TESTING OF SLUDGE PROPERTIES AND DEWATERING PERFORMANCE

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Introduction

Our laboratory is equipped with a pilot belt press simulator, which can simulate our various models of belt press, and test the properties of different types of sludges and slurries. I t can also simulate other manufacturer's press designs.

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The piloting process follows a number of stages:

• Sample analysis. In it's simplest form this is a percent solids analysis. In addition, pH measurement, Specific Gravity determination, and if necessary, for slurries, particle size analysis is carried out. The most time consuming stage is the flocculant selection. Here we compare different types of flocculants, including polymers, and evaluate their mixing properties, filtration characteristics and flocc strength. As there are many possible combinations of charge type, (anionic or cationic), and molecular weight, as well as dosage methods, the possible permutations are endless.

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• The next stage is simulation of the free drainage characteristics of the flocculated sludge/slurry. Low pressure dewatering is then carried out, either as a linear wedge action (pure compression), or a radial wedge, (compression and shear). The final stage is combinations of high pressure and shearing, and for some materials, very high line pressure. (The Nip Roll).

 

A number of different press filter configurations can be tested, and the following parameters investigated:

 

 

•         Surface Pressure

•         Line Pressure

•         Belt Speed

•         Flocculant Type and Dosage

•         Belt Type

•         Surface Loadings.

•         Cake release from the filter cloth

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