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Effects of Surfactant Addition on Dewatering of Alum Sludges |
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| Authors: | Chihpin Huang Jill Ruhsing Pan Cheng-Gang Fu Chi-Chao Wu |
| Affiliation: | 1Professor, Institute of Environmental Engineering, National Chiao Tung Univ., Hsinchu, Taiwan, Republic of China (corresponding author). 2Visiting Associate Professor, Institute of Environmental Engineering, National Chiao Tung Univ., Hsinchu, Taiwan, Republic of China. 3Master Student, Institute of Environmental Engineering, National Chiao Tung Univ., Hsinchu, Taiwan, Republic of China. 4Associate Professor, Graduate Institute of Environmental Engineering and Science, Feng Chia Univ., Taichung, Taiwan, Republic of China. |
| Abstract: | In Taiwan, surfactants are frequently used in the flotation process to aid in solid/liquid separation. Their effect on the dewatering of alum sludge was investigated. Various amounts of cationic and anionic surfactants were added to sludge samples, and the dewatering characteristics of the sludge and the water content of sludge cakes were evaluated. Both surfactants improved the dewatering of the sludge by lowering the specific resistance to filtration, decreasing the bound water content, and increasing the dewatering rate of the sludge. Different combinations of anionic and cationic surfactants and polyelectrolytes were also experimented on to study the effect of surfactant addition on the dewatering characteristics of polyelectrolyte-conditioned sludge. Experimental results indicated that both cationic and anionic surfactants adversely affected the dewatering of the conditioned sludge. The addition of surfactant to the oppositely charged polyelectrolyte proved to be most detrimental to sludge dewatering due to the precipitation between surfactant and polyelectrolyte. The addition of cationic surfactant to the cationic polyelectrolyte-conditioned sludge had the least effect. |
| Keywords: | Surface-active agents Sludge Dewatering Polyelectrolytes |