FORM 2
THE PATENTS ACT, 1970 (39 OF 1970) & THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
1. Title of the invention: PURIFICATION Of WATER
2. Applicant (s)
NAME NATIONALITY ADDRESS
TATA CONSULTANCY Indian Nirmal Building, 9th Floor. Nariman Point, 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
The present subject matter, in genera), relates to purification of water and. in
particular, to removal of microbiological and particulate contaminants in water.
BACKGROUND
Generally, consumption of untreated water leads to spread of waterborne diseases.
The spread of these diseases is likely to occur where water, used for consumption, gets contaminated by microorganisms, such as bacteria, viruses, and protozoan cysts. To curb the spread of such diseases, untreated water is treated at source, such as at municipal water treatment plants. Water from the source is distributed to various users for consumption. However, even after treatment at the source, contamination may occur during distribution.
Therefore, to curb spread of waterborne diseases, various water purification
systems are usually implemented at a point-of-use (POU) from where water can be directly consumed. The water purification systems implement various technologies, such as reverse osmosis, ultra violet (UV) radiation, membrane filtration, and chemical disinfection to treat the untreated water. The technologies based on reverse osmosis, ultra violet (UV) radiation, and membrane filtration usually need electricity and may also require elevated water pressure for operation. Using such technologies thus increases the cost of the water purification systems and limits the use of the water purification systems.
Further, chemical disinfects; n involves removing microbiological contaminants
by using high concentrations of disinfectants. which imparts pungency and objectionable taste to the treated water. Thus, additional steps are introduced during water purification method to remove excess disinfectants before delivering treated water for consumption. These additional steps may further increase the size and cost of the water purification systems. Additionally. purifiers implementing such water purification methods are often bulky and suffer from limitations, such as clogging and poor trapping of microorganisms like bacteria, protozoan cysts. etc.
SUMMARY
This summary is provided to introduce concepts related to purification of water,
which is further described below in the detailed description. This summary is not intended to

identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.
In one embodiment, a disinfectant treated porous media is described herein. The
disinfectant treated porous media includes at least one porous media treated with a disinfectant. Further, the at least one porous media includes rice husk ash and clay.
BRIEF- DESCRIPTION OF THE DRAWINGS
The detailed description is described with reference to the accompanying figures.
In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components.
Fig. la illustrates a water purification system for treating untreated water,
according to an embodiment of the present subject matter.
Fig. lb illustrates a configuration of a disinfectant treated porous media of the
water purification system, according to an embodiment of the present subject matter.
Fig. 2a and Fig. 2b illustrate cross sectional views of the water purification
system, according to various embodiments of the present subject matter.
Fig. 3 illustrates a cross sectional view of the water purification system, according
to another embodiment of the present subject matter.
Fig. 4a and Fig. 4b illustrate cross sectional views of the water purification
system, according to various embodiments of the present subject matter.
Fig. 5 illustrates an apparatus for water purification implementing the water
purification system, according to an embodiment of the present subject matter.
Fig. 6 illustrates an apparatus for water purification implementing the water
purification system, according to another embodiment of the present subject matter.
DETAILED DESCRIPTION
The present subject matter relates to purification of water. Generally, purification
of water is a process of removing microbiological and particulate contaminants from untreated

water. Microbiological contaminants, such as bacteria, viruses, and protozoan cysts, when present in water, for example, drinking water, contaminate the drinking water and cause waterborne diseases. Conventional methods of purification of water involve treating water at source. Other methods of water purification involve treating water by certain disinfectants, filtering, or combinations thereof at point-of-use (POU). The disinfectants used in such methods include chlorine and iodine which are effective against bacteria and viruses, but have limited effectiveness against other microorganisms such as protozoan cysts.
Also, the water purification process may introduce high concentrations of
disinfectants in water, which may impart unacceptable taste and odor to water. In order to remove the excess disinfectants before delivering the water for consumption, additional steps are introduced during the water purificatior: process. Such additional steps add to the cost and increase the size of a water purification system implementing such purification methods. Further, these water purification systems lose efficiency to trap the contaminants after a period of time.
A Method and a system for purification of water are described herein. According
to an embodiment, a water purification system has an inlet, a purification device, and an outlet. The inlet is used for receiving water, which requires further treatment, from one or more water sources. The water may or may not have undergone prior treatment and is hereinafter referred to as untreated water. In one implementation, the inlet may be connected to a reservoir of water. The untreated water is subsequently received by the purification device for treatment, and the purified water exits from the purification device through the outlet. In one embodiment, the purification device has a primary purificant unit and a secondary purification unit.
Although the terms primary and secondary have been used to identify the
purification units related to two stages of purification, it will be understood that these terms are used merely for the purpose of reference and not as descriptive of function or importance of the two stages of purification.
Untreated water is initially purified in the primary purification unit. The primary
purification unit includes a plurality of permeable membranes for removing particulate matter. for example, suspended particles and mud from the untreated water. In one implementation, the permeable membranes are cascaded in order of decreasing porosity so as to filter various particulate matters at different levels according to their size. Removing the particulate matter

