By Chandre Dharmawardana –

Prof. Chandre Dharmawardana

Reverse osmosis, and bio-scavengers for cleaning the water and soil in areas affected by Kidney disease

When kidney disease of uncertain origin (CKDU) appeared in the North-central province in the mid-1990s, some commentators hastened to claim that this was bio-terrorism associated with the Eelam wars. Today, a variety of opinions are touted regarding the origin and prevention of  the CKDU epidemic. News reports tell us that cases have been noted in other `dry zone’  ares like Hambantota and Jaffna. Places like Jaffna and other dry-zone towns are extremely vulnerable because of the rapidly increasing population while the water table remains limited.

A number of authors have raised the possibility of using special plants that accumulate metal toxins as a means of purifying the water.  Others have suggested using reverse osmosis.

Last October when I was in Colombo I gave several talks in symposia on Kidney disease, e.g., one of them  was at the Gannoruwa Institute of agriculture, while another symposium was at the Professional Institute in Colombo. I also raised this question of water hayacinth-like plants (water hayacynth, Japan jabara, lotus root etc), or even Murunga, and their capacity to extract and concentrate toxins from polluted water. This point has been raised by many others as well. Also, many of the relevant plans are listed in the Sri Lankan plants website (http://dh-web.org/place.names/bot2sinhala.html) that I maintain.

In principle, such plants can be used to “clean the water”. In practice this is NOT TRUE.  What do you do with the plants that have now collected all the toxic  heavy metals? Are you going to put the plants back into the soil, or disperse them in the ecosphere, or burn them? None of them will work as the pollution will just go back to the water table. You have to physically bury them in deep pits, or compound them in bitumen, or drop them in the ocean — all costly steps.

The same issue of getting rid of the waste matter arises with the reverse-osmosis process advocated in seminars by various  people and put in place by various NGOs like Sarvodaya. When 1000 litres of water are purified using reverse osmosis, 200 litres of highly polluted water remain in the reverse-osmosis machine. Now, where do you dump that water ? Do you dump it back to the soil? That will not help.

What we need to do is to cut the problem at the source. The source is the fertilizer runoff from the hill country, coming along the Mahaweli, and polluting all the water bodies connected to the mahaweli via the “accelerated mahaweli” project, and other similar irrigation projects which link agriculture and drinking water.

These problems did not exist prior to 1977. After the “open economy”, fertilizer sales became unregulated. The problem is not with the fertilizer, but with excess use where 5 to 10 times the required amount is used, and this gets washed off to our rivers like the Mahaweli, and end up in the drinking water. Testing for cadmium, arsenic etc in the drinking water shows no significant amounts of these ions, (as the WHO study found), because the culprit is not the presence of a few parts per billion of metal toxins. It is the excessive fertilizer run-off made up of phosphate, potassium, nitrate etc., that is causing the trouble. The WHO did not look at those ions, treating them as `benign’.

The fertilizer runoff adds to the already hard water in the Rajarata. The resulting high ionicity (brackishness or salinity)  of  the water destroys the inner layers of the kidney, just as brackish water corrodes anything it touches. Once the kidney is corroded, the small amounts of As, Cd etc., that are always found in any environment enter the body, and the human body accumulates them, just as many living organisms and plants do. The resulting kidney disease ultimately kills the patients. When you analyse their organs, they too are found to have accumulated As, Cd, etc, just as some plants (that do not have the capacity to filter out the toxins) do.

I have constructed a map of the areas stricken by Kidney disease of `uncertain origin’, and also drawn the river system on it. It is clear that the most affected ares are just those linked to the highly agricultural regions (e.g., the hill country and the Mahaweli) by rivers which bring in the excess fertilizer runoff. It is well known that most of our reservoirs are full of algae because of this fertilzer runoff. Furthermore, the benign algae that used to live in our tanks have, under the stress of excess phosphates etc., evolved into toxic varieties that did not exist in earlier times (e.g, 1960) in our tanks.

So the answe is clear. The fertilizer sales should be strictly controlled by the agriculture department. The government should issue  to the farmers only the recommended amount of fertilizer (as was done in the 1970s, prior to the `open economy’ ) and stop the free sale of fertilizers and agro-chemicals. Then, after a few monsoons, the soil will be clear of the contamination.

The majority of plants don’t have special fitration mechanisms like the kidneys. So such plants can be used as a means of monitoring the water as it is easy to analyse the in the laboratory the more concentrated toxin present in the plant. I pointed this out in my talks at Gannoruwa and Colombo, and of course, this is not a completely new idea and I am sure other have thought of it. But trying to use them for cleaning all the water in the rajarata ecosystem is, in my view, not feasible and extremely expensive. In any case, we want to grow paddy or vegetables, and not ‘Japan-jabara’ or Salvinia. If we grow such plants to as bio-clensers, we will need to work hard to clean up the Japan-Jabara itself, perhaps with powerful weedicides?

The sale of fertilizers should be controlled, and fertilizer subsidies should also be stopped. The money saved can be used to help the affected farmers. If the excess use of fertilizer is stopped, we also save foreign exchange, and will regain our pure water table in a few years. The digging and selling of  Eppawala phosphates should be stopped as the soil is already utterly saturated with phosphate.