The possibility of topping up dwindling supplies of groundwater with highly-treated sewage effluent is being researched by an EU-funded pilot project under way in Bulebel.
A pilot treatment plant has been developed by the Water Services Corporation and quality tests are being carried out on effluent filtered by the pilot project.
Malta is the first European country to treat all its sewage but there is as yet no use for the treated effluent. If treated, sewage water can be made suitable for industrial, agricultural and even domestic use.
According to Malta Resources Authority hydrogeologist Manuel Sapiano, the project envisages pumping “highly-polished effluent” into a nearby aquifer. Wells within a 600-metre radius will then be monitored over a 12-month period.
Mr Sapiano spoke of the pilot project at a Mediwat stakeholders’ conference held yesterday at Marfa. Mediwat is an EU-funded programme aimed at researching and developing innovative sustainable water management systems for Mediterranean countries.
The project, which started in 2007 and will end in 2013, involves nine EU member and four EU candidate states and has a budget of €193 million.
An initial analysis of the highly-polished effluent had revealed the presence of a number of synthetic pollutants.
“Although many of the pollutants are present in minute levels, below EU-required maximums, we are reassessing the filtering methodology to prevent the introduction of any such pollutants to Malta’s groundwater,” Mr Sapiano said.
Drainage engineer Philip Grech and hydrologist Marco Cremona both welcomed the project, although they argued that the risks and economic implications of injecting such recycled water into the ground had to be compared with using it directly to supplement the municipal water supply.
Over-extraction is seriously straining Malta’s groundwater reserves beyond sustainable limits and nitrate pollution and salt water invasion are impinging on its quality.
It would make more sense, Mr Cremona and Mr Grech said, to treat effluent and then re-use it directly.
Finance Minister Tonio Fenech told Parliament last year the government intended to further invest in sewage treatment plants to make polished sewage effluent functional for irrigation purposes.
With an extremely dry summer, a high rate of evapotranspiration (the rate of evaporation and transpiration from the earth’s surface), no significant surface water and limited reservoir capacity, Malta must grapple with a number of water scarcity issues.
The bulk of Malta’s water is derived from groundwater reserves and desalination plants. Although groundwater is being extracted beyond sustainable levels, Mr Sapiano said desalination plants were only running at half capacity, thanks to significant reductions in water leakages.
According to figures published by the Water Services Corporation, water losses due to leakages were down to 900 cubic metres per hour in 2009 from a high of over 2,600 cubic metres per hour in 1995.
The Maltese use an average of 115 litres of water a day. One third of that is used for hygiene purposes, with a further 24 per cent in toilet flushing. Drinking and cooking only accounted for five per cent of daily use, Mr Sapiano said.
The average Maltese uses less water than individuals in a number of EU countries, including the UK, Germany and Austria, and a mere third of the volume used by the average American.
Mr Sapiano argued that the price of water contributed to its wasteful use. Whereas one cubic metre of tap water costs about €2.30, the same amount of bottled water costs €125.
Asked whether he thought Malta’s water tariffs were set too low, the WSC’s CEO, Anthony Rizzo, said water prices in Malta ensured full cost recovery.
Mr Cremona, however, contested Mr Rizzo’s assertion. “Mr Rizzo’s claim doesn’t factor in the ‘resource cost’ of groundwater, which accounts for about 45 per cent of Malta’s municipal water supply. It essentially assumes that groundwater in the aquifers has no intrinsic economic value,” he said.
“At present, the WSC gets almost 14 million cubic metres per year of its supply from the aquifers without paying a cent for the resource it is exploiting. I am not saying this is wrong or right, I am just stating a fact,” he added.