하수 슬러지와 도시쓰레기 소각재의 혼합 용융소각 및 특성 연구

Abstract

Combined Melting Incineration and Leaching Characteristics for Sewage Sludge and Municipal Solid Waste

Kyoung Hag Lee Division of Clean Chemical Engineering, The Graduate School, Pukyong National University

Abstract Various wastes have been produced because of rapid economic growth. Among the various wastes, the government is managing noxious materials, which can pollute environment and threaten human's health such as waste oil or acid and so on. In this study, the characteristics of sewage sludge and municipal solid waste was investigated. In the case of sewage sludge, which produced 7,631 tons/day in 2007, and is forecasted 10,259 tons/day in 2011. Current sewage sludge treatment methods are reclamation, ocean disposal and destruction by fire. Among them, the mostly used process is ocean disposal method. However, the government establishes policy that totally prohibit the oceanic sewage sludge disposal as from 2012. Therefore, the alternative treatment method for sewage sludge was required within a few years. During the incineration process of municipal solid waste, 10~20% of ash waste were produced. Ash waste were classified by two kind of waste. One is bottom ash that happens from incinerator lower part after burning and another is fly ash that happen from boiler, lower part of dust collector from exhaust gas. Specially, because of it contains a lot of poisonous heavy metals, fly ash can generate serious environmental pollution if it just reclaims. Current methods that treat poisonous appointment waste safely are cement stabilization, medicine recipe, and use etc., solvent such as acid. These methods were widely used for most incineration ash. However, the cost of these methods were very expensive compare with other treatment processes. Melting incineration treatment that used in this study have advantages that are changing dangerous organic matter and hazardous substance to harmless melted slag. So, many studies to reduce melting temperature are investigated until now. However, most of existing studies are melting incineration for single waste. And most of cases are ineffective because cost is more expensive preferably by using chemical additives etc., to decrease melting temperature. So, we looked into mixing melting of sewage sludge that contains a lot of acidic oxide and municipal solid waste ash that contain a lot of basic oxide. Also, In this study, leaching characteristics of heavy metals in sewage sludge, bottom ash, flying ash were compared by Korean Leaching Test (KTL). And various of leaching characteristics were analyzed with different considering factors such as pH value of solvent, species of solvent, solid/liquid ratio and agitation time. Experimental results showed that mixed waste melting was decrease the melting temperature more than 100℃. In the leaching characteristics of heavy metals, there are results that the highest contents of heavy metals are found in strong acid and basic. In case of solvent is used by different reagent indicated various leaching tendency in general. In case of solid/liquid ratio, Leaching contents were increased as solid/liquid ratio was high. Leaching contents were decreased as agitation time.