INTRODUCTION
Water is spread on two third of the earth but most of the water is not useful for directhuman consumption. It is available as ice on the poles and the glaciers with a percentageof 2.14. The largest store is ocean with useless saline, brackish water (total dissolved solidsmore than 50000 ppm) having 97.24 per cent of total water. The total available freshwater (that can be used for irrigation and drinking) is 0.62 per cent. This fresh wateris distributed in surface sources (rivers, lakes etc), ground water (shallow and deep), soilmoisture and vapour in atmosphere. The surface water is only 1.5% of the total freshwater and most of the fresh water is the ground water. So the surface water is somethingaround 0.01% of the total water. Because of its easy availability the surface water had been the main source of water for irrigation and drinking purposes. That is why all theold civilizations started on the banks of rivers. We gave a high respect to the rivers asmother Ganges, to show our gratitude for their blessings of water, the basic requirementof human life. Whenever a new planet is discovered we check if signs of water are there,and if yes, then we assume that life could be there.This scarce limited water is becoming useless because of the human activity (pollution)and that is the main concern of study of water pollution.
WATER RESOURCES
The various sources of water, which can be harnessed economically, can be dividedinto the following two categories:-
(A)Surface sources such asSurface sources such asSurface sources such asSurface sources such asSurface sources such as
(i)Ponds and lakes
(ii)Streams and rivers(iii)Storage resources (dams)
(B)Subsurface or underground sources such asSubsurface or underground sources such asSubsurface or underground sources such asSubsurface or underground sources such asSubsurface or underground sources such as
(i)Springs(ii)Wells (open and tube-wells)
All of the above water resources are replenished by precipitation in various formslike rain, snow, hail, dew etc. Rainfall is the main source and forms the major constituentof the hydrological cycle. Water gets evaporated from the various exposed bodies ofwater depending upon the climatic factors like temperature, R.H. and the wind speed.RH or the relative humidity is the ratio of the amount of water vapour present in theair to the maximum amount of vapour that air can hold at that given temperature.Actually, air can hold only a fixed amount of water vapour at a given temperature.As the temperature goes up, the moisture retaining capacity increases and as thetemperature goes down, it reduces. That is the reason, why dew is formed at nightwhen the temperature of the air falls down, and at that reduced temperature, the extramoisture (more than its capacity at that temperature comes out and is condensed inthe form of dew). So if, for example, air can hold 3 gms of water vapour per Kg ofair at 20°C and the moisture present in any sample of air (at this temperature) is 1.5gms per Kg of air, then its RH will be- 50%. Lesser the RH of the air, higher the rateof evaporation as there is more deficits to be met with. Similarly, more is the differenceof temperature (air and water) higher will be the rate of evaporation. Same is true withwind speed. Like this, depending upon the climatic factors, evaporation shall take place.The yearly evaporation from an exposed body of water in North India may be 1.7mper year. The trees extract the subsoil water and during their breathing process, theyexhale water vapours into the atmosphere. This process is known as transpiration andthe combined process of evaporation and transpiration is known as ‘evapotranspiration’.
