Among major state-funded projects, the large-scale construction of urban waste water treatment plants is a key measure to protect the environment. However, a state working group found, during their recent inspection tour of Hebei Province, that waste water treatment plants have themselves become the polluters, China Youth Daily reported on December 11.

When the group visited a plant in Baoding City on November 26, an environmental official asked the plant managers how they disposed of their sludge. He was shocked to discover that the principal of the plant had no idea.

The principal explained that over the past ten years, the sludge had been placed in a 50-mu (about 3.33 hectares) ecological pool. In 2006, the city's hi-tech development zone rented the pool and agreed to manage the zone's sludge disposal itself.

Later the group found the driver who was responsible for removing the sludge and went to the sludge-dumping site – a garbage pit. The driver said it's the third place he has found in the last two years. The environmental protection agency of nearby Mancheng County reported they once found the driver dumping sludge into their river.

The group was deeply concerned about the situation, saying that sludge is the pollution sediment remaining after filtration of waste water. If it is not properly disposed of and if it enters the environment directly, it will result in secondary pollution.

A principal from the development zone said the waste water treatment plant produced over 10 tons of sludge a day which had no recycling value, and that it was a major headache to find suitable dumping places.

Sludge disposal is still a difficulty currently faced by most waste water treatment plants. Few plants made adequate plans for sludge disposal at their conception, and fees collected for treating waste water fail to cover treatment or disposal of the sludge.

The most serious issue is that even experts have no satisfactory solution on how to deal with sludge. The simplest way is landfill, but there are large quantities of sludge to deal with and it is hard to dry and solidify it. Any location where it is dumped risks turning into swampland. Given the value of land as a resource today, landfill is no longer an appropriate measure, the newspaper said.

Some places burn their sludge, but the cost of this process makes it unsuitable for central and western areas. Other enterprises have tried to turn the sludge into organic fertilizer, but have also failed as a result of high cost of the process, and a weak market.

China now has more than 1,200 waste water treatment plants and more will be built in the future, which will result in much more sludge. If it is not properly disposed of, it will become a huge hidden problem in terms of environmental pollution.

A few months ago, the Ministry of Environmental Protection circulated a notice of criticism of 11 poorly-regulated waste water treatment plants, saying that if they failed to comply with official requirements, the cities where they were located would no longer be eligible to apply for environmental permits for new projects.

(China.org.cn by Zhou Jing, December 15, 2008)