FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
J. Title of the invention: APPARATUS FOR WATER PURIFICATION
2, Applicant(s)
NAME NATIONALITY ADDRESS
TATA CONSULTANCY Nirmal Building, 9th Floor, Nariman Point,
Indian
SERVICES LIMITED Mumbai-400021, Maharashtra, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

TECHNICAL FIELD
[0001] The present subject matter, in genera), relates to water purification, and in
particular, to an apparatus for purification of domestic and industrial water.
BACKGROUND
[0002] Water, available in nature or as industrial waste, contains various
contaminants, such as soluble salts of arsenic and fluoride; heavy metals like barium, cadmium, chromium, lead, mercury, selenium, silver, iron; and microbes like pathogenic bacteria, protozoan cysts; particulate matter, etc. Presence of excess of contaminants in water makes water unsuitable for human consumption as consumption of contaminated water may cause various diseases, such as discoloration of the skin, gangrene, intestinal problems and carcinogenic effects to the skin, lung, liver, kidney, and bladder, problems in the gastrointestinal organs, etc. Thus, various purification techniques have been developed conventionally to reduce the concentration of contaminants in water to approved levels before human consumption.
[0003] Conventional methods of water purification are usually based on techniques
involving reverse osmosis, ion-exchange, adsorption, coagulation and precipitation, etc. However, methods based on reverse osmosis and ion exchange are expensive and require regular maintenance. The effectiveness of the reverse osmosis based methods usually depends on the oxidation state of the contaminant and hence, such methods may not be effective for all types of contaminants. For example, reverse osmosis process, used to remove arsenic contaminants, has better performance when arsenic is oxidized from +3 state to +5 state. Similarly, the ion exchange based methods are adversely affected by the presence of ions like sulphates, phosphates, and nitrates.
[0004] Other methods, such as adsorption, use adsorbents such as coconut shell
carbon, activated carbon, activated alumina, for the purification of water. Adsorption uses large quantity of adsorbents leading to high costs. Further, the efficiency of adsorption depends on the pH of source water, and hence, the use of the adsorption based methods is pertinent to areas where water has a favorable pH value. In addition, the efficiency of such methods usually degrades with time.

[0005] Studies show that methods based on coagulation and precipitation are more
effective than the other discussed methods. The conventional methods, based on coagulation and precipitation, are targeted for use in large scale water purification systems, typically meant for industries. These systems require voluminous water supply, have complicated operating procedures requiring trained manpower, have high cost of operation due to the use of large quantities of chemicals, and need regular maintenance. However, in many areas where such infrastructural facilities are not available, these systems may not be capable of getting scaled down to a community or a household level. In addition, high costs of maintenance, requirement of large quantity of chemicals and scarcity of trained manpower further make implementation of such systems difficult.
SUMMARY
[0006] An apparatus for water purification and a method thereof are described herein.
This summary is provided to introduce concepts related to an apparatus for water purification, which is further described below in the detailed description. This summary is not intended to identify essential features of the present subject matter nor is it intended for use in determining or limiting the scope of the present subject matter.
[0007] The apparatus for water purification, according to an embodiment of the
present subject matter, includes a source reservoir to store contaminated water having contaminant ions, such as arsenic contaminant ions, a chemical storage unit to store chemicals, a treatment unit comprising a stirrer unit to facilitate the reaction of the chemicals with the contaminated water so as to form a slurry, a separation unit to separate contaminant ions, particulate matter, colour, odour, turbidity from the slurry thus providing purified water, substantially free from contaminants.
[0008] The apparatus for water purification, according to another embodiment of the
present subject matter, includes a source reservoir, a treatment unit, a chemical storage unit, a chemical dosing unit, water metering units, a separation unit and a collection reservoir. In the said embodiment the treatment unit comprises a dosing section and a holding section whereas the separation unit comprises a solid liquid separation unit and a filtration unit. In operation, the first water mbtering unit delivers metered volumes of untreated water from the source reservoir to the dosing section. Predetermined amounts of chemicals are added to the water by

the chemical dosing unit. The water with chemicals is then delivered to the holding section by the second water metering unit. The holding section provides retention time as well as pressure head to the water entering the separation unit placed near and proximate the base of the holding section. Purified water emerging from the separation unit is stored in the collection reservoir.
[0009] These and other features, aspects, and advantages of the present subject matter
will be better understood with reference to the following description.
BRIEF DESCRIPTION OF DRAWINGS
[00010] The above and other features, aspects and advantages of the subject matter will
be better understood with regard to the following description and accompanying drawings,
where:
[00011] Fig. 1(a) illustrates an apparatus for water purification, according to an
embodiment of the present subject matter.
[00012] Fig. 1(b) illustrates the apparatus for water purification, according to another
embodiment of the present subject matter.
[00013] Fig. 2 illustrates a stirrer unit of the apparatus for water purification, according
to an embodiment of the present subject matter.
[00014] Fig. 3(a) illustrates a chemical storage unit of the apparatus for water
purification , according to a first embodiment of the present subject matter.
[00015] Fig. 3(b) illustrates a chemical storage unit of the apparatus for water
purification, according to a second embodiment of the present subject matter.
[00016] Fig. 3(c) illustrates a chemical storage unit of the apparatus for water
purification, according to a third embodiment of the present Subject matter.
[00017] Fig. 3(d) illustrates a chemical storage unit of the apparatus for water
purification according to a fourth embodiment of the present subject matter.
[00018] Fig. 4 illustrates a metering unit of the apparatus for water purification,
according to an embodiment of the present subject matter.
[00019] Fig. 5(a) illustrates a solid-liquid separation unit of the apparatus for water
purification, according to an embodiment of the present subject matter.

[00020] Fig. 5(b) illustrates a solid-liquid separation unit of the apparatus for water
purification, according to another embodiment of the present subject matter
[00021] Fig. 6 illustrates a filtration unit of the apparatus for water purification,
according to an embodiment of the present subject matter
[00022] Fig. 7 illustrates a graph depicting the effect of volume of contaminated water
on the concentration of arsenic contaminants present in water at various stages of the
apparatus for water purification, according to an embodiment of the present subject matter.
DETAILED DESCRIPTION
[00023] The present subject matter relates to an apparatus and method of water
purification. Water purification is a process of reducing the concentration of toxic chemicals, ions, biological contaminants, etc., from contaminated water so that purified water thus obtained can be used for human consumption without any adverse effects. Contaminated water is hereinafter referred to water which has concentration of contaminants above a threshold level, while the purified water is potable water which has concentration of contaminants below the threshold level. The threshold level is usually defined by the government or government approved agencies or globally recognized bodies like World Health Organization (WHO) in the drinking water standards.
[00024] Conventional methods of purification of water are usually based on
technologies involving reverse osmosis, ion-exchange, adsorption, coagulation and precipitation. The conventional apparatus for water purification implementing such methods involve high treatment costs, limited 'efficiency, scalability issues, complex operating techniques, skilled manpower, and regular maintenance. Also, dependence of the efficiency of a method on any parameter of the input water like pH, concentration of ions, oxidation state of contaminant, etc., limits the application of the method to certain geographic locations or to removal of only certain contaminants. Moreover, the conventional methods are designed for large scale operations requiring large supply of contaminated water. On the other hand, the conventional domestic water purifiers, employing one or a combination of the above techniques, are usually expensive due to cost of chemicals involved and scalability issues. Additionally some conventional apparatus for water purification need regular maintenance,

frequent renewal of filtering media, and operate on an external power source increasing the expenses further.
[00025] The embodiments described herein will help to address the aforementioned
issues in addition to providing several other advantages over the existing water purification methods and apparatus.
[00026] An apparatus for water purification, according to an embodiment of the present
subject matter, includes two reservoirs - a source reservoir for storing the contaminated water and a collection reservoir for collecting and dispensing the purified water. In said embodiment, the apparatus for water purification also includes a chemical storage unit, which stores selected chemicals. The chemicals are selected by the user so as to remove at least a particular contaminant or a plurality of contaminants. The apparatus for water purification uses cheap and readily available chemicals to purify water. In one embodiment, the chemical storage unit includes a coagulant, an oxidizing agent, and a pH adjuster and has a dispenser to add the chemicals to the contaminated water.
[00027] In one embodiment, the apparatus for water purification has a chemical dosing
unit, which adds pre-determined quantities of at least one of the chemicals from the chemical storage unit to the contaminated water.
[00028] In one embodiment, the apparatus for water purification also consists of
metering units, which delivers metered volumes of water from one unit/reservoir/section of
the apparatus for water purification to another unit/reservoir/section of the system.
[00029] The treatment unit, which includes a stirrer unit of the apparatus for water
purification, according to the said embodiment of the present subject matter, is used to uniformly mix the chemicals with the contaminated water. The mixing of chemicals in the contaminated water leads to flocculation or precipitation or both. Flocculation is a process in which colloids come out of suspension in the form of floe or flakes whereas in precipitation, a dissolved solute, in a solution of at least one solute and at least one solvent, due to certain chemical reaction form an insoluble compound which comes out of the solution as a precipitate. The mixture, so formed, is known as slurry.In another embodiment, the apparatus for water purification includes the treatment unit which comprises a dosing section and a holding section. Predetermined quantities of chemicals are added to the contaminated water by the chemical dosing unit in the dosing section and mixing of chemicals occurs partly in the

dosing section and partly in the holding section. Further, the holding section provides retention time as well as pressure head to the mixture of contaminated water and chemicals entering a separation unit.
[00030] In said embodiment, the separation unit of the apparatus for water purification
includes a solid-liquid separation unit having an inlet to receive the slurry. The solid-liquid separation unit separates particulate contaminants, the floe and/or the precipitate (henceforth referred to as suspended particles), from the slurry. The solid-liquid separation unit removes the, suspended particles to give clear water at its outlet.
[00031] Additionally, the separation unit may also have a filtration unit, which further
removes residual suspended particles as well as colour and odour from the clear water obtained from the solid-liquid separation unit thereby providing the purified water as the filtrate. The purified water is then stored in the collection reservoir of the apparatus for water purification.
[00032] The apparatus for water purification described herein reduces the concentration
of contaminants to approved levels, requires nominal maintenance, has high efficiency, and low operating costs. Further, the apparatus for water purification is compact, efficient and requires no external source of energy for operation. In addition, the apparatus for water purification substantially reduces the concentration of various contaminants like heavy metals, pathogenic micro-organisms, harmful ions, etc., to the approved levels. For example, contaminants, like arsenic, are removed irrespective of their oxidation state. Turbidity and suspended particles are also removed from the contaminated water thus providing purified water. The apparatus for water purification is suitable for use in a domestic setting or at a household level. Additionally, the apparatus for water purification is equally applicable for purifying industrial waste water. These and other aspects are discussed in detail in conjunction with the following figures.
[00033] Fig. 1(a) illustrates an apparatus for water purification 100, according to an
embodiment of the present subject matter. In said embodiment, the apparatus for water purification 100 includes a chemical storage unit 102 for storing chemicals, a source reservoir 104 for storing the contaminated water 106 and a collection reservoir 108 for receiving the purified water 110. Additionally, the source reservoir 104 has an inlet 112 to receive the

contaminated water 106. In said embodiment, the chemical storage unit 102 adds predetermined quantities of chemicals to the contaminated water 106 through a dispenser 114.
[00034] The chemicals may include at least one of a coagulant, an oxidizing agent, and
a pH adjuster. Any suitable coagulant like ferric-chloride, ferric sulphate, ferric nitrate, ferric acetate, aluminum sulphate, polyaluminium chloride, etc., may be used either alone or in combination. Similarly, any pH adjuster like sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide, calcium carbonate, calcium chloride, sodium carbonate, sodium bicarbonate, magnesium oxide, magnesium hydroxide, magnesium carbonate can be used either alone or in combination. The examples of oxidizing agent include but are not limited to potassium permanganate, sodium hypochlorite, hydrogen peroxide, etc. Further any combination of the coagulant, the oxidizing agent and the pH adjuster may be used. In one implementation, the concentration of the coagulant is within 1 to 1000 parts per million (ppm), concentration of pH adjuster is in the range of about 0.05 to about 1000 ppm and oxidizing agent's concentration is kept in the range of about 0.001 to 100 ppm. However, other concentrations may also be used as will be understood by a person skilled in the art.
[00035] For adding pre-determined quantities of the chemicals, the chemical storage
unit 102 may include a chemical dosing unit 116. The quantity of chemicals to be added in the contaminated water 106 may be dependent on various factors, such as concentration of contaminants in the contaminated water 106, volume of the contaminated water 106, etc. Due to the addition of chemicals in the contaminated water 106, chemical reactions occur between the added chemicals and contaminants present in the contaminated water 106. As a result, slurry is formed.
[00036] Further, said embodiment comprises a treatment unit 118, which includes a
stirrer unit 120 having a controller 122 and a plurality of blades 124 coupled to a shaft 126. The plurality of blades 124 helps in thorough and uniform mixing of the chemicals and the contaminated water 106. In operation, the chemicals react with the contaminants to form suspended particles usually by precipitation or flocculation. The suspended particles, so formed, coagulate, making it easier to separate the suspended particles from the slurry.

[00037] In said embodiment, the apparatus for water purification 100 may also include
a metering unit 128 to allow a pre-defined quantity of the slurry to flow into a separation unit 130 which includes a solid-liquid separation unit 132 and a filtration unit 134. The flow rate may be controlled by means of a control valve 136. The solid-liquid separation unit 132 is placed near the bottom of the source reservoir 104 and separates most of the suspended particles from the slurry to provide clear water 138. The clear water 138 is fed to the filtration unit 134. Another metering unit (not shown in the figure), simifar to the metering unit 128, may be placed between the solid-liquid separation unit 132 and the filtration unit 134 to allow a pre-defined quantity of clear water 138 to flow into the filtration unit 134. The filtration unit 134 further separates the finely suspended particles and removes any turbidity, color and odor from the clear water 138.
[00038J The purified water 110, thus obtained from the filtration unit 134 is stored in
the collection reservoir 108. In an example, the collection reservoir 108 is provided with a tap 140 to controllably dispense the purified water 110. Conventional tests and analysis, like silver diethyldithiocarbamate (SDDC) method were conducted on the purified water 110 for determining the concentration of contaminants such as arsenic. The purified water 110 was found to be deprived of excess contaminants and fit for human consumption. The operation and construction of the individual components of the apparatus for water purification 100 are described in detail in Figs. 2 to 6.
[00039] Fig. 1(b) illustrates the apparatus for water purification 100, according to-
another embodiment of the present subject matter. In said embodiment, the apparatus for water purification 100 includes a source reservoir 104, a treatment unit 118, a separation unit 130 and a collection reservoir 108. The treatment unit 118 comprises a dosing section 154 and a holding section 156 whereas the separation unit 130 comprises a solid-liquid separation unit 132 and a filtration unit 134. The apparatus for water purification 100 further includes metering units, namely first metering ifnit 160-1 and second metering unit 160-2, a chemical storage unit 102, and a chemical dosing unit 116. In one implementation, the first metering unit 160-1 is provided in the source reservoir 104 and the second metering unit 160-2 is provided within the dosing section 154. It will be appreciated that the metering units 160-1

and 160-2 are operationally and constructionally similar to the metering unit 128 and can be used interchangeably.
[00040] In operation, the contaminated water 106 flows into the source reservoir 104
through an inlet 112. In the said embodiment, the first metering unit 160-1 allows a predetermined quantity of the contaminated water 106 to flow from the source reservoir 104 to the dosing section 154 of the treatment unit 118. The chemical storage unit 102 adds predetermined quantities of chemicals to the contaminated water 106 in the dosing section 154 with the help of a chemical dosing unit 116.
[00041] The contaminated water 106 with added chemicals is then delivered to the
holding section 156 of the treatment unit 118 by the second metering unit 160-2. The holding section 156 is provided with the separation unit 130 comprising the solid-liquid separation 132 and the filtration unit 134 near and proximate its bottom end. The holding section 156 provides retention time as well as pressure head to the water entering the solid-liquid separation unit 132 and the filtration unit 134. Due to the addition of chemicals in the contaminated water 106, chemical reactions occur between the added chemicals and contaminants present in the contaminated water 106. As a result a slurry is formed. The slurry then flows through the solid-liquid separation unit 132. The solid-liquid separation unit 132 separates most of the suspended particles from the slurry to provide clear water, which is allowed to flow to the filtration unit 134. The filtration unit 134 further removes any residual finely suspended particles, color, and odor from the clear water to give purified water 110. In the said embodiment the purified water 110 is stored in the collection reservoir 108. Additionally, the collection reservoir 108 is provided with a tap 140 to controllably dispense the purified water 110.
[00042] Fig. 2 illustrates the construction of the stirrer unit 120 of the apparatus for
water purification 100, in accordance with an embodiment of the present subject matter. As mentioned before1, the stirrer unit 120 includes the controller 122 and the plurality of blades 124. In one implementation, the controller 122 controls the operation of the blades 124 and makes the blades 124 rotate in different directions. For this, the controller 122 includes a torsional spring 202 having a first end 204 and a second end 206. The first end 204 is attached

to the top of a casing 208 of the torsional spring 202 and the second end 206 is attached to the shaft 126. A rotor 212 having a plurality of vanes 214 is coupled with the shaft 126.
J00043J In said implementation, the rotor 212 is driven by a pulley 216 through a belt
218. Even though the pulley 216 is shown to be operated manually; however, it will be understood that other configurations are also possible. The plurality of vanes 214 facilitates the gripping of the belt 218 onto the rotor 212. In said embodiment of the stirrer unit 120, the rotor 212 may be enclosed in a first casing 222 and the pulley 216 may be enclosed in a second casing 224. The first and second casings 222 and 224 are provided with suitable openings to allow the belt 218 to be coupled with the rotor 212 and the pulley 216. Initially the belt 218 is wound on the rotor 212.
(00044] To operate the stirrer unit 120, a knob 220 is rotated so as to unwind the belt
218 from the rotor 212 and wind it on. the pulley 216. This causes rotation of the rotor 212 which in turn rotates the torsional spring 202 and the shaft 126, say in the clockwise direction. As mentioned before, the shaft 126 is coupled to a plurality of blades 124 due to which the shaft 126 and the blades 124 move in unison. As a result of such rotation, the chemicals get thoroughly mixed with the contaminated water 106. Also, on releasing the knob 220, the tension caused due to rotation of the torsional spring 202 causes the shaft 126 and the rotor 212 to be rotated in the opposite direction, i.e., in the anti-Clockwise direction, thus returning the stirrer unit 120 to its initial state. This is referred to as one cycle of the stirrer unit 120. In one implementation, one cycle is sufficient for thorough mixing of the chemicals with the contaminated water 106. However additional rotation(s) or cycle(s) may be used as desired. It may be appreciated that the rotations caused by operation of the pulley 216 are fast and help in uniform mixing of the chemicals with the contaminated water 106, whereas the rotations caused by the torsional spring 202 are slow and help in aggregation of the suspended particles.
[00045] Fig. 3(a) illustrates the chemical storage unit 102 of the apparatus for water
purification 100, according to an embodiment of the present subject matter. The chemical storage unit 102 includes at least one chamber for storing chemicals. Different chambers may be used for storing different chemicals. For example, the chemical storage unit 102 may include a first chamber 302-1 for storing a coagulant, a second chamber 302-2 for storing an

oxidizing agent, and a third chamber 302-3 for storing a pH adjuster. The first chamber 302-1, second chamber 302-2, and third chamber 302-3 are collectively referred to as chambers 302. As mentioned before, the chemical storage unit 102 has a chemical dosing unit 116, which adds pre-determined quantities of chemicals to the contaminated water 106. The chemical dosing unit 116 described herein includes a chemical metering device 304 for metering the quantity of chemical and a timing device 306 coupled to a valve 308. Similarly, each of the chambers is connected to their respective chemical metering devices, timing devices and valves. The timing device 306 operates the valve 308 for pre-determined time intervals such that a metered quantity of the chemicals is added to the contaminated water 106. According to said embodiment of the present subject matter, the chemical storage unit 102 has at least one dispenser 114 to add the pre-determined quantity of the chemicals to the contaminated water 106.
[00046J Fig. 3(b) illustrates the chemical storage unit 102 of the apparatus for water
purification 100, according to another embodiment of the present subject matter. The chemical storage unit 102 includes at least one chamber for storing chemicals. Different chambers may be used for storing different chemicals. For example, the chemical storage unit 102 may include a first chamber 302-1 for storing a coagulant, a second chamber 302-2 for storing an oxidizing agent, and a third chamber 302-3 for storing a pH adjuster. As mentioned before, the chemical storage unit 102 has a chemical dosing unit 116, which adds predetermined quantities of chemicals to the contaminated water 106. The chemical dosing unit 116 described herein includes a float 310 connected to a shaft 312. The shaft 312 is hinged at an orifice 313 of the chambers 302. In said embodiment, the chemical dosing unit 116 is placed inside a dosing chamber 314. In other embodiments, the chemical dosing unit 116 may be placed outside and in proximity to the source reservoir 104, or inside the source reservoir 104 or inside the dosing section 154 in the embodiment of Fig. I (b).
[00047] In operation, a water metering unit (not shown in the figure) adds pre-defined
quantity of contaminated water 106 to the dosing chamber 314. As the level of the contaminated water 106 rises in the dosing chamber 314, the float 310 also rises. This results in the shaft 312 opening the orifice 313 so as to add pre-defined quantity of chemicals to the contaminated water 106.

[00048] Fig. 3(c) illustrates the chemical storage unit 102 of the apparatus for water
purification 100, according to another embodiment of the present subject matter. Similar to the chemical storage unit 102 shown in Fig. 3(a) and Fig. 3(b), the chemical storage unit 102 illustrates different chambers for storing different chemicals. The chemical storage unit 102 also includes a chemical dosing unit 116 having the dosing chamber 314 and one or more wick(s) 316. In one embodiment, a wick is connected to each of the first chamber 302-1, the second chamber 302-2, and the third chamber 302-3. In another implementation, a plurality of chambers 302 may be connected to a single wick 316.
[00049] A water metering unit (not shown in the figure) adds pre-defined quantity of
contaminated water 106 to flow into the dosing chamber 314. When the water level touches the wicks 316, the requisite dose of the chemicals is added to the contaminated water 106. In the said implementation, the wicks 316 implement wicking or capillary action or both to add chemicals to the contaminated water 106. The wicks 316 may also be used to add chemicals to the contaminated water in other ways as known to persons skilled in the art.
[00050] Fig. 3(d) illustrates the chemical storage unit 102 of the apparatus for water
purification 100, according to another embodiment of the present subject matter. In said embodiment, the chemical storage unit 102 facilitates use of solid chemicals in the apparatus for water purification 100. In said embodiment, the chemical storage unit 102 stores the chemicals in the form of one or more candles 320. The candle 320 is held in place with the help of a support 322. Each of the candles, for example, candle 320 may be made of a single or a combination of several chemicals. In operation, a water metering unit 324 allows a predefined quantity of contaminated water 106 to flow into the chemical storage unit 102 via an inlet 326.
[00051] The contaminated water 106 comes in contact with the chemicals, which
causes the chemicals to react with the contaminants present in the contaminated water 106. In other examples, the chemicals may be fully or partially soluble in the contaminated water 106. The usage of chemicals in the purification process causes reduction in the dimensions of the candle 320 like height or diameter. In said implementation, one or more support 328 avoids tilting of candles by keeping them straight within the fixed space. Additionally the supports 328 may be made transparent so as to give a visual indication of quantity of chemicals

remaining in the chemical storage unit 102, thus making maintenance of the apparatus for water purification 100 easier.
[00052] The mixture of chemicals and the contaminated water 106 flows out through
an outlet 330 as indicated by arrow 332. Alternatively, in other embodiments, the chemical storage unit 102 may be configured to add a fixed quantity of chemicals, which may be in the form of solid, liquid, solution, powder, etc., to the contaminated water 106 using other configurations as known to a person skilled in the art.
[00053] Fig. 4 illustrates the metering unit 128, according to an embodiment of the
present subject matter. In said embodiment, the metering unit 128 includes an inlet 402 through which a liquid like contaminated water 106 can enter, as indicated by arrow 404 and a hollow structure 408 like a pipe or a tube, which has an inlet hole 406 and an outlet hole 410 such that the inlet hole 406 is at a higher level than the outlet hole 410. When the liquid flows into the metering unit 128, the level of the liquid keeps rising. When the liquid level reaches the top of the hollow structure 408, due to siphon action the liquid starts flowing out as indicated by arrow 412, through the outlet hole 410 till the liquid level falls below the level of the inlet hole 406. In one example, the level of the inlet hole 406 may be made adjustable so as to modify the volume of the liquid that is allowed to flow out of the metering unit 128. Since, the metering unit 128 works on the principle of siphon, it does not require any external energy source for operation, thus reducing costs of running the apparatus for water purification 100.
[00054] Fig. 5(a) illustrates a construction of the solid-liquid separation unit 132, in
accordance with an embodiment of the present subject matter. In said embodiment, the solid-liquid separation unit 132 has a connecting pipe 502 to receive the slurry from the source reservoir 104 as shown in the embodiment of Fig. 1(a) or the holding section 156 as shown in the embodiment of Fig. 1(b). The connecting pipe 502 may include a valve and knob system 504 to control the flow of the slurry into the solid-liquid separation unit 132. As shown in the figure, the solid-liquid separation unit 132 includes a container 506 having at least one hollow water permeable baffle 516. The sides 508 and bottom surface 510 of the container 506 are also lined with a water permeable membrane (not shown in the figure). At least one support 512 ensures that a gap exists between the water permeable membrane and the bottom surface

