Title of Invention

"AN APPARATUS AND A PROCESS FOR REMOVAL OF ARSENIC"

Abstract

An apparatus for removal of arsenic has been described. It comprises of two chambers, the top adsorption chamber being provided with cartridge having perforated top and packed with an adsorbing medium consisting of acrylic fiber, the lower collecting chamber is provided with any conventional means for tapping water substantially free from arsenic and optionally provided with the any known mechanical support at the bottom. A process for removing arsenic from water or liquid waste/ effluent using the apparatus is also disclosed. It consists of passing arsenic laden water through adsorption chamber and collecting water that is substantially free from arsenic from the lower collecting chamber.

Full Text

THIS INVENTION RELATES TO AN APPARATUS AND A PROCESS FOR REMOVAL OF ARSENIC. Particularly, this invention relates to an apparatus for removal of arsenic from water and wastewater. More particularly, this invention relates to an apparatus for removal of arsenic from ground water. Still more particularly, this invention relates to an apparatus for removal of arsenic from water that is safe and easy to handle. Yet more particularly, this invention relates to an apparatus that is cost effective and highly efficient. Further, this invention relates to an apparatus, which removes arsenic through adsorption wherein the adsorption medium used is acrylic fibers with high ion exchange capacity. Further the adsorption medium can be regenerated. The invention also relates to a process for removal of arsenic using the apparatus, which is a subject matter of this invention that produces water meeting the guidelines stipulated by WHO. In addition to being efficient, the process as claimed and described by this invention is also cost effective and easy to operate. BACKGROUND OF THE INVENTION: Arsenic contamination in natural water is a world wide problem. Highly elevated levels of arsenic are reported in water particularly in ground water. Arsenic level in ground water ranges from 0.1 mg/1 to about over 3 mg per liter. Seven districts of the state of West Bengal, have arsenic in their water, particularly in their drinking water at a concentration of much higher level than the permissible limit. Considering the health hazards resulting from the consumption of water contaminated with arsenic, WHO, in 1958, fixed 0.2mg/L as allowable concentration of arsenic in drinking water. These standards were revised in 1963 and restricted to 0.05 mg/L. Recent regulations have stipulated that the level of arsenic should be less than lOug/L. Further USA has proposed 0.005mg/L as a new standard for arsenic. Currently, arsenic is removed using one or more of the following methods:  OXIDATION/REDUCTION- These reactions either oxidize or reduce by adding or withdrawing electrons. It could be air or chemical oxidation. These reactions do remove arsenic necessarily but helps in optimizing processes by oxidising other impurities. The advantage is that the processes are simple, low cost. However, they are relatively slow.  PRECIPITATION- The soluble arsenic is converted to solid mineral such as calcium arsenate, which can be removed, by sedimentation or filtration. However, these processes produce solid toxic waste that requires additional means of disposal. Further, they are not useful for household purposes.  ADSORPTION- Using Activated Alumina, iron coated sand, ion exchange resins etc. These technologies are well known, commercially available, well proven and defined. However, the disadvantages associated with these technologies are limited adsorption capacity, produce large volume of toxic solid waste, cost extensive, require replacement or regeneration mechanism and are not environment friendly.  COAGULATION CO PRECIPITATION - Generally Alum iron coagulation is advised. Though the chemicals are easily available and operating cost is not very high, it requires large amount of land, high capital cost for construction of coagulation and precipitation tanks. They also produce large volume of toxic sludge. They also require pre oxidation under certain conditions. Further, the removal efficiency is on the lower side. Thus the processes prove to be cost intensive. Membrane techniques such as Nano-filtration, reverse osmosis electrodialyses are some more methods available for removal of arsenic. These techniques remove some of the disadvantages associated with other processes herein above described. They are efficient and do not produce high volume of solid toxic sludge. However, the reaction rate is low, require high capital cost, high operation and maintenance cost. Further these technologies produce toxic liquid waste and require pre-treatment to prevent media clogging. > BIOLOGICAL REMOVAL- Microorganisms are adapted suitably to remove arsenic. However, this technology produces biological waste, which has to be further disposed off. Thus the process becomes cost extensive and sometimes requires skilled personnel to operate the same. In-situ immobilization has also been reported. Oxidizing agent such as potassium permanganate is injected in wells contaminated with iron and arsenic. The removal efficiency is over 99% and the added advantage is of not producing any waste that must be disposed off. However, it is at an embryonic stage and thus needs more information and evidence in respect of its feasibility. Large number of patents have been filed and granted for arsenic removal since 1997. The