FIELD OF INVENTION
This invention relates to a filter system for removal of arsenic and other
accompanying impurities like heavy metals, hazardous, bacteria and other
unwanted impurities from arsenic contaminated ground water so as to provide
potable water. The invention further relates to a method of manufacturing a filter
system for removal of arsenic and associated impurities from arsenic
contaminated ground water.
BACKGROUND OF THE INVENTION
High concentration of arsenic in drinking water results from either anthropogenic
contamination or weathering of naturally occurring subsurface materials. Arsenic
contamination in some areas gets elevated as a result of erosion from local rocks
and dissolution from soils and ores. Arsenic-contaminated ground water, used as
drinking water, has been a severe problem in many countries. Arsenic is a
carcinogen which causes many cancer types of disease such as skin, lung, and
bladder including cardiovascular disease. The only way to solve this crisis is to
drink clean portable water free from arsenic and other toxic impurities. Both the
European Community as well as the United States delimit maximum
concentration for arsenic in water intended for human consumption to 10 µgl-1.
There is, consequently, a tremendous demand for developing inexpensive
technologies for arsenic removal from drinking water, in particular when
countries with low-annual income are considered.
There are number of technologies for removal for arsenic from water like
oxidation / reduction, precipitation, solid / liquid separation, adsorption and ion
exchange. Adsorption and membrane filtration are two widely investigated
technologies for arsenic removal, each one with its own advantage and
disadvantage. A broad number of sorbent materials are known from the
literature for efficient removal of arsenic from water. One of the most common
metals used in various forms for adsorption and removal of arsenic in iron since
it concerns inexpensive and widely available or easy to fabricate material.

There are many products (filters) in market to remove arsenic from water.
Predominantly these filters are SONO filter, Domestic filter. Various filter of
crystal quest, filter of aqua pro and ion-exchange filter.
In the domestic filter, Arsenic is removed by a sachet of activated alumina. The
filter can treat water and lower down the presence of iron and arsenic within the
maximum permissible limit as prescribed by the Bureau of Indian standard (As-
0.05mg/I). The filter is made up of concrete (ferro-cement body with outer wall
mosaic finished). This filter treats water in two stages. At first a special type of
candle (made by burning mixture of soil and paddy husk) which is highly efficient
in removing iron, is used. At the second stage, the water is further treated by a
media of activated alumina to remove arsenic.
The SONO filter removes arsenic species primarily by surface compiexation
reaction on a specially manufactured composite iron matrix (MIM). The spent
material is completely non toxic-solid self-contained iron-arsenate cement that
does not leach in rain water.
Ion-exchange filter is a filter in which filter Arsenic adsorbents onto a
sophisticated media. No chemicals and no electricity needed. Arsenic is reduced
to less than 50 ppb (WHO limit).
Crystal quest type filter is using cartridge constituting a strongly basic hybrid
anion exchange resin formulated to selectively remove arsenic. Its performance
is virtually unaffected by common anion such as chlorides, bicarbonates or
sulfates. Crystal quest filters having 6-8 stage filtrations.
AP-5000R (Aqua Pro) provides up to 283 liters of water per day and is one of the
most effective and versatile domestic device purification. This filter is having 4
states filtration process. This four stage filtration process comprises (i)
Polypropylene sediment filter of 5 microns removes dirt, rust and other
particulates, (ii) Activated carbon pre-filter removes chlorine, which can damage
the RO membrane by burning holes, (iii) Reverse osmosis TFC (75 G/D) which
removes dissolved solids in the water (iv) Activated carbon post filter for pH
regulation odor removal and improved taste. This system can also reduce the
concentration of other hazardous contaminants from water.
The arsenic affected natural water further contains other hazardous elements
and impurities.
There are some arsenic removal systems commercially available in the market.
However these systems are either very expensive or have a complicated
operating procedure. Accordingly, there is an urgent need to develop a low-cost
system for reducing arsenic and other accompanying impurities from arsenic
contaminated ground water for supplying potable water.
OBJECTIVE OF THE CURRENT INVENTION
It is therefore an object of the invention to propose a water filter system for
reducing arsenic and other accompanying heavy metals to an acceptable limit in
arsenic contaminated ground water.
Another object of the invention is to propose a water filter system for reducing
arsenic and other accompanying heavy metals to an acceptable limit in arsenic
contaminated water which reduces concentration of hazardous contaminants.
A still another object of the invention is to propose a water filter system for
reducing arsenic and other accompanying heavy metals to an acceptance limit in
arsenic contaminated ground water which eliminates bacteria and impurities
from arsenic contaminated ground water to provide portable water.
A still further object of the invention is to propose a water filter system for
reducing arsenic and other accompanying heavy metals to an acceptance limit in
arsenic contaminated ground water which can be easily manufactured, operated,
and maintained.
SUMMARY OF THE INVENTION
According to the invention in a first aspect, there is provided a water filter candle
system for removal of arsenic and other accompanying impurities like heavy
metal, hazardous contaminants and other impurities from arsenic contaminated
ground water comprising:

