In the water treatment plant, alum, hydrated potassium aluminum sulfate, has been used to flocculate by neutralizing the electrical double layer surrounding very fine suspended particles. The particles flocculated  are settled and removed as a sludge from the plant, which are disposed finally to landfill sites. Recently, it was reported that the alum sludge from the plant has adsorption capacity for As(III) and/or As(V). However, when the sludge is used for the adsorbent for As, the bed in the adsorption process is anaerobic condition and the sludge contains organic matter because the alum is used to remove organic matter from the water. Therefore, the anaerobic degradation of organic matter generates odor, which causes another problem on bad odor in the As treatment process. The organic matter in the alum sludge could be removed by calcination. The calcination process could solve the odor problem when the alum sludge is used for adsorbent of As. Calcination process removes natural organic matter from the alum sludge, which could provide more adsorption sites for As because the organic matter has negative charge. However, calcination could increase the crystallinity of aluminum oxide, which decrease the surface area of adsorbent and finally decrease the adsorption capacity. In this study, therefore, the characteristics of alum sludge after calcination process was investigated, and the optimum calcination condition was proposed.<br/>

Adsorption characteristics of As(III) and As(V) onto modified alum sludge by calcination process

251st National Meeting (2016)

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