Study on sludge dewatering evaluation techniques using a statistical model. In view of both quantity of filtrate and filtrate quality.

Abstract

In view of environmental systems, this paper aims at proposing a scientific and positive evaluation technique in sludge dewatering as viewed from both quantity and quality of the filtrate obtained without sludge conditioning. The contents are as follows: (1) Through a multivariate analysis of variance, the optimum condition which produces the maximal quantity of filtrate is determined under the condition of the three dewatering factors, that is, type of filter cloth, sludge thickness, and filtration pressure in both pressure and vacuum filters.(2) In terms of the filtrate quality, both the pressure filter and the vacuum filter are compared.(3) With respect to both the pressure filter and the vacuum filter, the trade-off relationships between the speed of filtration (quantity of filtrate) and filtrate quality are determined. By means of the mean values of the ranking numbers weighted by Japanese effluent standards, the correlation coefficients for the relationships are determined, and these values are compared with those values based on the mean values of non-weighted ranking numbers.