THE World Environment Day was observed recently. There were a couple of reports in newspapers, one of which on Karachi mentions that 90 per cent of the raw sewerage is flowing untreated into the sea. The other was a letter to the editor (June 6) talking about contaminated Phuleli Canal in Hyderabad.

Converting sewerage into water fit-for-irrigation is a practice used all over the world, and local expertise for which is available. Since we normally don’t treat our sewerage, the easiest thing for us to do is to connect it to the closest canal and river or let it rot in a filthy pond near every village.

It is not only happening in Phuleli Canal but also in Ravi near Lahore. We are a water-starved country and cannot afford to lose whatever water is left with us. WWF-Pakistan has brought this concept under its programme ‘Indus for all’.

Their proposed constructed wetlands and the upstream system treat raw sewerage and convert it into grey water.

The model is quite simple. The preliminary treatment is done by screening the sewerage. Anaerobic baffle reactor (simple baffle RCC tank), a secondary treatment, removes 65 to 90 per cent of COD. The tertiary treatment is provided when this water is made to flow over an impervious layer of sheets where shrubs are planted on top. These shrubs and their roots help remove whatever bacteria is left to be removed.

Clean water, minus the smell and dangerous bacteria, flows out. This prevents the growing menace of untreated sewerage going into the ponds, canals, lakes and the sea.

Pakistan’s first grey water harvesting project was set up in Majeed Keeriyo village, Nawabshah, which has been operating successfully for the last couple of years.

This is a low-cost, ecotechnological, biological waste water treatment technology, which mimics processes found in natural wetlands.

I saw the second grey water harvesting project set up in the newly-constructed Ittehad village in Ehsanpur, Muzzaffargarh, last year. It was also operating successfully.

We need to duplicate the successes of the Keerio village and Ittehad village all over Pakistan.

By doing so, we will not only eliminate this poor practice but would also eliminate the decease and ailments associated with every sewerage pond in thousands of villages in Pakistan. WWF supports such initiatives.

S. NAYYAR IQBAL RAZA Karachi