Title of Invention

"AN IMPROVED WATER FILTER"

Abstract An improved water filter which comprises two interconnected (9) chambers (2 & 4), characterized in that the said first chamber (2) having a valve controlled inlet (1) at the lower end and an outlet (9) at the upper portion, the said first chamber (2) being provided above the inlet (1) and below the outlet (9) with adjustably fixed wire mesh (5) and perforated sheets (6 & 8) so as to form an enclosure containing filter media (7), the said outlet (9) of the said chamber (2) being the interconnecting inlet (9) at upper portion of the second chamber (4), the said outlet / inlet (9) being connected by means of flexible piping (10) to perforated disc (15) covered inlet (11) of a tubular enclosure (12) containing disinfectant media (14), the disinfectant enclosure (12) having perforated disc (15) covered outlet (16) opening into the said second chamber (4) provided with a valve controlled outlet (18) at the lower end, the said chambers (2 & 4) and tubular enclosure (12) being provided with removably fixed lids (3, 19, 13)
Full Text The present invention relates to an improved water filter. The improved water filter of the present invention is particularly useful for organochlorine pesticides, present in water supplies, to make it safe for drinking purposes in addition to its capability for removal of pathogenic organisms total and faecal coliforms, turbidity and total organic carbon.
Our earlier patent application entitled a water filter for removal of organochlorine pesticides, was filed vide patent application No. 1526/DEL/96 dated 11.07.1996. The present invention is an improvement thereof. In the device of the present invention there are two interconnected chambers, whereas there is only one used in earlier device. In the present invention the ratio of/ iodine to filter media is changed and iodine has been used along with sand as a filler in a tube fixed in as separate chamber. These non-obvious inventive steps have resulted in the novelty of having increased the disinfection efficiency of the water filter. In this device the potability of treated water has been improved with respect to residual iodine levels in treated waters, in addition to faecal coliforms the present unit removes total coliforms and it has a additional advantage of having storing capacity for the treated water.
Because of the increasing and diversified use of non-degradable organochlorine pesticides in agriculture and public health sectors in India, contamination of natural water sources due to these pesticides can not be ruled out. Water may get contaminated due to the direct application of these pesticides for the control of nuisance vegetation, fish and aquatic insects, from nonpoint sources such as runoff from agricultural, urban and suburban areas, from accidental spills and/or from direct wastewater discharge from a point source. The extent of contamination and type of these pesticides in urban water resources in India have been documented in a report based on a national survey and research publications. Reference may be made to NEERI/Report/ATD-04
(1985) and P.Kaur, et al. Environ. Educ. & Information Vol. 16(4), 1997. Organochlorine pesticides are reported to be highly toxic and have a long persistence period even in low concentrations of micrograms per litre. Pesticides present in drinking water can cause taste and odour problems and are hazardous to human health. It is possible to significantly decrease this hazard either by using smaller quantities of pesticides in agriculture or by using alternative control measures. Currently both these trends are being followed.
In order to prevent serious health hazards caused by the presence of toxic pesticides present in drinking water, above the guidelines values regulated by WHO in 1996, it is necessary to remove such compounds from water to make it safe for human consumption. Modern municipal water treatment plants are designed to produce potable water supply free from pathogenic organisms, colour, turbidity, calcium and magnesium hardness, objectionable tastes and odors, iron and manganese. The existing conventional water treatment plants employ chemical coagulation with aluminium sulphate (alum), for the removal of colour and turbidity. Sedimentation and sand filtration follow coagulation process and chlorination is employed as the last step in the treatment plant for disinfection. These water treatment systems employed in most of the urban areas are not efficient for the removal of pesticides below the limits as prescribed in related guidelines or in their complete removal. There are many commercial gadgets and water filters available in the markets to improve the water quality. These systems do not remove the organochlorine pesticides present in water.
The main object of the present invention is to provide an improved water filter which is an improvement of our earlier patent application No. 1526/DEL/96.
Another object is to provide an improved water filter useful for the removal of organochlorine pesticides, total coliforms, faecal coliforms, turbidity and total organic carbon.
Yet another object is to provide an improved water filter having improved disinfection efficiency.
Yet another object is to provide an improved water filter with respect to treated water potability with residual iodine in permissible limit.
Yet another object is to provide an improved water filter with capacity to store treated water.
Yet another object is to provide an improved water filter, tap attachable easy to operate and consumes no electricity.
The water filter of the present invention is an improvement of our earlier patent no. 197032. In addition to only one chamber used in the earlier filter, the present invention includes two inter connected chambers with a tube inside one of the chambers. One chamber has been used for filter media and another chamber has been fitted with a tube filled with iodine along with sand as a filler. The ratio of filter media to that of disinfectant iodine is such that it provides effective residual iodine levels in treated water.
Accordingly the present invention provides an improved water filter which comprises two interconnected (9) chambers (2 & 4), characterized in that the said first chamber (2) having a valve controlled inlet (1) at the lower end and an outlet (9) at the upper portion, the said first chamber (2) being provided above the inlet (1) and below the outlet (9) with adjustably fixed wire mesh (5) and perforated sheets (6 & 8) so as to form an enclosure containing filter media (7), the said outlet (9) of the said chamber (2) being the interconnecting inlet (9) at upper portion of the second chamber (4), the said outlet / inlet (9) being connected by means of flexible piping (10) to perforated disc (15) covered inlet (11) of a tubular enclosure (12) containing disinfectant media (14), the disinfectant enclosure (12) having perforated disc (15) covered outlet (16) opening into the said second chamber (4) provided with a valve controlled outlet (18) at the lower end, the said chambers (2 & 4) and tubular enclosure (12) being provided with removably fixed lids (3, 19, 13).