510 of the container 506 to allow for the clear water to flow towards an outlet 514 so as to discharge the clear water 138 obtained by separating the suspended particles from the slurry. In operation, when the slurry is allowed to enter the solid-liquid separation unit 132, the water permeable membranes separate the suspended particles and the Clearwater 138 flows through the water permeable membranes towards the outlet 514,
[00055] Fig. 5(b) illustrates a construction of the solid-liquid separation unit 132, in
accordance with another embodiment of the present subject matter. As shown in the figure, the solid-liquid separation unit 132 includes a connecting pipe 502 to receive the slurry from the source reservoir 104 or the holding section 156. In one implementation, the connecting pipe 502 may have a valve and knob system 504 to control the flow of the slurry into the solid liquid separation unit 132. The solid-liquid separation unit 132 consists of at least one coarse water permeable membrane 518 enclosed inside at least one fine water permeable membrane 520. The coarse and the fine water permeable membranes 518 and 520 are placed inside a container 522. The coarse water permeable membrane 518 and the fine water permeable membrane 520 are attached to an upper surface of the solid-liquid separation unit 132. When the slurry is allowed to enter the solid-liquid separation unit 132, the slurry flows through the coarse water permeable membrane 518 and the fine water permeable membrane 520, which separates the suspended particles from the slurry to give clear water, as indicated by arrow marked 138. The clear water 138 flows out from the outlet 514.
[00056J In one implementation, the permeable membranes 516, 518 and 520 may be
made of any permeable material including, but not limited to, fabric, mesh or foam including but not limited to cotton, canvas, felt, nylon, polypropylene, pojyamide polyester, polyvinylalcohol and combinations thereof. The material used for making the permeable surface may be produced using a suitable process including but not limited to weaving, spinning, spun bound, melt blown and needle punched processes and formed in a woven or non-woven manner. The permeable membrane may also be made out of a porous material including but not limited to sand, fired clay, ceramics, glass wool, rice husk ash and activated charcoal.
[00057] Fig. 6 illustrates the filtration unit 134 according to an embodiment of the
present subject matter. The filtration unit 134 has a first container 602 and a second container

604, where the first container 602 is located inside the second container 604. The first container 602 has a plurality of perforations 605 and encloses the filtration media 606. In operation, the clear water 138 obtained from the solid liquid separation unit 132 flows into the filtration unit 134 by means of an inlet pipe 608. The clear water 138 flows through plurality of perforations 605 and enters the filtration media 606. The filtration media 606 may be made of fired clay, glass woo], rice husk ash, activated alumina, bone char, rice husk ash treated with ferric hydroxide, rice husk ash treated with aluminum hydroxide, rice husk ash treated with nano-silver etc. or a combination thereof. However, other filtration media 606, as known to those skilled in the art, may also be used. The filtration media 606 removes any residual suspended particles, contaminants as well as colour and odour from the clear water 138 and the purified water 110, so obtained, flows through a plurality of perforations 612 of the outlet pipe 610 to be collected in the collection reservoir 108 of the apparatus for water purification 100.
[00058] The different parts of water purification system 100 may be made of any
suitable material including but not limited to, metal, plastic, concrete, ceramic, wood, stone or combinations thereof. The plastics used for fabrication of these parts include but are not limited to polyethylene (PE), polypropylene (PP), acrylonitriie butadiene styrene (ABS), polycarbonate (PC), polyethylene terepthalate (PET), low density polyethylene (LDPE), high density polyethylene (HDPE), polystyrene, polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), nylons, polyesters, acrylics, polyolefins, polyurethanes, polyamides, polycarboxyamides, phenolics, polylactic acids, rubbers and combinations thereof.
[00059] Fig. 7 illustrates a graph 700 depicting the concentration of arsenic
contaminants in water at various stages of the apparatus for water purification 100. To test the apparatus for water purification 100, 1600 liters of water having about 250 parts per billion (ppb) of arsenic contaminants was stored in the source reservoir 104, As water traversed through various stages of the apparatus for water purification 100, the concentration of arsenic contaminants was measured at each stage by silver diethyldithiocarbamate (SDDC) method. Other methods, as known by those skilled in the art may also be used. It should be noted that even though the !test has been performed for measuring arsenic contaminants, it will be