BASICS OF THE WATER SUPPLY SCHEMES
This will enable to understand the root cause of water pollution
Actually wherever a water supply scheme is framed (scheme means a system to drawwater from suitable source, treat it and then supply it to the consumers) a comparisonis made between all the possible solutions. Preference is given to the nearest possiblesource as the conveyance of water is very costly. The underground water is generally pure (from suspended impurities point of view because of natural filtration) but containsmore dissolved salts. The lifting of water (pumping out from wells) also requires energy(electricity) whereas the filtration of surface water is a costly affair. So the environmentalengineers in the public health engineering departments (water works) make schemes(plans) to supply potable (fit for drinking from all points of view, i.e. clarity, dissolvedsalts, and free from bacteria etc.) water to the consumers. The schemes are basicallyof two types,rural water supply schemesrural water supply schemesrural water supply schemesrural water supply schemesrural water supply schemes andurban water supply schemesurban water supply schemesurban water supply schemesurban water supply schemesurban water supply schemes dependingupon the population of the habitation. The standards for the two types are different.For example the designed rate of water supply per person per day in rural areas is only40 litres (except the 11 desert districts of Rajasthan where it is 70 L.P.C.D. includingthe cattle water demand). The designed rate of water supply for urban area is minimum135 L.P.C.D. and above for industrial and commercial demands depending upon thepopulation of the city. Similarly, the availability of electricity in rural area is assumedas 8 hours per day whereas it is 20-22 hours per day in urban area. The rate of increaseof population is also different in rural and urban area for forecasting the populationfor the designed period.The next criteria is the source. Generally when there is no water or the quality ofwater available at some place is not fit for drinking or its harnessing is not economicaL (very deep),water is pumped through pipe lines or conveyed through canals fromdistant places. For example water is carried through 204 km long Rajeev Gandhi LiftCanal originating from R.D 1109 of Indira Gandhi Main Canal in Rajasthan for Jodhpurcity and many enroute villages. The Indira Gandhi Main Canal originates from Hari-Ke Barrage and flows by gravity for about 600 km. The water in Rajeev Gandhi Liftcanal is lifted at 8 places for about 200 meters for conveying it to Jodhpur. This involvesa great expenditure on electricity, construction and maintenance of canal. Some portionof this canal is made up of mild steel pipes where the construction of canal was noteconomical. So all these aspects like surety of availability of water, quality of water,cost of treatment, cost of supply etc. are to be considered before making a final decision.Some of the water supply schemes are as follows:
(i) Traditional Source scheme: Traditional Source scheme: Traditional Source scheme: Traditional Source scheme: Traditional Source scheme:
In this scheme the traditional source of the watersupply already existing in the village like an open well or the pond is electrified andpumping machinery is installed. The pumped water is distributed to the villagers bythe existing small tanks near the wells. After commissioning the scheme it was handedover to the villagers to run at their own cost through the Panchayats (local bodies ofthe villages). But the schemes were not run by them successfully due to lack of interestand money. Government of Rajasthan has started a new project namely ‘Swajaldhara’in which the villagers frame their own water supply schemes and pay 10% of the costto the government. Government pay 90% and get the scheme executed and hand itover to the villagers to run it at their own cost under the guidance of the government.Many N.G.Os (Non-Governmental Organizations made voluntarily for the service ofthe society) help them for this purpose. At present this is running well in some districtsof Rajasthan.
(ii) Pump and Tank Schemes: Pump and Tank Schemes: Pump and Tank Schemes: Pump and Tank Schemes: Pump and Tank Schemes:
In these schemes the government public healthdepartments develop a source in the village itself. It may be an open well or a tube-well generally. One ground level reservoir (G.L.R.) is constructed and the pump installedon the source fills water in this tank. Public stand posts (P.S.Ps) are constructed by thesides of this GLR and public is allowed to fetch water from herefree of costfree of costfree of costfree of costfree of cost but nohose connections are given.
(iii) Regional Water Supply Schemes: Regional Water Supply Schemes: Regional Water Supply Schemes: Regional Water Supply Schemes: Regional Water Supply Schemes:
When there is no feasible source of water ina village (water may be very deep or saline), then the water has to be carried fromdistant places like some other village well with enough potable water or some canalor river. So this is a combined scheme of many villages. Pipe lines have to be laid tocarry water from the source to the benefited villages. So it is a costlier option. Wateris generally supplied at one or two points in the villages free of cost. Some timesconnections to individual houses are also given depending upon the population andthe paying capacity and willingness of the consumers. There are some regional watersupply schemes which cater the needs of hundreds of villages alongwith the urbantowns in Rajasthan like the Rajeev Gandhi lift canal water supply scheme, Ganddheli–Sahawa scheme, Bisalpur Ajmer, Jaipur scheme and many others. The Rajeev Gandhi Scheme originates from RD1109 of Indira Gandhi Main Canal, constructed andmaintained by the Irrigation Department of Rajasthan. The Public Health EngineeringDepartment of Rajasthan (PHED or more commonly known as Water Works) hasconstructed about 204 Km long Rajeev Gandhi lift canal. In this water is lifted at 8places before it reaches to Jodhpur so it is known as a lift canal. The discharge in thefirst phase was about 200 cusecs which has been raised in the second phase for theincreased population and addition of more and more villages. This is one example ofa big Reg. Water Supply Scheme. Thousands of other Reg.W.S.S are running in Rajasthan because generally either there is no water or sline, brackish, fluoride water is there inmost of the villages of Rajasthan. This option is very costly because of the capital costof long lengths of conveying mains (canal or pipes), maintenance cost and the electricitycost of pumping in lifting of water. As a primary estimate the cost of raw water inRajeev Gandhi lift canal comes as Rs. 40 per thousand litres and the government chargesat the uniform rate of Rs. 4 per thousand litres from the average domestic consumer.One should realize it and conserve water.