In Fig.l of the drawings accompanying this specification the sectional view of an embodiment of the device of the present invention is shown.
The various parts numbered in Fig.1 are described below :
1) Inlet with valve
2) Chamber for Filter Media (7)
3) Lid for Chamber (2)
4) Chamber attached with Tube (12) inside for Disinfectant media (14)
5) Wiremesh
6) Adjustable Perforated Disc / sheet
7) Filter Media
8) Fixed Perforated Disc / sheet
9) Outlet of Chamber (2) and inlet of chamber (4) connected to Inlet (11) of
Tube (12) fixed in Chamber (4)
10) Flexible Tube joining Outlet (9) of Chamber (2) and Inlet (11) of Tube (12)
fixed in Chamber (4)
11) Inlet of Tube (12) joined through the Flexible Tube (10) to the Outlet (9) of
Chamber (2)
12) Tube for retaining Disinfectant Media (14)
13) Outlet with stopper for Tube (12)
14) Disinfectant Media for Tube (12)
15) Fixed Perforated Disc of Tube (12)
16) Outlet for Tube (12) opening in Chamber (4)
17) Clamps to hold Tube (12) in Chamber (4)
18) Outlet with stopper of Chamber (4) for treated water
19) Lid for Chamber (4)
20) Supports for the unit
21) Wooden base
In the present invention the means (5, 6, 8 and 9) forming the Chamber (2) and means (10, 11, 12, 13, 15, 16, 17 and 18) forming the Chamber (4) are such as Wiremash (5), Perforated Discs (6 & 8) which are capable of being adjustably fixed within the Chamber (2) for Filter Media (7) and Outlet (9) of Chamber (2) connected to Inlet (11) of Tube (12) fixed by Clamps (17) inside Chamber (4) through Flexible Tube (10), Fixed Perforated Discs are (15) provided in Tube (12) inlet (11) and Outlets (16). Tube (12) Outlet (16) for treated water opening
in Chamber (4) and another Outlet with stopper (13) is provided for refilling Disinfectant Media (14) in Tube (12). Chamber (4) Outlet (18) with stopper is for treated water and another Outlet (19) is provided for removing Tube (12) to replace Disinfectant Media (14). In an embodiment of the present invention there is provided an improved water
fitter which comprises two interconnected (9) chambers (2 & 4), the first chamber (2) having a valve controlled inlet (1) at the lower end and an outlet (9) at the upper portion, the first chamber (2) being provided above the inlet (1) and below the outlet (9) with adjustably fixed wire mesh (5) and perforated sheets (6 & 8) in such a manner so as to form an enclosure containing filter media (7), the said outlet (9) of the said chamber (2) being the interconnecting inlet (9) at upper portion of the second chamber (4), the said outlet / inlet (9) being connected by means of flexible piping (10) to perforated disc (15) covered inlet (11) of a tubular enclosure (12) containing disinfectant media (14), the disinfectant enclosure (12) having perforated disc (15) covered outlet (16) opening into the said second chamber (4) provided with a valve controlled outlet (18) at the lower end, the said chambers (2 & 4) and tubular enclosure (12) being provided with removably fixed lids (3, 19, 13).
In an embodiment of the present invention the Chamber (2) and Chamber (4) may be fixed, by means of, Supports (20) and Base (21).
The Filter Media (7) in Chamber (2) is granular activated carbon and Disinfectant Media (14) is iodine and sand mixture in Tube (12) attached to the Outlet (9) of Chamber (2) and fixed inside the Chamber (4).
At the rate of 1 kg of granular activated carbon treating 2500 liters of water
containing organochlorine pesticides viz., y-hexachlorocyclohexane (ﻻ-HCH), p,p'-DDT and p,p'-DDE in the range of 4-6 µgL-1, the ratio of granular activated carbon and iodine used is in the range of 1 : 0.005 to 1:0.006 . Sand has been used as a filler with iodine for Disinfectant Media (14) in Tube (12).
The granular activated carbon used as the Filter Media (7) may be selected from coconut shell based and pulp and paper mill based. The iodine used in Disinfectant Media (14) may be crystalline and granular in shape. Sand used as a filler with iodine in Disinfectant Media (14) may be of 1-2 mm mesh size and bulk density of the order of 2.5 gm ml"1 .
The improved water filter of the present invention is based on the characteristics of Filter Media and Disinfectant Media, raw water quality. The functioning of the improved water filter of the present invention is described here under:
a) Stainless steel, PVC, perspex or any material having resistance to
commonly present cations, anions and organic substances in potable
water may be used for the manufacturing of basic structure of the
Chamber (2) and Chamber (4) of the unit
b) This unit may be cylindrical or rectangular in shape
Filter Media (7) in the unit in Chamber (2) may be selected from coconut
shell based and pulp and paper mill based granular activated carbon and
sand-crystalline iodine for Disinfectant Media (14) filled in Tube (12) fixed
in Chamber (4). The amount of granular activated carbon and iodine were
taken in the ratio of 1 : 0.005 to 1:0.006. Sand of 1-2 mm mesh size and
2.5gmmr1 bulk density has been used as a filler with iodine for
Disinfectant Media (14) in Tube (12). These chemicals may have the
following characteristics.
(Table Removed)
ii) Preferred Specifications of iodine are given in Table 2
(Table Removed)
d) Water upflow rate in the unit to be controlled at 2 mh-1 (cubic metre
volume/square metre area/hour) using valve at the Inlet
e) The system works at optimum performance using raw water up to the
following quality : y-HCH = 5±1.6 µgL"1 and DDT (sum of p.p'-DDT and
p,p'-DDE) = 5.6±1.3 |agL'1; faecal coliforms = 500 ± 60 CPU 100 ml'1; total
coliforms 955 ± 50 CPU 100 ml"1; Turbidity at and below 27±13 NTU and
total organic carbon (TOC) at and below 20 mgL-1.
f) The exhausted Filter Media (7) granular activated carbon needs to be
taken out from the upper part of Chamber (2) by removing the Lid (3),
Wiremesh (5) and Perforated Disc (6). The virgin refilling Filter Media (7)
can then be replaced in the same space and Perforated Disc (6),
Wiremesh (5) and Lid (3) can be refitted in the same sequence in the
Chamber (2).
g) The exhausted Disinfectant Media (14) sand-iodine of Tube (12) in
Chamber (4) needs to be taken out by removing the Lid (19) of Chamber
(4) taken out Tube (12) from it after disconnecting it from the Outlet (9) of
Chamber (2) and Clamps (17). The stopper of Outlet (13) of Tube (12) is
removed and the virgin Disinfectant Media (14) can then be replaced in
the same Tube (12) and stopper of Outlet (13) can be refitted and Tube

