Thermal pollution)

1. Oxygen-demanding wastes: They are degradable by bacterial activity or strong acids/chemicals. Hence, cause depletion of dissolved oxygen. Most of them,  primarily   organic materials  hence,  get oxidized to CO₂ & H₂O. If degraded in anaerobic condition, give out foul odour and decrease  the usable  & recreational value of waterbodies. This process may cause fish kills & danger to other aquatic life, also affect colour, odour, taste of water.

Typically such pollutants come from sewage (domestic and animal), and industrial wastes.  The amount of such substances is estimated in water by quantity called Biochemical Oxygen Demand (BOD).

2. Disease causing agents: 75% – 80% infant deaths are caused by water borne diseases. Water has been a potential carrier of pathogens hence, causing epidemics of typhoid, para-typhoid, dysentery, cholera. Water also transmits diseases like polio and hepatitis. Modern disinfection and treatment plants have greatly reduced this danger in cities. Sewage and such discharge make the waterbody infected with such pathogens and that acts as source of this category of pollutants.

3. Plant Nutrients: For plant growth, nutrients are limiting factor. N  & P enter freshwater and lead to plant growth. When in excess, they cause eutrophication. They tend to accumulate in ground water. Excess concentration also renders water unsuitable for certain uses as they cause high BOD and disagreeable odours. Nutrient enrichment is a natural process (e.g. peat and muck soils or coal and oil deposits). Human activities hasten this leading to aging of lakes in shorter time.

N-P-K fertilizers applied in agriculture get into run off. Run off coefficient is a function of solubility of fertilizer, rate of absorption by plant, rate of decomposition. In the process excess nutrients flow to water and cause eutrophication.

4. Organic chemicals: Detergents (surfactant), pesticides, various industrial products, decomposition products. Some of them are toxic to fish at very low concentration, such as 1 ppm (phenol). Many are not biodegradable or very slowly degradable. Agrochemicals are some special chemicals which may be toxic to biota, human, extremely stable like DDT or have tendency to accumulate in animal and human body.

5. Oil : Production, distribution and use of huge quantities, result is contamination of water with oils. Some are accidental and some operational.

6. Inorganic chemical and mineral substances: Mineral acids, inorganic salts, metal compounds, which come through, smelting, metallurgical, chemical industries, mine drainage etc.. They may injure or kill fish and other aquatic life, may concentrate in food chain, e.g. Mercury. Inorganic mercury may be converted to methyl mercury CH₃Hg⁺ by certain anaerobic bacteria. This causes mercury poisoning.

Water draining to pyrite containing coal mines cause formation of acid (H₂SO₄).  This affects long stretches of streams, turns them acidic cause fish kills, corrosion of plumbing systems, boats, piers, related  structures  and  agricultural crop damage.

7. Sediments: There are soil and mineral particles, washed from land to waters, from croplands, unprotected forest soils, overgrazed pastures, strip mines roads and bulldozed urban areas. Sediments are able to:

• fill stream, channels and reservoirs.
• erode power turbines and pumping equipment
• cause turbidity hence perturb sunlight
• plug water filters
• blanket fish nests, spawn, food supplies to fish and shell fish.

Natural process of erosion causes sediments and its extent is a function of type of soil, geology, topography, precipitation and vegetation cover.

8. Radioactive materials: Wastes of Uranium and Thorium²³⁰ and Radium²²⁶ mining, refining from nuclear power plants, industrial, medical and scientific utlisation of radioactive material  cause  the   pollution. The  effects are lethal or mutagenic. Nuclear weapon tests also cause radio isotopes to come to air & soil and then in water.

The dust and debris of radioactive materials do not settle quickly after explosion hence, can contaminate air for long time. Hence, there is a proposal of Comprehensive Test Ban Treaty (CTBT). Accidental explosion of Chernobyl nuclear power plant caused such pollution.

Strontium⁹⁰ (Sr) (half life 28 years) is chemically similar to calcium. Hence, absorbed by plants and  passed  to  animals,  deposited  in  bones.  This may cause anemia or serious disorders. Cesium¹³⁷ (CS) is chemically similar to K. Hence, its contamination with leafy vegetable, grains cause disorders.

Type of pollutants caused by nuclear power generating plants:

1. Low level radioactive liquid wastes.
2. Heat.
3. Liquids and gaseous wastes from fuel.
4. Fission products within 1-3 years.
5. Heat :

Cooling water from power plants is released in river which  cause  risk  to fish life and other biota. This leads to starvation of newly spawned population, decreased density and viscosity of water, increase settling rate of suspended sediments, evaporation hence higher salinity and less DO. Today  70%  water  used in industries  is  used  as  cooling medium.

