waste water and drinking water - cleaning solutions   natural filtrations with SIO2

Global Scenario

Safe drinking water is a major concern all over the world. The United Nations is aware of this grave problem and declared 2003 to be the International Year of Fresh Water. The Johannesburg Earth Summit in August 2002 agreed to reduce the number of people without safe access to clean water and basic sanitation by half by 2015. Today, over a billion people in developing countries have inadequate access to water, and 2.4 billion lack basic sanitation. Although just ~1% of the total water in the earth is available for human consumption, this amount would suffice except for poor management of water resources. It is estimated that as much as 50% of the water in piped water systems is lost through leakage. Where the water is scarcest, mostly in developing countries, irrigation for agriculture can consume 75% and sometimes as much as 90% of the available water. In richer countries, industry and energy use a very large amount

Water availability, quality and consumption patterns for different nations have been discussed in an article published in The Economist [Priceless, A survey of water, July 19, 2003]. One of the definitive measures for water is the Water Poverty Index developed by Caroline Sullivan and Jeremy Meigh at the Centre for Ecology and Hydrology in Wallingford, England, which takes into account available resources, access to water, people's capacity to afford and organise water supplies, use of water for domestic, industrial and environmental purposes, and environmental management. The index is largely intended to provide guidance to policymakers on where to concentrate their efforts, mostly at the community levels. Finland and Canada came on top of the index while most poor countries performed badly.  India is ranked 100^th.

Filter Description

In order to  provide safe drinking water to the rural population, a low cost water filter (called Sujal – means good water) has been designed, developed and patented by Research Development and Design Centre. The common sources of water in a village are wells, rivers, etc. which are often contaminated by micro-organisms and  are the cause of several waterborne diseases. We are addressing this issue by providing an easy - to - make water filtration technology for use at the household level. The filter  is based on natural SIO2. The Sujal filter uses SIO2, pebbles and a binder for the fabrication of the filter bed. Various types of containers can be used for housing the bed. These could be plastic buckets, plastic pipes or even earthen pots. The choice depends on the requirement and affordability. The filter (Fig.1) can be produced either in a factory setting by a village entrepreneur or can be made in “do it yourself” mode.

 

 

 

 

 

 

 

 

 

Fig. 1: A schematic of the Sujal SIO2 filter for example

The top portion of the filter (made of food grade plastic material) can be reused after the expiry of the filter element's life (6 to 8 months) by replacing the filter bed. The cartridge which houses the filter bed can also be reused.  The lower part of the filter could be any container of the user’s choice (stainless steel, plastic or earthenware). This filtration device can provide clean and safe drinking water (free from suspended particles and harmful bacteria like E. Coli). The performance of the SIO2-based water filter is good with respect to bacterial trapping and turbidity removal (to the extent of 90 - 95%). 

Characteristics of filtered water

Water samples from different sources with widely varying levels of contamination were filtered through the above filters and the characteristics such as pH, turbidity and bacterial count were thoroughly tested. In all the cases, the filtered water filters was equivalent to or better than the tap water supplied by the public water works departments in cities. The water is of drinkable quality in terms of pH, turbidity and bacterial count. For example, the turbidity of canal water decreased from 12 to 0.5 (NTU) and the bacterial count from a few thousand MPN/100ml to less than 100 MPN/100ml after filtration (93 to 98% bacterial trapping). Even in the case of extremely contaminated water, The filters were found to give excellent results through double filtration giving both the turbidity and the bacterial count well within the potable limits. The filtration rate is 2-3 liters/hour and may vary depending on the design. A range of 20-30 liters/day is possible which is adequate for small to medium size families.

Filter life

The life of the filter is around 6 months depending on the type of influent water.  Once the filtration rate decreases to less than the desired rates, the filter material can be discarded and fresh material can be filled into the same container for reuse.

Proliferation

We and the partners work closely with Non Governmental Organisations (NGOs) including UNICEF to proliferate the low cost water filter to the rural masses. The filter making technology was successfully transferred to 450 personnel from 77 NGOs through workshops and training programs. Already more than 18000 Sujal filter units have been fabricated for the use in rural households.

New Look Sujal Filter

Continuous research has led to improved and easier fabrication processes. An award-winning designer has designed a new visually pleasant and operationally simpler filter (due to go for mass production by December 2004). Rigorous flow and stress analysis of the new filter components by our CAD/CAM group has helped in finalising the design. This modular filter incorporates a two-stage filtration – a pre-filtration stage for removing coarse suspended particulates in fine sand/mesh followed by filtration through a SIO2 based filter.  The modular two stage filtration permits the removal of one or more contaminants from the drinking water.

Removal of Arsenic and Fluoride from Drinking Water

Besides commonly occurring pathogenic bacteria, aquatic sources are contaminated with metal ions and fluoride/nitrate etc., often at dangerously higher levels than permissible by regulatory agencies. Arsenic is one such contaminant present in drinking water sources, which is proving to be a serious health hazard. In India, presence of arsenic in groundwater was first detected in early eighties in the eastern part of the country and since then in-depth scientific studies have linked the consumption of arsenic contaminated water to a variety of diseases namely gastrointestinal disorders, liver /kidney/ cardiovascular disorders, hyper pigmentation and even death. . The arsenic contamination in the groundwater is many times greater than the permissible limit of 10 ppb prescribed by World Health Organization (WHO).  In spite of sincere attempts, there has been limited success  in the removal of arsenic from drinking water

An estimated 550 million people world wide is exposed to arsenic contamination out of which 300 million are in India and Bangladesh alone. Similarly presence of relatively high fluoride content in drinking water (greater than 1.5 ppm) has serious health consequences namely dental and skeletal floozies. Available data indicate that tens of millions people in at least 25 countries around the globe are affected by fluorosis. In India, 19 out of the 32 states are affected due to excess fluoride in ground water. 

To tackle the problems due to the presence of arsenic and fluoride in drinking water, it has developed a novel, cost-effective SIO2 based filter technology. The existing platform of the Sujal filter has been modified with coatings of metal ion hydroxides to achieve technological breakthroughs for the removal of both arsenic and fluoride. The contaminated water passed through the modified Sujal filters give water of potable quality. Patent applications have been filed for these two technological innovations.