Natural techniques for the treatment of waste water are not expensive and very successful
(Des stations écologiques pour le traitement des eaux usées : des techniques naturelles pas très onéreuses et pleines de promesses)
01 / 2002
Urban decae du to ineffective treatmant of sewage
It is now widely recognized that the lack of adequate treatment of waste water in urban areas, particularly in the developing world where migration to cities is also causing other problems, is a major health hazard. In many areas even treated water is getting contaminated due mixing of this with sewage caused by degraded and leaking old drainage and pipe systems. The treatment of sewage is also being carried out inadequately. Considering that the above handicaps were faced by many developing countries, this writer and the NGO Paani Morcha, designed and developed a natural sewage treatment park, which they dubbed as ’Eco-Parks’. Brief particulars of this natural treatment system are given in the succeeding section of this paper.
Treatment of waste water
Today congested cities are causing another grave problem due to the large quantities of waste water generated by them. We have failed to deal with this problem, as demonstrated by the failure of the Ganga Action Plan.
The governments of developing countries continue to favour high cost foreign technologies that aim to treat sewage only up to the secondary stage, and are failing to do achieve even this, due to lack of power, insufficient pondage, poor maintenance etc..
Fortunately natural techniques for the treatment of waste water have been successful in this sub-continent. Utilising five such technologies, the NGO, Paani Morcha, has designed and developed ’Eco-Parks’ for the treatment of highly toxic urban sewage up to the tertiary stage. After some hesitation, Indian authorities have finally seen merit in such projects that avoid the high capital and maintenance costs of the mechanical STPs, and a pilot project of this natural technology is likely to be set-up in Delhi. It is expected that the ’Eco-Parks’ would be able to achieve waste water treatment up to the tertiary stage and achieve the re-cycling of waste water at one fourth the cost of presently advertised western technologies..
Eco-Parks’ Brief details of the technology of treating waste water in the five or six tanks of an ’eco-park’ are given below’ :
- in the first tank, it is hoped to neutralize most of the toxicity of urban sewage through the addition of chemicals. It is also hoped that most of the heavy metals would be consumed by plants such as water hyacynths in this tank.
- in the second tank, oxygen would be pumped in using a compressor or inducted using rotary machinery, with the tank being left bare to absorb maximum sunlight.
1. Root zone technology is utilized in the next tank; rooted phragmites and some fruit trees like bananas are planted to absorb most of the biological wastes.
2. Floating duck weeds are planted in the fourth tank for further treatment.
3. Non-edible fish that consume sewage are bred in the next tank for final ‘polishing’ of the waste water.
4. Sale-able fish is bred in the next tank, which along with the fruits and dried duck-weed, provides income for meeting the revenue expenditure of the park.