The federal government intends to construct 6,559 water treatment plants, all over the country, to provide safe drinking water to people. The project is to cost around Rs7.5 billion and, the project is to be completed by December 2007. Some 554 plants have already been installed in various parts of the country under phase I and, 6005 plants would be installed under phase II. According to reports, about 30 million people are to benefit from the project. On volumetric basis, three types of plants would be installed: 2,000, 1,000 and 500 gallons per hour capacity. The project is a component of the “Khushal Pakistan Programme.”
Clean Drinking Water Initiative: The Clean Drinking-Water Initiative Project will be executed through five packages. Package ‘A’ talks of tube well as source water. It says that source water should not contain high concentrations of nitrates, nitrites, calcium, magnesium, and TDS (total dissolved solids). The water shall be treated through rapid sand (multimedia) filters, GAC (granular activated carbon) filter and ultraviolet steriliser.
Package ‘B’ lists source of water as overhead tank, with other conditions same as in package ‘A’. Package ‘C’ lists source of water as tube well, with same conditions as in package ‘A’. Package ‘D’ says that source of water contains high concentrations of nitrates, nitrites, calcium or magnesium. Treatment system should contain nitrate chamber and water softener chamber. Package ‘E’ is for source waters containing high levels of arsenic, TDS and other organic pollutants. It further says that additional appropriate treatment technology will be provided. Introductory note indicates that “pre-filtration” will also be provided.
It is not known what pre-filtration intends to mean, in this context. Typically, pre-filtration, in the shape of “roughing filters” is provided for treating highly turbid surface waters (more than 50 Jackson Turbidity Units - JTU), when conventional slow sand filters are used, as a rural water system.
Critical review of the five packages shows that, either they have been prepared by people unqualified in the field of water and wastewater engineering, or by some outside “fly-by-night” consultant.
Surface water sources are available through out the country. They should have been given preference. That would have made the water treatment system relatively cheaper and reliable. This could have avoided costly, problematic, and maintenance-intensive GAC and UV filters.
Granular Activated Carbon Filters: Granular activated carbon (GAC) filtration is effective in removing organic contaminants from water. Since, organic chemicals are implicated in producing taste, odour and colour problems, GAC filtration is used to improve water aesthetically. When water is passed through GAC filter, the carbon particles attract and remove contaminants, like hydrogen sulphide, heavy metals (lead, mercury and copper), chlorine and organic compounds. GAC filters use a cartridge packed with granules of activated carbon.
While some filters contain bacteriostatic materials (which prevent the growth of bacteria), these filters can still eventually start trapping bacteria, allowing it to grow on the filter. For this reason, it is essential to flush the filter daily with cold, treated, potable water to remove any bacterial residue.
Activated carbon is expensive. A disadvantage with activated carbon is the high emissions of sulphur dioxide generated from the heating process in manufacturing carbon from coal. The media can become a breeding ground for micro organisms. One of the drawbacks of a GAC filter is its tendency to “channel,” where water creates distinct paths through the media. This greatly reduces the available contact area, which shortens the effective life of the filter. It also means that additional pre-filtering becomes necessary because the carbon is not at a uniform pore size for this purpose.
The GAC constitute an advanced treatment system and, requires highly trained operators for their operation. All this would show that the GAC system is not advisable for communal water systems. Alternate source of water should be selected, if a particular source contains high levels of organic contaminants.
UV filters: An ultraviolet (UV) disinfection system transfers electromagnetic energy from a mercury arc lamp to an organism's genetic material (DNA and RNA). When UV radiation penetrates the cell wall of an organism, it destroys the cell's ability to reproduce. UV radiation, generated by an electrical discharge through mercury vapour, penetrates the genetic material of micro organisms and retards their ability to reproduce. The main components of a UV disinfection system are mercury arc lamps, a reactor, and ballasts. The source of UV radiation is either the low-pressure or medium-pressure mercury arc lamp with low or high intensities.
UV disinfection system has many disadvantages to its credit. Some viruses, spores and cysts are not fully inactivated by low dosage. Organisms can sometimes repair and reverse the destructive effects of UV through a "repair mechanism," known as photo reactivation, or in the absence of light, known as "dark repair.” A regular maintenance program is necessary to control fouling of tubes. Turbidity and total suspended solids (TSS) in the water can render UV disinfection ineffective, as they shield the bacteria. UV disinfection is not as cost-effective as chlorination.
While UV technology has a restricted application in water treatment, its design is still undergoing the process of refinement. Because UV light is harmful to micro organisms, it is also dangerous to human beings. In this respect, UV light may cause skin irritation and severe eye damage if direct exposure takes place. The system is not suitable for rural areas, as power source for UV treatment may be difficult to be obtained. Because the UV-tube does not offer residual disinfection, some bacteria can repair its DNA and re-activate after a few days of exposure to visible light.
Logic of water treatment: When tube wells are the source of water, then, typically, filtration unit is not required. Most of the tube wells are relatively free of pesticides, which would preclude the use of GAC. GAC are appropriate for waters containing high levels of pesticides and other organic chemicals. UV filters are not suitable for communal water systems. Either conventional method of disinfection (chlorine or chlorine dioxide) should be used, or, to avoid chemicals at all, a post slow sand filtration system, designed to remove organic contaminants, should be used. This will have an additional useful advantage of removal of faecal coli forms.
Overhead tank water, as a source of water is a strange water source, never heard of in the writer’s over 3 decades of experience in water and wastewater engineering. Only water of acceptable quality is pumped to high service reservoir. There is no need for any treatment for overhead tank’s water. Stagnant overhead tank water may become low in dissolved oxygen, which can be treated, if required, through sprinkling or splashing (e.g., use of cascades).
