석회주입이 상수슬러지 고형화에 미치는 영향

Abstract

As dumping the sludge formed from water clarification into the see has been banned since the second half of 2006, and judging from domestic and foreign circumstances and actual nowadays environmental problems, recycling needs of the sludge, as an effective way of transforming into a resource, into a top-soil layer or any other forms are thought to be increasing. In this study methods of use as top-soil layer by solidifying the sludge are presented and waste ash as a solidifying agent is tried for the first time. Properties of the sludge from water clarification can vary with seasons. Besides they differ with input water characteristics and further are affected by amount of generally used alum family inorganic or synthetic organic polymer flocculating agents in the water clarification processes. Solidification of the sludge from water clarification by solidifying agent of limestone as a main component consists of a series of processes, i.e., exothermic reaction of water absorption, ion exchange reaction, Pozzolanic reaction, and carbonation reaction. Performance of the prepared specimen as a top-soil layer was tested through specification tests, according to uses, including compressive strength and coefficient of permeability. As no study on the use of the sludge from water clarification as a top-soil layer, by mixing with traditional limestone, ash as an admixture and cement, has been reported, the present study can be used as basic data. Experimental results of the prepared top-soil layer by mixing with solidifying agents, i.e., limestone with cement, limestone with ash, respectively, were as follows; ① Optimal ratio of water clarification sludge:limestone:cement was 69.28:28.19:2.53andthetop-soillayerspecimenpreparedthiswaysufficedthetop-soillayer'sspecificationstandard,0.5kg/㎠ of the unconfined compressive strength. ② Optimal ratio of water clarification sludge:limestone:ash was 66.38:25.75:7.87 and the top-soil layer specimen prepared this way sufficed the top-soil layer's specification standard, 0.5kg/㎠ of the unconfined compressive strength. ③ Solidification characteristics of water clarification sludge Experimenting on the solidifying agents, i.e., limestone, cement and ash, by utilizing mixture design, and testing the unconfined compressive strength showed that 30%, dry weight basis, of limestone sufficed the top-soil layer's specification standard, 0.5kg/㎠.