Title of Invention	A PROCESS TO PRODUCE ARSENIC FREE DRINKING WATER AND AN ARSENIK REMOVAL PLANT THEREFOR
Abstract	A process to produce arsenic free drinking water comprising passing arsenic contaminated drinking water through first an iron filter selected from gravel, sand and manganese dioxide and subsequently through a container having granular ferric hydroxide and β-FeooH to obtain arsenic free water.

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FIELD OF INVENTION This invention relates to a method for removal of arsenic from ground water and the apparatus used therefore. BACKGROUND OF THE INVENTION Rural population of India uses ground water specially tubewell water for drinking purpose. But groundwater has been frequently found to be contaminated with arsenic. Consumption of Arsenic contaminated water causes serious stomach and skin diseases. This is a very acute problem and several methods are being used to remove arsenic from arsenic Contaminated water. The used and known processes are not effective in removing Arsenic from contaminated water. Different technologies and processes to remove Arsenic from ground water are now available. The processes are (i) Co-precipitation (ii) membrane technology (iii) Adsorption technology (iv) distillation method and solar technology. According to co-precipitation technology the Arsenic contaminated water is treated with alum and the precipitate containing Arsenic is removed. But in this process removal of As III is not possible. According to another co- precipitation method Arsenic contaminated water is treated with Ferric Sulphate and precipitate-containing Arsenic is separated. In this method the efficiency of removal of arsenic is very low above pH 7.5 yet another co-precipitate method is iron coagulation which is more efficient than alum treatment, but still removal of As III is medium. In the lime softening method lime is added to soften arsenic contaminated water. The addition of lime to soften Arsenic contaminated water requires adjustment of pH above 10.5. The technology generally cannot remove Arsenic III. It further requires oxidation and addition of other chemicals, which is a very complicated method and generates enough sludge. The second method is membrance technology, which includes Reverse Osmosis (RO), Nano Filtration (NF) and Electro Dialysis Reversal. Arsenic can be removed by this method. In addition other impurities are also removed. But the investment, operation and maintenance are very costly. Moreover the reject water is very toxic which affects the environment. The other method is adsorption technology. This method involves use of activated, iron coated sand and Iron exchange resin. Though the method is simple in operation and is less expensive, it cannot remove As III completely. Moreover, the method requires monitoring of breakthrough. In this method periodical regeneration and/or change of media and pH adjustment are necessary. Sulphate, TDS etc. can affect run length. Operation and maintenance of the technology are highly technical. It creates regeneration of highly concentrated waste. The solid waste is toxic and the media is cosily. In addition there are associated problems. The solar distillation method consists of basin and vacuum or multi- effect type. This technology can remove Arsenic having three valences, its operation and maintenance is simple, there is no need for chemicals, but its capacity is small. Addition of chemicals and microbial contaminants as part of the treatment process can also produce adverse effect. For example use of granulated activated carbon is known to be susceptible to microbial infestation. Besides, the disposal of the Arsenic removed from water can also become a major problem. Every technology will have a by-product that contains Arsenic. Other byproducts are produced after treatment of the Arsenic contaminated water. All by-products obtained after treating contaminated water are to be disposed of to avoid environment pollution. OBJECTS OF THE INVENTION It is therefore an object of the invention to propose a method and apparatus for the removal of Arsenic from water, which is simple and cost effective. It is a further object of this invention to propose a method and apparatus for the removal of arsenic from water, which brings down the level of arsenic below the permissible level for potable use. Another object of this invention to propose a method and apparatus for the removal of arsenic from water, which does not generate toxic sludge and the apparatus is virtually maintenance free. DESCRIPTION OF THE INVENTION Thus according to this invention is provided a process for the removal of arsenic from drinking water comprising passing arsenic contaminated water through an iron filter and thereafter through a container having ß-granular ferric hydroxide to obtain arsenic free water. According to this invention is further provided an arsenic removal plant arsenic removal plant for removal of arsenic from ground water