prior art known to the inventor includes Japanese patent having Publication No. 2002-079015. The patent describes a filter for removal of arsenic from ground water. The filter, as claimed, comprises of fired diatomaceous earth impregnated with 5-30% ferric ion. The filter can be regenerated several times. The removal is effected by adsorption. Another PCT Application No. W002/081385A2 teaches removal of arsenic using reactive material such as titanium oxide granulates thereby increasing available surface for reaction and removal of arsenic. The system can continue and remains effective over the serviceable life of the granulates. PCT Application No. WOOl/62670 describes an apparatus and method for removal of Arsenic. The apparatus uses a bed of granulated ferric hydroxide to absorb the metal in pressurized adsorption chamber. The process and apparatus is useful for community water treatment and requires more land and manpower. Household filters are also available for removal of arsenic from water. "Safi" filter is a ceramic candle filter composed of hydrated aluminium, manganese, iron oxides, mesoporous silica and alkaline earth silicate and aluminate. It comprises of 2 containers each of 15 L with a single candle in the upper container. Mechanism involved is filtration adsorption. Final arsenic concentration was inconsistent depending on the methodology used for testing. However, the system is not efficient to bring down arsenic removal below WHO guideline standards. The filters are in the market since January 2000. Breakthrough capacity is 10% influent concentration. The other household filter "AMAL" also has Breakthrough capacity of 10% influent concentration. The conventional two-chamber filter widely available in the market was converted to a filter for arsenic removal. The candles were removed and replaced by the adsorption medium, which is activated alumina, enclosed in an impervious nylon bag. The unit is expected to operate for 6-8 months. The alumina/medium can be regenerated. SUMMARY OF THE INVENTION: The present invention seeks to provide advantageous apparatus and method for removal of arsenic. Thus the main object of the present invention is to provide an apparatus to remove arsenic from water and arsenic laden liquid waste. Other object of the present invention is to provide an apparatus to remove arsenic from water, particularly ground water substantially avoiding the problems associated with the existing Apparatuses/ Filters. Another object of the present invention is to provide an apparatus to remove arsenic from ground water through adsorption using high exchange capacity acrylic fibers as adsorbing medium. Yet another object of the present invention is to provide an apparatus, to remove arsenic from ground water that is simple, portable, easy to handle, cost effective and highly efficient. Still another object of the present invention is to provide a process using the said apparatus to remove arsenic from ground water to safe levels as stipulated by WHO guidelines. The process of this invention proves to be simple, economic, efficient and easy to operate while maintaining the quality of the water. The process is capable of removing arsenic with three and five valency. The process does not require large amount of land, high capital cost for infrastructure or skilled personnel. Further, the process also does not require any additional measures to take care of liquid or solid toxic waste management as such toxic waste is not generated. After continuous and prolonged experimentation, the inventors found that using acrylic fiber as adsorption media allows increased metal adsorption when compared to the existing adsorption media. Particularly, the amidoximated acrylic fibers show considerable increase in ion exchange capacity and thereby substantial increase in arsenic removal. The amidoximation can be carried out by any conventional methods. However, when the amidoximation of the said fibers is carried out using hydroxylamine, it is possible to get fibers with amidoxime content of 11.3 mmol/g having a maximum ion exchange capacity of 3meq/g. Moreover, the added advantage is that the fibers can be regenerated using easily available hydrochloric acid. Another additional advantage of using amidoximated acrylic fiber is the elimination of toxic waste in either liquid or solid form. Thus the apparatus is environment friendly and in turn cost efficient. The apparatus has no restriction as far as size/ volume is concerned. The efficiency, for removal of arsenic, of the apparatus is not directly correlated to the size of the apparatus. Depending on the market need, apparatuses of varied capacity can be manufactured. The crucial aspect of the apparatus of this invention is the cartridge packed with the adsorbing medium that is provided in the adsorbing chamber. Both the chambers may or may not be of same size or volume. However, they should have same configuration. According to the first aspect of the present invention there is provided an apparatus for removal of arsenic comprising two chambers, the top adsorption chamber being provided with cartridge having perforated top and packed with an adsorbing medium consisting of acrylic fiber, the lower collecting chamber is provided with any conventional means for tapping water substantially free from arsenic and optionally provided with any known mechanical support at the bottom. According to one of the embodiments of the present invention, the apparatus may be of any three dimensional