Heinz-Peter Mang is obsessed with turning human waste into gold. As millions of Chinese move to cities, the German engineer is convinced the country is on the way to hitting the jackpot.
A growing portion of China’s toilet waste is converted into fertilizer and biogas. In Beijing, 6,800 tons of human excrement are treated each day by some estimates: enough to fill almost three Olympic-size swimming pools.
Over the past decade, China’s economic ascent has driven millions of rural workers into its cities in the largest migration in human history. In 2013, the number of urban dwellers crossed 731 million, overtaking the rural population by more than 100 million. Some fallouts: water shortages in the North and toilet waste routed into rivers in the south.
That’s forcing city planners to get creative in dealing with toilet refuse, and drawing engineers like Mang to help refine models. The push to re-purpose feces into energy resources or fertilizer is expanding across China, and Mang is advocating for the model to be copied in other parts of the world.
Globally, a variety of techniques are used to handle human waste: some cities dump it in rivers, others choose to incinerate, and still others bury it in ditches. United Utilities Group Plc, Britain’s largest publicly traded water company, handles the sewage of 1.2 million people in Manchester and operates a sludge recycling center that runs on enough human waste to power 25,000 homes.
The world’s most populous nation scaled up a model used in farms. Originally used to keep humans from doing their business in pig troughs, today 40 million farm homes across China have a holding tank for human and animal waste that is partly sanitized by depriving the solids of oxygen. What’s left is then converted to liquid fertilizer for the farms.
What’s happening in Beijing is an industrialized, scaled-up version of that model, said Mang, who has lived in the capital for a decade. Across the city, which has seen its population double to 21 million in the past decade, the average annual amount of human waste processed will increase by 200 to 300 tons a day, said Zhang Jiang, general manager of Beijing Century Green Environmental Engineering & Technology Ltd., which operates night-soil treatment plants. Treating waste is set to be a growing area of business, Zhang said.
The catch-up of waste treatment from low penetration rates in China is driving “a waste revolution,” with key treatment operators likely to grow 200 to 400 percent in volume in the next five years.