(12) is again attached in the same sequence to the Outlet (9) of Chamber (2) and Clamps (17) inside the Chamber (4) and Lid (19) can be refitted to the Chamber (4).
The novelty of the present invention includes an improved water filter for domestic purpose which is portable, having storage capacity, removing pathogenic organisms, tap attachable pesticide removal unit requires no energy consumption, incorporates fixed bed media adsorption and sand-iodine for disinfection and can be converted to smaller and larger units. It is suitable for the removal of (1a, 2a, 30, 4a, 5a, 6p isomer) -1, 2, 3, 4, 5, 6 -hexachlorocyclohexane (y-HCH), 1,1' -(2, 2, 2,-trichloroethylidene)-bis-(4-chloro-) benzene (p,p'-DDT) and 1,1' (dichloroethenylidene)-bis-(4-chloro-) benzene (p,p'-DDE) from water at concentrations levels below 5ugL"1. Treatment of contaminated water resulting in removal of 60-90% pesticides, 99% reduction in total organic carbon (TOC), 99% reduction in trubidity and 100% removal of total and faecal conforms, can be carried out by the device in its present status. The same can be up scaled appropriately for required capacities as a single unit or in the form of modular units.
The inventive step resides in the ratio of Filter Media (7) granular activated carbon and Disinfectant Media (14) sand-iodine for marginal residual iodine levels in treated water within permissible limit. Another inventive step is the additional facility of storing capacity for treated water in the developed device. The present invention is a modification to earlier Patent Application No. 1526/DEL/96/dated 11.07.96 entitled "A Water Filter for Removal of Organochlorine Pesticides" which was comprising a single chamber for filter media and disinfectant media. The ratio of filter media and disinfectant media in earlier device was less effective with respect to potability of treated water, disinfection efficiency and residual iodine levels. The earlier device do not have the capacity for storing the treated water.
The following examples are given by way of illustration and should not be construed to limit the scope of the present invention.
Example 1
The improved water filter of the present invention was tested for the treatment of raw water contaminated with organochlorine pesticides (OCIPs), viz. y-HCH, p,p,'-DDT and p,p,'-DDE, faecal conforms and total organic carbon. The characteristics of test water passed through the system is described in Table 1.1.
(Table Removed)
A unit for higher disinfection efficiency with optimum residual iodine levels and having storing capacity for treated water was designed for the removal of OCIPs at most commonly encountered concentrations in field waters. The laboratory unit was made out of perspex comprising two cylindrical shape inter-connected Chambers, Chamber (2) and Chamber (4) of sizes: Chamber (2) of 32 cm length
and 16 cm internal diameter (ID) and Chamber (4) of 28 cm length and 16 cm ID. The Outlet (9) of Chamber (2) was connected to Tube (12) through a Flexible Tube (10) to Inlet (11) of Tube (12) fixed inside Chamber (4). Tube (12) was of 9 cm length and 4 cm ID fixed up by Clamps (17) in upper part of Chamber (4). The Inlet (11) of Tube (12) was attached just 2 cm above the Filter Media (7) to the Outlet (9) of Chamber (2). The Outlet (16) of Tube (12) opened into Chamber (4). Tube (12) was provided with another Outlet (13) with stopper in the center of Tube (12), for refilling Disinfectant Media (14). The Tube (12) can be taken out easily from the Chamber (4) through the Lid (19) provided with it for refilling purpose. The Chamber (2) was filled with 1.3 lit (780 gm) of Filter Media (7) granular activated carbon (GAG) and Tube (12) with sand-iodine mixture containing 20 gm iodine as Disinfectant Media (4). Sand of 1 - 2 mm mesh size and 2.5 gm ml-1 bulk density was used as a filler with iodine in Tube (12). The granular activated carbon was thoroughly washed with nearly 10 liters of pesticides free clear water and dried at 100°C for 48 hours prior to filling in Chamber (2) of the unit. After filling the Filter Media (7) in Chamber (2) and sand-iodine Disinfectant Media (14) in Tube (12). The unit was flushed with 50 - 60 liters of pesticides free water at a upflow of 6 mh"1 (cubic meter volume per square meter area per hour) prior to its application in treatment of raw water contaminated with pesticides, faecal and total coliforms and trace organics. The specifications of the granular activated carbon and iodine used were as reported in Table 1 and 2. The raw water was supplied through Inlet (1) to the unit through Chamber (2) containing the Filter Media (7). The OCIPs present in raw water were adsorbed on Filter Media (7) of Chamber (2) and treated water was collected in Chamber (4), after passing through Tube (12) which contain sand-crystalline iodine as Disinfectant Media (14). The purpose of sand-iodine in Tube (12) of Chamber (4) was for the disinfection. The final water was collected from the Outlet (18) of Chamber (4). The unit was operated to study the removal of y-HCH, p,p' - DDE and p,p' - DDT at a upward flow of 6 mh"1 in test water contaminated with y - HCH at 5 ± 1.6 µg L"1, DDT at 4.3 ± 0.8 µg L"1 (sum of p,p'-DDT and p.p.'-DDE), faecal coliforms (900±100 CFU 100 ml"1) and total organic
carbon in the range of 15±10 mgl_~1. The resulting treated water quality was monitored at fixed intervals. The unit was operated continuously until comparatively constant potable level of y-HCH, p,p'-DDE, p,p'-DDT as total DDT and faecal conforms as nil in treated water could be achieved. Guideline level for each of y-HCH and total DDT in potable water is 2 µg L"1. Two cubic metres of test water was treated by the improved water filter for a duration of 90 hours with 90 to 60 percent removal of y-HCH, p,p'-DDT, p,p'-DDE, 100 percent removal of faecal coliforms and 99% reduction in TOC could be achieved . Results obtained are shown in Table 1.2 :
(Table Removed)
Example 2
The improved water filter of the present invention was tested for the leachates characteristics of the granular activated carbon used as Filter Media (7) in Chamber (2) and sand-iodine as Disinfectant Media (14) filled in Tube (12) fitted in Chamber (4) of the unit. The unit was operated at upward flow of 6 mh"1. (cubic meter volume per square meter area per hour). The essential physicochemical parameters, pH, heavy metals, TOC, organochlorine pesticides and microbiological tests were conducted in the leachate of the Filter Media (7) and Disinfectant Media (14). All the parameters tested were found within the prescribed permissible levels for drinking water quality as per Indian Standard (IS) specifications and WHO regulations for health related guideline values for pesticides. The characteristics of test water passed through the system is described in Table 2.1.
(Table Removed)

