WATER POLLUTION AND ITS CONTROL
$\displaystyle \small \bullet$ Human beings have been abusing the water-bodies around the world by using them for disposal of all kinds of waste.
$\displaystyle \small \bullet$ Due to improper disposal activities of human kind the ponds, lakes, stream, rivers, estuaries and oceans are becoming polluted in several parts of the world.
$\displaystyle \small \bullet$ The Government of India has passed the Water (Prevention and Control of Pollution) Act, 1974 to safeguard our water resources.

Domestic Sewage and Industrial Effluents
$\displaystyle \small \bullet$ Sewage is a domestic wastes containing large amount of waste organic matters including human fecal matter and microbes.
$\displaystyle \small \bullet$ A mere 0.1% impurities make domestic sewage unfit for human use.
$\displaystyle \small \bullet$ Sewage contains dissolved salts such as nitrates, phosphates, and other nutrients and toxic metal ions and organic compounds.
$\displaystyle \small \bullet$ Composition of waste water
Suspended solids: Sand, silt, clay etc.
Colloidal materials: Faecal matter, bacteria, cloth, paper fibres etc.
Dissolved materials: Nutrients like nitrate, NH3, phosphate, Na, Ca etc.
$\displaystyle \small \bullet$ The amount of organic matter in sewage water is estimated by measuring Biochemical Oxygen Demand (BOD).
$\displaystyle \small \bullet$ BOD is defined as the amount of Oxygen required for oxidizing all organic matter present in one liter of water by the aerobic microbes.
$\displaystyle \small \bullet$ When the amount of waste is more, then the BOD value is also more. Thus BOD values indicate the degree of water pollution.
$\displaystyle \small \bullet$ During bio-degradation, microbes consume $\displaystyle O_{2}$. It results in a sharp decline in dissolved $\displaystyle O_{2}$. This causes death of aquatic organisms.
$\displaystyle \small \bullet$ Presence of large amounts of nutrients in waters also causes excessive growth of planktonic (free- floating) algae, called an algal bloom.
$\displaystyle \small \bullet$ Algal bloom imparts a distinct colour to the water bodies.
$\displaystyle \small \bullet$ It cause deterioration of the water quality and fish mortality.
$\displaystyle \small \bullet$ Some bloom-forming algae are extremely toxic to human beings and animals.
$\displaystyle \small \bullet$ The world’s most problematic aquatic weed is water hyacinth (Eichornia crassipes) called “Terror of Bengal” introduced to India for their beautiful mauve-colored flowers. Their excessive growth causes blocks in our waterways. They grow faster than our ability to remove them.
$\displaystyle \small \bullet$ They grow abundantly in eutrophic water bodies, and lead to an imbalance in the ecosystem dynamics of the water body.

Sewage Associated with Diseases
$\displaystyle \small \bullet$ Sewage from homes & hospitals contain pathogens that cause dysentery, typhoid, jaundice, cholera, etc.   
$\displaystyle \small \bullet$ Industrial waste water contains toxic substances like DDT, heavy metals (mercury, cadmium, copper, lead, etc.) and organic compounds.

Biomagnification
$\displaystyle \small \bullet$ “Increase in concentration of the toxicant or non-bio-degradable pollutants at successive trophic levels”.
$\displaystyle \small \bullet$ A  toxic  substance  accumulated  by  an  organism  cannot  be metabolized or excreted.
$\displaystyle \small \bullet$ The accumulated toxic passed on to the next higher trophic level. This phenomenon is well-known for mercury and DDT.
$\displaystyle \small \bullet$ The concentration of DDT is increased at successive trophic levels; say if it starts at 0.003 ppb (ppb = parts per billion) in water, it can ultimately reach 25 ppm (ppm = parts per million) in fish-eating birds, through biomagnification.
$\displaystyle \small \bullet$ High concentrations of DDT disturb calcium metabolism in birds, which causes thinning of eggshell and their premature breaking, eventually causing decline in bird populations.

Eutrophication
“The process of nutrient enrichment of water and consequent loss of species diversity is referred to as Eutrophication”  or “Eutrophication is the natural aging of a lake by biological enrichment of its water”.

