Compact Accelerated Precipitation Softening (CAPS) with Submerged Filtration: Role of the CaCO3 "Cake" and the Slurry
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- 作者：Y. Oren ; V. Katz ; and N. C. Daltrophe
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2002
- 出版时间：October 16, 2002
- 年：2002
- 卷：41
- 期：21
- 页码：5308 - 5315
- 全文大小：313K
- 年卷期：v.41,no.21(October 16, 2002)
- ISSN：1520-5045
文摘
A new concept for compact accelerated precipitation softening (CAPS), comprising in-tank mixingand filtration, is presented. Softening with CAPS is both fast and efficient, because CaCO3precipitation is achieved in a well-stirred calcite slurry and in a compact cake formed on thefilter elements. Other advantages of the CAPS process are its compactness, technical simplicity,and low cost. In this study, laboratory CAPS units were run continuously (up to 600 h) for tap-water softening. The effects of the initial concentration of the CaCO3 slurry, the pumping speed,and the pH and the individual effects of the slurry and the cake and of the filter cake load wereanalyzed in terms of the reduction of the saturation index (SI) and the precipitation capacity. Itwas found that calcium reduction in the cake was 10-100 times faster than that in the slurry.In addition, turbidity was reduced significantly because of the microfiltration capability of thecake. CAPS can be used as a stand-alone water-treatment process or in conjunction with pressure-or electricity-driven membrane processes (UF, NF, RO, ED) as an effective pretreatment routinefor increasing recovery and decreasing fouling rates.