helps in avoiding direct exposure of the secondary purification unit to such particulate matter, thereby avoiding premature clogging of the secondary purification unit. Untreated water is thus filtered by the primary purification unit to receive filtered water.
The filtered water is then disinfected by the secondary purification unit. The
secondary purification unit includes one or more disinfectant treated porous media to inactivate microbial contaminants present in the filtered water. As the filtered water passes through the secondary purification unit, the microbial contaminants are inactivated by the disinfectants incorporated in the disinfectant treated porous media. Further, the disinfectant treated porous media may have different porosities and grengths. In one implementation, one or more of the disinfectant treated porous media may have pore sizes in the range of about 1 micron to 10 microns to trap contaminants, such as protozoan cyst, which are not only small in size, but also resistant to disinfectants. Thus, such disinfectant treated porous media facilitates removal of contaminants which earlier could not be inactivated using disinfectants or were inactivated only when a substantially high quantity of the disinfectants was used. Further, the disinfectant treated porous media are cascaded in such a manner that the pore size of the disinfectant treated porous media decreases in the direction of flow of the water. Upper layers of the disinfectant treated porous media trap bigger or coarser particles and lower layers of the disinfectant treated porous media trap fine particles, thereby preventing clogging of the pores of the lower layers by the coarser particles. The filtered water is thus disinfected to receive purified water.
The water purification system described herein inactivates microorganisms
present in the untreated water, requires norr;naI maintenance, has high efficiency, and low operating costs. Further, the water purifsation system as described herein is durable and effective in trapping particulate and microbial contaminants. These and other advantages of the present subject matter would be described in greater detail in conjunction with the following figures. While aspects of described systems and methods for the water purification system can be implemented in any number of system(s), the embodiments are described in the context of the following exemplary system(s)
Fig. la illustrates a water purification system 100, according to an embodiment of
the present subject matter. The water purification system 100 facilitates removal of contaminants, for example, particulate and microbiological contaminants from untreated water,

thereby making the water suitable for consumption. The water purification system 100 includes an inlet 102 for receiving untreated water a purification device ]04 for removal of the contaminants from the untreated water, and an outlet 106 for providing purified water. The untreated water, entering the water purification system 100 through the inlet 102, is hereinafter interchangeably referred to as water.
Jn one implementation, one or more structural components of the water
purification system 100 can be made from plastics, for example, 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), polytetrafluoroethyiene (PTFE), nylons, polyesters. acrylics. polyolefins, polyurethanes, polyamides, polycarboxyamides, phenolics. polylactic acids, and any combination thereof. Additionally or alternately, one or more of the structural components of the water purification system 100 can also be made from metals, ceramics, or any combination thereof.
In one embodiment, the purification device 104 has a primary purification unit
108 and a secondary purification unit 110. The primary purification unit 108 and the secondary purification unit 110 are disposed such that the untreated water received by the inlet (02 first flows in the primary purification unit 108 and. from the primary purification unit 108, flows into the secondary purification unit 110. The secondary purification unit 110 is placed in such a way that an opening of the secondary purification unit 110 discharges into the outlet 106 to provide purified water for consumption. In one implementation, the primary purification unit 108 is placed between the inlet 102 and the secondary purification unit 110 to avoid direct exposure of the secondary purification unit 110 to suspended physical particles present in the untreated water. Avoiding direct exposure of the secondary purification unit 310 to suspended physical particles helps in preventing premature clogging of the secondary purification unit 110.
ingress of the untreated water in the paification device 104 via the inlet 102 is
indicated by an arrow 112. The untreated water initially passes through the primary purification unit 108. In one implementation, the nimary purification unit 108 includes one or more permeable membranes, such as permeable membranes 114-1 and 114-2, hereinafter collectively referred to as the permeable membranes 114. In one implementation, the permeable membranes

114 can be made up of any material, such as. fabric, mesh, foam, cotton, canvas, felt, nylon, polypropylene, polyamide, polyester, sard, gred clay, ceramics, glass wool, rice husk ash. and activated charcoal. In addition, permeable membranes 114 may be formed in various shapes and sizes, for example, the shape of the permeable membranes 114 may be in the form of a cup having a cross section, such as cylindrical, triangular, rectangular, square, and the like. Different processes can be used to fabricate the primary purification unit 108, such as weaving, spinning. spun bound, needle punched, and melt blown processes. Further, the primary purification unit 108 can be formed in a woven or a non-woven manner.
In one implementation, the permeable membranes 114 are cascaded in decreasing
order of porosity such that the pore size of a preceding layer of a permeable membrane is greater than the pore size of a subsequent permeable membrane. For Example the permeable membrane 114-1 has a pore size greater than the permeable membrane 114-2. Owing to such cascading ol the permeable membranes 114, the first permeable membrane 114-1 can trap bigger and coarser particles, thereby preventing the clogging of subsequent lower permeable membranes 114-2 which may trap fine particles. In one implementation, the pore size of the permeable membranes 114 decreases in the direction of the flow of water. Further, the permeable membranes 114 are placed such that they can be easily removed for cleaning purpose, which in turn facilitates easy installation and maintenance of the water purification system 100.
As the untreated water passes through the primary purification unit 108, the
coarse and fine particulate matter, such as suspended particles, present in the untreated water are removed to provide filtered water. Subsequently, the filtered water enters the secondary purification unit 110 as indicated by an arrow 116.
In one embodiment, the secondary purification unit 110 includes one or more
disinfectant treated porous media 118-1 and 118-2, hereinafter collectively referred to as the disinfectant treated porous media 118. The disinfectant treated porous media 118 may be fabricated in the form of a flat structure which can be of any suitable cross-section, such as circular, square, rectangular, triangular, and the like. For example the disinfectant treated porous media 118 can be fabricated to have a circular cross-section and therefore may be in the form of a disc, as illustrated in Fig. lb.

