A Case Study of the Effect of a Natural Disaster on the Generation of Municipal Solid Wastes and Emission of PCDD/Fs from Its Combustion

摘要

Natural disasters may produce large amount of municipal solid wastes (MSW). The management of such wastes becomes an enormous task for municipal authorities in the aftermath of disasters. Although many cities of the world have been devastated by such disasters every year, systematic studies on the amounts and compositions of MSW produced during and after the disasters are rare. In this study, the aftereffect of one such natural disaster, the typhoon, on various aspects of solid waste management in a Japanese city is evaluated. The Typhoon no. 18, passing through coastal areas of western Japan on September 24, 1999, caused widespread damage in the city. The study first analyzed the amount of additional solid wastes generated by the disaster and then conentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were measured in fly ash samples obtained from the local incineration plant, where those additional amount of wastes were combusted. Both long and short-term effects of typhoon on the generation and collection of MSW were observed. The short-term aftereffect was characterized by a sudden increase in the production of combustible wastes generating an additional 1,800 tons of waste in three weeks after the disaster, while the long-term aftereffect prolonged for almost six months, from September to March, and produced an estimated 5,200 tons of combustible wastes, which is equivalent to one month's total collection. The study also investigated whether the typhoon caused an enhanced emission of PCDD/Fs. Since the typhoon caused flooding in coastal area, most of the wastes brought to the incineration plant were soaked in seawater and contained high concentration of salt. Ten fly ash samples were obtained from the electrostatic precipitator outlet of the plant and analyzed for PCDD/Fs. One sample was taken before the typhoon and nine samples were obtained after the occurrence of the disaster. Fly ash samples obtained after the natural disaster yielded higher concentrations of PCDD/Fs in comparison with those obtained before the event. Maximum concentration of PCDD/Fs detected in samples was almost 270 ng-TEQ/g, while the minimum was around 49 ng-TEQ/g. A link between the composition of wastes incinerated after the disaster and increased amount of PCDD/Fs was established.