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Zhang J.-H.,Tianjin Eco city Environmental Protection Co. | Liu Z.-H.,Tianjin Eco city Environmental Protection Co. | Lu D.,Tianjin Eco city Environmental Protection Co. | Wang W.-Q.,Tianjin Eco city Environmental Protection Co.
Huaxue Gongcheng/Chemical Engineering (China) | Year: 2011

Ultrasonic treatment combined with flocculants was used in dewatering of sediment by geotextile tube. For obtaining low sludge water mass fraction, the effect of the sequence of adding flocculants and ultrasonic on the dewatering performance was discussed. The optimal conditions of ultrasonic treatment were also determined. The results show that adding flocculants firstly and then ultrasonic treatment can achieve better dewatering performance. When the flocculants dosage is 5‰ (dry basis, mass fraction), the ultrasonic energy density is 0.5 W/mL and treatment time is 10 s, the dehydration effect is the best. Finally, the pilot test of geotextile tube structure was performed. The result indicates that when flocculation mass fraction is 4‰, the dewatering performance of geotextile tube with ultrasound is better than that of the control group without ultrasound, and the curing time of geotextile tubes is shorten. Appropriate ultrasound can decrease the amount of flocculants, reduce costs and shorten the curing time of geotextile tubes, thus improving the efficiency.

Song Z.,Tianjin Eco city Environmental Protection Co. | Song Z.,Tianjin Contaminated Site Remediation Technology Engineering Center | Yang W.,Tianjin Eco city Environmental Protection Co. | Yang W.,Tianjin Contaminated Site Remediation Technology Engineering Center | And 6 more authors.
Journal of Polymer Engineering | Year: 2015

Polyvinylidene fluoride (PVDF) membranes were prepared via a thermally induced phase separation (TIPS) process using mixed diluent consisting of dibutyl phthalate (DBP) and dibutyl sebacate (DBS). The compatibility between PVDF and mixed diluent was predicted via the solubility parameter theory and verified by experimental results. The effects of mixed diluent composition on cloud point temperature, crystallization temperature, crystallinity, crystal phase and morphology of the membrane were investigated. As a result, as DBS mass fraction in mixed diluent increased, the cloud point temperature and the crystallinity increased, the crystal phase transformed from β phase to α phase and the morphology of the membrane cross-section changed from spherulitic structures to a bicontinuous structure. PVDF hollow fiber membranes were prepared successfully with the PVDF/DBP/DBS system via the TIPS method. The coagulant composition had a significant influence on the water permeability. When the dimethylacetamide (DMAc) content in the coagulant was 60%, the water permeability reached 877 l/m2·h, while the rejection rate to the particles with a size of 200-500 nm was above 95%. © by De Gruyter 2015.

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