An additional threat  to aquatic life is  created  by  the common practice of chlorinating coolant water prior to use.  This is done to prevent bacterial growth that clog pipes.

What can we as individuals do?

1. a) We, as consumers, need to realise the value of water in the city and put in our whole hearted efforts to conserve and utilise available water very carefully.
2. b) We also need to avoid as much as possible the paving of the open areas around our flats to help percolation of rain water into the ground and replenishment of the water table.

Manohar Khushalani was a Panelist in a discussion on Niti Aayog report on Loksabha TV

https://www.business-standard.com/article/news-ani/no-drinking-water-will-be-available-by-2030-if-we-don-t-conserve-now-report-119062000071_1.html

It is beyond the shadow of a doubt that a healthy environment is the crucible in which human life and activity blossoms. Yet we all know that human activity is mauling and mutilating this crucible just like the woodcutter who is cutting the branch on which he is perched.

most vulnerable country to climate change.

It is election season and the manifestoes of political parties reflect their perceptions of the concerns of society at large. The manifestoes are drawn up carefully after large scale feedback. Yet inspite of the looming environmental crisis this critical concern is all but absent from manifestoes. That being the case it would be too much to expect drastic proactive action in favour of environmental conservation from the next government.

Just last week Iceland elected Ms.Katrin Jakobsdottir, a 41 year old environmentalist who is committed to clean energy, as Prime Minister. “As Chairwoman of the Left-Green Movement, a grass-roots organization that focuses on democratic socialist values, feminism, and environmentalism, Katrin has already taken big steps to move towards clean energy in Iceland.”

To expect a green manifesto is a cry in the wilderness. But if a political party were to devote a section of its manifesto to a green action plan then they could draw upon the following draft.

“On coming to power our party promises to the people of India that

The budgetary allocation of the Ministry of Environment would be raised from current 7% to 15% of the annual budget of the Central Govt. The enhanced budgets would not only increase the scope and depth of work undertaken but also vastly increase the monitoring and knowledge gathering and knowledge creation activity of the Ministry and its agencies

The legal and institutional framework for environmental protection and regulation would be strengthened. Specifically :

appointment and terms of service of members/Chairman of the National Green Tribunal leaving the original rules of appointment undisturbed

benches of the National Green Tribunal would be doubled progressively over 5 years

dilution of EIA notifications would be withdrawn. The quality of EIAs would be raised by rigourous scrutiny, rejection of shoddy EIAs, blacklisting of conniving EIA consultants

Forest Rights Act would be enforced without dilution and the pace implementation of forest dweller rights would be quickened while ensuring sympathetic hearing to their claims – strengthening the law – new laws – forest rights act, wetland rules, coastal zone management, rigorous implementation of existing rules

Dilutions to the Coastal Regulation Zone would be examined afresh as also the development oriented approach of the Island Development Agency which appears to have overridden environmental concerns of the several island territories.

strengthen the independence of institutions such as NBWL, FAC, WII and all regulatory and advisory agencies under the MoEF

implementation of existing rules would be done with greater rigour than ever before. For eg. the capacities and performance of CPCB and State Pollution Control Boards would be greatly strengthened

Carbon neutrality : The Govt. would aim to achieve carbon neutrality by progressively reducing carbon intensity of the economy. The Govt. would aim to outdo its Intended Nationally Determined Contributions (INDCs) and attain carbon neutrality by 2050

Coal fired plants will be gradually phased out so that our virgin forests can be protected as no go areas

dispersed green cover. The spatial dimensions of this cover would follow earlier distribution of forests so as to maintain a continuity in climatic and weather patterns

tree cover on private lands. Presently, other than commercial tree plantations there are several disincentives to grow a diverse tree cover on private lands. This would also include emphasis on promoting agro-forestry.