understood that other contaminants can also be removed by some variations as will be understood by a person skilled in the art.
[00060] As depicted in the graph 700, the concentration of arsenic contaminants in
water in parts per billion (ppb) is taken as the first reference and is depicted on the vertical axis 702 of the graph 700 and volume of water treated in liters is taken as the second reference and is depicted in the horizontal axis 704 of the graph 700. Data points 706 may be considered to form a notional curve that shows the concentration of arsenic contaminants in the contaminated water 106. Data points 708 may similarly form another curve that shows the concentration of arsenic contaminants in the clear water 138 coming out of the outlet of the solid-liquid separation unit 132. Likewise, the curve resulting from data points 710 depicts the concentration of arsenic contaminants in the purified water 110, coming out of the filtration unit 134. Curves 712 and 714 show the current limit of concentration of arsenic contaminants set by India and WHO respectively. Thus, as seen from the graph 700 since the level of arsenic contaminants is lower than the approved levels by WHO and other agencies, the purified water 110 is fit for human consumption.
[00061] In another example, the efficiency of the apparatus for water purification 100
in removing pathogenic contaminates was determined. For this, Escherichia coli, a microbe known to cause diseases like gastroenteritis, urinary tract infections, and neonatal meningitis, was selected as the pathogenic contaminant. Water spiked with 2.68 x 10 6 colony forming units (CFU) of Escherichia coli per milliliter was fed into the source reservoir 104. The purified water 110 had a concentration of 4.53 x I01 CFU of Escherichia coli per milliliter indicating a removal efficiency of 99.9983%. Thus the apparatus for water purification was found to efficiently remove pathogenic contaminants as well.
[00062] Hence, the apparatus for water purification described herein is efficient,
compact and easy to use. It can be easily scaled, facilitating its use at both industrial and household levels. It can be used for point of use operation especially in a domestic setting. Further, the apparatus for water purification is efficient in substantially reducing contaminants from industrial wastewater. The contaminants which the apparatus for water purification can remove include, but are not limited to, heavy metals, pathogenic micro-organisms, harmful ions, etc. The removal of contaminants is not dependent on the oxidation state of the

contaminants. For example, the apparatus for water purification efficiently removes arsenic contaminants irrespective of the oxidation state of arsenic. Further the apparatus for water purification also removes heavy metals like iron, barium, cadmium, chromium, lead, mercury, selenium, silver, etc. Additionally, colour, odour, and turbidity are also removed so as to make the purified water safe for human consumption.
[00063] In addition, the embodiments of the apparatus for water purification described
herein are cost effective as readily available chemicals are used for the purification process and electricity or a power source is not required. The contaminants, particulate matter, etc., removed during the purification process is contained within the apparatus for water purification and can be readily disposed after a prescribed time interval.
[00064] Although embodiments for an apparatus for water purification have been described in language specific to structural features and/or methods, it is to be understood that the invention is not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed as exemplary implementations of the apparatus for water purification.

1/We Claim:
1. An apparatus (100) for purification of contaminated water (106), the apparatus (100) comprising:
at least one chemical storage unit (102) to provide at least one chemical to the contaminated water (106) having contaminants ions wherein the contaminant ions comprise at least arsenic contaminants;
at least one treatment unit (118) comprising a dosing section (154) and a holding section (156), wherein the holding section (156) facilitates substantially complete reaction of the at least one chemical with the contaminated water (106) to form a slurry; and
at least one separation unit (130) to filter a substantial portion of the contaminant ions from the slurry to provide purified water (110).
2. An apparatus (100) for purification water (106), the apparatus (100)
comprising:
at least one chemical storage unit (102) to provide at least one chemical to the contaminated water (106) having contaminants ions wherein the contaminant ions comprise at least arsenic contaminants;
at least one treatment unit (118) comprising a stirrer unit (120), wherein the stirrer unit (120) allows substantial mixing of the at least one chemical with the contaminated water (106) to form a slurry; and
at least one separation unit (130) to filter a substantial portion of the contaminant ions from the slurry to provide purified water (110).
3. The apparatus (100) as claimed in claim 2, wherein the stirrer unit (120) further
comprises:
a controller (122) comprising, a casing (208);
a torsional spring (202) with one end attacheq to one end of the casing (208); a rotor (212) attached to the other end of the torsional spring (202); and
a pulley( 216) coupled to the rotor (212); and;
a shaft (126) mechanically coupled to the controller (122), the shaft (126) having a plurality of blades (124) to facilitate the stirring.

4. The apparatus (100) as claimed in any one of the preceding claims, wherein the apparatus 100 further comprising at least one source reservoir (104) to receive the contaminated water (106) and at least one collection reservoir (108) to receive the purified water (110).
5. The apparatus (100) as claimed in any one of the preceding claims, wherein the at least one separation unit (130) comprises:
at least one solid-liquid separation unit (132) to provide clear water (138) by removing a portion of the contaminant ions from the contaminated water (106); and
at least one filtration unit (134) to filter a substantial portion of remaining contaminant ions from the clear water (138) to provide purified water (110).
6. The apparatus (100) as claimed in claim 5, wherein the solid-liquid separation unit (132) comprises at least one water permeable baffle (516) to separate the portion of the contaminant ions from the slurry to provide clear water (138).
7. The apparatus (100) as claimed in claim 6, wherein the at least one water permeable baffle (516) is made of a material selected from at least one of sand, fired clay, ceramics, glass wool, rice husk ash, activated charcoal, fabric, mesh, foam comprising cotton, canvas, felt, nylon, polypropylene, polyamide polyester, and polyvinyl alcohol.
8. The apparatus (100) as claimed in claim 5, wherein the solid-liquid separation unit (132) comprises at least one coarse water permeable membrane (518) enclosed inside at least one fine water permeable membrane (520) to separate the portion of the contaminant ions from the slurry and provide clear water (138).
9. The apparatus (100) as claimed in claim 8, wherein the at least one coarse water -permeable membrane (518) and the at least one fine water permeable membrane (520) are made of a material selected from at least one of sand, fired clay, ceramics, glass wool, rice husk ash, activated charcoal, fabric, mesh, foam including cotton, canvas, felt, nylon, polypropylene, polyamide polyester, and polyvinylalcohol.
10. The apparatus (100) as claimed in claim 5, wherein the filtration unit (134) comprises:
a first container (602) having a plurality of perforations; a second container (604) enclosing the first container (602); an outlet pipe (610) having a plurality of perforations; and
at least one filtration media (606) enclosed between the first container (602) and an outlet pipe (610).