configuration preferably cylindrical. According to another embodiment of the present invention, the two chambers of apparatus may be fixed permanently to each other or placed one above the other. According to yet another embodiment of the present invention, in case of cylindrical apparatus, height to diameter ratio may vary from 1.5 to 5, preferably about 3 and in case of individual chambers, the height to diameter ratio may be 1.5. According to another embodiment of the present invention, adsorption chamber to cartridge ratio in respect volume may be 5, preferably 3, more preferably about 2. According to yet another embodiment of the present invention, the ratio of perforated area to circumferential area of cartridge may vary from 0.5 to 5/cm . According to still another embodiment of the present invention, size of perforations may be in the range of 0.2 to 2mm preferably 1mm. Further the cartridge may be made of non-toxic rigid material that would not leach out components hazardous to health, preferably plastics, more preferably polystyrene, polypropylene. The acrylic fiber used to pack the cartridge may be amidoximated polyacrylonitrile. The fiber may have amidoxime content in the range of 6.15 to 11.3 mmol/g and ion exchange capacity in the range of 1.05 to 3 meq/g. The fiber may be regenerated by any known acid treatment preferably hydrochloric acid treatment. And the regeneration cycle be in the range of 6 to 10 preferably 6 to 8. According to second aspect of this invention there is provided a process for removing arsenic from water or liquid waste/ effluent using the said apparatus, which comprises passing arsenic laden water through adsorption chamber and collecting water that is substantially free from arsenic from the lower collecting chamber. The water is passed at a rate of 5 to 200 ml/minute, preferably at 5 to 20ml/min. The process is suitable for the removal of arsenic having arsenic content of about 250 ppb. The invention will now be described with reference to the accompanying drawings and examples in addition to the detailed description. Figure 1 is a schematic illustration of the apparatus. Figure 2 is a schematic representation of a cartridge. The apparatus as shown in figure 1 comprises adsorption chamber (1), collecting chamber (2), cartridge packed with adsorbing medium (3) and perforations on the cartridge (4). Although the apparatus can function with one cartridge, plurality of cartridges as well can be used may be with added efficiency. The presently disclosed process is explained with the help of the following examples, which are not intended to limit the scope of the present invention. Any modification, which is obvious to the persons working in this field, may fall within the scope of the present invention. AMIDOXIMATION OF FIBER EXAMPLE-I An aqueous solution of hydroxylamine of 1 to 4% concentration was added to a reaction tube containing acrylic fibre keeping an material: liquor ratio (MLR) of 1:50. The flask was then immersed in water bath maintained at a constant temperature. The reaction time was varied between 1-4 hours. The content in the reaction tube was shaken occasionally during the reaction. After the reaction was over, the fibre was removed from the tube and was made free of hydroxylamine by washing thoroughly with deionised water. Finally, the fibre was dried in an hot air oven at 60 C. The amidoxime content of acrylonitrile fibre was found to attain a maximum value of 11.3 mmol /g. EXAMPLE-II Acrylic fibre was taken in a reaction tube and the reaction temperature was kept constant by placing the flask in a thermostatically controlled water bath. The concentration of hydroxylamine in the solution was varied between 1 - 3 % keeping an MLR of 1:50. The reaction was carried for a fixed reaction time. After the reaction, fibre was removed from the flask and washed thoroughly with deionised water so as to remove the last traces of hydroxylamine from the fibre. Finally, the fibre was dried in an hot air oven. The maximum amidoxime content of acrylonitrile fibre was found to vary between 2.2 to 11.3 mmol / g EXAMPLE-III In aqueous solution of hydroxylamine of specific concentration was added to the fibre in a reaction tube maintaining an MLR of 1:50. The reaction was carried out for a fixed time period. The variation in the reaction temperature was carried out in the range of 80 C by placing the flask in a thermostatically controlled water bath. The fibre was stirred occasionally during the reaction. After the reaction, the fibre was washed with deionised water and dried in a hot air oven. The amidoxime content of acrylonitrile fibre was found to increase from 11.3 mmol/g as reaction temperature changes from 80 °C ARSENIC REMOVAL EXAMPLE-IV The acrylic fibre with 11.3 mmol/g of amidoxime content was placed in water containing arsenic of 100 ppb. The separation upto 97% was achieved in the system. The separation for both As3+ and As+5 was determined. The time taken to the maximum mercury separation was 30 minutes. EXAMPLE--V The acrylic fibre with 11.3 mmol/g of amidoxime content was placed in a column to have a column density of 0.16g/cc. The water containing arsenic of 100 ppb was eluted across the column at a rate of lOml/min. The arsenic rejection was 97%. EXAMPLE-VI The acrylic fibre with 11.3 mmol/g of amidoxime content was placed in a column (cartridge) to have a column density of 0.16g/cc. The water containing arsenic of 100 ppb was eluted across the column at a rate of 20 ml/min. The arsenic