ND - Not Detectable * - Indian standards for drinking water quality, IS 10500-1983
+ - WHO regulations for health related guideline values
(Table Removed)
Example 3The improved water filter was tested for the residual iodine concentration released by sand-iodine used for Disinfectant Media (14) in Tube (12) of Chamber (4) of the unit in the treated water. The unit was operated at a upward flow of 6 mh"1. (cubic meter volume per square meter area per hour). All the parameters tested were found within the permissible levels for drinking water quality as per Indian Standard (IS) specifications and WHO regulation for health related guideline values for pesticides. The tolerance level for iodine concentration in drinking water is 10 µgL"1, this is as per WHO regulations for community water supply. The water filter has treated 2500 liters of test water in 79.5 hours duration, which is more than the water filter capacity of two cubic meters of the unit. The characteristics of test water passed through the system is described in Table 3.1. The resulting treated water quality was monitored at fixed intervals for the iodine concentration and microbiological quality for faecal and total coliforms, as shown in (Table 3.2).
Example 4
The improved water filter was tested for the treatment of raw water contaminated with organochlorine pesticides, viz. y-HCH at 5 ± 0.1 µgL"1, DDT sum of p,p'-DDT and p,p'-DDE at 5.6 ± 1.3 µgL'1, turbidity levels in the range of 27±13 NTU and total organic carbon levels 8 mgL"1. The characteristics of test water passed through the system is described in Table 4.1.
(Table Removed)
The unit was operated at a upflow of 6 mh-1 (cubic meter volume per square meter area per hour) to treat the test water. The resulting treated water quality was monitored at fixed intervals. The unit was run continuously until comparatively constant potable levels of y-HCH and total DDT in treated water could be achieved. Guideline value for each of y-HCH and total DDT in potable water is 2 µgL'1. Two cubic metres of test water was treated by the improved water filter resulting in to 90-60 percent reduction in y-HCH, p,p'-DDT and p,p'-DDE, 99 percent reduction in TOC and residual turbidity below 5 NTU. The results are shown in Table 4.2 and 4.3.
ND : Not Detectable
* : Indian standards for drinking water quality for turbidity (IS 10500-1983): 10 NTU
(Table Removed)
The main advantages of the Improved Water Filter for Organchlorine Pesticides are :
1. Capable of removing commonly present organochlorine pesticides,
viz. y-HCH, p,p' - DDT and p,p'-DDE of the order of 4 - 6 µg /L
from drinking water available through taps in houses in combination
with removal of total and faecal coliforms, treating turbidity levels of
27 + 13 NTU and reducing turbidity to 5 NTU or below and total
organic carbon of the order of 8 - 10 mg/L upto 99 % thus making
the water bacteriologically safe.
2. It has a capacity to store treated water.
3. Tap attachable.
4. Needs no electricity.
5. Easy to operate by unskilled persons.





