Rejuvenating a river with green technology

Just a few years ago, the Ahar river in Udaipur in Rajasthan was in a path­etic condition and the people had given up hope. Thanks to some innovative steps taken by the active civil society and the government extending all needed help, now the river is live and home to many birds and aqua animals.

The work has been lauded as a model for integrated water resources management (IWRM) and integrated lake basin management (ILBM) in the country. The
project is shortlisted for National Urban Water Awards this year. 

The Udaipur lake system consists of chain of lakes-- Pichola, Rang Sagar, Swaroop Sagar, Badi, Madar,  Fathesagar and Udaisagar-- and their source of water was from the Ahar river.  Udaipur depends on these lakes for its drinking water and tourism. But in course of time, the portion of the river passing through the city became a huge drain polluting the lake system. It carried entire domestic and industrial waste water of Udaipur and,
totally depriving of oxygen to aquatic life. 

Anil Mehta and Dr Tej Razdan of Jheel Sanrakshan Samiti who initiated revival project can now feel proud as their initiat­ive has come in for great appreciation by the Planning Commission as a perfect model of public private partnership (PPP). The “green bridge technology’”uses some natural bacteria, water purifying shrubs, plants, loose stones and sand, coconut coir and sunlight.

This was unlike conventional systems, which require power, chemicals and machinery. In this venture, energy source is sun, air and they synthesise their own chemicals and assimilate. There is no comparison of expenditure at all.

Talking about the initiative, Anil Mehta said Udaisagar, on the downstream, was the most polluted lake as it received the entire untreated domestic and industrial waste water of Udaipur through the Ahar river. Even the ground water on the 21-km stretch of river was highly polluted and contaminated.

The Jheel Sanrakshan  Samiti sought the help of Dr Sandip Joshi, an expert on sewage treatment at Srusthi Eco Resea­rch Institute, Pune, for applying eco-te­ch­niques in the Ahar river and Udaisagar lake. The uphill task of cleaning of water hyacinth, removal of polythene from the river-bed was taken up by the civil society groups. The seed money for the project was donated by Singhal Foundation headed by Anil Singhal, a businessman. The project committee collected donations from various organisations and
individuals to execute the project.

Mehta said the installation of green bridges started in December 2009 at Sukha Naka, end of the Ahar river, the point from where the river enters into Udaisagar. Green Bridge technology uses filtration power of biologically originated cellulosic / fibrous material in combination with sand and gravels and root systems of green plants. It’s an innovative approach to minimise the cost of pollution treatment when the cellulosic / fibrous materials like coconut coir or dried water hyacinth or aquatic grass are compacted and woven to form a bridge / porous wall like structure strengthened by stones and sand.

He said: “ bridges acts as  filters. All the floatable and suspended solids are trapped in this biological bridge and the turbidity of flowing water is reduced substantially. The green plants help in absorption of soluble substances, including heavy metals. The treatment scheme comprised six green bridges. The green bridges varied from 12 to 14 metre, depending on the width of river.  The river banks were strengthened by planting trees and shrubs those are also major component in treatment of waste water”.

The results started coming within one month of the installation process, which was over  in the second week of March 2010. The foul smell started disappearing and aerobic conditions began setting up. The height of froth where river falls into backwater portion of Udaisagar reduced to four to five feet.

And the real changes occurred and were visible. Birds started converging on the treatment location. The whole animal life regenerated and one could see fish, water snakes and tortoises. The quality of water in wells around the river course
improved. Even cattle started drinking the flowing water.

The physical, chemical and biological examination of water before and after of the green bridges showed great improvement within one month of the installation of green bridge system. The dissolved oxygen increased up to eight and biological oxygen demand  and chemical oxygen demand  reduced by 70 Per cent. To everyone’s surprise, the bridges withstood the onslaught of  monsoon and floods. Only the bridge positions had shifted slightly.