Delhi, The biggest culprit
"Round-the-clock monitoring by a network of zonal laboratories and a central laboratory ensures water quality. In Delhi, where people are very vocal, we cannot afford to be lax even for a moment," claims a dwssdu spokesperson. However, Delhi itself is the Yamuna's biggest polluter. "The stretch in the vicinity of Delhi (between Delhi and the Chambal confluence) is highly degraded and not fit for any designated use," says the cpcb's 1996 Report on Water Quality Monitoring of Yamuna River.
Yamuna enters Delhi at Palla village 15 km upstream of Wazirabad barrage, which acts as a reservoir for Delhi. Delhi generates 1,900 million litre per day (mld) of sewage, against an installed wastewater treatment capacity of 1,270 mld. Thus, 630 mld of untreated and a significant amount of partially treated sewage enter the river every day.
The Wazirabad barrage lets out very little water into the river. In summer months especially, the only flow downstream of Wazirabad is of industrial and sewage effluents. Lesser discharge means lesser river flow and thus, greater levels of pollution.
Water treatment plants have been known to face the prospect of closure due to high pollution loads in the raw water. Risk Assessment of the Yamuna River , the report of an Indo-Dutch government project on water quality monitoring stations that was released inJanuary 1996, notes that the Haiderpur water intake had, at an average, to be closed five times a year. "These 'accidents' were mainly related to flushing of drains and canals upstream of Delhi, without appropriate communication between the concerned authorities," says the report. However, dwssdu authorities maintain that they would get to know any change in the pollution load on wyc six hours before it reached Haiderpur, as water is monitored upstream. In February 1996, the Wazirabad treatment plant had to down its shutters for eight hours on a day when the organic pollution load of the raw water was unusually high. In surface water, do level has to be at least four mg/l to make it fit for use after treatment; at Wazirabad, the do level was nil. This depletion was caused by effluents from breweries in Panipat.
From the Okhla barrage, which is the exit point for the river in Delhi, the Agra canal branches out from Yamuna. During the dry months, almost no water is released from this barrage to downstream Yamuna. Instead, discharges from the Shahadara drain join the river downstream of the barrage, bringing effluents from east Delhi and noida into the river. This is the second largest polluter of the river after the Najafgarh drain.
Pesticides: ignoring the main problem: But the main problem comprises of undetected and untreated chemical impurities -- pesticide residues. Delhi, so far, seems to have studiously ignored the problem. Asked specifically about pesticide contaminants such as ocs in water, a dwssdu spokesperson replied: "We do not test for them." A waterworks expert with the undertaking points out: "We do not have the system. In Delhi, if you want to test for pesicide contaminants, you will have to send the samples to Sriram lab." Waterworks officials in Delhi and Agra point out that pesticide traces cannot be removed with conventional treatment.
"Organic substances can be assimilated in freshwater, provided there is enough freshwater in the river," states R Dalwani, scientist, mef. "But for micropollutants such as pesticides, only more freshwater can reduce the percentage of traces in water. These cannot be dissolved or assimilated, but certainly can be diluted to an extent." The river has a dilution requirement of 75 per cent, which implies that for every 100 l of wastewater, 75 l of freshwater is required. Scientists state that with the flow of water, pollutants (especially organic pollutants) degrade to a large extent. But at every step, this purified water is abstracted, and larger and larger loads of pollution enter the river.
Yet, the fact remains that no amount of freshwater would make traces of micropollutants such as pesticides go away. Also, stagnant water hinders pollution dispersion and assimilation; the mainstream water stagnates at the different barrages that have been built on the river. While they agree with the proposed solution that releasing water into the river at Tajewala could help in dilution and assimilation of pollutants, mef officials also point out that such decisions were entirely political, and not based on the need of the hour.
Though the government has elaborate water quality monitoring systems, studies or efforts to minimise the entry of pesticides into the river are non-existent. The mef claims that its job is to keep track of pesticide sources such as traces from industries. It professes that in instances where pesticide traces from agricultural fields become a cause for concern, it informs the ministry of agriculture. But as of now, other than the proposal to ban ddt from agricultural use throughout the country, nothing has been done about pesticide traces in the Yamuna. Or for that matter, any Indian river. "Large amounts of pesticides and fertilisers do enter the river while it traverses Haryana before entering Delhi," admits A K Mehta, senior scientist with the department of environment, Haryana. "So far we have not carried out a study as to how much enters from which specific district, nor have we been able to get some outside agency to do so."
Government agencies involved in monitoring tend to underplay these levels of pesticides, saying that the traces settle in the river sediment. "This contaminated river sediment gets washed away during monsoons," says Virendra Vats, a senior scientist with the Yamuna Action Plan. But not all of it, as recent studies would imply. The report of the Indo-Dutch project states, "Discharge of effluents from domestic, industrial and agricultural sources are reflected in the water quality of the Yamuna river water and the wyc. In addition, pollutants are absorbed by the sediments in the river, the drains and the wyc. This may result in high concentrations in the water of the Yamuna and wyc when the drains are flushed or at the start of the monsoon." R C Trivedi, senior scientist with the cpcb, who has been working on monitoring pollution levels in the Yamuna for almost 15 years, corroborates: "There have been many instances when dead fish are found in the river as soon as the monsoons get underway. This is because of the sudden rise in bod levels."