Natural Eutrophication
$\displaystyle \small \bullet$ In a young lake the water is cold and clear, supporting little life.
$\displaystyle \small \bullet$ With time, streams draining into the lake introduce nutrients such as nitrogen and phosphorus.
$\displaystyle \small \bullet$ Increase in nutrient encourages the growth of aquatic organisms.
$\displaystyle \small \bullet$ As the lake’s fertility increases, plant and animal life burgeons, and organic remains begin to be deposited on the lake bottom.
$\displaystyle \small \bullet$ Over the centuries, as silt and organic debris pile up, the lake grows shallower and warmer.
$\displaystyle \small \bullet$ Warm-water organisms dominate over that thrive in a cold environment.
$\displaystyle \small \bullet$ Marsh plants take root in the shallows and begin to fill in the original lake basin.
$\displaystyle \small \bullet$ Eventually, the lake gives way to large masses of floating plants (bog), finally converting into land.
$\displaystyle \small \bullet$ Depending on climate, size of the lake and other factors, the natural aging of a lake may span thousands of years.
$\displaystyle \small \bullet$ Pollutants from man’s activities (Anthropocentric) like effluents from the industries and homes can radically accelerate the aging process. This phenomenon has been called Cultural or Accelerated Eutrophication.
 
Effects
$\displaystyle \small \bullet$ They overstimulate the growth of algae. It causes unsightly scum and unpleasant odors, and robs the water of dissolved oxygen. It leads to death of other organisms.
$\displaystyle \small \bullet$ At the same time, other pollutants flowing into a lake may poison whole populations of fish, whose decomposing remains further deplete the water’s dissolved oxygen content.

THERMAL POLLUTION OF WATER
$\displaystyle \small \bullet$ Warming up of an aquatic ecosystem to the point, where desirable organisms are adversely affected.
Causes
$\displaystyle \small \bullet$ Heated (thermal) wastewaters flowing out of electricity-generating units, e.g., thermal power plants, constitute another important category of pollutants.
Effects
$\displaystyle \small \bullet$ Thermal  wastewater  eliminates  or  reduces  the  number  of  organisms  sensitive  to  high temperature.
$\displaystyle \small \bullet$ It may enhance the growth of plants and fish in extremely cold areas but, only after causing damage to the indigenous flora and fauna.

A Case Study of Integrated Waste Water Treatment
$\displaystyle \small \bullet$ Wastewater including sewage can be treated in an integrated manner, by utilizing a mix of artificial and natural processes.
$\displaystyle \small \bullet$ An example of such an initiative is the town of Arcata, situated along the northern coast of California.
$\displaystyle \small \bullet$ Collaborating with biologists from the Humboldt State University, the townspeople created an integrated waste water treatment process within a natural system.
$\displaystyle \small \bullet$ The cleaning occurs in two stages
(a) the conventional sedimentation, filtering and chlorine treatments are given.
(b) the biologists developed a series of six connected marshes over 60 hectares of marshland. $\displaystyle \small \bullet$ Appropriate plants, algae, fungi and bacteria were seeded into this area, which neutralize, absorb and assimilate the pollutants. Thus, as the water flows through marshes, it gets purified naturally.
$\displaystyle \small \bullet$ The marshes also constitute a sanctuary, with a high level of biodiversity in the form of fishes, animals and birds that now reside there.
$\displaystyle \small \bullet$ A citizens group called Friends of the Arcata Marsh (FOAM) are responsible for the upkeep and safeguarding of this wonderful project.

Ecological Sanitation
$\displaystyle \small \bullet$ Ecological sanitation is a sustainable system for handling human excreta, using dry composting toilets.
$\displaystyle \small \bullet$ This is a practical, hygienic, efficient and cost-effective solution to human waste disposal.
$\displaystyle \small \bullet$ With this composting method, human excreta can be recycled into a resource (as natural fertilizer), which reduces the need for chemical fertilizers.
$\displaystyle \small \bullet$ ‘EcoSan’ toilets are being used in many areas of Kerala and Sri Lanka.

SOLID WASTES
$\displaystyle \small \bullet$ Solid wastes refer to everything that goes out in trash.
$\displaystyle \small \bullet$ Municipal solid wastes are wastes from homes, offices, stores, schools, hospitals, etc., that are collected and disposed by the municipality.
$\displaystyle \small \bullet$ The municipal solid wastes generally comprise paper, food wastes, plastics, glass, metals, rubber, leather, textile, etc.
$\displaystyle \small \bullet$ Burning reduces the volume of the wastes, although it is generally not burnt to completion and open dumps often serve as the breeding ground for rats and flies.
$\displaystyle \small \bullet$ Sanitary  landfills:  Wastes  are  dumped  in  a  depression  or  trench  after  compaction  (depth compression or condensation), and covered with dirt every day. These were adopted as the substitute for open-burning dumps.
Disadvantages
$\displaystyle \small \bullet$ Shortage of space for huge garbage’s.
$\displaystyle \small \bullet$ Danger of seepage of chemicals, etc., from these landfills polluting the underground water resources.

