International Journal of Renewable Energy and Environmental Engineering ISSN 2348-157, Vol. 2, No. 3, July 214 Development of a hybrid treatment system using solar still cum sand filter with ceramic media ABDULLAH AL SADEEK, KHONDOKER MAHBUB HASSAN Department of Civil Engineering, Khulna University of Engineering &Technology, Khulna-923, Bangladesh, Email: aasadeek8@gmail.com, khmhassan@yahoo.com Abstract: A vast problem in developing the appropriate supply system for the communities is that the aquifers containing fresh are not always found at convenient locations. Especially in coastal areas, there is a much scarcity of pure because of high salinity in ground. Again, surface is being contaminated by various kinds of organisms and compounds. In that case, Desalination is very effective for drinking supply. This study has been carried out to improve the quality by using tubular solar still and ceramic media along with sand filtration to provide adequate and safe supply in coastal areas. In this study, solar desalination with a tubular solar still along with sand filter (TSS-SF) was designed and constructed. The laboratory experiment was carried out on the top roof of the Civil Engineering Department of Khulna University of Engineering and Technology (KUET). The distilled quality and quantity were properly monitored. Various quality tests were performed between raw and treated. Based on the analysis in study, some proposals are given for the modification of TSS-SF. Keywords: Aquifer, Salinity, Desalination, Organisms and Ceramic Media 1. Introduction: Water is a basic need for human being for physiological processes. Water demand is increasing day by day due to increasing population. According to World health Organization (WHO), one third of the world s populations are without access of clean drinking. In 2, 1.1 billion people worldwide lacked sufficient resources due to contamination (Sobsey, 22). Although is one of the abundant resources on earth but only about 3% of it is potable and remaining 97% is saline which is lying in the sea. This small percentage of the earth s which supplies most of human and animal needs exists in ice caps, glaciers ground and surface source (Ahmed and Rahman, 2). Ground has been used for various purposes such as drinking, domestic purposes, irrigation, industrialization and so on. So, level is lowering day by day. Surface is being polluted by various organisms, organic and inorganic compounds. Ground also has less exposure to airborne contaminants as well as animal faeces. Generally, ground is clear, colourless with very little or no suspended solids and it is free from disease producing micro-organisms which normally present in surface. For these reasons ground is the main source of supply in urban and rural areas of many developing countries but in some areas ground is contaminated with arsenic, and excessive dissolved iron. Besides, in coastal areas ground contains higher level of salinity. Solar desalination is the process that removes excess salts and other organic compounds from the. Though basin type solar still is most popular method in solar desalination, but tubular solar still is easy for construction, operation and maintenance than the basin type solar still. It is the process for purification where solar energy is used as input energy, raw is evaporated from the storage channel of solar still and finally accumulated into the outlet. It creates distilled in undeveloped places that have access only to sea, brackish or contaminated. Among many processes of purification, filtration is a process in which is allowed to pass through a bed of filtering media, usually sand and gravel. Among various techniques of filtration slow sand filtration or biological filtration is the process where raw passes through a bed of sand. Slow sand filtration is a suitable method for treatment in developing countries because it does not require any complex electrical and mechanical equipment or coagulating chemicals. The major advantages of slow sand filter are it has very high removal turbidity, color and bacteria; cleaning of filter bed by scraping and removal of a top layer of sand and low cost of operation and maintenance. It reduces the number of micro-organisms and other physicochemical compounds present in the. The fundamental requirements of drinking are that it should be free from disease producing pathogenic micro-organisms; contain no elements or compound in concentrations that can cause acute or long-term adverse effect on human health; be fairly clear and aesthetically attractive (i.e. low turbidity and color); contain no compounds that can cause an offensive taste and odor; not cause corrosion, scale formation discoloration or staining. There has been a belief that if the technology is simple, low-cost and run by the local community; then it will be effective in promoting a better quality of life. So, the TSS-SF IJREEE 2316 Copyright 214 BASHA RESEARCH CENTRE. All rights reserved
