Several years ago, satellite remote sensing image, Pukou District Balizhuang had a large legacy of abandoned quarry dang mouth, like engraved on the land “scar skin disease”, a bare. Can now here we are everywhere verdant, leafy. This is a demonstration of ecological restoration project to bring change.
City (Nanjing, the same below) the current legacy of abandoned open pit mine has more than 170 dang mouth. Want to restore green vegetation on bare rock, we must first solve the foundations of green vegetation growth – the source of the soil. In the absence of a suitable source of soil, vegetation restoration Pits city currently only about 20% from 80% of the ecological city building requirements still a big gap.
Meanwhile, the city sewage treatment plant construction and expansion project in full swing. The city’s sewage treatment capacity has more than 1 million tons of sludge handling problems attendant increasingly grim.
Municipal Environmental Research Institute of Experimental and demonstration projects undertaken by “urban sewage sludge used for ecological restoration dang mouth” of the two issues as a combined research took two years, and achieved the advanced level of breakthrough innovation . Currently, the results of the study have been identified by the Environmental Protection Agency and the Science and Technology Bureau jointly conducted.
City Central ASTRI engineering director, said sludge used in the test, taken Jiangxin Island sewage treatment plant, the choice of crop stalks and researchers in the pharmaceutical dregs as accessories, after adding the fermentation broth, sludge the stabilization process. After 21 days of composting fermentation process, fresh black sludge turns brown, a few meters outside of the original will be able to smell the stench has also been watered down. After testing analysis, sludge Central Plains and some pathogenic bacteria, parasite eggs, almost all were killed, fully meet the security conditions for the use of forest land.
From the point of view the study, after the treated sludge, organic matter content of 31.4%, far higher than the pig manure content of 25% and 20% of the standard limits, nitrogen, phosphorus and potassium content is far more than pigs, horses, cattle manure and other content.
Monitoring found Greenwood to test the heavy metal content in the body of trees and shrubs, although high compared to other forest plants, but does not affect the normal growth of plants, and to avoid the human food chain, will not pose a threat to the surrounding environment and human direct harm.
It is reported that Jiangxin Island sewage treatment plant sludge than 30 million tons per year, per ton incineration costs about RMB 140 , while the cost of sludge disposal in the study, about RMB 60 per ton. Pits vegetation restoration project investment of about RMB 120 / square meter per square meter can be used 0.12 tons of sludge. If the sludge composting enter the industrial stage, can have a greater market value, ecological value is immeasurable.