Title of Invention

A NOVEL PLANT FOR REMOVAL OF ARSENIC FROM WATER

Abstract

1. A novel plant for removal of arsenic from water comprising in combination : (i) a plurality of tanks or containers made of polymeric material having at least one opening at the upper region and another two openings at the lower region of said tanks. (ii) a means for supplying water contaminated with arsenic to the said tank(s); (iii) means for removal of arsenic loaded into the first few tanks upto a predetermined level; (iv) means for removal of final traces of arsenic from water flowing out of the said first few tanks; (v) means for removal of arsenic enriched waste water and sludge flowing out of the treatment plant and (vi) means for storing arsenic - free water flowing out of the last tank.

Full Text

The present invention relates to a novel plant for removal of arsenic from water. More particularly this invention is concerned with a novel plant comprising a plurality of tanks made of inert, food-grade polymeric material, packed with naturally occurring or processed mineral like red haematite and activated alumina which have been found to be capable of removing arsenic from arsenic-contaminated water and rendering water safe for use by humans and animals alike. Over the years the scourge of arsenic bearing water has been the cause of show, painful death of thousand of hapless victim both in West Bengal and also in Bangla Desh. When the problem reared its head, authorities tried to play it down and asked people not to panic. Eventually incidence of skin cancer by prolonged use of arsenic contaminated water forced the Authorities in both sides of the border, namely, in West Bengal and Bangla Desh to tackle the problem right earnest. Pioneering researchers like Prof. K. G. Nath of School of Tropical Medicine and Dr. Dipankar Chakraborti of Jadavpur University had put in lots of effort in identifying the connection between black skin spots and quantum of arsenic content in the drinking water. They identified areas in the vicinity of river Ganges in North Bengal and northern districts of Bangla Desh as arsenic prone areas. Later on. even areas in southern West Bengal Like Baruipur, Garia and even certain parts of Garia were found by Drs. Nath and Chakraborti to be riddled with arsenic menace. Efforts have been and are being made for evolving ways and means to tackle this problem effectively. Non Government organizations (NGOs) like Rotary International, CARE, OXFAM, and a few others have provided funds and equipments for removal of arsenic from water in order to render it safe for drinking, washing and other common uses. Government agencies like "Council of Scientific & Industrial Research" ('CSIR' in short), "Indian Council of Medical Research" (ICMR), and others have also been active in this field to evolve ways and means to remove arsenic from water. In fact, CSIR had filed Patent Application directed to compositions effective for arsenic removal, such as, for instance, Indian Patent Application Serial Nos. 188959 and 189168. the former relating to a 'synergistic composition' of- i) complexing and co-precipitating agent - 73-87%, ii) oxidising agent - 9-18%, and iii) adsorbing agent - 4-10%, and the latter pertaining to "arsenic removing agent" having the composition : - i) arsenic coprecipitating - 30 to 35 wt%, ii) oxidising agent - 40 to 47 wt% and iii) activated carbon - 22 to 28 wt% Compositions useful for removing arsenic from water and also a process therefor have been developed by Dr. Chakraborti and his co-workers at School of Environmental Studies, Jadavpur University. The inventions have been made subject matters of- i) Bangladesh Patent No. 1002827 dt. 27.6.1996, ii) Indian Patent Application No. 1618/Del/94 dated 14.12.1994 and iii) Indian Patent Application No. 1621/Del/94 dated 14.12.1994, respectively. Equipments for removal of arsenic in the form of special filters to be filled with tube wells have also been in use, and some of them have been functioning satisfactorily over a period of time; but often spares are difficult to obtain and cost of such equipments of ten stand in the way of wide use. Compositions of the type described above suffer from a practical difficulty, particularly in far-flung rural areas, as the constituent components are not always available even in district headquarters, not to speak of rural towns. Moreover, special type of containers, usually of stainless steel, are needed to use reactive components like oxidizing agent, complexing agent, coprecipitating agent, and the like. Designing and fabrication of stainless steel or other non-reactive materials necessitate skilled workmen and special equipments. Cartage of the finished, heavy reactors may pose problems, particularly in areas with difficult accessibility and unsatisfactory road condition. Plants made of ordinary mild steel also suffer from the problems of corrosion and rusting. A recurring expenditure of application of protective coats of primer and paints may prove to be counter - productive in the long run. It is to be borne in mind that arsenic in the trivalent state is much more harmful than in the pentavalent state. Thus, arsenious oxide (As2O3) is more toxic and induces skin cancer much faster. As compounds have greater solubility in water and hence underground water, usually tube well sunk to a depth of around 350 - 450ft, readily dissolves arsenious (As3) compounds and is a potential health hazard. On the other hand, As- compounds are for less soluble in water and tend to separate out from aqueous phase on standing. Hence, the primary step in removal of arsenic is to provide an oxiding atmosphere to convert As no As It has also been observed that arsenic is not found in surface water, that is, in water bodies of shallow depth, such as ponds, shallow tube wells, etc. However, to maintain a pond in hygienic condition is a difficult task, in view of lack of literacy and awareness among village people in general. In draught - prone areas, tube wells are virtually the only source of water and if the underground strata are arsenic bearing, then the effluent water becomes a silent killer. The principal object of the invention is to provide a novel plant which can effectively overcome the problems mentioned above. A further object of this invention is to provide a plant which uses inexpensive, indigeneously available materials for removal of arsenic from water. A still further object of this invention is to provide a plant comprising a plurality of interconnected containers or tanks of special design made from light weight, food grade, polymeric material. Another object of this invention is to provide a plant for removal of arsenic from arsenic - contaminated water said plant comprising four tanks in parallel, first three being filled with red haematite blocks, nuggets or chips of irregular shapes and dimensions and the fourth tank being filled with activated alumina in globular form contained in nylon sacks. Yet another object of this invention is to provide a plant comprising a plurality of tanks each equipped with a detachable perforated plate at the bottom, the perforations capable of being closed as and when desired, which plate in turn is connected to an outlet at the base of the said tank for draining out waste water and sludge to be collected at the sludge pit. A still another object of this invention is to provide a plant for removal of arsenic from arsenic - contaminated water comprising a plurality of tanks or containers wherein the tank - tops are covered with mosquito - net to prevent mosquito/larvae to thrive inside water and breed during non-operation of the plant. A yet further object of this invention is to provide a plant for removal of arsenic from arsenic-contaminated water wherein the waste-water line from the second, third and fourth tanks is connected to the sludge pit through a pipeline. The foregoing objects are achieved by the present invention which relates to a novel plant for removal of arsenic from water, characterized in that the said plant comprises in combination : (i) a plurality of tanks or containers made of polymeric material having at least one opening at the upper region and another two openings at the lower region of said tanks: (ii) a means for supplying water contaminated with arsenic to the said tank(s); (iii) means for removal of arsenic loaded into the first few tanks upto a predetermined level; (iv) means for removal of final traces of arsenic from water flowing out of said first few tanks; (v) means for removal of arsenic - enriched waste water and sludge flowing out of the treatment plant and (vi) means for storing arsenic free water flowing out of the last tank. Usually the plant has four specially designed tanks fabricated from lightweight, food grade polymeric material which may be of any geometrical shape, size and configuration, circular/cylindrical being preferred. Arsenic - contaminated water is sprayed into the first tank from or gantry or a suitable inlet pipe, the said first tank being placed at a level higher than the rest of the tanks to facilitate transfer of liquid to the subsequent tanks under force of gravity. This avoids use of pump(s) with consequent saving on energy expenditure. As mentioned earlier, the plant usually has four tanks or containers in parallel, the first three are filed with red haematite blocks, nuggets or chips of irregular shape and configuration and the fourth tank is packed with activated alumina contained in nylon sacks. The alumina used is preferably in globular form. Each of the tanks is of lower diameter and greater height i.e. cylindrical or barrel - like in shape, and is capable of holding a plurality of layers of red haematite blocks or nuggets ensuring greater contact time of water percolating through the layers of red haematite. Furthermore, each one of those tanks is fitted with a detachable perforated plate at the bottom, the perforations capable of being closed at will, which in turn is connected to an outlet at the base of the said tank for draining out arsenic - enriched water and sludge to be collected in the sludge pit. A further unique feature of this invention is envisaged in the novel plant in which arsenic contaminated water is allowed to trickle down the red haematite layers in the first tank, but is pushed up in the next three tanks through the layers of red haematite and activated alumina for achieving highest efficiency in arsenic removal. As indicated earlier in this specification, the tanks are made from lightweight, food grade, plastic material which enables easy transport and installation, requiring less manpower, tools and tackles. The size of red haematite blocks or nuggets vary between ¼' and ½' in irregular shapes, and particle size of activated alumina is around 2 mm globular form. The latter, namely, activated alumina, is held in nylon sacks, having pores of around 50 mesh size. These alumina - filled sacks are placed in the fourth tank, layer upon layer, through which water is made to travel from bottom to top to allow greater contact time with activated alumina. The tank tops are covered with mosquito net to prevent mosquito / larvae to thrive inside water and breed during non-operation of the plant. The waste - water line from the second, third and fourth tanks, along with the sludge is connected to the sludge pit through a pipeline inclined at an angle to facilitate sludge flow. The outlet of the aforesaid pipeline is usually at a level of around 1" lower than the inlet connection of the pipe from the fourth tank. The sludge pit may optionally be covered with a fine-perforated plastic sheet which allows sludge to be removed from time to time, and clear water seeps into the ground. The invention will now be particularly described and illustrated in the flowsheet diagram accompanying this specification in which (1) is inlet for raw water. (2) is the mosquito net covering the tanks, (3) is the inlet for washing, (4) is a valve, (5) shows the perforated cover, (6) shows the sand layer and (7) shows the layer of gravels, (8) is the outlet for treated water, (9) is the bob cork, (10) shows the perforated plate, (11) shows the perforated pipe, (12) is the P.V.C. pipe support, (13) shows the level 25 mm above from bottom, (14) is the sludge pit, (15) is the means for aeration. (16) is the overflow pipe, (17) is the waste water line, (18) is the inlet for raw water from source, (19) stands for activated alumina in nylon sacks and (20) stands for blocks or nuggets of irregular shaped red haematite. As will be evident from the accompanying drawing, raw water coming through inlet (1) is sprayed into the first tank attended with aeration by a suitable means (15) which is usually an air blower. Water trickles down the red haematite layers (20) and partially arsenic - depleted water travels by pipe (11) to the second tank C2through the inlet at the bottom and gradually travels up the column after filling the same. Valve (4) is opened to allow water to pass into tank C3. The same operation is repeated in the case of fourth column C4also in which water travels through bed of pebbles (7), then through bed of sand (6) and finally traces of arsenic remaining in water gets trapped in the layers of activated alumina in nylon sacks (19). Arsenic free water goes out via pipe (8) and is collected in reservoir by opening the bob-cork (9). Periodically the tanks may be washed by sending water through pipe (3) by opening valve (4). This cleans the red haematite and activated alumina layers and the wash liquid with fine sludge go out through the openings of the bottom plate (10) and travel to the sludge pit (14) via the waste water line (17). Arsenic enriched water which collects at the bottom of each tank during normal operation of the plant is automatically led away to the sludge pit through the waste water line (17). The novel plant of this invention offers a number of advantages, such as. for example - 1. The tanks being lightweight, it is much easier to handle them during installation as well as during cleaning operation from time to time. 2. The tanks being made from food grade plastic material, these would be entirely hygienic and risk - free to store / treat drinking water after / for removal of arsenic. 3. The tanks being made from inert polymeric material, they do not run the risk, of developing rust or corrosion, as is the case with imported steel tanks. 4. The tanks are extremely cost - effective, being almost a quarter in price in comparison with steel tanks using imported technology. 