Mapping the impact of a large municipal waste disposal area on surface water: 1993-2017, case of Laogang, Shanghai.

In China, the impact of waste disposal facilities is always a cause of concern for the government and the public. Laogang Municipal Waste Disposal Area (LMDA), Shanghai, one of the largest municipal waste disposal areas in the world was selected as case in this study, and it was attempted to analyze the changes in the surface water quality, and map the impacted area by LMDA on surrounding streams from its operation period of 1993-2017. The results showed that, during the whole period, only biochemical oxygen demand (BOD) showed a continuous improvement with a percentage of 85.92%, however, chemical oxygen demand (COD), ammonia (NH-N) and total phosphorus (TP) significantly improved but BOD slightly deteriorated began from 2013. Using spatial analysis tools and Kendall's concordance test, COD and phenol at LMDA showed a significant impact on surrounding surface water; especially, the impacted area for COD decreased from 106.30 km to 22.86 km from 1993 to 2017, which dropped from 4.3 to 0.9 times the area of LMDA. Surprisingly, NH-N and TP at LMDA were affected by the surrounding streams, instead of having an impact on them. Interestingly, heavy metals and non-metals such as Hg, As, Zn, and Se in the surrounding streams were unlikely affected by LMDA. The driving forces for surface water quality improvement included the eco-remediation of closed unsanitary landfills, upgrade in waste shipping and terminals, operation of sanitary landfills and incineration plants for landfill diversion. Capsule: Impacted area of municipal waste disposal area is not so large.