| Abstract: | A technique based on measurements of fluctuations in the intensity of light transmitted through a flowing sludge suspension was used to evaluate polymer performance in alum sludge conditioning. The ratio of the r.m.s. of the fluctuations to the average transmitted light intensity exhibits a well-defined response, usually a substantial increase, to sludge particle aggregation. This aggregation reflects the improvement in sludge filterability as also indicated by concurrent CST measurements. Five polymers, cationic, anionic and nonionic were used in conditioning the sludge. Tests were conducted using a mixer set at 700 rpm with a corresponding velocity gradient of 1900 s−1. The technique was shown to give a very rapid convenient indication of the conditioning effect of polymeric flocculants. It could be very easily adapted to online applications. |
