PREDICTING PRESSURE FILTER NET SOLIDS YIELD USING BUCKINGHAM-Π METHOD OF LMT DIMENSIONAL ANALYSIS

A model for predicting Pressure filter Net Solids Yield has been derived using Buckingham-π method of LMT Dimensional Analysis. It was observed in previous studies that addition of large amounts of chemical conditioners could alter the initial solids content of the original slurry to be filtered. Increment in the initial solids content also occurs when skeleton builders are mixed with chemical conditioners. The filter cake yield of such slurry would definitely be higher while the resulting specific resistance would be lower. To account for these additions, it is important that a valid filter cake yield model with a correction factor, F be derived. In furtherance of the above, a new equation expressing the filter cake yield as net sludge solids was derived with further incorporation of the cake compressibility coefficient. It was established that filter net solids yield is directly proportional with the operating pressures, initial sludge solids content, and conditioner dosages while being inversely proportional to specific resistance to filtration, pressing time, sludge viscosity and sludge compressibility . The difference between the actual cake yields and the net solids yield accounts for the quantity of the ferric chloride coagulant used in this study. The new equation enables performance of a pressure filter (Filter Press) to be predicted from a simple laboratory determination of cake yields. Moreover, curves derived from the model show how increasing ferric chloride dosage from 11.87% to 22.61% increased net solids yield from 2.4254g/Cm2.S to 2.7052g/Cm2.S while reducing specific resistance from 1.7372 x 1010Cm/g to 1.5940 x 1010Cm/g. The optimum dosage from the graph to attain acceptable filtrate quality was 19.61% at an operating pressure of 5098.58g/Cm2. Also, considering the differences in the parameters tested, it is significant that they all responded similarly when compared with previous research works.