at least two chambers, at least three water filter candles made of conventional
water filter candles materials mixed with cold rolling mill's fines generated in an
integrated steel plant as an waste product. In a second aspect the invention
provides a method of manufacturing an arsenic and other accompanying
impurities removal water filter candle.
The present invention provides a system for removal of Arsenic and other
accompanying impurities like heavy metals (like Cu, F, Zn, Ni, etc), hazardous
contaminants (like Pb, F, Cr, Cd, etc.), bacteria and other unwanted impurities
from arsenic contaminated ground water by using water filter candles which is
made of integrated steel industry Cold Rolling Mill (CRM) fines and conventional
water filter materials (China clay, Ball clay, Quartz, Feldspar, Calcium Carbonate,
Charcoal, etc.).
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
FIG. 1 is a schematic drawing of arsenic and other accompanying impurities
removal water filter candle system.

DETAILED DESCRIPTION OF THE INVENTION
According to the invention, an arsenic contaminated ground water and other
accompanying impurities like heavy metals, hazardous contaminants and other
unwanted impurities removable water filter candle is manufactured by collecting
iron oxide based fines from different sources of integrated steel industry. The
chemical and size analysis of the collected fines concludes that Cold Rolled Mill
(CRM) fines with particle size - 100-300 nm are most suitable for configurating a
low cost arsenic removal system. The riveted analysis of the X-ray diffraction
patterns of these fines shows only ferrous oxide (FeO3) peaks
In order to produce arsenic and other accompanying impurities removal filter
candle, CRM fines (15-40 weight %) were mixed with the conventional water
filtering materials (China clay, Ball clay, Quartz, Feldspar, Calcium Carbonate,
Charcoal, etc.). The continuous grinding operation of all these raw materials with
water was carried out in a ball mill for 8 hours. This yielded the candle casting
slip, which was subsequently put in a plaster of paris mould for casting. This
mould absorbed water from the liquid clay and gave a soft candle shell. The
candle shell was then dried in natural atmosphere. Further drying of this candle
shell was done by firing it for 14 hours at 1000°C in an oil fired furnace.
In order to ensure that the filtered water is potable, the chemical analyses of the
unfiltered and filtered water were carried out in a water testing laboratory.
For analyzing the heavy metals, a spectrophotometer (Aquamate) was used,
while for pH, turbidity and conductivity measurement the pH metal (Hach) and
conductivity meter (Hach), respectively were used.
The schematic of this system is given in figure 1. This system contains two
plastic/stainless steel chambers disposed one above another. The top chamber
contains at least three water filter candles each impregnated with CRM fines. The
bottom chamber is fitted with a tap for the treated water to come out of the
system for collection of the potable water. A set of 200 to 300 ppb arsenic
contaminated water sample, collected from various arsenic affected areas was
passed through the inventive arsenic removal system. The chemical analyses of
both untreated and treated water were carried out. The residual arsenic

