An effective and inexpensive process to remove contaminants from oil sands wastewater using only sunlight and nanoparticles has been developed by researchers.
Researchers from the University of Waterloo found that photocatalysis - a chemical reaction that involves the absorption of light by nanoparticles - can completely eliminate naphthenic acids in oil sands wastewater, and within hours.
Naphthenic acids pose a threat to ecology and human health. Water in tailing ponds left to biodegrade naturally in the environment still contains these contaminants decades later.
"With about a billion tonnes of water stored in ponds in Alberta, removing naphthenic acids is one of the largest environmental challenges in Canada," said Tim Leshuk from the chemical engineering department at Waterloo, who led the study.
"Conventional treatments people have tried either haven't worked, or if they have worked, they have been far too impractical or expensive to solve the size of the problem. Waterloo's technology is the first step of what looks like a very practical and green treatment method," he added.
This new technology is energy-efficient and relatively inexpensive, unlike conventional treatment methods such as treating polluted water with chlorine or membrane filtering.
Nanoparticles become extremely reactive when exposed to sunlight and break down the persistent pollutants in their individual atoms, completely removing them from the water.
This treatment depends on only sunlight for energy, and the nanoparticles can be recovered and reused indefinitely.
The study was published in the journal Chemosphere.
Shekhar also underscored a need for states to work
"shoulder-to-shoulder" with the Centre for drawing up a 10-year joint action plan to address the issue in a sustainable manner.
The Union government is to come up with the bill at a time when parts of 10 states, especially Maharashtra, Karnataka, Telangana, Chhattisgarh and Jharkhand, are facing drought-like conditions.
According to Central Water Commission, water level in 91 major reservoirs across the country has dipped to 22 per cent of their total capacity.
Only 34.082 billion cubic metre (BCM) of water was available in the reservoirs for the week ending April 21. The total storage capacity of the reservoirs is 157.799 BCM.
While water stocks across reservoirs are on decline, depleting groundwater levels too do not augur well, raising prospects of drought in more areas.
According to an assessment of dynamic groundwater done by the government in 2011 the report of which came in 2014, out of the total 6607 units (administrative blocks) covered, 1071 in 16 states fall under "over-exploited" category. The report concluded that 217 and 697 units were "critical" and "semi-critical".
Out of the total 138 blocks assessed in Punjab, 110 fall under "over-exploited" category. Of the 243, 116 and 27 units assessed in Rajasthan, Haryana and Delhi respectively, 172, 71 and 18 units were found to be "over-exploited".
It said states like Punjab, Haryana, Rajasthan and Delhi are staring at a serious threat due to decline in groundwater levels. Among southern states, 374 units in Tamil Nadu were in "extreme" category.
