Posted on May 09, 2011

Qatar could develop a number of small, decentralised sewage treatment and water-recycling units instead of relying on centralised plants that receive all the greywater and blackwater through a communal system.

“This would be the better option, given the enormous amount of pressure we have here in the Gulf region on fresh water,” Unesco’s ecological science adviser in the Arab region, Dr Benno Boer, told Gulf Times. Greywater is the leftover water from baths, showers, hand basins, washing machines and kitchen sinks whereas any water containing human waste is considered blackwater. “The sewage (treatment) capacity in Qatar has by far not reached the capacity that the country needs,” Dr Boer pointed out.

Independent sewage treatment facilities, if installed at housing complexes, shopping centres, and institutions with a large number of employees, would streamline the entire process and save huge quantities of fresh water. “The water produced by such small units could be used to irrigate gardens and flush toilets, replacing precious fresh water, obtained through energy intensive desalination plants which cause environmental pollution as well,” he explained.

The Arabian Gulf, a shallow marine embayment system with an average depth of just 35m (as against the 3,000m of the Indian Ocean next door) and one of the most saline areas in the world, already has the highest density of desalination plants on the planet and one of the highest rates of water consumption. The Qatar National Development Strategy (NDS) 2011-2016, unveiled recently, revealed that Qatar has become increasingly dependent on desalinated water, which accounts for about half the water used in the country.

Dr Benno Boer: Unesco’s ecological science adviser in the Arab region

With rapid population growth and urbanisation, the use of desalinated water has tripled since 1995, reaching 312mn cubic metres in 2008. Based on current trends, consumption through 2020 is expected to increase 5.4% a year for Qataris and 7% a year for expatriates. As of 2009, however, studies show that Qataris consumed 1,200 litres per person per day, while the figure for expatriates was only 150 litres per person per day.

The NDS document also highlighted the fact that compared with other countries, Qatar has low water tariffs (free for Qatari households and low-cost for non-Qatari households) that recover less than a third of the costs of water production. The Unesco official observed that the natural climatic condition is also not favourable, with an annual average precipitation of 50 to 80mm per year per sq m and evaporation rates reaching up to 3,000mm per sq m per year and more.

“We not only live in a hyper arid region, but also in a region seriously dependent on desalination plants. This is a very critical situation. Without desalination plants, even inland cities like Riyadh (in Saudi Arabia) and Al Ain (in the UAE) would not receive fresh water anymore,” he cautioned. The desalination plants are not really clean factories, Dr Boer stressed. They cause brine pollution in the marine environment with the output of higher saline water, which in turn brings biodiversity down.

The desalination plants, which cause thermal pollution by heating the water a little bit, are also responsible for substantial air pollution as they are using fossil fuel. “Of course, the more water needs to be produced, the more these plants will pollute the air. So taking care of the waste water, trying to recycle it, is in all of our interest, it is in the interest of our environment, and human health,” Dr Boer added.

source: Gulf Times