Dispersion Stability of Drinking Water Treatment Sludge

The objective of this study is to improve the particle suspension stability of drinking water treatment sludge (DWTS) and comparable to other silicate powder which are bentonite, micro silica (micro-SiO2), and nano-silica (nano-SiO2). The main dispersion characteristic are related to particle size, and dispersion force. The representative samples of bentonite, micro-SiO2, nano-SiO2, and DWTS were dispersed at the same solid content in water. The particle size distribution and chemical composition of samples were analyzed. The suspended samples were measured for Zeta potential at the controlled pH value. Furthermore, turbidity of suspended samples were investigated at various sedimenting time. The results indicated that nano-SiO2 has the highest Zeta potential value at pH 8-12. The stability of particle dispersion could be implied from turbidity of suspension at various sedimenting time. Bentonite suspension performed more stability than other samples for longer time. However, stability of DWTS particles can be improved by particle size controlling and treatment with dispersion agent to create repulsive force from the charge on the particle surface.