The results presented herein are intended to aid in a fundamental understanding of conditioning water treatment residuals by the freeze/thaw process. Residuals were frozen such that the effects of freezing rate, solids content, and curing timewere isolated. Residuals were frozen directionally on a copper surface maintained at subfreezing temperatures. In contrast to many of the results in the literature, freezing rate did not seem to affect the final dewaterability. However, the effects ofinitial solids content and curing time were noticeable. High solids content residuals yielded cake solids contents greater than 30 following freezing, thawing, and drainage under a vacuum. Samples cured at -10℃ for 1 h dewatered much more readily thanuncured samples. The results will aid in the design of a mechanical freezing process; the cost optimum conditions for such a process appear to be fast freezing of a high solids content residual, followed by approximately 1 h of curing.
展开▼
