Natural Freshwater Resources: Considered Safe for Drinking, Washing, and Cooking - Research Paper Example

Introduction Water distributed to consumers, that is considered safe for drinking, washing and cooking purposes is defined as potable or drinking water. It is not possible to effectively examine water quality without the appropriate facility of laboratory. In the context of scant natural fresh water resources, the city of Kuwait has to always depend upon other sources so that it can protect its requirements of potable water. The Ministry of Electricity and Water (MEW) in Kuwait has worked religiously in order to establish, secure and further develop its water resources. In spite of the fact that many techniques for producing drinking water has been researched and explored by the MEW, drinking water in Kuwait has been acquired through desalinating the sea water since 1950. Thus, the government in Kuwait has implemented the method of multi stage flash or MSF in its desalination plants. The water desalinated through MSF plants is then mixed with 5 to 10 percent Brackish water so that small amount of essential minerals are included in it in order to improve its palatability after which the water is pumped to the distribution system ready to be supplied to the consumer. The water distribution system of Kuwait comprises of main pumping stations, elevated storage towers, underground reservoirs and subsidiary networks with distribution lines along with the tanker filling stations through which the water is distributed to all destinations with out the line supply. The Government of Kuwait created a centre in 1968 with the purpose of analyzing the quality of drinking water. The centre was also held responsible to undertake the research for developing water resources and for examining different functions in relation to water resources. The name of this centre is Water Resources Development Centre or in short, WRDC. The Ministry of Electricity and Water (MEW) is responsible for constantly monitoring the quality of drinking water for the Water Resources Development Centre (WRDC) which is executed in the following three ways: • Assessment of water samples taken from different points of the distribution system. • Interpreting and examining the results of the tests taken of all the sample of drinking water. • Analysis and approval of the materials are used in the distribution system following the international specifications. The Ministry of Electricity and Water or MEW is accountable for supervising and controlling the quality of drinking water through out the distribution system. Moreover, the Environment Public Authority or EPA and the Ministry of Health or MOH take water samples from the premises of the consumer for further testing. The share of each laboratory in collecting water samples and analyzing them are provided in the table 2 given below. In comparison to the water distribution system in Kuwait, the Norfolk Department of Utilities supplies water to above 820,000 people in Norfolk, Virginia Beach. The City of Norfolk possesses 9 reservoirs which provide raw water. The Blackwater River, Nottoway River and other four deep wells placed in Suffolk constitute the additional water sources to the Norfolk city where as supplied from Lake Gaston is treated for distribution to the Virginia Beach.. Norfolk’s reservoirs supply raw water from to one of its two plants for water plants. First Water Treatment Plant at 37th street Second Water Treatment Plant at Moores Bridge (Source: http://www.norfolk.gov/Utilities/Res_to_Tap.asp) These water treatment plants treat around 72 million gallons of water each day in Norfolk city. Useful Information The water treatment facility in Kuwait has capacity of producing 82,455 MIG of distilled water per year. For this purpose, 5 MSF plants having 44 distillation units in total are placed at Shuaiba, Shuwaikhm Az-Zour, Doha East and Doha West while the pumping stations and blending plants are placed near to the desalination stations. The total capacity of these four blending plants is 88,475 MIG per year as provided in table 1 above. Since over years the population has increased and new residential and industrial areas have been set up to cater the rise in population, thus, the water distribution system has also expanded significantly to supply adequate of amount of drinking water to the entire population. The existing water distribution in Kuwait consists of 39 storage towers and 65 underground reservoirs. The total capacities of tower and reservoir are 25 MIG and 2, 158 MIG respectively as provided in table 1 above. The distribution and transmission piping systems has a total length of 13,175 km. The checks for the quality standards of both water and materials used in the distribution systems have considerably increased in number keeping in view the hike in both consumption and production of drinking water in Kuwait and expansion the water distribution system due to this increase. Regular monitoring and examination of the water producing and distributing facilities involved have to be followed. These periodic checks include: analysis and maintenance of the