We claim:
1. An improved water filter which comprises two interconnected (9) chambers (2 & 4), characterized in that the said first chamber (2) having a valve controlled inlet (1) at the lower end and an outlet (9) at the upper portion, the said first chamber (2) being provided above the inlet (1) and below the outlet (9) with adjustably fixed wire mesh (5) and perforated sheets (6 & 8) so as to form an enclosure containing filter media (7), the said outlet (9) of the said chamber (2) being the interconnecting inlet (9) at upper portion of the second chamber (4), the said outlet / inlet (9) being connected by means of flexible piping (10) to perforated disc (15) covered inlet (11) of a tubular enclosure (12) containing disinfectant media (14), the disinfectant enclosure (12) having perforated disc (15) covered outlet (16) opening into the said second chamber (4) provided with a valve controlled outlet (18) at the lower end, the said chambers (2 & 4) and tubular enclosure (12) being provided with removably fixed lids (3, 19, 13).
2. An improved water filter as claimed in claim 1 wherein the Chamber (2) and Chamber
(4) are fixed, by means of Supports (20) and Base (21 ).
3. An improved water filter as claimed in claims 1 and 2 wherein the Filter Media used is
selected from granular activated carbon and Disinfectant Media used is selected from a mixture of sand and iodine.
4. An improved water filter as claimed in claims 1 - 3 wherein the granular activated
carbon used is selected from coconut shell based and pulp and paper mill based.
5. An improved water filter as claimed in claims 1 - 4 wherein the granular activated
carbon & sand and iodine used is at the rate of 1 kg of granular activated carbon for
treating 2500 liters of water containing pesticides in the range of 4-6 µgL-1 and the ratio
of granular activated carbon and iodine used is in the range of 1 :005 to 1: 0.006.
7. An improved water filter as claimed in claims 1 - 6 wherein the sand used with iodine in
is of 1 - 2 mm mesh size and bulk density of the order 2.5 gm/ml.
8. An improved water filter substantially as herein described with reference to the
examples and drawing accompanying this specification.