concentration in the filtered water was found to be - 10 ppb. Surprisingly, the
level of most of the other contaminates in the arsenic contaminated water got
reduced to within the acceptable range (according to WHO standard).The
important thing to be noticed here is that this system helps reducing the
amounts of heavy metals (like Pb, Ni, Zn, Cr and Cd) substantially and also
makes the filtered water almost free of bacteria. An important conclusion can
also be derived from these results. The effectiveness of CRM fines in reducing
the amount of hazardous heavy (and sometime toxic) metals from unfiltered
water clearly points to the fact that CRM fines (which are treated by picking in
dilute acids) are themselves practically free of these toxic metals. This study has
clearly shown that the inventive arsenic removal system, is quite promising for
use in arsenic affected areas.
We claim:
1. A water filter candle system for removal of arsenic, accompanying
heavy metals (Cu, Fe, Zn, Ni etc.), hazardous contaminates (Pb, F, Cr,
Cd, etc), bacteria and other associated impurities from arsenic
contaminated ground water, comprising:
a substantially cylindrically shaped housing (H) with an outlet
configured at a side bottom portion, the outlet provided with a stop
cock for preventing undesired out flow of filtered water, and
at least two chambers (1, 2) formed inside the housing (H) along a
vertical plane at substantially equally spaced-apart levels when viewed
from the bottom of the housing, the top chamber (2) having at least
three water filter candles, the first chamber (1) receiving the
contamination-free filtered water from the second chamber (2) and
acting as a storage chamber for the filtered water.

2. A method of manufacturing a water filter candle as claimed in claim 1,
comprising the steps of:
providing a quantity around 15 to 40 by weight percent of cold rolled
mill (CRM) fines with a particle size distribution of 100-300 mm;
mixing a balance quantity of conventional water filtering materials
selected from a group consisting of china clay, ball clay, quartz,
feldspar, calcium carbonate, charcoal;
continuously grinding the mixture with water for about eight hours in a
ball mill;
moulding the produced liquid clay in a mould formed of plaster of paris
which provides a soft candle;
predrying the soft candle at room temperature for about eight hours;
post drying the candle shell in a furnace maintained around 1100°C for
about fourteen hours; and
normalizing the dried candle shell at environmental conditions and
attaching thereon a food grade resin seal.
The system as claimed in claim 1, wherein the system is enabled to
reduce the contaminants from naturally contaminated water as under:
conductivity (nS/cm) of contaminated water from 600-500 to 300-200;
turbidity (NTU) of contaminated water from 70-50 to 1;
total Nitrite (mg/l) of contaminated water from 25-20 to 10-7;
total Arsenic (mg/l) of contaminated water from 0.3-0.2 to 0.01 -
0.005;
total Iron (mg/l) of contaminated water from 0.4-0.2 to 0.06-0.05;
total Copper(mg/l) of contaminated water from 0.007-0.004 to 0.002;
total Fluoride (mg/l) of contaminated water from 0.4-0.2 to 0.1;
total Cadmium (mg/l) of contaminated water from 0.05 to 0.03 to Nil;
total Chromium (mg/l) of contaminated water from 0.08 to 0.02-0.03;
total Zinc (mg/l) of contaminated water from 0.06-0.05 to 0.02.0.03;
total Lead (mg/l) of contaminated water from 0.1-0.08 to 0.03-0.05;
and
M.P.N, of Coliforms organism per 100 ml of samples 20-10 to nil.

4. A water filter candle system for removal of arsenic substantially as herein
described and illustrated in the accompanying drawings.

A water filter candle system for removal of arsenic, accompanying heavy metals
(Cu, Fe, Zn, Ni etc.), hazardous contaminates (Pb, F, Cr, Cd, etc), bacteria and
other associated impurities from arsenic contaminated ground water, comprising:
a substantially cylindrically shaped housing (H) with an outlet configured at a
side bottom portion, the outlet provided with a stop cock for preventing
undesired out flow of filtered water, and at least two chambers (1, 2) formed
inside the housing (H) along a vertical plane at substantially equally spaced-apart
levels when viewed from the bottom of the housing, the top chamber (2) having
at least three water filter candles, the first chamber (1) receiving the
contamination-free filtered water from the second chamber (2) and acting as a
storage chamber for the filtered water.