Development of a hybrid treatment system using solar still cum sand filter with ceramic media unit could be a good source of producing potable because of simple construction, locally available materials and semi-skilled or unskilled operators for operations and maintenance. The main objective of this study is to develop a novel treatment technique using solar still cum sand filter which would increase the production of treated and retain the salinity within a permissible level. 2. Methodology: A low cost Tubular Solar Still cum Sand Filter (TSS- SF) was designed and constructed. It was constructed of tubular frame covered with a Raw Evaporation Solar energy transparent normal polythene paper and a black rectangular tray used as channel for storing saline along with sand filter. In the tray, 3 ceramic filters were used as ceramic media for enhancing surface area. The sand filter consists of a circular filter box and an outlet. The filtration materials were clean and free from clay and gravel. The influent raw quality in both TSS and SF was remained same. The effluent treated s from these treatment operations were blended together and stored in a container. The schematic diagram of the TSS-SF unit is shown below: Raw Channel Transparent Polythene Treated Sand Filter Outlet Figure 1: Schematic diagram of TSS-SF unit 2.1 Construction of Channel: A black rectangular tray of length 1.22 m, width.25 m and height.15 m is used as a channel which is made by cartoon paper wrapping black polythene. Figure 3: Tubular Solar Still (TSS) Figure 2: Black rectangular tray 2.2 Construction of Tubular Solar Still: A circular tubular frame of.3 m diameter was constructed by using 1 and 14 no GI wire & a tray was used as a channel inside it. It was supported by a wooden stand of 1.22 m length,.25 m width and some bricks around the bottom of the stand also with a simple outlet. 2.3 Construction of Sand Filter: A circular slow sand filter was constructed using 8cm thickness of gravel and charcoal layer, thickness of sand layer (sieve 1#, 5#, 3# retain, 16# passing) 55cm, diameter of sand filter 16cm and a simple outlet pipe. The surface area of sand filter 2 sq. cm. ISSN 2348-157, Vol. 2, No. 3, July 214, pp 232-236
Chloride conc. (mg/l) TC (N/1 ml) TC (N/1 ml) Chloride conc. (mg/l) Development of a hybrid treatment system using solar still cum sand filter with ceramic media 25 2 15 1 5 Raw TSS SF TSS-SF Figure 7: Variation of salinity in summer season Figure 4: Sand Filter (SF) 2.4 Ceramic Filter: In the tray 3 circular hollow ceramic media are kept. They are about 5 in. in length and 3 in. in diameter. They are used specially to increase surface area on tray and evaporation effect. It is made by a mixture of sand (8%) and rice husk (2%). In winter season, the total coliform (TC) of raw was found to be 22 N/1 ml. After treatment process, the values of total coliform of treated from TSS, SF and TSS-SF were N/1 ml (Fig. 8). In summer season, the total coliform (TC) of raw was found to be 21 N/1 ml. After treatment process, the values of total coliform of treated from TSS, SF and TSS-SF were N/1 ml (Fig. 9). According to WHO guideline (1993) and Bangladesh standards (ECR, 1997), the TC value of drinking is zero. So, the TC value of treated is within the permissible limit. 25 2 15 Figure 5: Ceramic Filter 3. Results and discussion: 3.1 Quality of Treated Water: In winter, salinity value of raw was found about 155 mg/l. After treatment, the values of salinity of treated from TSS, SF and TSS-SF were mg/l, 1481 mg/l and 4 mg/l, respectively (Fig.6). In summer, salinity value of raw was found to be 21 mg/l. After treatment, the values of salinity of treated from TSS, SF and TSS-SF were mg/l, 1983 mg/l and 4 mg/l, respectively (Fig.7). But, the maximum value of salinity in that is acceptable for drinking is 1 mg/l. So, the salinity of treated of TSS-SF unit is within the permissible limit. 16 12 8 4 Raw TSS SF TSS-SF Figure 6: Variation of salinity in winter season 1 5 Raw TSS SF TSS-SF Figure 8: Variation of TC in winter season 25 2 15 1 5 Raw TSS SF TSS-SF Figure 9: Variation of TC in summer season In winter season, the total dissolved solids (TDS) value of raw was found to be 288 mg/l. After treatment process, the values of total dissolved solids of treated from TSS, SF and TSS-SF were mg/l, 1745 mg/l and 85 mg/l, respectively (Fig. 1). In summer season, the total dissolved solids (TDS) value of raw was found to be 35 mg/l. After treatment process, the values of total dissolved solids of treated from TSS, SF and ISSN 2348-157, Vol. 2, No. 3, July 214, pp 232-236