11. The apparatus (100) as claimed in claim 10, wherein the at least one filtration media (606) is made of a material selected from at least one of fired clay, glass wool, rice husk ash, activated alumina, bone char, rice husk ash treated with ferric hydroxide, rice husk ash treated with aluminum hydroxide and rice husk ash treated with nano-silver.
12. The apparatus (100) as claimed in any one of the preceding claims further comprising a metering unit (128) to allow a pre-defined quantity of the slurry to flow into the separation unit (130).
13. The apparatus (100) as claimed in any one of the preceding claims further comprising a metering unit (160-1) to allow metered volumes of the contaminated water 106 to flow from the source reservoir (104) to the dosing section (154) of the treatment unit (118).
14. The apparatus (100) as claimed in any one of the preceding claims further comprising a metering unit (160-2) to allow metered volumes of the contaminated water 106 to flow from-the dosing section (154) to the holding section (156) of the treatment unit (118).
15. The apparatus (300) as claimed in any one of the preceding claims further comprising a chemical dosing unit (116) to add a metered quantity of the at least one chemical to the contaminated water (106).
16. The apparatus (100) as claimed in any of the preceding claims, wherein the chemical storage unit (.102) comprises the chemical dosing unit (116).
17. The apparatus (100) as claimed in claim 15, wherein the chemical dosing unit (116) comprises:
a chemical metering device (304) for metering the quantity of the at least one chemical;
a valve (308) to facilitate flow of the at least one chemical from the at least one chamber (302);
a timing device (306) to operate the valve (308) for pre-determined time intervals; and
a dispenser (114) to add the at least one chemical to the contaminated water (106) based on an operation of the valve (308).
18. The apparatus (100) as claimed in claim 15, wherein the chemical dosing unit (116)
comprises
a shaft (312) hinged at an orifice (313) of the at least one chamber (302); and

a float (310) connected to the shaft (312).
19. The apparatus (100) as claimed in claim 15, wherein the chemical dosing unit (116) comprises a wick (316) connected to the at least one chamber (302) to add metered doses of the at least one chemical to the contaminated water (106) using capillary action.
20. The apparatus (100) as claimed in claim 15, wherein the chemical dosing unit (116) comprises at least one candle (320) made of the at least one chemical.
21. The apparatus (100) as claimed in any one of the preceding claims, wherein the apparatus (100) is made of a material selected from at least one of metal, concrete, ceramic, wood, stone, polyethylene (PE), polypropylene (PP), acrylonitrile butadiene styrene (ABS), polycarbonate (PC), polyethylene terepthalate (PET), low density polyethylene (LDPE), high density polyethylene (HDPE), polystyrene, polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), nylon, polyester, acrylic, polyolefin, polyurethanes, polyamide, polycarboxyamide, phenolic, poly lactic acid and rubber.
22. The apparatus (100) as claimed in any one of the preceding claims, wherein the chemical is selected from at least one of ferric chloride, ferric sulphate, ferric nitrate, ferric acetate, ferric lactate, ferric ammonium sulphate, ferric ammonium chloride, ferric citrate, ferric hydroxide, ferric oxide, ferrous chloride, ferrous acetate, ferrous lactate, ferrous ammonium sulphate, ferrous ammonium chloride, ferrous citrate, ferrous hydroxide, ferrous oxide, aluminum sulphate, polyaluminium chloride, aluminium chlorohydrate, polyamines, polyacrylamides, sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide, calcium carbonate, calcium chloride, sodium carbonate, sodium bicarbonate, magnesium oxide, magnesium hydroxide, magnesium carbonate, potassium permanganate, sodium hypochlorite, and hydrogen peroxide.
23. The apparatus (100) as claimed in any one of the preceding claims wherein the chemical storage unit (102) stores at least one of:
a coagulant, wherein the concentration of the coagulant varies in the range of about lppm to about 1000 ppm;
a pH adjuster, wherein the concentration of the pH adjuster varies in the range of about 0.05 ppm to about 1000 ppm; and
an oxidising agent, wherein the concentration of the oxidising agent varies in the range of about 0.001 ppm to about 100 ppm.

24. A household purification device comprising the apparatus (100) as claimed in any one of the preceding claims.
25. A method for purification of contaminated water having at least arsenic contaminant ions, the method comprising:
providing at least one chemical to the contaminated water;
stirring the at least one chemical with the contaminated water with a stirrer unit, to allow formation of a slurry having floes, and wherein the floes comprise at least a portion of the arsenic contaminant ions removed from the contaminated water; and
removing the floes from the slurry by filtering the slurry.
26. The method as claimed in claim 25, wherein the providing comprises metering the at least one chemical to provide a metered dose of at least one chemical into the contaminated water, wherein the metered dose is based on a volume of the contaminated water.
27. The method as claimed in claim 25, wherein the separating of the floes from the slurry comprises:
removing solid components from the slurry to obtain clear water; and filtering residual contaminants from the clear water and obtain purified water as the output.