Documents:

1089-del-2001-abstract.pdf

1089-del-2001-claims.pdf

1089-del-2001-correspondence-others.pdf

1089-del-2001-correspondence-po.pdf

1089-del-2001-description (complete).pdf

1089-del-2001-drawings.pdf

1089-del-2001-form-1.pdf

1089-del-2001-form-18.pdf

1089-DEL-2001-Form-2.pdf

1089-DEL-2001-Form-3.pdf


Patent Number 230839
Indian Patent Application Number 1089/DEL/2001
PG Journal Number 13/2009
Publication Date 27-Mar-2009
Grant Date 28-Feb-2009
Date of Filing 30-Oct-2001
Name of Patentee COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH
Applicant Address RAFI MARG, NEW DELHI-110001, INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 NEETA PRADIP THACKER WATER TECHNOLOGY DIVISION, NEERI NAGPUR-440020,(INDIA)
2 MAYA VINAYAKRAO VAIDYA WATER TECHNOLOGY DIVISION, NEERI NAGPUR-440020,(INDIA)
3 SUNIL PURANCHANDRA PANDE WATER TECHNOLOGY DIVISION, NEERI NAGPUR-440020,(INDIA)
4 SHRIKUMAR BABURAO LAKHE WATER TECHNOLOGY DIVISION, NEERI NAGPUR-440020,(INDIA)
5 WAMAN NARAYAN PAUNIKAR WATER TECHNOLOGY DIVISION, NEERI NAGPUR-440020,(INDIA)
6 PRAKASH SHANKARRAO KSHIRSAGAR WATER TECHNOLOGY DIVISION, NEERI NAGPUR-440020,(INDIA)
7 SUDHAKAR RAMDAS SAKHARE WATER TECHNOLOGY DIVISION, NEERI NAGPUR-440020,(INDIA)
PCT International Classification Number B01D 35/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA