Desalination plant for Karachi!
By SYED M. ASLAM
Aug 11 - 17, 2003
The World Health Organisation of the UN has declared the year 2003 as the International Year of Freshwater. The decision reflects the importance that the international body accords to life-sustaining role that water plays in human life and all activities related to it, be it individual, collective, personal, economical, industrial or commercial. It is also aimed at creating awareness at the grassroot levels about the declining availability of freshwater and problems which it is causing.
Pakistan, like a great part of the world, is also facing water crisis. Though heavy rains across the country has helped reduce the severity of the problem substantially the time should be used by the related authorities to come up long-term and permanent solutions to ensure smooth supply to a population which is growing at over 2.5 per cent each year.
Just how bad the situation globally is obvious from the following. People already use over half of world's freshwater and they are expected to use 75 per cent of it by 2025. Some 1.5 billion people, one-fourth the population of the world, lack access to potable water and if the current consumption pattern continues their number would rise to 3.5 billion in next twenty years. Agriculture has emerged as the single biggest threat to availability of already scarce freshwater consuming an average of 70 per cent of it globally and a threatening over 90 per cent of it here in Pakistan.
In Pakistan, the problem has become all the more acute as about 25 per cent or over 39 Million Acre Feet (MAF) of some 154 MAF of the total freshwater available from Indus River and its tributaries flows wastefully into the sea and another 9.9 MAF or 6 per cent is lost in the distribution system. The remaining 104 MAF is diverted to the canals, the bulk of which is consumed by the agriculture leaving little for drinking, domestic and industrial uses.
What has made the situation even more worse is that the massive exodus from rural to urban areas over the decades have resulted in the urbanization of water which in turn has resulted in its industrialisation and commercialisation. However, before putting up the case for desalination plant, or plants as the case may be, for Karachi let us look at the various factors responsible for widening gap between demand and supply of water not only in Karachi but across the country.
Rains and glaciers are the two primary sources of freshwater in Pakistan. In addition, about 79 per cent of the area in Punjab and 28 per cent of the area in Sindh has fresh groundwater. In last three decades groundwater has helped supplement the water supplies through tubewell pumping that started in the early 1960s. There are over 500,000 tubewells in the Indus Basin Irrigation System.
The quality of groundwater differs in various areas from fresh, salinity less than 1000 mg per 1 TDS (Total Dissolved Solutions), to high salinity of over 3,000 mg/1 TDS. Seawater, the most saline variety, has a salinity of 28,000 mg per 1 TDS.
A total area of 29.31 million acres of the land in Pakistan is underlain with groundwater of which 20.76 million acres is in Punjab and 8.20 million acres is in Sindh. Only 49 per cent or 14.4 million acres of it has underground water with a salinity of less than 1,000 mg/1 while 10.55 million acres or 36 per cent of it is underlain with highly saline water with a salinity of over 3,000 mg/1 TDS and 15 per cent or 4.39 million acres of it is underlain with water with a salinity between 1,000-3,000 mg/1 TDS. Excessive extraction in some areas of NWFP has lowered the water table while underground water in most parts of Balochistan is highly brackish and thus unfit for human consumption but people in various areas of the province are forced to use as saline a water as that having high TDS of 3,000 mg/1 for drinking purposes.
AGRICULTURE: THE BIGGEST CONSUMER
As mentioned earlier over 90 per cent of the total freshwater available is used by the agriculture way above to acceptable 70 per cent in the rest of the world. Globally, agriculture has been using increasingly quantity of available freshwater anywhere as in the last 50 years the area of irrigated land in the world has tripled. True that the world has been growing more food today without which the vast majority of the people across the globe would be starving and yet it has come at a drastic cost to the people in term of rampant water shortages across the world.
Industrial areas in Pakistan are concentrated primarily around the urban centres and in specific industrial complexes such as the ones in Gadoon Amazai, Hattar, Kalashah Kaku, Hub, etc. Water consumed by major products is estimated as 1.18 MAF (million acre feet) and this consumption is expected to increase to 1.47 MAF by 2011 and to 1.84 MAF by 2025. Many of the industriial units use ground water and abstract it at their own expense. It is estimated that currently about 23,500 acre feet of water is provided to the industries through the municipalities.
Agriculture is not only the top consumer of freshwater but is also responsible for water pollution and soil erosion. For instance, cotton is grown on irrigated land and along the river banks in Pakistan like elsewhere in the world. It accounts for just less than 3 per cent of the arable land but uses an un-proportionately high 70 per cent of the pesticides. Cotton is thus a major reason for the deteriorating water quality in Pakistan and also the cause of soil erosion.
Karachi: Surface water from Indus and Hub Dam. However underground water in the city is mainly brackish and thus unfit for human consumption. It is also limited and meet Karachi's growing industrial, commercial and domestic needs. Desalination seems to be the only meaningful and permanent solution for Karachi.
WASTE WATER DISPOSAL
In urban areas sewage is collected through piped sewers as well as open-surface drains which is disposed off either in the nearest water bodies present or in depressions and fields. In areas where there is no sewerage collection system soakage wells are used which results in contamination of the ground water.
In rural areas, which lack sanitation, the sewage is collected through open drains and disposed off in fields and open ponds. Absence of surveys and monitoring makes it impossible to assess the flow of municipal and industrial wastewater into the rivers, sea and other water-bodies.
According to an estimate over 975,000 million gallons of wastewater is produced in the country annually the bulk of 674,000 million gallons comprises municipal water and the remaining 301,000 million gallons from industrial use. Over 392,000 million gallons of the total 975,000 million gallons wastewater produced in the country finds its way into the major rivers of which over 316,000 million gallons is from the municipal and remaining 75,000 million gallons industrial effluents. In Pakistan, neither the municipal nor the industrial wastewater is treated though a number of treatment plants are already working and some are in the process of construction. Only about 1 per cent of wastewater is treated before it is disposed off into the rivers.
The massive discharge of wastewater comprising untreated municipal refuse and industrial effluents is extremely harmful to the quality of the river water. In addition, uncontrolled discharges into the rivers are exacerbated by an increasing incidence of low river flows as diversions to agriculture and other uses are increased thus increasing the threat to the water quality and for that matter aquatic life.
Recycling the municipal and industrial waste-water for the industrial use on the one and treating the effluents before dumping it into the water bodies; be it a rivers, canal, sea or other water-body, on the other would not only help reduce water consumption but would also help stop further degradation of the environment and soil-erosion.
WIDENING GAP BETWEEN DEMAND AND SUPPLY OF WATER IN KARACHI
Karachi is the most populated city of the country and is called its heart. It also houses the biggest clusters of industrial units anywhere in the country. The population of the city is growing more rapidly than any other city in the country at the rate of over 5.5 per cent annually, half each by birth and influx from the rural areas. Each year the population of the city, put by many observers at 15 million already, is being pushed by 600,000-700,000 additional souls. That puts an immense pressure on water supply.
The city has three sources to meet its water needs. The oldest source of historic Dumlotee wells, 30 in all, which used to supply around 5 Million Gallon Day (MGD) of water to the city at the time of independence in 1947 have been depleted. The other major source, Hub Dam, has only last week was filled to capacity by recent rains after touching dead levels many times due to absence of rains during last 7 years. The city's major source of supply, the Indus River, also have many problems. For instance, the supply from Indus needs pumping from the lower to the upper areas while the system does not have the power to perform the function.
Estimates about supply and demand of water differs widely depending upon who one talks too. However, one thing is agreed that there is a wide gap between supply and demand. For instance, the KWSB says that it is drawing 450 MGD from the Indus and will be drawing 100 MGD from the Hub Dam filled to capacity after the recent heavy monsoon rains. The total supply to Karachi, thus, would be 550 MGD shortly. On the other hand, observers put the demand around 810 MGD if calculated on the basis of 15 million population and WHO benchmark of 54 gallons a day per person. Even if calculated on a lower per person per day basis of 40 gallons the demand of water in Karachi stands around 600 MGD.
However, according to estimates as little as 20 per cent or as high as 40 per cent of the water supplied to the city is lost in the system which is over 50 years old. This further worsens an already bad situation. According to an estimate, the demand for water in Karachi is around 600 MGD and until recently the supply was 480 mgd thus showing a shortfall of 120 MGD. Of the 480 MGD water supplied to the city about one-third was lost due to the leakages and seepiy leaving just 320 MGD available for consumption, be it domestic or industrial.
Others put the water demand in Karachi at over 800 mgd basing their calculation on a population of 15 million and citing WHOís recommendation of 54 gallon per person per day. They also say that only about 435 mgd is supplied, a substantial potion of which is lost in the system before reaching the consumers. The actual gap, they say, is much bigger than that floated by the KWSB.
TANKER WATER SUPPLY: A COSTLY AND UNWORKABLE ALTERNATIVE
The severe shortage of water over the years has helped the 'tanker mafia' to flourish at the misery of the water-starved population. The tanker mafia which was already well-entrenched 8 years ago when the Rangers were mandated to took over the distribution of water from various hydrants across the city.
Today, an estimated 5,000 water tankers are plying in the city selling water both on official rates ranging between Rs 250-350 and commercial rates that range between Rs 600-1,000. Initially started as an alternate service to address growing public unrest about non-delivery of municipal water, the service has turned completely commercial grossing the operators a cool 10 million a day.
The KWSB, the inability of whom to deliver water to the consumers was the primary reason for the initiation of tanker water service, strongly defends the operations saying that is providing an essential service. However, the sheer amount of money minted by the operators of the 'service' in a single day totaling over Rs 3.6 billion a year clearly shows the weakness of KWSB's defence of tanker service.
Even if the KWSB's defense of tanker operations is true, the very fact that the tanker operators are left to do their business on cash outside the pale of audits poses many questions. Not only the water tanker business have acquired a completely commercial outlook but it is also interesting to note that the KWSB allocates around Rs 60 million in its annual budget for the delivery of water through the tankers. The tanker water operations effectively controlled by the Rangers have acquired total commercial dimensions over the years.
The low-income and salaried classes are particularly hurt by being a victim of double payment they have to pay the KWSB even if they don't receive a drop of the municipal water and they have to pay for the water tankers for the all too precious necessity.
Tanker service is not only far more expensive but hardly can be seen as a substitute for the tap-delivered municipal water it is only extremely inconvenient, particularly for the marginalised segments of the society. It costs time, energy and money to buy tanker water taking heavy toll on the people financially, psychologically and mentally. Started as an emergency service it should not be allowed to become a permanent fixture of the civil life of the city at such extracting costs. Tanker water never had and would never replace the tap-water service, both in terms of finance and convenience. It should be treated as emergency service, no more no less.
GROUND-BREAKING DESALINATION INITIATES
The supply of water to Karachi remains heavily dependent on the benevolence of water as the persistent dry spell over the years clearly show. Attempts to justify tanker water as a viable alternate would also be futile. Abundance of seawater, and its proximity offers the only hope to solve the water shortage problem in the long run.
True that the recent monsoon rains have helped completely fill the Hub Dam and Indus to offer the much needed relief. However, one must remember that time does fly and that the fillings have come after prolonged dry spells over the years that can be repeated in the years to follow.
The lull should provide the policy makers and all those related with water in any manner the time to find 'real' alternate to find a solution to water woes of Karachi, a city whose population is growing more rapidly elsewhere.
A beginning has already been made towards installing of a couple of desalination plants and a treatment plant in Karachi to help augment supply and help save water. The capital cost of desalination plant is high, but not as high as one is made to believe, and it also offers savings depending on the type of water desalinated, technology, size of plant, etc. For instance, brackish underground water in Karachi cost much less to desalinate than the seawater. In addition, a number of desalination plants installed by public-private partnerships could also help augment the supply of potable water for a population which is on a constant rise. The need for a futuristic planning can hardly be over-emphasised.
Let's talk about the 'beginning'. KPT has initiated the development of 25 MGD desalination plant. On January 23, this year the KPT signed an agreement with a US company, California Enviro-Management for the setting of a desalination plant. Under the agreement the US Trade and Development Agency will provide a grant of $ 28 million to partially fund a feasibility study for the 25 MGD desalination plant at a foreign exchange cost of $ 60 million. The plant will also produce 15 Mw of electricity. The plant will be built on BOT basis for a 20-year lease.
The feasibility report, estimated to cost $0.381 million or around Rs 22 million at the current exchange rate, is expected to be finished within 6 months and the construction of plant building is expected to take another 18 to 24 months. The KPT has already allocated 100 acre of land for the plant which would supply potable water not only to the KPT to meet its own needs as well as ships visiting the port but also to the Karachi City District Government for industrial and domestic use.
The Defence Housing Authority is in the process of installing the first desalination plant a co-generation plant comprising both desalination and power generation in the country based on advanced Reverse Osmosis (RO) technology. The plant would intially produce 1 MGD of potable water and generate 30 megawatts of electricity daily. However, the plant would be only economical when it produces 20 MGD of desalinated water. The DHA announced the launching of the project in February this year and said it had earmarked 30 acres near the Golf Club for the plant. The DHA had signed a memorandum of understanding for the setting up of the plant with Siemens Pakistan Limited last year in September. The plant would cost around $ 50 million and desalinate enough water to meet its own requirement of around 10 MGD (it is getting around 8 MGD water from the Karachi Water & Sewerage Board) but would also be sell extra water to the Clifton Cantonment Board, the civic body in the DHA and any excess electricity will be sold to the Karachi Electric Supply Corporation. The project is in the implementation phase at present and is expected to become operational by end next year.
