It's a phenomenon known locally as the "black cloud", and it plagues Egypt every autumn after the rice harvest: an estimated 4 million tonnes of rice straw is burnt every season, spewing some 80,000 tonnes of carbon dioxide into the skies. It leaves a choking, toxic layer of thick smog hanging just 25 meters above over the entire Nile valley for weeks, and adds to the already polluted air over the Cairo megalopolis.
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Although Egyptian authorities have tried to stop farmers from setting the straw ablaze, many ignore the appeals, saying it is easier to burn than bring it to government-affiliated recycling centres. Now, however, ingenious research could banish the black clouds: by turning the rice straw into products as varied as table tops, food supplements, and activated carbon for water filters. By showing how rice straw, husks and bran have value as commodities, it could not only chase away the autumn smoke, but also foster a hitherto untapped recycling business in the region.
"We've been looking into how this environmental burden can become a source of income," says Amr Helal, a board member of the Egyptian Chamber of Industry and Engineering, who is leading key pilot projects researching different uses for rice waste. "I don't call it rice waste. I call it rice residue, and I see it as a blessing rather than a curse."
In one project, aided by a €132,093 grant from the European Union, Helal and his research partners in Cairo, France and Germany have turned rice straw and husks into activated carbon and natural fibre plastic composites.
The research partnership converted the rice husks into activated carbon through the process of pyrolysis, which involves exposing fibres to a high temperature in an airless environment. The resulting material, with its high absorption capacity, is used commercially to purify water, oil and gas. For the natural fibre plastic composites which are used to make furniture, marine decking and consumer goods the husks and straw were first reduced into powders and granules, then mixed with plastic polymers, resulting in a material that is half the price of conventional polymer.
Another EU-funded project, supported by a €154,000 EU grant, involves using rice's brown outer layer, the bran, for 'nutraceuticals', which are nutritional pharmaceuticals or food products that promise health and medical benefits like lowering blood pressure. Rice bran contains 65% of the total nutrient capacity of the grain, and is a potent source of vitamins, minerals, proteins and fibres.
It is usually used to feed cattle, because it turns rancid within a few hours of milling. However, the latest research, involving partners in Cairo and Germany, has stabilised the bran through an infrared heating process. Helal says the project has already succeeded in producing rice bran extract in pill form, and looking at mixing it with fish oils to get Omega 3 to create a unique dietary supplement.
While it may still be a while before these innovations are rolled out on a large scale, they have already attracted the interest of businesses in Europe keen to partner production. And they offer the potential to rid Egypt of a blight that makes the rice harvest a bittersweet time of the year for locals. "Rice is a wonderful crop, but we should be using all of it," says Helal. "With smart research, we can create useful businesses, and at the same time cast out that vile black cloud."