What is fluoride removal?
Fluoride removal is the removal of fluoride from water by various methods. The methods are such that only fluoride as an element from water is removed and not any other water constituent. There are some processes like demineralization or desalination which using reverse osmosis remove the fluoride from water and also all the other minerals.
Removal of excessive fluoride from drinking water is a difficult and an expensive process. The preferred option is to find a supply of safe drinking water with safe fluoride levels. But places where access to safe water is limited, de-fluoridation may be the only solution.
Treatments used for fluoride removal
Several methods of fluoride removal have been developed and used in different parts of India. Fluoride can be removed with a chemical method where a portion of water is taken and certain chemicals are added to react with the fluoride content. This content is then allowed to precipitate. The water is then decanted for use.
Water can also be filtered through certain types of media to remove most of the fluoride. One of these media is made by using bone meal. Another media is activated alumina. However, the performance of such media has not been consistent and research on new methods of fluoride removal has resulted in some useful, effective solutions. Some of the ion exchangers used in water treatment also called ion exchange resins have proved to be more effective and consistent in removing higher levels of fluoride contamination than any of the other media or methods.
Fluoride removal equipment in India
One of India's leading water management companies which manufactures ion exchangers has developed an ion exchanger specifically for fluoride removal and developed devices that are installed near hand pumps in rural areas so that, the water can be pumped out of the wells.
In some rural areas, with the funds donated by international aid agencies, a large centralized fluoride removal system has been installed. The fluoride free water from the system is stored in an overhead tank and the people living in the village collect the water in containers or pots for their use.
Community Solutions
In all installations it is important that the people of the rural areas feel involved. This is usually ensured by getting them to contribute to a part of the cost of fluoride removal equipment and training them to operate and maintain the system.
In a couple of fluoride affected areas in Gujarat where such installations are in use, the villagers have found ways to sustain the use of the system by selling the excess water to nearby villages. With the availability of relatively fluoride free water, people living in these villages have gained some respite from fluorosis and their health has improved.
The availability of power is a challenge in rural areas. Therefore, fluoride removal systems have been developed which are connected to the outlets of the hand pumps installed in villages to produce relatively fluoride free water. The fluoride content in the water is below 1.5 mg/l. Such installations do not need power to operate. A majority of the installations in rural India therefore are the hand pump attachments.
Various initiatives for fluoride removal
Individual and household solutions are now being tried out for point of use application. The involvement of UNICEF has lead to work on the Domestic De-fluoridation Units (DDUs).In 1998/99, with assistance from UNICEF, a pilot project was started in Kadri Mandal of Anantapur district in Andhra Pradesh.
The DDUs using activated alumina were first made with plastic containers and costed Rs.410 each and were sold at price of Rs.250 to each scheduled caste household and for Rs.50 to each scheduled tribe household in the first phase. Three hundred (300) such DDUs were distributed in 6 villages.
In the second phase, 2000 DDUs made with stainless steel containers were distributed in 25 additional villages. Each DDU cost Rs.1000, but was given to families below the poverty line for Rs.250 and for Rs.400 to families above the poverty line in 1999-2000.
In the third phase (2001-2002), 1800 more DDUs were distributed at the same prices in 25 more villages. All this was done with the help of a non-government organization (NGO) called Mytry. By 2003, Mytry which started making these DDU filters, had 60 dealers for these filters in Andhra Pradesh and 20 dealers in Karnataka and had sold about 60000 such filters.
Long term precautions for fluoride removal
It is very important to take appropriate long term care of fluoride removal equipment to ensure its effective functioning and for the health of the people. All devices using a fluoride removal media need to be washed or regenerated after a specific amount of water has been treated to remove the accumulated fluoride in that media. This is very essential, as the media will not remove fluoride in the incoming water if excess fluoride has accumulated in the media.
In the long run, recharge of the water table by rain water harvesting is the most sustainable solution to the fluoride problem. The decrease in the ground water tables is a major threat in preventing fluorosis. When the water table drops below a certain level, it will not be possible to pump out water beyond a certain level using a hand pump. Therefore, by constantly renewing the water levels in the ground by rain water harvesting, we can combat the problem of fluorosis in the long run.
Fluoride removal and associated problems
Whatever is the method for fluoride removal, there persisits the problem of waste production either in liquid form or as sludge with a very high concentration of the fluoride removed from the water. Disposing of this sludge or liquid in a way such that it does not re-enter the source of water from which it was removed has been proved to be beyond the capability of any community. Re-activating or regenerating the media or material used for fluoride removal was another activity that saw communities avoiding it. There was a marked lack of ownership by the communities.
To view the other parts of the course refer:
Basic course on fluorosis and fluoride removal (part 1 of 4)
Basic course on fluorosis and fluoride removal (part 2 of 4)
To view the multimedia course refer:
Basic course on fluorosis and fluoride removal (part 4 of 4)