Both the KPT and the DHA have made an important beginning. Not only they will be desalinating 28 million gallons of sea water collectively but in the process would also be generating 71 Mw of electricity. However, the population of Karachi is increasing by around 6 per cent each year, half each by birth and exodus from rural areas as well as other towns. Each year Karachi absorbs some 700,000 extra persons thus pushing the demand by an additional 28 million gallons every year if calculated on 40 gallons per person per day way below the criteria of 54 gallons prescribed by the WHO. At the current rate of growth compounded over the years the city would need a 1,000 MGD by 2010. Desalination, once again, is the only viable solution to meet the growing water needs of Karachi to offer permanent long-term solution in the years to come. This is particularly so that supply of fresh water from Indus and Hub much remains dependent on benevolence of nature and thus unpredictable. The fact that desalination also offers added power generation option, as is the case with the DHA project, should encourage investment in the large-scale desalination projects in Karachi which offers an ideal location due to its proximity with the sea. Build-own-operate-transfer (BOOT) projects can offer a viable choice for investment in desalination plants.
The Karachi Water and Sewerage Board had also submitted a feasibility study, costing Rs 23.2 million to the Sindh government, last September for the installation of a seawater desalination plant in the city. While Indus River remains the only viable and economic source of water for the KWSB the reduction in downstrean flow at Kotri and the drying of the water in the catchment area of the Hub Dam (the recent rains have filled the Dam totally) and the persistently increasing demand for water by the industries in particular and domestic consumers in general were the primary reasons for the KWSB to carry out the study.
Pakistan ranks 75th among 102 nations in terms of desalination capacity. According to a country-wise study of desalination capacity Pakistan had a total capacity of 4,560 cubic meters a day in 1996. The country with the top desalination capacity of 5.006 million cm/day was Saudi Arabia followed by the US with a capacity of 2.799 m, UAE 2.134 m, Kuwait 1.3 m; Libya 0.6383 m, Japan 0.7679 m, Qatar 0.560 m, Spain 0.492 m, Italy 0.483 m and Iran 0.423 m.
Three decades ago desalination used to cost as high as $ 3 per cubic meter which has fallen to below the level of one dollar today. A Chinese firm has offered to desalinate seawater in Pakistan for as low as 0.60 dollar per cubic meter. The latest reverse osmosis process costs as low as 0.70 dollar. However, there are many technologies, including individual ones, and many costs parameters to calculate the capital and operational costs for desalination depending on the capacity and the type of plants, thickness of the water, etc., etc.
Zubair Motiwala, former chairman SITE Industrial area, said that the estate needs 25 MGD of water but it allocated a quota of 9 mgd and is supplied with just 4 mgd of water a substantial portion of which lost in the system. "SITE is the only area in the whole of the country allocated a quota some 30 years ago. Rest of the Karachi, including the other industrial areas, namely Landhi, Korangi, North Karachi and F.B. Area, has no such quota restrictions and just six industrial units in Landhi alone consumes water which is more than the entire supply of 4 MGD to the SITE. In fact, Landhi industrial area is the biggest consumer of water all of the other such areas in the city and yet it never complains of any shortage. Unlike the other industrial areas, the allocation of water quota to SITE create impediments to demand water from the Karachi Water and Sewerage Board, the water supplier to the rest of the city, including the other three industrial areas. The quota is a catch and puts us in a bind which is impossible to rectify the situation. However, the filling up of the Hub Dam to capacity due to heavy lashing of monsoon rains recently is expected to improve the situation due to increased water supply from Hub, a direct source to SITE."
The acute shortage of water has resulted in installation of a water treatment plant at SITE. The plant is being built on 45 acres of land and would replace old and obsolete machinery of an old treatment plant of 51 MGD capacity. The plant would treat some 20 MGD of water used by industries in SITE converting it into 15 MGD water good for industrial use. The cost of the project is $ 20 million which is a part of the Japanese government's grant of $ 300 million for the revamping of industrial infrastructure, research and training as well as setting up of desalination plants in Karachi. The project is handled by an Austrian company VATech and is in the implementation stage expected to be operational in July next year. Once installed the operational cost of the plant would be Rs 72 per 1,000 gallons of water with a salinity of 400 mg/1 TDS which would be good for industrial use but not human consumption. The plant would not only help solve perpetual shortage of water for the industrial units located in SITE but would also help save it to fulfil demand elsewhere.