TDS (mg/l) TDS (mg/l) TSS-SF were mg/l, 1813.2 mg/l and 868 mg/l, respectively (Fig. 11). According to WHO guideline (1993) and Bangladesh standards (ECR, 1997), the TDS value of drinking is 1 mg/l and TDS value of treated from our TSS-SF was lying below 1 mg/l. So, the TDS value is within the permissible limit. 3 25 2 15 1 5 Raw TSS SF TSS-SF Figure 1: Variation of TDS in winter season 35 3 25 2 15 1 5 Raw TSS SF TSS-SF Figure 11: Variation of TDS in summer season Other quality parameters such as TS, FC, DO, color and ph of the treated from TSS-SF unit were within the permissible limit of drinking quality standards. 3.2 Quantity of Treated Water: In winter, the average daily production rate of TSS was 2.1 L/m 2 and average daily production was.65 L. The average daily production rate of TSS-SF was 2.63 L/day. Each seven days total output in winter is shown in Table 1. Table 1: Treated from TSS-SF during winter season Observation Period Quantity of Treated (Week) Water on TSS-SF (L) Dec. (19 25): 1st 19.2 Dec. 29 Jan.4: 2nd 18.7 Jan. (6 12): 3rd 18 Jan. (13 19): 4th 17.6 In summer, the average daily production rate of TSS was 3.15 L/m 2 and average daily production was.98 L. The average daily production rate of TSS-SF was 3 L/day. Each seven days total output in summer is shown in Table 2. Table 2: Treated from TSS-SF unit during summer season Observation Period (Week) Mar. (6 12): 1st 2 Mar. (13 19): 2nd 2.6 Mar. (2 26): 3rd 21.1 Mar. 27 Apr. 2: 4th 21.7 Quantity of Treated Water on TSS-SF (L) According to Molla and Biswas (29), the average daily production rate of distilled from TSS was 3.54 L/m 2. According to Bokshi and Khatun (21), the average daily production rate of distilled from TSS was 2.38 L/m 2. According to Saha (211), it was 3.4 L/m 2 and according to Rab (211), it was 1.89 L/m 2 and the average daily production was.32 L. According to Raihan (211), the average daily production rate of distilled from the inclined basin type solar still (BSS) was 3.78 L/m 2 and the average daily production was 1.85 L. But in this above TSS, the average daily production rate in winter and summer were 2.1 L/m 2 and 3.15 L/m 2 respectively. Average daily production on TSS in both winter and summer were.65 L and.98 L respectively. According to Sultana and Jesmine (29), flow rate of slow sand filter was.45 m 3 per m 2 per hr. Flow rate of this above sand filter was.62 m 3 per m 2 per hr. There was great difference in the production rate because it depends on the design and maintenance. In operation time, some ceramic filters were kept in the tray. Again tray stored about 15 L Water. As a result, a huge amount of load was created upon the tubular frame and the tray. It caused a great amount of bending on the tray as well as the tubular frame. This situation is shown in Fig. 12. Figure 12: Condition of TSS because of heavy loading ISSN 2348-157, Vol. 2, No. 3, July 214, pp 232-236
Development of a hybrid treatment system using solar still cum sand filter with ceramic media This situation would have been removed by inserting a wooden slit into tubular frame. This wooden slit was kept under the tray to support the TSS set-up. This condition is shown in Fig. 13. Figure 13: Wooden slit is placed under the tray 4. Conclusions: At present, the interest of potable is increasing day by day because of industrial progress, intensified agriculture, improvement of standard of life and increase of the population of the world. The supply of pure drinking is a serious problem for most parts of the world. In summer, there is a serious problem about getting pure drinking. In coastal areas, there is a much scarcity of pure because of high salinity in. Again, surface is being contaminated by various kinds of organisms and compounds. In this cage, TSS-SF provides a good result for ensuring a good quality of. The TSS-SF unit is suitable for producing potable from mostly available saline in the coastal belt of Bangladesh. Its production cost is also very low. On the other hand, ceramic filter has shown a good result in productivity. The construction of the TSS- SF unit is very easy and one can use this technology easily in the house roof-top. So, it is concluded that the application of TSS-SF technique can fulfill the demand of potable in the coastal areas of many developing countries like Bangladesh. References: [1] Ahmed, M.Feroze and Rahman, Md. Mujibur (2). Water Supply & Sanitation. ITN- Bangladesh, BUET, Dhaka, pp. 33-45. [2] Bangladesh Bureau of Statistics (1997), Statistical Year Book of Bangladesh. Ministry of Planning Govt. of people s Republic of Bangladesh, pp. 99-15. [3] Bokshi, A. and Khatun, H (21). Desalination using low cost Tubular solar still Thesis report of B.Sc. Program, KUET, pp. 17-3. [4] Molla, Rabiul and Biswas, Chandra (29). Solar Desalination using Low Cost Tubular Solar Still - Thesis report of B.Sc. program, KUET, pp.1-18. [5] Rab, Md. Abdur (211). Solar Desalination using Low Cost Tubular Solar Still (TSS) with Normal Polythene Paper as Tubular Cover - Thesis report of B.Sc. Program, KUET, pp.1-4. [6] Raihan, Abu (211). Solar Desalination with inclined Basin Type Solar Still (BSS) - Thesis report of B.Sc. program, KUET, pp. 19-33. [7] Saha, A. Kumar (211). Solar Desalination using Low Cost Tubular Solar Still Thesis report of B.Sc. Program, KUET, pp. 19-25. [8] Sobsey, M. (22). Managing Water in the Home: accelerated Health Gains from Improved Water Supply. World Health Organization (WHO), North California, USA, pp.3-5. [9] Sultana, Shammi and Jesmine, Mansura (29). Monitoring Bacteriological Quality of Water from Household Taps and Filter - Thesis report of B.Sc. Program, KUET, pp.16-25. [1] WHO (1993). Guidelines for Drinking Water Quality. 2 nd Edition, World Health Organization, Geneva, Swizerland, pp. 6-7. ISSN 2348-157, Vol. 2, No. 3, July 214, pp 232-236