In one implementation, the disinfectant treated porous media 118 are incorporated
within the secondary purification unit 110 in such a manner that there is no gap between an inner surface of the secondary purification unit 110 and an outer surface of the disinfectant treated porous media 118, thereby preventing leakage of the filtered water. In one implementation, a sealant or a washer (not shown in the figure.-) may be introduced between the inner surface of the secondary purification unit 110 and the eursurface of the disinfectant treated porous media 118 to prevent any leakage.
In one example, the disinfectant treated porous media 118 are formed by treating
a porous media with a suitable disinfectant to inactivate microbial contaminants. The examples of the disinfectant that may be used for treating the porous media may include, but are not limited to, metal salts like silver nitrate, silver chloride, copper sulphate, and zinc sulphate; metal oxides like aluminum oxide, copper oxide, titanium dioixed, and ferric oxide; metal nanoparticles like nano silver, nano copper, nano zinc, nano aluminum, nano copper oxide, nano iron oxide, nano aluminum oxide, and nano titanium dioxide; metal hydroxides, such as ferric hydroxide and aluminum hydroxide; peracetic acid; perforrnic acid; lactic acid;: potassium permanganate; quaternary ammonium compounds like quaternery ammonium chloride: halogen containing compounds like calcium hypochorite, sodium hypochlorite, chloramine, iodine, chloramine T, halazone, sodium dichlcricryanurate, and trichloroisocyanuric acid; and oxygen releasing compounds like hydrogen peroexide, magnesium peroxide, and sodium perborate. Further, naturally occurring disinfectants, such as extracts of medicinal plants may also be used for treating the porous media.
Examples of the porous media include, but art not limited to. RHA. activated
carbon, charcoal powder, saw dust, ceramics, cellular plastics, zeolites. silicates, organosilicas, silicon, alumina, aluminosilicates. metals, metal foams, metal oxides. rninerals. carbons and carbon nanotubes. synthetic and natural organic polymers, and any combination thereof.
In one implementation, the disinfectant treated porous media 118 are fabricated
using a combination of RHA and clay. The RHA, as will be known to a person skilled in the art, is a residue obtained after combustion of rice husk, which is a renewable agro-waste. The RHA includes mainly silica and carbon, and trace amounts of various metal oxides, such as alkali. alkali earth metal, and iron oxides. The FUP may be produced be burning rice husk in heaps, in

a step grate furnace, fluidized bed furnace, or tube-in-basket burner. Additionally, the RHA may also be obtained from boiler and brick kilns. Further, different types of clay such as kaolin, i.e., white clay, red clay, black clay, synthetic clay, and combinations thereof may be used in fabrication of the disinfectant treated porous media 118. Using the combination of low cost raw materials, such as RHA and clay, for maki; g the disinfectant treated porous media 118 provides for reduction in manufacturing cost of the water purification system 100.
In one implementation, in order to strengthen the binding of RHA and/or clay to
metal disinfectants, the RHA and/or clay are pre-treated, for example, by functionalizing surface of the RHA and/or clay. In one embodiment, the surface of RHA and/or clay is silanized with 3-aminopropyltriethoxysilane (APTES). The silanization is carried out by soaking the RHA and/or clay with an aqueous solution of APTES, where, the concentration of APTES used may be in the range of about 0.1 % to 30 % by weight. The RHA and/or clay are mixed with the aqueous solution of APTES to form a slurry. After uniform mixing, the RHA and/or clay slurry may be kept at ambient temperature for at least 3 hrs. The RHA and/or clay slurry may be subsequently dried at a temperature in the range of 20 to 250 °C. The dried mass of clay may then be grinded to fine powder and sieved to get particles of the size in the range of 10 micrometer (µm) to 800 micrometer (µm). The dried mass of RHA is reieved to get particles of the size in the range of about 10 µm to 800µm. Such RHA and relay functionalized with APTES have strong binding to metal disinfectants. Pre-treated RHA and pre-treated clay thus received are treated with the disinfectants.
In one implementation, in order to incorporate the disinfectants, at least one of
RHA, clay, pre-treated RHA, and pre-treated clay are soaked in the disinfectants. However, other methods of incorporating disinfectants, for example, passing a disinfectant solution through a bed of at least one of RHA, clay, pre-treated RHA, and pre-treated clay; painting or spraying at least one of RHA. pre-treated clay, pre-treated RHA, and pre-treated clay with the disinfectant solution; and in-situ synthesis of the disinfectants such as nanometals within at least one of RHA, clay, pre-treated RHA, and pre-treated clay may also be used. In one embodiment, at least one of RHA, clay, pre- treated RHA and pre-treated clay may be incorporated with different disinfectants to make them effective against a variety of contaminants.