5. No separate pump is used for transferring water from one tank to another, thereby saving in energy and cost and rendering the plant suitable even for remote, arsenic - prone areas. While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing or deviating from the spirit and scope of the invention. Thus the disclosure contained herein includes within its ambit the obvious equivalents and substitutes as well. Having described the invention in detail with particular reference to the illustrative flow sheet diagram accompanying this specification, it will now be more specifically defined by the claims appended hereafter. I claim : 1. A novel plant for removal of arsenic from water characterized in that the said plant comprises in combination : (i) a plurality of tanks or containers made of polymeric material having at least one opening at the upper region and another two openings at the lower region of said tanks; (ii) a means for supplying water contaminated with arsenic to the said tank(s); (iii) means for removal of arsenic loaded into the first few tanks upto a predetermined level; (iv) means for removal of final traces of arsenic from water flowing out of the said first few tanks; (v) means for removal of arsenic - enriched waste water and sludge flowing out of the treatment plant and (vi) means for storing arsenic - free water flowing out of the last tank. 2. A plant as claimed in Claim 1. wherein arsenic - contaminated water is sprayed into the first tank from a gantry or a suitable inlet pipe, the said first tank being placed at a level higher than the rest of the tanks to facilitate gravity feeding into the subsequent tanks. 3. A plant as claimed in Claims 1 and 2. wherein there are provided four tanks in parallel, first three being filled with red haematite blocks, chips or nuggets of irregular shape and the fourth tank being packed with nylon sacks containing activated alumina in globular form. 4. A plant as claimed in Claims 1 to 3, wherein each one of said tanks is fitted with a detachable perforated plate at the bottom, the perforations capable of being closed at will, connected to an outlet at the base of the said tank for draining out arsenic enriched waste water and sludge to be collected in the sludge pit. 5. A plant as claimed in Claims 1 to 4, wherein the said tanks are of lower diameter and greater height which can hold plurality of layers of red haematite blocks ensuring greater contact time with water percolating through the layers of red haematite. 6. A plant as claimed in Claims 1 and 5, wherein arsenic - contaminated water is allowed to trickle down the red haematite layers in the first tank, but is pushed up in the next three tanks through the layers of red haematite and activated alumina for achieving highest efficiency in arsenic removal. 7. A plant as claimed in any of the preceding claims, wherein the tanks are made from light-weight, food grade plastic material. 8. A plant as claimed in Claims 1, 3 and 4, wherein particle size of red haematite varies between ¼' and ½' in irregular shapes and particle size of activated alumina is around 2 mm in globular form. 9. A plant as claimed Claims 1. 3 and 8. wherein activated alumina is packed in nylon sacks having pores of around 50 mesh size, and the sacks are placed in the fourth tank layer upon layer of pebbles and sand, through which water is made to pass from bottom to top to allow greater contact time with activated alumina. 10. A plant as claimed in Claims 1 to 9. wherein the tank tops are covered with mosquito net to prevent mosquito / larvae to thrive inside water and breed during non- operation of the plant. 11. A plant as claimed in Claims 1 to 10. wherein the waste water line from the second, third and fourth tanks, along with the sludge, is connected to the sludge pit through a pipeline inclined at an angle for ease of sludge flow. 12. A plant as claimed in Claim 11. wherein the outlet of the said pipeline is a a level of around 1" lower than the inlet connection of the pipe from the fourth tank. 13. A plant as claimed in Claims 1 to 12, wherein there is provided a fine perforated plastic sheet covering the sludge pit. allowing sludge to be removed from time to time and letting clear water to seep into the ground. 14. A novel plant for removal of arsenic from water substantially as hereinbefore described with particular reference to the accompanying drawing. 1. A novel plant for removal of arsenic from water comprising in combination : (i) a plurality of tanks or containers made of polymeric material having at least one opening at the upper region and another two openings at the lower region of said tanks. (ii) a means for supplying water contaminated with arsenic to the said tank(s); (iii) means for removal of arsenic loaded into the first few tanks upto a predetermined level; (iv) means for removal of final traces of arsenic from water flowing out of the said first few tanks; (v) means for removal of arsenic enriched waste water and sludge flowing out of the treatment plant and (vi) means for storing arsenic - free water flowing out of the last tank.

Documents:

30-KOL-2003-(04-05-2012)-CORRESPONDENCE.pdf

30-KOL-2003-(12-12-2011)-CORRESPONDENCE.pdf

30-kol-2003-abstract.pdf

30-kol-2003-claims.pdf

30-kol-2003-correspondence.pdf

30-kol-2003-description (complete).pdf

30-kol-2003-drawings.pdf

30-kol-2003-examination report.pdf

30-kol-2003-form 1.pdf

30-kol-2003-form 13.pdf

30-kol-2003-form 18.pdf

30-kol-2003-form 2.pdf

30-kol-2003-form 3.pdf

30-kol-2003-reply to examination report.pdf

30-kol-2003-specification.pdf