comprising a plurality of overhead water tanks (1) installed on a plurality of supporting structures (2) having a sheet cover (5); an automated lifting means constituting of an electric motor (10) and a force lift pump (10), optionally constituting of a hand tubewell (8) for lifting ground water contaminated with arsenic through a delivery pipe (6) to an upper one of said plurality of overhead water tanks (1); an iron filter (3) containing gravel/sand/manganese Di-oxide disposed above a lower one of said plurality of overhead water tank (1); an arsenic filter (7) interposed on an opposite face of said iron filter (3); raw water from said upper tank being first passed through said iron filter (3) and then through said arsenic filter (7) via a second delivery pipe fitted with a flow control valve and a water meter, the filtered arsenic-free water being accumulated in said lower tank provided at the bottom with a plurality of taps (9) for human consumptions. In accordance with this invention, the method for removal of Arsenic from ground water comprises lifting tube well water contaminated with Arsenic manually or by electric motor to an overhead tank to the required size passing the water through iron filter containing gravel/sand/manganese Di-oxide and then through another container having ß-Granular Ferric Hydroxide, the Arsenic filter on which As III and As V adsorbed wherein are fixed flow control valve and water meter and finally transmitting the filtered As III and As V free filtered water to the reserve tank below and direct delivery for human consumption. The ß-Granular Ferric Hydroxide used has a high specific surface 5- 10 times higher efficiency for adsorption of Arsenic from water than other adsorbers. Because of this density and highly selective adsorption characteristics granular ferric hydroxide is used for effective removal of contaminants from natural as well as wastewater. The main application of this is the adsorptive removal of Arsenate and Arsenic binds on the Surface of ferric hydroxide by chemisorption process forming a stable surface complex therewith. The Granular Ferric Hydroxide does require chemical regeneration and does not produce any regenerate sludge. The residual mass of the spent ferric hydroxide is small and it poses no health risks to personal handling the material during installation or replacement. It conforms strictly with the standards for quality of drinking water. Of aH the known Arsenic removal systems the adsorption technique with Granular Ferric Hydroxide in fixed bed reactor is the most simple, safe and effective method for elimination of Arsenic from contaminated ground water. Depending on the concentration of Arsenic in raw water 50,000 bed volumes can be treated with Granular Ferric Hydroxide. Granular Ferric Hydroxide reactors are fixed adsorbers operating like conventional filters with a downward water flow. The technique aims at the combination of high Arsenic removal efficiency with the simple operation of the fixed bed adsorption. This technology is not only economical but also the most effective system as far as the efficiency in eliminating Arsenic from groundwater is concerned. It can find application for small requirements in rural areas in connection with hand tube wells as well as for larger requirements in towns in connection with community waterworks. The configuration is compact and easy-to-install. It can be easily and quickly connected to a hand tube well and does not require any skilled hand for installation. It consists only of a gravel filter followed by an adsorption tower filled at the top and down the gravel bed to be freed from the hand pump enters the first filter at the top and flow down the gravel bed to be freed from suspended particles contained in groundwater. The water exits at the bottom of the gravel filter and enters the adsorption tower at the top where it flows downwards through the AdsorpAs® bed. The Arsenic concentration in water will thereby brought down by AdsorpAs® to a level below the acceptable limits. There is no need to man the system round the clock. It cuts considerably down on operating and personal costs. The gravel filter of the ARP is to be back-washed two to four days to remove the suspended particles and iron from the top of the filter-bed which otherwise reduce the flow rate of water through the ARP. The frequency of back washing will depend on the quality of water treated. In order to back-wash the gravel filter, water from lift-pump is to be pumped for 6 to 7 minutes through the filter bed in the filter bed in the reverse flow direction by closing the normal operation. The back wash water from the gravel filter is led into a bucket, where a great part of the contaminants wiN be retained. The water drained out of the bucket contains less hazards than the groundwater itself. The invention wiU now be explained with the help of the accompanying drawings where Fig. 1(a) represents an elevational view of the novel arsenic removal