In one embodiment, the disinfectant treated porous media 118 arc fabricated by
mixing disinfectant treated RHA and disinfectant treated clay in a predetermined ratio with
continuous addition of a predefined quantity of water to get a wet mixture. In another
embodiment, the disinfectant treated porous media 118 are fabricated by mixing RHA and
disinfectant treated clay in a predetermined ratio with continuous addition of a predefined
quantity of water to get a wet mixture. In yet another embodiment, the disinfectant treated porous
media 118 are fabricated by mixing disinfectant treated RHA and clay in a predetermined ratio
with continuous addition of a predefined entity of water to get a wet mixture. The wet mixture
is compacted in a mould under a predefined ferce to form a compact layer. For example either
clay or disinfectant treated clay in the range of about 10 % to 90 % by weight is mixed with
either RHA or disinfectant treated RHA in the range of about 10 % to 90 % by weight with
'continuous addition of a predefined quantity of water to form the wet mixture. The water is
added in the range of about 5 % to 90 % of total weight of RHA and clay mixture. The wet
mixture is then compacted in a mould under force in the range of J 0 kg to 200 kg to form a
compact layer. The compact layer is then heated in two stages, first in the temperature range of
about 20 °C to 250 °C and then in the range of about 500 °C to 1500 °C, to obtain the disinfectant
treated porous media 118.
In another embodiment, the disinfectant treated porous media 118 are fabricated
by mixing RHA and clay in a predetermined ratio with continuous addition of a predefined quantity of water to get a homogeneous wer mixture. The wet mixture is compacted in a mould under a predefined force to form a porous media. The size of the RHA and clay particles may vary across different layers. The porous media is then dried at a predefined temperature, for example, in the temperature range of about 20 °C - 250 °C. The porous media can be dried by different methods, such as open air drying, sun drying, oven drying, hot air drying, microwave drying, and combinations thereof. The dried layers are then heated at a predefined temperature, for example, in the temperature range of about 500 °C to 1500 °C providing appropriate heating rates and holding times to obtain the porous media. Holding time may be understood as the time for which the dried porous layers are kept in the furnace after reaching the predefined temperature. The holding time affects the strength and porosity of the porous layer and is typically in the range of 0 minutes to 8 hours.

Further, the dried layers are heated in various environments environment, such as
inert gases, vacuum, oxidizing, reducing environments, and combinations thereof, inside one or more heating device including, but not limited to furnace, kiln, masonry oven, and combinations thereof. Such fabrication processes used for fabricating the disinfectant treated porous media 118 are simple and cost effective, thereby reducing the cost of the water purification system 100.
In one implementation, surface of the porous media can be functionalized using a
silane compound such as APTES before treatment with the disinfectant. The silanization is carried out by soaking the porous media in an aqueous solution of APTES to obtain a soaked porous media. In one implementation, me concentration of APTES may be in the range of about 0.1 % to 30 %. The soaked porous media is men heated in a temperature range of about 20 °C to .250 °C to obtain a pre-treated porous media. The pre-treated porous media may be further treated with the disinfectants to get the disinfectant treated porous media 118.
)n one implementation, in order to incorporate ihe disinfectants, the pre-treated
porous media are soaked in the disinfectants. However, other methods of incorporating disinfectants, for example, passing a disinfectant solution through a bed of the pre-treated porous media, painting or spraying the pre-treated porous media with the disinfectant solution, and in-situ synthesis of the disinfectants, such as nanometals, within the pre-ireaied porous media, may also be used. In one embodiment, different disinfectant treated porous media 118 may be incorporated with different disinfectants to make them effective against a variety of contaminants. Although method for obtaining the disinfectant treated porous media has been described in relation to incorporating disinfectants in the pre-treated porous media, it will be understood that the disinfectant treated ;orous mn'ia may be obtained by incorporating disinfectants in the porous media directly vvithout the process of pre-treating. Further, the disinfectant treated porous media may be obtained using one pre-treated porous media and one porous media that has not been pre-treated.
Further, the disinfectant treated porous media 118 may have different porosities
and strength. In one implementation, different strength of the disinfectant treated porous media 118 may be achieved by using sintering techniques. The use of sintered material enhances the strength of the disinfectant treated porous media 118 and makes them resistant against structural damages. The porosities of the disinfectant treated porous media 118 may be varied, for

example, by changing the particle sizes of the RHA and clay. The disinfectant treated porous media 118 is prepared by mixing clay and RHA with sufficient amount of water to form a wet mixture. In one implementation, wet mixture is prepared by mixing clay of size in the range of about 10 urn to 800 urn in the range of about 10 % to 90 % by weight with RHA of size in the range of about 10 urn to 800 µm in the range of about 10 % to 90 % by weight. The wet mixture is compacted, dried, and subsequently heated at temperature in the range of about 500 °C to 1500 °C.
In another implementation, the disinfectant treated porous media 118 is prepared
by mixing clay of size in the range of about 50 urn to 425 µm in the range of about 40 % to 60 % by weight and RHA of size in the range of about 50 µm to 425 urn in the range of about 40 % to 60 % by weight with sufficient amount of water to form a wet mixture. The wet mixture is compacted, dried, and subsequently heated at temperature in the range of about 1000 °C to 1500 °C. The disinfectant treated porous media 118, thus.- formed, is effective against removing protozoan cysts and fine particulate matter in the range of about 1 to 10 micron. In one example, proportions of RHA, clay, and water in the wet mixture and/or the fabrication condition, such as heating time and heating temperature may be changed to fabricate the disinfectant treated porous media 118 to obtain a desired porosity and strength.
Further, the disinfectant treated porous media 118 are cascaded in such a manner
that a first layer, such as the disinfectant treated porous media 118-1 has pore size greater than a subsequent disinfectant treated porous media, such as the disinfectant treated porous media 118-2. Owing to such cascading of the disinfectant treated porous media 118, the first disinfectant treated porous media 118-1 can trap bigger and coarser particles thereby preventing the clogging of subsequent disinfectant treated porous media 118, which trap finer particles. Thus, the primary purification unit 108 and the secondary purification unit 110 work in tandem to remove particulate matter and microbes.
In one embodiment, the disintertant treated porous media 118 are fabricated by
mixing the RHA and clay with a binder selected from polyvinyl alcohol, epoxy resin, gum, maltodextrin, lactose, polyvinylpyrrolidone (PVP) such as PVP K-30, polyethylene, polypropylene, polyolefin, cellulose ethers, and bentonite.