Feasibility study has also been conducted for many smaller brackish water desalination plants including 2 plants of 25,000 GPD each for the palaces of Sheikh Zayed in Pakistan.
THE CAPITAL COST
The 25 MGD seawater desalination plant of the KPT would cost $ 60 million that translates into a capital cost of $ 2.4 million for a plant with a capacity of 1 mgd. The extremely saline seawater with a salanity of 28,000 mg/1 TDS is the most expensive to desalinate and it costs much less to desalinate underground brackish water found in Karachi abundantly. The choice offers a viable option for various range of investments to desalinate sea and/or brackish water to help reduce the vast, and growing gap between the demand and supply of freshwater in Karachi. Building desalination plants for specific organizations and areas, though an encouraging beginning, should also help encourage the construction of such plants to meet the overall growing demand of water for the mainstream population. Certainly, a metropolis such as Karachi should not be allowed to be divided into water-scare and water-affluent areas to create a water divide. What's good for the DHA and KPT should also be good for the rest of the city.
The majority of desalination plants today are bases on Reverse Osmosis (RO) process which is more expensive than the traditional Osmosis technology. Without getting into technical intricacies let us understand that RO is much more expensive costing over $ 4 per gallon per day including both the membranes, modules, cartridge prefiltration system and chemical injection system and the piping and other systems. Thus a million gallon a day RO desalination plant would cost in excess of $ 4 million way above the $ 2.4 per mgd KPT plant.
The capital cost of desalination plant may be high but its operational costs are affordable. The capital cost of a plant for desalinating brackish water is much lower than the one used for the desalination of the sea water. Big plants are more capital intensive than smaller counterparts but they are more economical. Karachi can definitely afford to install many smaller plants instead of one large one.
Easy access to water, and its abundance, is linked to economic growth anywhere. The same is true for the Karachi, the "heart" of Pakistan. Despite the costs, desalination plants seems to be the only alternative source of water for the coastal areas of the country, the most prominent being Karachi.
The term 'Planet Earth' is a misnomer as 75 per cent of the planet's surface is covered with water compared to just 25 per cent by earth. Fresh water makes up less than 2 per cent of the Earth's water supply. Human body is 75 per cent water and so is the human brain. Chicken is 75 per cent water, tomato 90, and potato 80. Over 90 million kilogram of contaminants are dumped into water resources every year globally. Around 110 million gallons of water is drink by the people across the world each day. More than quarter of all domestic consumption of water is used by showering and bathing, which makes it the one of the top domestic usage. In the US, the average water consumption per person per day is a high 150 gallons. Ninety-five per cent of the developed nations have adequate water supply compared to 40 per cent of the Third World nations and only 25 per cent of them have water for sanitation needs.
It took the desalination technology 50 years to reach where it is today. Five decades ago desalination technology had a much smaller base of use it was undertaken only commercially and on a small scale. In the mid fifties witnessed the installation of 1 MGD plant. Two events changed the course of desalination during the same period the introduction of multistage flash distillation (MSF) process significantly reducing the capital costs of bulk plants, and secondly, the government backed Research and Development programmes in the developed world, particularly the US which led to development of Reverse Osmosis (RO) as a commercially viable desalination process.
The seawater desalination has been refined the MSF distillation technology in many ways. It has also witnessed the development of the reverse osmosis membranes capable of desalinating seawater in a single pass, more durable membrane and reduction in energy requirements.
Similarly, improvements have been made in the desalination technology for less saline brackish water including elimination of distillation technology. However, RO has emerged as the leading desalination technology.
There are many processes for seawater desalination:
The Multistage Flash Distillation is affective for warm high concentration seawaters and produces a high purity product. It has the capacity to install bulk size plants of 10 mgd and above.
The Thermocompression Multiple Effect Distillation is in use for the last three years ideally for comparatively small seawater desalination plants of 1 to 2 mgd.
The Seawater Reverse Osmosis (SWRO) was first developed in the mid fifities. The technology was a two-pass process until the progress in the 60s and 70s lead to the development of single-pass seawater desalination. However, a two-stage desalination is still sometimes necessary if either a high concentration seawater is used or if a relatively purer product is required, or both. One of the most salient feature of SWRO is that it requires energy consumptions compared to MSF distillation which producer a better quality product.
In the Hybrid Seawater Desalination Plant the power generation cycle provides waste heat to distillers and power to both the distillers and the SWRO plant products a power generation cycle. This offers considerable savings in shared facilities and the products of the two processes can be blended to lessen the effect of high TDS of the SWRO produced water.