Solution to Solid Wastes
$\displaystyle \small \bullet$ All waste that we generate can be categorized into three types –
(a) Bio-degradable
(b) Recyclable
(c) Non-biodegradable
$\displaystyle \small \bullet$ It is important that all garbage generated is sorted.
$\displaystyle \small \bullet$ It can be reused or recycled if separated out; kabadiwallahs and rag-pickers do a great job of separation of materials for recycling.
$\displaystyle \small \bullet$ The biodegradable materials can be put into deep pits in the ground and be left for natural breakdown.
$\displaystyle \small \bullet$ Only non-biodegradable wastes are left and required to be disposed.
$\displaystyle \small \bullet$ Hospital wastes contain disinfectants, harmful chemicals, and pathogenic micro-organisms. They are incinerated.
$\displaystyle \small \bullet$ E-wastes (electronic wastes):
$\displaystyle \small \bullet$ All irreparable electronic goods are known as e-wastes.
$\displaystyle \small \bullet$ They are buried in landfills or incinerated.
$\displaystyle \small \bullet$ Recycling is the only eco-friendly solution for the treatment of e-wastes. But during recycling, the workers are exposed to toxic substances present in e-wastes.
$\displaystyle \small \bullet$ Over half of the e-wastes in developed world are exported to developing countries (China, India, Pakistan etc.), where many metals (Cu, Fe, Si, Ni & Au) are recovered during recycling process.

Prevention
$\displaystyle \small \bullet$ The need to reduce our garbage generation should be a prime goal.
$\displaystyle \small \bullet$ Governments across the country are trying to push for reduction in use of plastics and use of eco- friendly packaging.
$\displaystyle \small \bullet$ Carrying cloth or other natural fibre carry-bags when we go shopping and by refusing polythene bags.
$\displaystyle \small \bullet$ Case Study of Remedy for Plastic Waste:
$\displaystyle \small \bullet$ A plastic sack manufacturer in Bangalore has managed to find the ideal solution to the ever- increasing problem of accumulating plastic waste.
$\displaystyle \small \bullet$ Ahmed Khan, aged 57 years old, has been producing plastic sacks for 20 years. About 8 years ago, he realized that plastic waste was a real problem.
$\displaystyle \small \bullet$ Polyblend, a fine powder of recycled modified plastic, was developed then by his company.
$\displaystyle \small \bullet$ Polyblend mixture is mixed with the bitumen that is used to lay roads.
$\displaystyle \small \bullet$ In collaboration with R.V.College of Engineering and the Bangalore City Corporation, Ahmed Khan proved that blends of Polyblend and bitumen, enhanced the bitumen’s water repellent properties, and helped to increase road life by a factor of three.
$\displaystyle \small \bullet$ The raw material for creating Polyblend is any plastic film waste.
$\displaystyle \small \bullet$ So, against the price of Rs. 0.40 per kg that rag pickers had been getting for plastic waste, Khan now offers Rs.6.
$\displaystyle \small \bullet$ Using Khan’s technique, by the year 2002, more than 40 kms of road in Bangalore has already been laid.
$\displaystyle \small \bullet$ At this rate, Khan will soon be running short of plastic waste in Bangalore, to produce Polyblend.

Agro-chemicals and their effects
$\displaystyle \small \bullet$ Use of inorganic fertilizers and pesticides has increased manifold for enhancing crop production.
$\displaystyle \small \bullet$ Pesticides, herbicides, fungicides, etc., are being increasingly used.
$\displaystyle \small \bullet$ These are toxic to non-target organisms that are important components of the soil ecosystem.
$\displaystyle \small \bullet$ Increasing amounts of artificial fertilizers in aquatic ecosystems causes eutrophication.

Case Study of Organic Farming
$\displaystyle \small \bullet$ Integrated organic farming is a cyclical, zero-waste procedure, where waste products from one process are cycled in as nutrients for other processes.
$\displaystyle \small \bullet$ Maximum utilization of resources and increases the efficiency of production.
$\displaystyle \small \bullet$ Ramesh Chandra Dagar, a farmer in Sonipat, Haryana, includes bee-keeping, dairy management, water harvesting, composting and agriculture in a chain of processes, which support each other and allow an extremely economical and sustainable venture.

Advantages
$\displaystyle \small \bullet$ There is no need to use chemical fertilizers for crops.
$\displaystyle \small \bullet$ Cattle excreta (dung) are used as manure.
$\displaystyle \small \bullet$ Crop waste is used to create compost, which can be used as a natural fertilizer or can be used to generate natural gas for satisfying the energy needs of the farm.
$\displaystyle \small \bullet$ Enthusiastic about spreading information and help on the practice of integrated organic farming, Dagar has created the Haryana Kisan Welfare Club, with a current membership of 5000 farmers.