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BIZCHINA> Review & Analysis
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Sludge solution
By Zhang Qi (China Daily)
Updated: 2008-03-31 14:05 As Chinese city governments throw money into water projects, one Beijing company is trying to arm them with a solution to turn sewage sludge into something useful. The sewage treatment process collects wastewater and channels it into a sewage plant. The wastewater is pumped from one stage to another along the treatment process before it's channeled back into rivers as clean water. But, as engineers from Beijing-based Zhongke Bolian Hi-tech Co (ZB High-tech) point out, what about the sludge? Up to now, they tell China Business Weekly, sludge from urban and industrial wastewater treatment has been dumped into landfills, oceans and waterways. In fact, nearly 90 percent of sludge is dumped into landfills, the Chinese Academy of Agricultural Sciences (CAAS) says. Without further treatment, this waste product is a pollutant that can be toxic. If it accumulates, it can pose a threat to the environment - especially when all sewage plants are running in full steam. The waste product usually contains heavy metals, viruses and bacteria that's harmful to humans. Another way ZB High-tech has spent 10 years researching and developing a sludge recycling solution, which it has now patented. The company was founded in 2001 by Chen Tongbin, who majored in fertilizer and composting at the CAAS in the 1990s and has worked at the Institute of Geographic Sciences and Natural Resources Research since he graduated. ZB High-tech's solution is based on neutralizing toxic content in the sludge while retaining nutritious elements - such as nitrogen and phosphorous - to turn it into a fertilizing substance useful for organic farming. The composting process involves two key steps - making the toxic metals passive and killing pathogenic organisms and controlling odor. Traditional composting is based on biological decomposition of the waste's organic constituents in open air. It usually requires large areas to heap up and remix sludge, which needs to be turned over from time to time to let oxygen in and keep down the odor. The process has two disadvantages. First, as it's out in the open, the heap can be easily washed away by rain. (For more biz stories, please visit Industries)
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