As the filtered water flu "s through the secondary purification unit 110, the
microbial contaminants present in the filtered water are inactivaicd and residual particulate and microbial contaminants are trapped in the pores of the disinfectant treated porous media 118-1 and 118-2. The purified water thus received is provided by the outlet 106 as indicated by the arrow 120. The purified water may be stored, for example, in a reservoir for consumption and distribution. The water purification system 100 can handle a large volume of water while maintaining a good flow of water throughout ifs operational life.
In an embodiment, a carbonaceous adsorbent material, such as activated charcoal.
charcoal powder, RHA, or any combination thereof nay be incorporated at the outlet 106 of the water purification system 100. Such materials facilitate removal of color and odor from the purified water.
Although the terms prima y and secondary have been used to identify the
purification units related to two stages oi purification, it will be understood that these terms are used merely for the purpose of reference and not as descriptive of function or importance of the two stages of purification.
Fig. 2a and Fig. 2b illustrate the water purification system 100 according to
various embodiments of the present subject matter. As previously described, the water purification system 100 includes the inlet 102, the purification device 104, and the outlet 106. In one embodiment, the purification device 104 has a lid 202, which may be used, for example, to remove the primary purification unit 108 from the purification device 104 Tor cleaning purpose. Further, the lid 202 may be a removable or an ope. .able lid. The easy removal of the lid 202 facilitates regular cleaning of the primary purification unit 108. Thus, the particles trapped in the primary purification unit 108 are removed regularly, thereby increasing the operational life of the water purification system 100. In one embediment, the lid 202 can be attached to the top of the purification device 104, as illustrated in fig. 2a. In mother embodiment, the lid 202 may be attached to a base of the purification device 104, as illustrated in Fig. 2b.
The primary purification unit 108. as discussed has one or more permeable
membranes, such as the permeable membrane 114-1 and the permeable membrane 114-2. For the purpose of explanation only two permeable membranes 114 are illustrated in Fig. 2a and 2b;

however it will be understood that the primary purification unit 108 may have any number of permeable membranes 114. In one implementation, the permeable membrane 114-1 is connected to adaptors 204-1 and 204-2. The adaptors 204-1 and 204-2 can further be removably attached to holders 206-1 and 206-2, respectively, provided in the lid 202. Similarly, the permeable membrane 114-2 is connected to adapters 204-3 and .204-4, which are removably attached to holders 206-3 and 206-4, respectively, provided in the lid 202, The adaptors 204-1. 204-2. 204-3. and 204-4 are collectively referred to as the adaptors 204. Likewise, the holders 206-1, 206-2, 206-3, and 206-4 are collectively referred to as the holders 206. In one implementation, the permeable membranes 114 may be attached to the top of the purification device 104, as illustrated by Fig. 2a. In another implementation, the adaptors 204 may be directly placed in between the lid 202 and the purification device 104 in a leak proof manner. In yet another 'implementation, the permeable membranes 114 can be attached to the base of the purification device 104 so that they envelope the secondary purification unit 110. as illustrated in Fig. 2b.
In operation, the unseated water enters through the inlet 102 as indicated by the
arrow 112 and flows through the primary purification unit 108. As the untreated water flows through the permeable membranes 114. particulate matter present in the untreated water is trapped in the permeable membrane: art As illustrated in Fig. 2b, since the permeable membranes 114 are placed at the bottom of the purification device 104. the water can enter the primary purification unit 108 laterally as well as from an upward direction.
The filtered water from the primary purification unit 108 then enters the
secondary purification unit 110 as indicated by the arrow 116 In one embodiment, the secondary purification unit 110 includes a receptacle 208 which further incorporates the disinfectant treated porous media 118. For the purpose of explanation only two disinfectant treated porous media 118-1 and 118-2 are illustrated in Fig. 2a and 2b, howevcer it will be understood that the receptacle 208 may have any number of the disinfectant treated porous media 118. As discussed previously, the disinfectant treated porous media 118 are treated with disinfectants to inactivate microbial contaminants. In one embodiment, the disinfectant treated porous media 118 may be cascaded in the order of decreasing porosity with respect to the flow of the filtered water. For example, the disinfectant treated porous media 118-1 has more porosity than the disinfectant

treated porous media 118-2. Further, porosity of the disinfectant treated porous media 118 may be lesser than the porosity of the permeable membranes 114.
In one implementation, the receptacle 208 may be placed such that an outlet of the
receptacle 208 coincides with the outlet 106 of the water purification system 100. The receptacle 208 further includes an opening 210 for the entry of the filtered water from the primary purification unit 108. In one implementation, the opening 210 is a perforated opening. As the filtered water flows through the disinfectant treated porous media 118, the microbial contaminants present in the filtered water are inactivated by the disinfectants present in the disinfectant treated porous media 118. The microbes and the residual particulate matter are then trapped in pores of the disinfectant treated porous media 118. Subsequent to purification by the secondary purification unit 110, the purified water exits the water purification system 100 through the outlet 106 as indicated by an arrow 212.
Fig. 3 illustrates the water purification system 100, according to an embodiment
of the present subject matter. In one implementation, the water purification system 100 resides inside and proximate the base of a reservoir 302. As previously mentioned, the untreated water enters the primary purification unit 10? through the inlet 102 as indicated by the arrow 112. In the present embodiment, the inlet 102 is previded close to the base of the purification device 104. Further, the inlet 102 may include multiple holes provided at the periphery of the purification device 104 as illustrated in the Fig. 3. The untreated water enters the primary purification unit 108 and flows through the permeable membranes 114. The coarse and fine particles, such as the suspended particles are removed by purification performed by the primary purification unit 108. The filtered water received from the primary purification unit 108 enters the secondary purification unit 110.
The secondary purification unit 110 includes the disinfectant treated porous media
118 provided inside the receptacle 208. The filtered -vater enters the receptacle 208 through the opening 210. In one implementation, the opening 210 is a perforated opening. As the filtered water flows through the disinfectant treated porous media 118, the microbes present in the filtered water are inactivated by the disinfectant in the disinfectant treated porous media 118. Further, the physical contaminants and anrobes of small size are trapped in the pores of the

