Infographic: Conquering China’s Sludge Mountains

While Chinese officials make full frontal regulatory attacks on smog, untreated sludge, an often toxic byproduct from sewage treatment, continues to quietly spread into groundwater and contaminate soil and food.

One Tsinghua University study estimated that 34 percent of so-called “sludge,” which contains a mix of human excreta and industrial waste, ends up in landfills, 14 percent is discharged untreated into the environment, and a whopping 48 percent is used as fertilizer by farmers.

A group of private citizens in Beijing have started their own “war on pollution,” as the government has branded its anti-smog efforts, by creating a “sludge siege map” that pinpoints the locations of more than 30 dumping sites around the city. Caixin Media produced a video report (in Chinese) in March 2014 touring sites along the outer edges of the capital; at least four are on farmlands or forested areas.

China’s environmental problems are myriad, but without proper treatment and disposal, pollutants from this untreated sewage byproduct are like a hidden time bomb, endangering the long-term safety of food, water, and public health. Cleaning up heavy metals that have accumulated in the soil is difficult and contamination can affect generations to come.

A Budget Gap

According to a report by the Asian Development Bank, China’s wastewater plants produced approximately 30 million tons of sludge in 2012, or five of Egypt’s Great Pyramid of Giza. Less than 20 percent of this ever-expanding mountain of sludge is being treated.

China’s wastewater plants produced approximately 30 million tons of sludge in 2012

Wastewater facilities in the United States and Europe are designed to separate solids from wastewater. The residuals go through a tertiary treatment to reduce disease-causing bacteria, viruses, parasites, and heavy metals so the remaining solids (dry sludge) can be safely disposed. Chinese wastewater treatment plants typically stop at secondary treatment and the remaining watery slurry is only lightly treated, if at all.

Many existing wastewater treatment plants either lack the sludge treatment facilities or are unwilling to pay the extra costs of using them. During the 12th Five-Year Plan (2011-2015), the Chinese government planned to invest RMB 427 billion ($69.4 billion) into wastewater treatment, a 22 percent increase over investments during the previous Five-Year Plan. According to Suez Environment, 350 to 450 grams of sludge is produced per cubic meter of wastewater. Since the amount of sludge swells proportionately with the growth of wastewater treatment capacity, the budget should too. Strikingly, the sludge treatment sector received only RMB 35 billion ($5.6 billion), a growth of 7 percent over the previous period.

Mind the Regulatory Gaps

Poor sludge management is driven by three main factors: lack of data, a fragmented regulatory system, and low water prices.

Perhaps the most troubling is the paucity of detailed, reliable data on treatment and disposal. According to the Asian Development Bank, only about 20 percent of sludge undergoes a secondary stabilization process in China, and 13 percent of the stabilized sludge is properly prepared for agricultural application or other productive uses. The “dominant practice,” they write, for more than 80 percent of sludge is simply dumping it into landfills, raw and untreated. Besides the Bank report and Tsinghua study cited above, however, there is little data available.

Many plants would run at a loss if they processed sludge

Another barrier is a highly fragmented administrative system. It is unclear which ministry is in charge of overseeing treatment facilities, falling somewhere between no less than five ministries: Environment, Agriculture, Finance, Health, and Housing and Urban-Rural Development. Thus far, most government-issued documents on sludge treatment only focus on technical guidance or minor policy details rather than industrial standardization and regulations.

Low water prices also introduce perverse incentives for treatment facilities. The cost of sludge treatment is often not included in wastewater fees or charged at an insignificant rate. For instance, a miniscule RMB 0.04/ton of wastewater is charged for sludge treatment in Guangzhou. As a result, many plants would run at a loss if they processed sludge and with lax oversight, many simply choose not to.


Perhaps not surprisingly, the ambitious targets set in the 12th Five-Year Plan for sludge treatment, including a requirement that all municipal wastewater treatment plants install sludge treatment equipment by the end of 2012, have not been met.

While policy implementation is behind the curve, it’s not for lack of attention from Chinese environmentalists. On a Chinese messaging and discussion app called WeChat, Chinese experts in the Sludge Network, which is chaired by Professor Chen Tongbin at the Chinese Academy of Social Sciences, share and discuss information. Over the course of a month in August 2014, I interviewed several experts from the network, who highlighted three core areas for Chinese policymakers to address in order to create incentives for sludge treatment:

China’s massive investments in wastewater collection and treatment systems in recent years have not been matched by complementary investment in sludge management. Consequently, while significant improvements have been made in reducing surface and groundwater pollution, there is now a growing challenge to prevent secondary pollution from accumulating waste. Appleton holds that sludge management in China should be tied to dealing with water pollution in general. Perhaps the most promising opportunity then is the upcoming Water Pollution Prevention and Control Action Plan, China’s equivalent to the U.S. Clean Water Act, which is expected to elevate water pollution prevention and pretreatment across the country.

Hongli Liu is a Master’s candidate in public policy at the School of Public Policy, University of Maryland. Siqi Han produced the infographic and is a Master’s candidate in environmental economics and policy at the Duke University Nicholas School of the Environment. The authors would like to thank Jennifer Turner, Ilaria Mazzocco, Susan Chan Shifflett, Qinnan Zhou, Darius Izad, and Xiupei Liang for their help.

Sources: Asian Development Bank, Caixin News, China Greentech Initiative, ChinaDialogue, Jiangsu Institute of Environmental Industry, Reuters, Sohu, Suez Environment.

Image Credit: Siqi Han/China Environment Forum.