plant according to the present invention. Fig. 1(b) and Fig. 1(c) show respectively a plan view and a side view of the embodiment of Fig. 1(a) according to the invention, in which, a plurality of overhead water tank (1) is installed at a different height supported by framed structure (2). The upper tank (1) has a sheet cover (5) made of corrugated sheets. A plurality of basement (4) is provided for installation of each of the plurality of overhead water tank (1). A platform (11) constructed at the ground level and fixed to the ground with a plurality of foundation bolts and nuts (12). A lifting means (8,10) is installed on the platform at the ground level for extracting and lifting ground water contaminated with arsenic. For smaller-capacity plant, the lifting means can be selected as a tubewell (8) and for the higher-capacity plant, the lifting means can constitute of an electric motor with a pump (10). The raw water is lifted through a delivery pipe (6) to the upper tank for storage. An iron filter (3) containg gravel/sand/manganese dioxide is placed above the lower tank and raw water from said upper tank is passed through the iron filter (3). The filtered water then passed through an arsenic filter (7) arranged at an opposite side of the lower tank (1). The arsenic free filtered water is stored in the lower tank having a plurality of taps (9). The tubular network for multi-stage delivery of raw-water, semi-filtered water and filtered water has a plurality of flow-control valves and a water meter. Samples of water collected from different areas of the country have shown Arsenic concentration to a level of 2000 micrograms per liter. Concentration of 50 micrograms per liter is taken to be safe for human consumption according to Indian standard. The method being simple, economical and environment friendly can be used for removing Arsenic from ground water of the area where water is contaminated with Arsenic. The system is so efficient that it can bring down the Arsenic concentration to a level less then 0.01 mg. or 10 microgram per liter. Moreover, spent adsorbent is utilized in the brickfield where 5% of Granular Ferric Hydroxide is normally required for the manufacture of bricks. The design of the Arsenic Removal Plant (ARP) includes all the parameters. The proposed ARP has been customized to meet the demand of the village people and to suit their needs. It has been designed in such a way as to be fitted to hand tubewells/electric motors. Widely varying raw water contaminated with Arsenic can be treated by the system. The operation of ARP is simple and users friendly. WE CLAIM; 1. A process to produce arsenic free drinking water comprising passing arsenic contaminated drinking water through first an iron filter selected from gravel, sand and manganese dioxide and subsequently through a container having granular ferric hydroxide and ß-FeooH to obtain arsenic free water. 2. Arsenic removal plant to produce arsenic free drinking water from ground water comprising a plurality of overhead water tanks (1) installed on a plurality of supporting structures (2) having a sheet cover (5); an automated lifting means constituting of an electric motor (10) and a force lift pump (10), optionally constituting of a hand tubewell (8) for lifting ground water contaminated with arsenic through a delivery pipe (6) to an upper one of said plurality of overhead water tanks (1) characterized by an iron filter (3) containing gravel/sand/manganese dioxide disposed above a lower one of said plurality of overhead water tank (1); an arsenic filter (7) interposed on an opposite face of said iron filter (3) raw water from said upper tank being first passed through said iron filter (3); and then through said arsenic filter (7) via a second delivery pipe fitted with a flow control valve and a water meter, the filtered arsenic-free water being accumulated in said lower tank provided at the bottom with a plurality of taps (9) for human consumptions. 3. The arsenic removal plant as claimed in claim 2, wherein said iron filter (3) is formed of a washable ingradients capable of being periodically back-washed in-situ through transmission of water from said lifting means (10). A process to produce arsenic free drinking water comprising passing arsenic contaminated drinking water through first an iron filter selected from gravel, sand and manganese dioxide and subsequently through a container having granular ferric hydroxide and β-FeooH to obtain arsenic free water.

Documents:

341-kol-2003-granted-abstract.pdf

341-kol-2003-granted-claims.pdf

341-kol-2003-granted-correspondence.pdf

341-kol-2003-granted-description (complete).pdf

341-kol-2003-granted-drawings.pdf

341-kol-2003-granted-examination report.pdf

341-kol-2003-granted-form 1.pdf

341-kol-2003-granted-form 18.pdf

341-kol-2003-granted-form 2.pdf

341-kol-2003-granted-form 26.pdf

341-kol-2003-granted-form 3.pdf

341-kol-2003-granted-reply to examination report.pdf

341-kol-2003-granted-specification.pdf