Vats throws up his hands about the government's inability to monitor the pesticides influx into the river system: "It is difficult to quantify what percentage of pesticides or fertilisers enter the river, this form of pollution being a non-point source of pollution. We can only identify point sources of pollution (those that are known to bring in pollution), and make suitable recommendations to lessen pollution loads entering from these sources."
This lack of interest is evident everywhere. Even the Indo-Dutch project report skirts the issue of solution to the problem. When Down To Earth met T D Dogra, head of the department of forensic medicine and toxicology at New Delhi's All India Institute of Medical Sciences with data of pesticide and other micropollutant traces in 19 stations on the Yamuna, he declined even to see the data. Ironically, Dogra is involved in studying the effects of pesticides on users like farmers and farmhands. "The main problem, as far as pesticides go, are faced by the actual users. City dwellers get minor pesticide traces from vegetables and other food items they consume," he says. However, he admits that ingested pesticides, which were slow poisons, manifested themselves in the long run in numerous illnesses.
They do not come cheap : Water treatment technologies in practice in the West are mostly governed by steep costs, something which India can ill-afford. Says Mary Taylor, senior research officer of the Friends of the Earth, a global environmental ngo, in the uk, "The estimated capital costs to remove pesticides in uk (which has one-sixteenth the population of India) is expected to be us $1.5 billion, and running costs would also be significant." Besides, "it is now widely acknowledged that conventional water treatment processes, based on chemical coagulation and filteration or biological slow sand filteration, have little capacity to remove water-soluble pesticides," say Western experts.
One way of removing pesticides is by adding granular activated carbon (gac) to sand filter beds. It is an expensive procedure since the cost of carbon determines the expense; greater the contamination, more the use of carbon and higher the cost. According to a paper presented at a symposium on 'Pesticides and Water Industry' in the uk, "These processes (using ozone, which is used to oxidise pesticides, and gac) were not originally installed for pesticide removal, but for taste, colour and other reasons." The paper says that for a process designer, it is essential to know what is the nature of the applied load (of pesticides); the variability -- average concentrations of each pesticide; raw water peak concentrations; and seasonal and time variations. It is also essential to know the levels of other materials to establish the capacity of ozone to oxidise pesticides, or activated carbon to remove them. The paper also says that both ozone and gac can introduce new problems in drinking water -- organic and inorganic breakdown products resulting from ozonation, fragments of gac or changes in biological solubility. Also, these processes and the role of ozone in pesticide removal is not yet fully understood.
Another procedure in use in desalination plants, which remove salts from brackish and sea waters, involves reverse osmosis membranes. However, removal of organic materials (including pesticides) depends on a wide range of variables such as molecular weight. Pesticides are generally highly water-soluble and have low molecular weight; hence it is difficult removing them using membranes. Moreover, after a period of time the membrane becomes fouled and toxic substances begin to appear in the treated water.
In Delhi, the treatment system incorporates prechlorination, coagulation with alum, sedimentation, clariflocculation, filteration (using sand beds) and chlorination. However, this cannot remove pesticide traces in the water. According to S D Badrinath, a water treatment expert, "Flocculation may remove five-10 per cent of the pesticide traces in raw water. But chlorination may oxidise the various pesticide traces and eventually aggravate the situation." He suggests cheaper methods of treatment which India can go in for, like capping the filter with bituminous charcoal or coconut shells.
According to the Indo-Dutch study, one way in which pollutant loads can be controlled is by better communication between the different agencies involved in the management of the Yamuna, its canals and the water treatment works in Delhi, and by upgrading the monitoring capabilities. This would serve to provide forward information to water treatment plants as to when a heavily polluted mass of water was due to reach certain waterworks. But these suggestions avoid the problem of agricultural runoffs.
Catchment protection: Western researchers are coming to the conclusion that protecting the catchment from chemical contamination -- by switching to organic or biological farming methods and curtailing the use of pesticides and fertilisers -- is possibly the best way to deal with the problem. According to cse researcher Sangeeta Agarwal who spoke to officials of the Sacramento department of utilities, California (us), which faced problems with pesticide contamination from rice fields upstream: "The problem was resolved by persuading polluting farmers to use pesticides in such a manner that it does not enter surface water."
A similar situation confronted New York three years ago. When the city awoke to the fact that the E coli bacteria was present in its water, it examined its 3,200 sq km watershed area. Increased sewage and septic discharges as well as agricultural runoffs had entered the water supplies, leading to a situation when the 'champagne of municipal water' had to be boiled before being consumed. When the city appealed to the farming community in the catchment area, the farmers cried foul about New York's attempt at 'throttling' their development. The city realised finally that it would cost only $2 billion to buy off 32,400 ha of land compared to the requisite $8 billion for water treatment plants!
|(A) Recovery of DDT and its metabolites from Yamuna, upstream of Wazirabad barrage|
|p,p: para, para o,p: ortho, para|
|Source: DDT Residues in the River Yamuna|
|(B) Micropollutant characteristics in sediments of Yamuna (in ng/l)|
|Agra canal (midstream)||375.71||12|
|Agra canal (quarterstream)||294.23||NT|
|ng/l: Nanogram per litre|
|Source: Report on Water Quality Monitoring of Yamuna River|
pollution outfall in each segment of the Yamuna: Delhi emerges as the problem area, followed by the eutrophicated segment
|Comparison between abstraction and outfall in three segment|
Million litre per
BOD: Biological oxygen demand
MCM: Million cubic metre
|Source: Ecological Analysis of the River Yamuna, a Functional Approach in a Diversified Ecosystem in India, published in Archive fur Hydrobiologie, 1995|
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