Rain is the only source of water on the subcontinent. The winter monsoon has almost disappeared whereas the reliability of the summer monsoon does not have the same certainity as before with more frequent El Nino events. The Govt. will promote urgent research on the monsoon phenomena, not merely about forecasting, but about increasing its reliability

Rivers are the life-giving arteries of the country. Yet they are becoming anaemic before our very eyes. The present focus on pollution is a comparatively smaller problem which has a technological fix and can be resolved can be resolved by appropriate capital expenditures. The revival of flows in rivers and streams is a far more complex issue amenable to appropriate stern remedies and only in the long term. Here the Govt. would :

Promote basin management at all orders of streams. The basin approach would optimize the use of intra basin resources such as rainfall, surface and subsurface resources, recycled waters on the supply side while the demand side management would enhance efficiencies in water use in agriculture, industry and domestic sectors

floodplain protection the Ganga Authorities Notification, 2016 would be extended to all rivers upto 2^nd order streams

v All relevant social statistics, economic statistics, scientific data, natural resource data would be collected at least at the level of 3^rd and perhaps 2^nd order streams

Irrigation is the sector where 80% of India’s water is used. If this can be significantly curtailed water diversion from rivers can be substantially reduced as also ground water extraction. Several technological and agronomic practices can increase crop productivity while reducing water input. The Govt. will take up this thrust on a war footing

free flowing rivers and, as efficiencies increase, would examine decommissioning of various dams and barrages

Urban water efficiencies would be enhanced and the individual water supply norm per capita would be brought down progressively to below 100 lpcd over next 5 years. Recycling and demand management practices would be given preference over fresh water supply side solutions. Ultimately smart cities would sustain themselves on an almost closed loop of local water resources

v Research would be promoted to incorporate dry toilet systems to almost eliminate the requirement of flushing water and eliminate sewage and centralized sewage treatment plants. Decentralized sewage treatment plants having nature based solutions would be promoted

Wetlands provide several critical eco-system services. Yet the loss of wetlands to encroachments and reclamation continues unabated. The countries network of wetlands will be protected by :

o Strengthening the Wetland [Conservation and Management] Rules 2010 enhancing their applicability to all wetlands noted in National Wetland Atlas as required by Supreme Court ruling of February, 2017

o Wetlands not included in the National Wetland Atlas would also be given a legal protection

o A sub-continent sized country can have thousands of Ramsar sites. India has only 27. Work in identifying and notifying more sites would be expedited. Pragmatic management plans would be drawn up for these sites which would have Lake Management Authorities with overriding powers on the lines of Chilika Lake Development Authority.

v wetlands – aquifers sanctuaries– traditional water management openness of data wetlands

Groundwater meets a majority of irrigation and domestic consumption needs. India has the dubious distinction of being the largest user of groundwater in the world racing to exhaust its aquifers. Management and sustainability of aquifers and springs would now on be considered in conjunction with surface water as advised in the Mihir Shah report. Groundwater sanctuaries and good recharge zones would be protected from contrarian landuse especially in the course of urbanization and infrastructure development. The budget for groundwater monitoring and management would be stepped up

Agriculture Sector – here it is proposed to shift MSP support towards the lesser grains and millets which consume less water. Water saving technology and agronomic practices would be supported vigourously. The use of traditional seeds, crop diversity, organic inputs, improvement of exhausted soils, enhancement of pollinator diversity and populations, increased acreage under agro-forestry, elimination of chemical inputs would be thrust areas. Sikkim’s success in becoming 100% organic would be a bench mark for other states.

Wildlife – improvement of habitat and prey base in existing Protected Areas would be stressed. The growing man-animal conflict would have to be addressed even as humans and wildlife adapt to being at closer quarters. More protected areas and corridor connectivity would be given priority in the landscape as well as the urbanscape

urban areas would stress on more humane character with greater play of natural elements such as habitats, urban forests, urban agriculture, groundwater recharge, conservation of waterbodies, macro-water harvesting, larger percentage of area under green cover.

Tree Cover – current norms allow tree cutting by replacement with larger numbers of trees. In actual practice this encourages small canopy trees in order to meet the number requirement. This would be revised to replace the canopy cover lost by a greater extent of canopy cover. In Himalayas the tree cover would be densified to promote cooler temperatures especially close to the tree line

XVI. Achievement of Indian National Biodiversity Targets, SDGs, Aichi Targets would be biodiversity targets would be pushed vigourously. Towards this end ecologists would be attached to various decision making bodies on a regular basis such as in Ministries, Departments, Boards, PSUs, Planning Departments, District Planning Committees, urban development authorities, local bodies and panchayats

air emissions is already being addressed by a variety of techniques and technologies including promoting mass transport, NMVs, electrical vehicles. The Govt. would energize these efforts

If political parties could include the above statement of intentions in their manifestoes they would emerge as being truly sensitive to the well being of India.