[Jiangnan Evening News 8/31] A set of processing equipment, placed on 120 square meters of land, can achieve bio-safety disposal of food waste produced by tens of thousands of people from Jiangnan University (JU). Yesterday, we saw an anaerobic methane center located in the campus, which is to be put into use in the new semester. The heat generated can satisfy the needs of thousands of people for bathing.
In this center, we can see a long slug of stainless steel pots and conveyor belts. According to Mr. Liao Jialin who’s in charge of the center, Jiangnan University has multiple dining halls, which produce 2-3 tons of food garbage a day. The center is designed on the scale of dealing with garbage 1 ton per hour and up to 30 tons per day. It also gives consideration to the rubbish produced by restaurants around the campus. “After delivery carts pour the garbage into the funnel, the relatively enclosed pipeline will start preprocessing in the interior.” Liao said. The composition in the food waste is complex, consisting of plastic bags, glass, etc, which needs to be crushed and sorted out first. The garbage will be processed into pulped state, and then sent to the methane coffer for fermentation. It takes different periods of time for different materials to ferment. Generally, sugar ferments quicker than starch. Such time difference may ensure a steady stream of methane supply.
The equipment has been set up for more than a year, mainly used for regular scientific research and teaching. Moreover, the device is equipped with hot water boilers and generators. The boiler can be heated in winter to ensure the normal use of the fermentation tank. But in terms of power generation, Liao said it’s not realistic so far as pipelines are yet to be in place and the equipment can’t generate until now enough electric quantity to reach the threshold of grid access. Currently, the processed food garbage still contains waste residue, most of which are organic matter. By dehydration, the waste residue can be made into fertilizer, which has been used in greening and fertilization on campus.
It is learned that 1-ton food garbage could generate 80-100 cubic meters of methane through complete fermentation, whose heat value is equivalent to 50 cubic meters of gas. In the new term, says Liao, JU plans to recycle all the food garbage from dining halls, and then translate it into methane, which can be used as a fuel to produce hot water, meeting the demands of 1,000 to 2,000 people for hot shower.
