Turning organic waste into power
Civic garbage can generate biogas that can be converted into fuel or electricity. This could help reduce the amount of garbage in landfills and prove an asset
MUSCAT: Oman produces more than 1.5 million tonnes of municipal solid waste per year but much of it is organic waste that could be converted to energy, say researchers at the Caledonian College of Engineering who have been producing energy in a lab using fruit and vegetable waste.
The research project, which is funded by The Research Council (TRC), is looking primarily at how organic waste from the Mawaleh Central Fruit and Vegetable Market can be treated with a process called anaerobic digestion, in which microorganisms break down the material and generate a biogas that can converted to fuel or electricity.
Professor Joseph Thanikal, who is heading the research, said this process could be applied to waste throughout Oman, reducing the amount of garbage in landfills and providing a sustainable source of energy.
“They say that from all the wilayats (in Muscat Governorate) there are 5,000 tonnes of waste, combining all kinds of biodegradable waste, per day. We have proven that it’s possible to convert it to biogas and we have enough quantity of waste that can supplement the energy so it could be one of the sources,” Thanikal said.
The project included lab scale and pilot scale experiments at the college and has shown significant findings that establish that anaerobic co-digestion is a safe method of waste treatment that can be adopted to convert organic waste into useful products like reformed bio-solids and energy from biogas. According to the research that Thanikal and his team have carried out, five tonnes of biodegradable waste per day can produce 240 KW power, worth $100 per day in useable electricity.
Currently, organic waste is dumped in landfills around Oman, though the Oman Environmental Services Holding Company has plans to open four waste treatment plants, Thanikal explained. The landfills full of waste aren’t just unsightly; they also cause a lot of environmental damage if waste isn’t disposed of properly or in alternative ways such as converting it to energy.
“In the landfills there is some leakage and that affects the groundwater. Secondly, there is methane in the landfill that escapes in the air and that will have an effect on the greenhouse gasses,” explained Hatem Yazidi, one of the researchers on the project.
Jumaa Al Amri, Deputy Director for the Health Department at Mawaleh Central Fruit and Vegetable Market, says the amount of waste produced in the market each day is approximately 50 tonnes, most of it biodegradable.
Some of the unsellable produce is taken away by people as animal feed but most of it ends up in Al Amerat landfill. “I become very sad when I throw all these vegetables and fruits to the dumping area. We spend time, we spend money on the people who collect, on the cars going to the dump. You feel sad that no one gets a benefit from this organic waste,” Al Amri commented.
Al Amri said that the cardboard is shipped to Dubai for recycling, as is much of the plastic, but that most of the fruits and vegetables that aren’t sold simply go waste. He said he would like to see a wasteto-energy system, like the one be- ing tested at Caledonian College of Engineering, introduced to the market so that the waste could be used to generate electricity. Given the amount of waste produced there, the market could become self-powered.
“It could have full power. Everything for free, and there would be no need to spend on petrol and affect the environment,” he said.
Much of field research was undertaken by three Omani graduate students from Caledonian College of Engineering (CCE) who spent hour upon hour in Mawaleh Cen- tral Fruit and Vegetable Market calculating how much waste there was. In the lab they experimented with different fruit and vegetable waste, as well as grease waste from the Saham water treatment plant and animal fat from Muscat’s central slaughterhouse, to see what produced the best results for generating biogas.
Siham Said Al Siyabi focused on watermelon, pomegranates and apples, also using grease sludge from the municipal waste water treatment plant in Saham. She tested the grease sludge, which comes from things like cooking grease, and tried combining it with the fruits to see what combinations make the best gasses that can be converted to biofuel or energy. She said the oily grease waste can generate a lot of biogas.
Suad Said Al Hosni looked at different vegetables - tomato, lettuce and onion - as well as slaughterhouse fat from the central slaughterhouse, which can also be converted to biogas. She said that the fat is also dumped into landfills, adding to the methane gas and groundwater pollution, but a much better use of the fat is biogas.
“When I added the fat to the vegetable waste I found that it enhanced the production of biogas by 50 to 60 percent. We get good results for biogas production. I hope in the future there will be a plant here in the Sultanate of Oman for the production of biogas from this biodegradable solid waste,” Al Hosni commented.
The research at CCE is in line with the strategies planned at the Oman Environmental Services Holding Company (Beah), which is the state-owned waste management company which has begun a feasibility study for a waste-to-energy project in Dhofar Governorate.
Speaking at the Oman-Spain Investment and Business Cooperation Forum in April in Muscat, Mohammed Sulaiman Al Harthy, Executive Vice President - Corporate Strategic Development, said: “As a result of the utilisation of waste for energy generation, we will be spending less on developing and maintaining landfills, reducing Co2 emissions, providing economic alternatives to natural gas as a fuel source, saving the subsidy that the government allocates on natural gas use, and tackling the issue of potable water capacity.”
For the Omani researchers, the waste-to-energy project is not just about the scientific research, but about protecting their country. They have concerns about global warming and environmental damage to the earth and groundwater from organic waste.
“We want a clean environment. We want to get rid of these types of waste with a good way, not like the traditional way of just throwing them in landfills. We are also looking for renewable energy because as we know oil and gas maybe in the future will disappear. This type of project is the big chance to produce energy such as biogas and it’s very easy to do that,” Al Hosni added.