(iv)Piped Water Supply Schemes: Piped Water Supply Schemes: Piped Water Supply Schemes: Piped Water Supply Schemes: Piped Water Supply Schemes:
These are generally for towns or big villages(urban areas). In these schemes house connections are given and the consumption ischarged. The source may be in the locality or a distance source ( like Rajeev Gandhilift canal for Jodhpur). R.C.C. Overhead tanks known as elevated service reservoirs(E.S.R) are constructed for the distribution of water through the distribution mains. Firstof all the raw water is treated by all means including disinfection (most important).Then pumped to ESRs and then distributed either for the whole day or at certain fixedtime. The consumption is generally metered and charged on monthly basis. After someyears the existing water supply schemes are reframed and executed. Such schemes areknown as Reorganized Water Supply Schemes.
(v)Urban Water Supply Schemes: Urban Water Supply Schemes: Urban Water Supply Schemes: Urban Water Supply Schemes: Urban Water Supply Schemes:
These are the schemes implemented for the urbanareas. The main difference of urban and rural area is the population. Generally morethan 10000 population is considered as urban area. The main difference in design of ruraland urban water supply scheme is the rate of water supply. The design rate of watersupply in rural areas as per the governments norms is 40 litres per capita per day exceptthe 11 desert districts of Rajasthan for which it is 70 LPCD (including the cattle waterdemand). For urban area the rate is 135 litres minimum and it increases with thepopulation. The other main difference is the house connections. In most of the rural watersupply schemes water is supplied at a common point and people have to fetch it fromthis common place also known as public stand post. In urban water supply schemes everyhouse is given a metered or flat rate service connection through which water is generallysupplied intermittently (say twice in a day). The water obtained from a surface or groundsource is treated and lifted in an elevated service reservoir. Then it is distributed througha properly designed and maintained distribution system. Though some of it is wastedin leakages but the loss should not be more than 10%. The water is also supplied for industrial and commercial purposes. Some of the water is always stored for fire fighting.As there is a depletion of ground water, and uncertainty of rainfall due to global warmingand other reasons, it has become very difficult to maintain the urban water supplyschemes these days
Replies
HI !
mANY MANY THANKS FOR UR SUGGESTION.
Ratnakar Pandey said:
Thanks sir it was useful information.can anybody share their views on advanced waste water treatment technology like MBR Technology ..
Dear Binay,
Thanks for sharing,i would suggest you to pl.put this kind of article under the head of books, documents & papers inspite of ideas for innovation.
Since you are with state pollution control board hence I would also request you to pl. pour/share your experiences for common breach/violation of law (AP&CP,WP&CP,Water cess act etc.) by the industries/project proponent & how it can be countered within the legal framework.
Thanks & Regards
Ratnakar Pandey
thnks for sharing the information this is very useful sir
Sir,
Thanks a lot for sharing the valuable info. but information regarding the subject matter is not available kindly do write something on this topic.
Regards,
Radhika Buwa.
Thanks a lot for sharing valuable information on Water Pollution.
Thanks for the info
thanks sir for sharing such type of valuable information ...........