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pH Control in Coagulants Recovery Process from Water Works Sludge
- 언어ENG
- URLhttps://db.koreascholar.com/Article/Detail/342473
Since water works sludge have a high aluminum content, recycling aluminum has become a significant environmental issue. Generally, the method of recovery of aluminum from water works sludge are acid digestion, alkalization, ion exchange and membrane separation. However aluminum hydroxide may be dissolved in strong acidic and alkaline media due to its amphoteric nature. So, the traditional acidification and alkalization methods still being explored. Chemically, aluminum recovery from the water works sludge is a simple process. The acid digestion is however, somewhat complicated by pH control in the mixture of dewatered water works sludge (DWS) and sulfuric acid solution. Under strong acidic condition, probe of pH meter, which is a key part of a pH meter, can be easily damaged. Also it is not easy to control pH during the process of mixing DWS and acid solution because high concentration of total solid are present in the mixture. Furthermore, the moisture content of DWS is very serious change. Most of the previous studies have mainly focused on the adsorption properties of dewatered alum sludge; little attention has been put on how to improve its phosphorus adsorption capacity. In this study, batches of experiments were conducted using DWS, artificially controlling moisture content (64~78%), to investigate the effect of concentration of sulfuric acid on pH of the sludge for pH control without pH meter in the coagulants recovery process. The water content of DWS was measured in 30 minutes using Infrared Moisture Determination Balance (FD 660, Kett). Experimental results show that the concentration of sulfuric acid for acidification of DWS is higher with higher water content of that.
