Development of dewatering textile materials incorporating slit-pore geometries

ABSTRACT

The use of engineering textile materials has emerged as a viable alternative to conventional methods of sludge dewatering in numerous application areas including municipal wastewater, mining, and pulp and paper. Previous studies have focused on the development of empirical ratios between dewatering performance and the porous properties of the textile material, the challenge is that the latter is difficult to characterize using currently available techniques. In this study, a series of dewatering filters were produced using advanced microfabrication techniques to create well-defined slit-pore geometries; a full-factorial design-of-experiments was employed to evaluate the effects of slit-pore dimensions and slit-pore spacing on the cake layer development and overall dewatering performance in constant-rate dewatering tests with municipal digestate that had been pre-treated with a commercial polymer flocculant. The results from this study provide new insights into the importance of the cake layer in textile dewatering and the impact of textile porosity and flocculation conditions on dewatering performance. It was found that an inverse relationship exists between the porosity of a dewatering fabric and both medium and cake resistances between 0.1% and 1.0% filter porosity, while these properties are comparatively independent of pore structure beyond 1.0%. In addition, the efficacy of the polymer pre-treatment conditions employed was determined to have a substantial impact on solids retention.

GRAPHICAL ABSTRACT

KEYWORDS:

• Engineered textiles
• sludge dewatering
• microfabrication
• municipal digestate
• design-of-experiments

Acknowledgements

We thank Kemira for generously providing the Superfloc^® polymers employed in this work, as well as Mr. Mark Solomon and the operations staff at the Woodward Avenue Wastewater Treatment plant for providing the municipal digested sludge samples. From McMaster University, we are grateful to Mr. Paul Gatt for his assistance in the design and construction of the lab-scale constant-rate dewatering system, Dr. Jake Nease for providing helpful resources related to the development of the multiple linear regression model, and the staff at the McMaster Manufacturing Research Institute for their technical assistance with the Keyence VHX Digital Microscope.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The funding for this work was mostly provided by Ontario Centres of Excellence through their Voucher for Innovation and Productivity I Program. Financial support was also provided by McMaster University in the form of the Kulperger Experiential Learning and Discovery Fund (to M. J. Archer) and the Dean’s Undergraduate Student Summer Research Award (to M. Cusack-Striepe).