disinfectant treated porous media 118. The purified water received after purification from the secondary purification unit 110 exists via the outlet 106 as indicated by an arrow 308.
Fig. 4a and Fig. 4b illustrate the water purification system 100 according to
various other embodiments of the present subject matter. In said embodiments, the water purification system 100 resides inside and proximate the base of the reservoir 302. The untreated water from the reservoir 302 enters the purification device 104 through the inlet 102. In said embodiments, the inlet 102 is located close to a base of the purification device 104. The untreated water enters the purification device 104 in horizontal direction as indicated by the arrow 112. The untreated water enters the primary purification unit 108 and flows through the permeable membrane 114 located within the primary purification unit 108. In one implementation, the permeable membranes 114 are placed in such a way that they form an enclosure around the receptacle 208.
The purification performed at the primary purification unit 108 facilitates removal
of coarse and fine particulate matter, such as suspended particles from the untreated water. The filtered water received from the primary purification unit 108 enters the secondary purification unit 110 as indicated by an arrow 402. The filtered water enters the receptacle 208 through the opening 210. In said embodiments, the opening 210 is provided at the base of the receptacle 208. while the top of the receptacle 208 is closed. As the filtered water enters the receptacle 208, the water level in the receptacle 208 stairs increasing and the filtered water passes through the disinfectant treated porous media 118 as indicated by an arrow 404.
In the present embodiment, the disinfectant treated porous media 118 are
cascaded in such a manner that the pore size of the disinfectant treated porous media 118 decreases in the direction of flow of water, for example, a lower layer, such as the disinfectan! treated porous media 118-1 is more porous than a subsequent layer, for example, the disinfectant treated porous media 118-2. As the filtered water flows through the disinfectant treated porous media 118, the microbial contaminants present in the filtered water are inactivated. Further, the disinfectant treated porous media 118 traps the residual particulate contaminants and microbes that are not inactivated by the disinfectants present in the disinfectant treated porous media 118. As the level of water in the receptacle 208 goes above the level of the disinfectant treated porous media 118, the purified water exits through a channel 406 in a downward direction as indicated

by an arrow 408. In said embodiments, the disinfectant treated porous media 118 and the channel 406 may be understood to be connected to form a siphon, thereby facilitating the egress of the purified water. The egress of the purified water may be discontinued when the level of the water falls below the level of the inlet 102. In one implementation, the channel 406 is positioned at the centre of the receptacle 208 as illustrated by Fig. 4a. In another implementation, the channel 406 is positioned at lateral side of the receptacle 208, as illustrated by Fig. 4b. The receptacle 208 is placed such that the channel 406 coincides with the outlet 106.
Fig. 5 illustrates an apparaters 500 implementing the water purification system
100, according to an embodiment of the present subject matter. In said embodiment, the water purification system 100 is disposed between a first reservoir 502 and a second reservoir 504. The .first reservoir 502 holds the untreated water and the second reservoir 504 holds the purified water received after being treated by the water purification system 100. In one implementation, the water purification system 100 may be connected to the first reservoir 502 and the second reservoir 504 in a leak proof manner using a sealer or washers.
The untreated water enters the first reservoir 502 through an inlet 506. The inlet
506 may be closed through a lid 508. In one embodiment, the first reservoir 502 includes a filter 510 that facilitates filtration of the untreated water prior to ingress of water in the first reservoir 502 and hence prior to the purification of the water by the water purification system 100. The filter 510 may be, for example, a fabric, a mesh, or a foam. The filter 510 may be made of materials, such as cotton, canvas, felt unlon, polypropylene, polyamide, polyester, or any combination thereof. The filter 510 can be fabricated using different methods, such as weaving, spinning, spun bound, melt blown, and needle punched process. Further, the filter 510 can be formed in a woven or a non woven manner.
Thus, the water entering the first reservoir 502, as indicated by an arrow 512, is
treated by the filter 510. The filter 510 removes large suspended particle and may also reduce turbidity present in the untreated water. Water, received after treatment of the untreated water by the filter 510, enters the water purification system 100 as indicated by an arrow 514. The water enters the purification device 104 through the inlet 102. The water is initially treated by the primary purification unit 108, which removes suspended and coarse particles present in the water to provide the filtered water. Subsequently, the filtered water enters the secondary purification