rejection was 92-97%. The exhaustion is achieved faster at higher permeation rate. Purification of 2L water was achieved EXAMPLE-VII The acrylic fibre with 11.3 mmol/g of amidoxime content was placed in water containing As+5 of lOOppb. A column was prepared with the fibres. The flow rate was maintained in the range of 5 ml/min. Breakthrough curve was obtained at about 2.5L water. EXAMPLE--VIII The acrylic fibre with 11.3 mmol/g of amidoxime content was placed in water containing As+5 of l0ppb. A column was prepared with the fibres (column density 0.16/cc). The flow rate was maintained in the range of 5 ml/min. Almost 18 L water could be purified under these conditions. EXAMPLE-IX The acrylic fibre recovered from the column after arsenic separation was regenerated by treating with 0.5M HCl for 2h. The regeneration was between 96.8-99.4%. The regeneration cycles for the regenerated fibres were repeated a few times and at each time, the regeneration was almost 99%. EXAMPLE-X The acrylic fibre with 11.3 mmol/g of amidoxime content was used to separate As-m from water. The water was treated with oxidizing agents such as hydrogen peroxide, to convert As-III into AS-V. The oxidizing agent was kept at 1.0 gpl and arsenic contaminated water was eluted at a rate of l0ml/minutes. The efficiency of As-III was enhanced from 68 to 93% separation. EXAMPLE-XI The acrylic fibre with 11.3 mmol/g of amidoxime content was used to separate As-III from water. The water was treated with oxidizing agents hypochlorite, to convert As-III into AS-V. The oxidizing agent was kept at 1.0 gpl and arsenic contaminated water was eluted at a rate of lOml/minutes. The efficiency of As-III was enhanced from 68 to 96% separation. As can be seen it is first time the fibers are used for treating arsenic laden water. The whole process is based on the use of low cost chemicals and the process does not require any sophisticated infrastructure or skilled personnel. The capital requirement as well as running cost is also very low. Further the cartridge can be removed, regenerated and reused. ADVANTAGES The apparatus is safe and easy to handle.  The apparatus is cost effective and efficient.  The apparatus does not require any sophisticated infrastructure and skilled personnel to operate.  The apparatus is useful for household as well as community level.  The apparatus is having flexibility in shape and or size while maintaining efficiency for arsenic removal.  The apparatus is capable of removing arsenic of 3+ or 5+ WE CLAIM: 1. An apparatus for removal of arsenic comprising two chambers, the top adsorption chamber (1) being provided with cartridge having perforations (4) the said cartridge being packed with an adsorbing medium (3) consisting of acrylic fiber, the lower collecting chamber (2) is provided with any conventional outlet (5) for tapping water substantially free from arsenic the lower container (2) is optionally provided with the any known mechanical support at the bottom wherein the acrylic fiber employed as adsorbing medium is amidoximated polyacrylonitrile, 2. An apparatus as claimed in claim 1 wherein, the apparatus is of any three dimensional configuration preferably cylindrical. 3. An apparatus as claimed in claims 1 and 2 wherein, the two chambers of apparatus are either permanently fixed to each other or placed one above the other. 4. An apparatus as claimed in claims 1 to 3 wherein, height to diameter ratio in case of cylindrical apparatus varies from 1.5 to 5, preferably about 3 and height to diameter ratio in case of individual chambers is ~ 1.5. 5. An apparatus as claimed in claim 1 wherein, the adsorption chamber to cartridge ratio in respect of volume should be 5, preferably 3 more preferably about 2. 6. An apparatus as claimed in claim 1 wherein, the ratio of perforated area to circumferential area of cartridge varies from 0.5 to 5 /cm . 7. An apparatus as claimed in claims 1 to 6 wherein, the size of perforations (4) ranges from 0.2 to 2 mm preferably 1mm. 8. An apparatus as claimed in claims 1 to 7 wherein, the cartridge is made of non-toxic rigid material that would not leach out components hazardous to health, preferably plastics, more preferably polystyrene, polypropylene. 9. An apparatus as claimed in claim 1 wherein, the amidoxime content of fiber is in the range of 6.15 to 11.3 mmol/g and ion exchange capacity in the range of 1.05 to 3 meq/g. 10. A process for removing arsenic from water or liquid waste/ effluent using the apparatus as claimed in preceding claims, which comprises passing arsenic laden water through adsorption chamber and collecting water that is substantially free from arsenic from the lower collecting chamber. 11. A process as claimed in claim 15 wherein, the water is passed at a rate of 5 to 200 ml/minute, preferably at 5 to 20 ml/min. 12. An apparatus and a process using the said apparatus for removal of arsenic substantially as herein described.

Documents:

210-DEL-2004-Abstract-(30-05-2012).pdf

210-del-2004-abstract.pdf

210-DEL-2004-Claims-(30-05-2012).pdf

210-del-2004-claims.pdf

210-del-2004-Correspondence Others-(21-07-2014).pdf

210-DEL-2004-Correspondence Others-(30-05-2012).pdf

210-del-2004-correspondence-others.pdf

210-del-2004-correspondence-po.pdf

210-del-2004-description (complete).pdf

210-DEL-2004-Drawings-(30-05-2012).pdf

210-del-2004-drawings.pdf

210-del-2004-form-1.pdf

210-del-2004-form-18.pdf

210-del-2004-form-2.pdf

210-del-2004-form-3.pdf

210-del-2004-form-5.pdf

210-DEL-2004-GPA-(30-05-2012).pdf