Job's Tears Answer to Southeast Asia's Wastewater Problem 29 August 2013, by Vicky Manley

Job's Tears answer to Southeast Asia's wastewater problem 29 August 2013, by Vicky Manley

energy, cost-effective and has potential on a large scale," Dr Konnerup says.

"[We] investigated the growth of C. lacryma-jobi and its capacity to take up nitrogen and nutrients under differing pH conditions in a constructed wetland system."

Dr Konnerup says the plant proved extremely efficient in removing nitrogen from polluted water.

Research also found C. lacryma-jobi absorbs Job’s Tears (Coix lacryma-jobi L.) is a tall grain-bearing nitrogen especially well in the form of nitrates plant of the family Poaceae (grass family) native to (NO3-) from wastewater. Southeast Asia. Credit: Dinesh Valke Job's Tears is a tall grain-bearing plant of the family Poaceae (grass family) native to Southeast Asia and is also known as Chinese Pearl Barley. A tropical plant species could revolutionise the way wastewater is cleaned and managed in the Dr Konnerup says it has been used for wastewater developing world, field research has shown. treatment in China but limited knowledge of the eco- physiology of the plant exists. A visiting Danish biologist with the University of Western Australia has spent several months in Seedlings were planted in different nitrogen based Thailand conducting experiments on the tropical solutions consisting of either ammonium (NH4+) or plant species Job's Tears (Coix lacryma-jobi L.) by nitrate (NO3-) and at four levels of pH: 3.5, 5.0, 6.5 growing it in various wastewater solutions to and 8.5. assess its suitability to grow in and filter constructed wetland systems. After a 40 day period the growth rate (plant tissue analysis) for each individual plant was calculated. Developing countries such as Thailand and Vietnam often pump untreated wastewater into The plant species demonstrated higher growth their waterways causing a serious disease threat to rates due to its preference of NO3- nutrition, says human health such as the spread of E.coli Dr Konnerup. bacteria. "We recorded nitrates being absorbed within days," Study co-author Dennis Konnerup says water he says. treated using C. lacryma-jobi can be safely used for irrigation or returned to waterways such as The plant also favoured water-saturated soils. rivers and the sea. Increased growth rate of C. lacryma-jobi was "Treating wastewater by using a native plant evident in slightly acidic conditions (pH 5-6.5). species is particularly relevant for developing countries such as Thailand as it is low tech, low Warm climatic conditions aided the bacterial

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breakdown of solid masses allowing for fast uptake of nitrates.

"This is particularly important in vertical flow systems," Dr Konnerup says.

Dr Konnerup is also involved in researching the potential for growing ornamental flowers in constructed wetland systems.

More information: www.sciencedirect.com/science/ … ii/S0304377013000910

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