unit 110. The disinfectant treated porous media 118 in the secondary purification unit 110 inactivate microbial contaminants and capture fine particulate matter present in the water. After being treated by the secondary purification unit 110, the purified water exits through the outlet 106 and flows in the second reservoir 504 as indicated by an arrow 516. In one implementation, the purified water exits the second reservoir 504. as indicated by an arrow 518. through a faucet 520, such as a tap for consumption purposes.
Fig. 6 illustrates another apparatus 600 implementing the water purification
system 100, according to an embodiment of the present subject matter. As illustrated, the water purification system 100 is connected to a reservoir 602 which holds the untreated water. In one implementation, the inlet 102 of the water purification system 100 may be connected to an outlet of a faucet 604 of the reservoir 602. Thus, the untreated water enters the water purification system 100 via the faucet 604, as indicted by an arrow 606. The untreated water is treated in the water purification system 100 to provide the purified water. The purified water exits through the outlet 106 as indicated by an arrow 608. In one implementation, the purified water can be stored in a reservoir. In another implementation, the purified water exiting through outlet 106 can be directly used for consumption. In said embodiment, the water purification system 100 may be used as an on-tap water purification system.
Table 1 illustrates performance of the water purification system 100 when
connected to a reservoir of untreated water as illustrated by Fig. 6. The untreated water used for the experiment contained the bacterium Escherichia coli (E. coli) (ATCC 11229). Further, the performance of the water purification system 100 was tested at a flow rate of 2.5 - 3 L/hr, The test was conducted at a loading recommended by the National Science Foundation (NSF) F248 standard for microbiological water purifiers. A sample of the untreated water was collected in a sterile container to check the input load. The output water, i.e., the purified water from the water purification system 100 was collected in a separate sterile container to determine its microbial load, i.e.. to determine effectiveness of the water purification system 100 in treating the untreated water. The performance of the water publication system 100 was evaluated by comparing the bacteria count in the purified water and the untreated water, It should be noted that even though the test has been performed by measuring bacteria count, it will be understood that other microorganisms can also be removed. The test results are illustrated in table 1.

Table 1

Average Input
CPU (Colony Forming Unit)/
milliliter (ml) Average Output CFU/ml Log reduction
5.03 x 105 0 5.7
Thus, it can be gathered from table 1 that the output water purified by the water
purification system 100 is substantially free from bacterial contaminants and is lit for human consumption. Log reduction is a mathematical term which shows the relative number of live .microbes eliminated from a medium, which is water in present subject matter, by purification methods. For example, a "5-log reduction" means lowering the number of microorganisms by 100,000-fold, that is, if a medium has 100000 pathogenic microbes, a 5-log reduction would reduce the number of microorganisms to one
Hence, the water purificati JU system 100 as described herein is efficient, compact.
inexpensive and easy to use. Further, the water purification system 100 can be used at point of use operation and may be effectively used for example, in developing and underdeveloped countries where proper water purification facilities are not available. Furthermore, since the water purification system 100 is cost effective, therefore it can be readily used across various regions, for example, rural regions, where cost effectiveness is a primary concern,
Moreover, as the porosity of the primary purification unit 108 is greater than that
of the secondary purification unit 110 large suspended particles are trapped at the primary purification unit 108 thus preventing clogging of the secondary purification unit 110. Owing to varying porosities of the various layers in the-primary purification unit 108 and the secondary purification unit 110; a large range of corterinants arc trapped without requiring separate units of purification for trapping these contaminants, thus reducing the cost and size of the water purification system 100. Also, different disinfectants may be incorporated within the disinfectant treated porous media 118 in the secondary purification unit 110 due to which a large range of microbial contaminants may be inactivated without requiring separate units of purification for

inactivating these contaminants, thus also reducing the cost and size of the water purification system 100.
Additionally, since the water flows through the water purification system 100
owing to the action of gravity, no additional energy is required to keep the water flowing in and out of the purification device 104. which in turn further reduces the operational cost of the water purification system 100. Also, the water purification system 100 does not require additional storage unit as the inlet 102 can be attached directly to the source of the untreated water and the outlet 106 can be connected directly to the point of use thereby reducing the size and the cost of the water purification system 100.
As mentioned previously, the water purification system 100 is cost effective since
it uses raw materials like rice husk and clay. Further, the fabrication process used in making the permeable membranes 114 and the disinfectant treated porous media 118 is simple, thereby reducing the cost of the water purification system 100. further, as the water purification system 100 has an openable lid 202, the primary purification unit 1 OS can be easily removed and cleaned thereby increasing the life of the purificatios device 104.
Although implementations of a water purification system have been described in language specific to structural features and/or methods, it is to be understood that the appended claims are not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed as implementations of the water purification system.

1/We claim:
1. A disinfectant treated porous media (118) comprising:
at least one porous media treated with a disinfectant, wherein the at least one porous media comprises rice husk ash (RHA) and clay.
2. The disinfectant treated porous media (118) as claimed in claim 1, wherein the at least one
porous media comprises:
the RHA in the range of abor. 10 % to 90 % by weight; and the clay in the range of about 10 % to 90 % by weight.
3. The disinfectant treated porous media (118) as claimed in claim 1. wherein the at least one disinfectant treated porous media (118) is fabricated by heating a mixture of RHA and clay in a temperature range of about 500 °C to 1500 °C.
4. The disinfectant treated porous media (118) as claimed in claim 1, wherein the at least one porous media further comprises a binder selected from the group consisting of polyvinyl alcohol, epoxy resin, gum. maltodextrin. lactose, polyvinylpyrrolidone (PVP). polyethylene. polypropylene, polyolefin, cellulose ethers, bentonite, and combinations thereof.
5. The disinfectant treated porous media (118) as claimed in claim 1, wherein the disinfectant is at least one of a metal salt, a metal neno-pariticle, a metal oxide, and a metal hydroxide.
6. The disinfectant treated porous media (118) as claimed in claim 1, wherein the disinfectant is at least one of a silver nitrate, silver chloride, copper sulphate, zinc sulphate, copper oxide, titanium dioxide, aluminum oxide, ferric oxide, nano silver, nano copper, nano aluminum, nano zinc, nano copper oxide, nano iron oxide, nano aluminum oxide, nano titanium dioxide, ferric hydroxide, and aluminum hydroxide.
7. The disinfectant treated porous media (118) as claimed in claim 1, wherein the disinfectant is at least one of a quaternary ammonium compound, halogen containing compound, an oxygen releasing compound, and a natural disinfectant.
8. The disinfectant treated porous media (118) as claimed in claim 1, wherein the disinfectant is at least one of a potassium permanganate, peracetic acid, per formic acid, lactic acid. quaternary ammonium chloride, calcium hypochlorite, sodium hypochlorite, iodine. chloramine T. sodium dichloroisocyanurate, tri chloroisocyanuric acid, hydrogen peroxide. magnesium peroxide, sodium perborat., and extract of medicinal plants.