water sources to secure them, approval of materials, training of personnel and assessment of the quality and performance shown in work by different laboratories. Materials such as different pipe materials, coating materials, fittings in addition to the materials required for the construction of storage tanks are strictly examined and tested. Drinking water must fulfill safe chemical, physical and bacteriological parameters, must be distributed through approved sources to perfectly planned, constructed and functioning treatment and disinfection system and must also be supplied to the consumer by a perfectly planned, constructed and functioning distribution system. Moreover, the water should be at a reasonable temperature must acquire the confidence of consumers due to its quality and taste. The chemical composition can not completely separate the physical properties of water. Some tests of these physical characteristics measure collective properties caused due to the existence of a various constituents. The generalized physical requirements of drinking water include appropriate color, odor, turbidity, pH, salinity and conductivity whereas the chemical parameters of potable water are categorized as major parameters, trace elements and compounds. The anionic constituents found in water such like sulphates, chlorides, carbonates and bi carbonates and the cationic constituents of water such like potassium, sodium, magnesium and calcium are all included in the category of major parameters. On the other hand, there are numerous compounds and trace elements tested in water and special attention is applied at those that are mentioned in the World Health Organization (WHO) Guideline Value tables since they are potentially hazardous for human health. Cadmium, arsenic, lead, antimony, boron, nickel, selenium, barium and a wide range of organic compounds are some to name that fall among these potentially hazardous substances. The microbial quality of water must be carefully examined on account of the potential transmission of water born diseases and infections. Distillation plants: At present, Kuwait has 6 distillation plants that used Multi stage flash evaporation method. 24-46 stages are contained in each distillation unit which has different unit capacities according to each station. These capacities are: 4.4, 7.2 and 12.5 MIGD. The Al-Zour North seawater desalination plant which is the world’s 5th largest desalination plant in production capacity (Al-Damkhi et al., 2009) produces 29.3 percent of the entire production capacity that equals to 567,000 m3 of freshwater per day. A new RO desalination plant in Kuwait beginning production from 2010 has a capacity of 137, 000 m3 per day (Al-Damkhi et al., 2009). Quality of Groundwater: The quality of the Brackish groundwater is different for different fields relying on the utilized aquifer. Table 3 below shows the chemical test results of the brackish groundwater in Kuwait. Table 3: Table 3: Chemical analysis of the brackish groundwater of water well fields in Kuwait (Source: Am. J. Environ. Sci., 6 (3): 260-267, 2010) Drinking water samples: Collection and Analysis Field analysis: At the time of sampling, portable equipments are used to do the field analysis of temperature, pH, residual chlorine, EC and turbidity where as the chlorine sampling is done at the plant and faucet of the consumer which ensures that the consumer is getting potable water that is safe to drink. Quality of Potable Water: Potable water must safe in terms of its chemical, physical and biological parameters. Commonly and widely water is treated through Chlorine and Kuwait also uses this method. The safe to drink potable water must not contain harmful organisms, odor, color, turbidity and taste (Fredrick, 1990). TDS has to be less than 500 mg L-1 so that the water is of good quality. Water having above 1000 mg L-1 of dissolved solids mostly carries minerals due to which it has a bad taste or becomes inappropriate in other respects. Different experts have rated the palatability of potable water on the basis of its TDS level as: if less than 300 mg L-1 then Excellent, 300-600 mg L-1 then Good, 600-900 mg L-1 then fair, 900-1200 mg L-1 then poor and above 1200 mg L-1 then unacceptable (WHO, 2006). Quality of Water in Kuwait: The ground water in Kuwait produced from the fields of water well is brackish and posses the TDS ranging from 2 to 10 mg L-1. Thus, the drinking water produced is pure and has low concentration of salts and gases dissolved in it. The potable water produced in Kuwait has a total alkalinity below 1 mg L-1 in the form of Calcium Carbonate or CaCO3 that is not appropriate for humans. Therefore, this water is mixed with the brackish groundwater to obtain fresh water that is safe for drinking. Sample Collection and Analysis of Potable Water Produced in Kuwait: Kuwait uses the Multi-Stage-Flash Method (MSF) in distillation plants to convert sea water in to distilled water which is then blended with the brackish groundwater to produce potable water that complies with the guidelines of World Health Organization (WHO). The blending operation is executed in the blending plants or lines to obtain the drinking water of best quality. On the basis of the data collected in the period of 2003-2008 from the MEW, the blending ratios ranged from 6.1-13.7 percent in Shuwaikh blending plant, 2.3-14.1 percent in Shuaiba blending plant, 2.9- 15 percent in Doha blending plant, 1.7-6.4 percent in Az-Zour blending lines and 4-5percent in Sabiya blending lines. According to this information, the potable water produced in Kuwait bears excellent/good quality as per the guidelines of WHO. Water samples were obtained from all the blending plants and lines in Kuwait at different blending ratios and the collected samples were then tested during 2007-2008 for about 18 months. The analysis of the tests on the collected water samples indicated that the best blending ratio for the potable water producing at Shuwaikh is 7 till 8 percent, at Shuaiba is 8 till 9%, at Doha is 8%, at Az-Zour is 3 till 4% and at Sabiya is 4 till 5% that obtain the excellent quality of potable water having TDS below 300 mg L-1. It has been found that the distilled water produced in Kuwait is corrosive and causes red water problem. Thus, the re-carbonation plant was created in 1987 and formulated to produce re-carbonated water having the total alkalinity of 60 till 80 mg L-1 in the form of calcium carbonate, CaCO3. Moreover, water samples were obtained from the main pump station to determine the Langelier Index for knowing the corrosives of the potable water produced in Kuwait. The results calculated infer that the potable water is slightly corrosive bearing the mean values of the total alkalinity from 21.4-53.78 mg L1 as CaCO3 where it should have been 60-80 mg L1 as CaCO3. Also, the results show that the average value of Langelier Index at the pump station of Shuaiba is -0.6 and the average value of the total alkalinity has been found to be 21.4 mg L1 as CaCO3 which infer that the drinking water produced at Shuaiba is more corrosive that that produced at the rest of the pump stations. The reason behind this is that the re-carbonation process has not been implemented as yet at the Shuaiba distillation plant. Norfolk's Potable Water Production Flash Mixing/Coagulation When the water reached the plant for treatment then the water is immediately blended with certain chemicals in a container that is known as flash mixer. The chemical added are: powdered activated carbon or PAC for controlling taste and odor, ammonia and chlorine for disinfection, hydrated lime for adjusting acidity (pH) and polymer and sulfate for coagulation. The alum or aluminium sulphate and the dirt in water reacts together to create coagulated sediment called floc. The dirt in the raw water gets trapped in the floc particles. Flocculation The water then flows in to the flocculation chamber where it is stirred slowly through large paddles due to which the delicate floc particles increase in size and meanwhile it further traps additional dirt and other suspended material. Sedimentation The floc changes in to a large brown snowflake after it is formed completely. Then the water is transferred in to the sediment basin. Due to its weight, the floc settles down at the sedimentation basin creating a layer of sludge at its bottom. Llamella plate settlers are used at the Moores Bridge Plant to increase the floc sedimentation. The sludge is then removed through the Solids Dewatering Facility. Filtration The cleared water from the Solid Dewatering Facility, then flows in to the dual media filter for further cleaning. The dual filters contain a layer of anthracite coal on its top and a layer of sand below the top layer. The filters remove any suspended material left in the water. Even the smallest particles of algae and dirt are discarded here. Chlorine is added here because it oxidizes the iron and manganese dissolved in water and it also disinfects water. The oxidized iron and manganese in water are then trapped in the filter media. Water Storage Hydrated lime is then added to the water to make neutral from acidic (pH). Further , Fluoride is added to avoid tooth decay. The water is then transported to the elevated storage tank for being stored for several hours. Water Distribution The water is then supplied to the water pipes on demand using the powerful centrifugal pumps that keeps the water pressure invariably at 60-75 pounds per inch2. The water is delivered to the consumer through the water distribution system comprising of many miles of pipes of different sizes. Moores Bridge Plant Table 4: Common Water quality parameters at the Moores Bridge Plant (Source: http://www.norfolk.gov/Utilities/quality/WQAMB1st10.PDF) 37th Street Plant Table 5: Common Water quality parameters at the 37th Street Plant (Source: http://www.norfolk.gov/Utilities/quality/WQA371st10.PDF) Conclusion Through investigating the water treatment and monitoring processes in Kuwait and Norfolk, Va, it has been found that Norfolk caters better facilities and processes for the treatment water. However, Kuwait also fulfills the international guidelines of WHO for the quality of potable water. References Al-Ruwaih et al., 2010. 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