Water from deep wells does not require rapid sand filtration, GAC and UV treatment units. The only concern in deep wells is that of presence of iron. It is preferable to discard the source with high iron content. Iron levels of more than 4 mg/l (milligrams per litre) are not acceptable, as it imparts taste and stains cloth. UNICEF conducted extensive study in Sindh in 2002, regarding presence of arsenic in wells and, designed a household filter system for its removal. If other sources of water are available, then well water containing high level of arsenic [greater than 0.3 mg/l; WHO (1996) gives a guideline value of 0.01 mg/l], should be discarded.
In packages ‘D’ and ‘E’ water source with high inorganic constituents (nitrates, arsenic, calcium) has been listed, with treatment units of rapid filters, GAC, UV system and other appropriate units. Since, communal water system is the focus of the project, it is not advisable to go for advanced or tertiary treatment units. They incur heavy recurring costs and, would not be a sustainable water system.
Package ‘D’ mentions provision of nitrogen chamber and water softener chamber. Nitrate is removed by ion exchange method. Ion exchange of chloride for nitrate is the simplest method for removing nitrate from water. Sulphate content in water influences the nitrate removal efficiencies. More the content of sulphate in water, lesser the removal efficiencies for nitrate. The system is complicated to operate and, is not suitable for small-scale communities. One major problem is the disposal of nitrate-laden brine, which cannot be easily disposed of, due to eutrophication potential. The best course is to discard the source of water containing high levels of nitrates. WHO (1996) gives a maximum value of nitrate in drinking water as 50 mg/l. The primary concern is that of methaemoglobonaemia (blue-baby syndrome).
Water softening: Water softeners are employed to convert hard water to soft water. Hardness in water is caused by divalent metallic cat ions. The main hardness-causing cat ions are calcium, magnesium, strontium, ferrous iron and manganous ions. The major anions associated with the cat ions are bicarbonate, sulphate , nitrate and chloride. Waters are commonly classified in terms of degree of hardness, as follows: 0-75 mg/l soft; 75-150 mg/l moderately hard; 150-300 mg/l hard; and above 300 mg/l very hard. Calcium and magnesium cat ions, which cause hardness, are removed through ion exchange method. Water softeners usually use sodium as the exchange cat ion.
Hard waters are as satisfactory for human consumption as soft water. The only problem is that considerable amount of soap is required to produce foam or lather. And since, hard waters in the country are not a common occurrence, water softener units should be excluded right away.
Way Forward: In order to rationalise the institutional set-up, the project offices should be set up in all provinces, instead of having one in Islamabad. The provincial offices should be headed by persons qualified in the field of environmental engineering, with field of specialisation as water and wastewater engineering. It should be equipped with qualified support staff. The provincial office should adopt participatory approach for water supply, sanitation and hygiene interventions. The days of solving water and sanitation problems with concrete and pipes are over. Participatory approach allows community’s involvement, empowers people for responsibility, respect tradition and culture, include gender considerations, mobilise public-private partnerships and, creates willingness-to-pay criterion. A demand-responsive approach to the water and sanitation interventions will determine what levels of service the users are willing to adopt.
Suitable projects should then be formulated. They should preferably be conventional water treatment plants, with slow sand filtration systems. Presence of a particular pollutant in water should be dealt with, for that particular plant, with an option of discarding that source for a more favourable source. The locations of the plants should be fixed in consultation with district and taluka administrations.
The water treatment plants must be coupled with the water distribution system. The level of service should be decided with local administration. For example, in case of water supply, the level of service can range from high (piped connections in houses) to minimum (communal hand pumps). In case of sanitation, the level of service can range from high (sewerage system, or flushed toilet with septic tank and soak pits) to minimum (simple pit latrines on householder’s plot). Hygiene education would be an important adjunct of the programme. Extensive programme of hygiene promotion needs to be laid out. The whole system should be made sustainable by making the community to pay for the facilities.
The proposal given here will not allow quick construction of the water and sanitation facilities. For whatever facilities are constructed, through the proposed action, all facilities would be functional; there would be no case of non-functional water treatment plants. Integrated and holistic approach would allow marked improvement in public health and, the public money would be well spent in transparent and judicious manner.
With Rs7.5 billion in hand (the cost is likely to escalate to Rs10 billion) and 6,005 plants to be installed, it is a “tall order” and constitute a mega programme, having tremendous potential for and impact on the health of the people, provided it is managed by technically qualified and honest people. It is a one-time, great opportunity for the country to improve the environmental conditions and public health of the people, provided a sensible and technically sound framework is laid down.
The prime minister should right away stop the further execution of the project. The current approach, which is most fallacious, should be changed. The plants should be constructed on (a) case-by-case basis, with plants to be designed according to specific site conditions; (b) participatory should be adopted so that, the community owns the plant; (c) water treatment plants should be designed in a holistic matter (water demand considerations, water treatment, water storage, water distribution) and with “demand-responsiveness” approach (ascertaining the needs of the people, by involving community). The water project should be coupled with sanitation facilities and hygiene promotion, for accruing full benefits.
This programme, is not only of national significance, but international importance also. This would bring dynamic revolution in the health of the people. At international levels, the country can claim proudly the qualitative improvements in the life of the people, after the programme is completed.
However, a technically sound institutional setup, with project directors qualified in water and wastewater engineering (to understand and analyse the technicalities of water treatment and distribution; and sanitation) is a very important pre-requisite. The present “business-as-usual” approach, at the end of the day, will not result in any tangible improvements in public health.