9. The disinfectant treated porous media (118) as claimed in claim 1, wherein pore size of the at least one disinfectant treated porous media (118) is based on size of the RHA.
10. The disinfectant treated porous media (118) as claimed in claim 1 or claim 3. wherein the size of the RHA is selected from the range of about 10 micrometer (urn) to 800 urn. to form a porous layer to trap protozoan cysts and fine particulate matter with a mean size in the range of about 1 to 10 urn.
11. A water purification system (100) fer purification of water, the water purification system (100) comprising:
a primary purification unit (108) comprising a plurality of permeable membranes (114), to filter particulate matter present in the water to provide filtered water; and
a secondary purification unit (110) comprising a plurality of disinfectant treated purification media (118) as claimed in any of the preceding claims, wherein the disinfectant treated purification media (118) is configured to inactivate microbial contaminants present in the filtered water.
12. The water purification system (100) as claimed in claim 11. wherein the primary purification unit (108) encloses the secondary purification unit (110),
13. The water purification system (100) as claimed in claim 11. wherein the plurality of permeable membranes (114) are made of at least one of a fabric, mesh, foam, cotton canvas, felt nylon, polypropylene, polyamide, polyester, woven cloth, nonwoven cloth, sand, fired clay, ceramics, glass wool, rice huekes and activated charcoal.
14. The water purification system (100; as claimed in claim 11, wherein the plurality of disinfectant treated purification media (118) are cascaded in decreasing order of porosity, wherein the porosity decreases in the direction of flow of water.
15. The water purification system (100) as claimed in claim 11 further comprising a channel (406) for providing purified water purified by the secondary purification unit (110). wherein the channel (406) and the secondary purification unit (110) are connected to form a siphon.
16. The water purification system (100) as claimed in claim 11 further comprising an outlet (106) for providing purified water, and wherein the outlet (106) comprises a carbonaceous adsorbent material selected from at least one of an activated charcoal and RHA to facilitate removal of color and odor from the purified water.

17. The water purification system (100) as claimed in claim 11, wherein the water purification system (100) is made from a material selected from the group consisting of plastics, metals. ceramics, and combinations thereof.
18. A method comprising:
treating at least one of RHA and clay to obtain at least one of disinfectant treated RHA and disinfectant treated clay, respectiyely:
mixing, with water, at least one of: the RHA and the disinfectant treated clay, the disinfectant treated RHA and the clay, ano the disinfectant treated clay and the disinfectant treated RHA. to get a wet mixturer and
heating the wet mixture to obtain a disinfectant treated porous media (118).
19. The method as claimed in claim 18. wherein the treating comprises exposing at least one of
the RHA and the clay to the disinfectant using a method comprising at least one of:
passing a disinfectant solution through a bed of at least one of the RHA and the clay; soaking at least one of the RHA and the clay in the disinfectant solution: spraying the disinfectant solution at least one of the RHA and the clay: painting the disinfectant solution on at least one of the RHA and the clay: and synthesizing nano particles of the disinfectant in situ within at least one of the RHA and the clay.
20. The method as claimed in claim 18 or 19. wherein the RHA comprises pre-treated RHA
obtained by a method comprising:
soaking the RHA in an aqueous solution of 3-aminopropyltriethoxysilane (APTES) to obtain soaked RHA, wherein conceredion of APTES is in a range of about 0.1 % to 30 %; and
heating the soaked RHA the in n temperature range of about 20 °C to 250 °C to obtain pre-treated RHA.
21. The method as claimed in claim 18 or 19, wherein the clay comprises pre-treaied clay
obtained by a method comprising:
soaking the clay in an aqueous solution of APTES to obtain soaked clay, wherein concentration of APTES is in a range of about 0.1 % to 30 %: and
heating the soaked clay the in a temperature range of about 20 °C to 250 °C to obtain pre-treated clay.

22. A method comprising:
mixing clay with RHA and water to get a wet mixture; heating the wet mixture to obtain a porous media; and
treating the porous media with a disinfectant to obtain a disinfectant treated porous media (US).
23. A method comprising:
mixing clay with RHA and water to get a wet mixture:
heating the wet mixture to obtain a porous media:
soaking the porous media in an aqueous solution of APTES to obtain a soaked porous media, wherein the concentration of APTES is in a range of about 0.1 % to 30 %:
heating the soaked porous media in a temperature range of about 20 °C to 250 °C. to obtain a pre-treated porous media; and
treating the pre-treated porous media to the disinfectant.
24. The method as claimed in claim 22 or claim 23 wherein the treating comprises exposing at
least one of the pre-treated porous media and the porous media to the disinfectant using a
method comprising one of,
passing a disinfectant solution through at least one of the pre-treated porous media and the porous media:
soaking at least one of the pre-treated porous media and the porous media in the disinfectant solution;
spraying the disinfectant solution on at least one of the pre-treated porous media and the porous media:
painting the disinfectant solution on at least one of the pre-treated porous media and the porous media: and
synthesizing nano particles of the disinfectant in situ within at least one of the pre-treated porous media and the poroes media..