title: Impact of Joule Heating and pH on Biosolids Electro-Dewatering.
abstract: Electro-dewatering (ED) is a novel technology to reduce the overall costs of residual biosolids processing, transport, and disposal. In this study, we investigated Joule heating and pH as parameters controlling the dewaterability limit, dewatering rate, and energy efficiency. Temperature-controlled electrodes revealed that Joule heating enhances water removal by increasing evaporation and electro-osmotic flow. High temperatures increased the dewatering rate, but had little impact on the dewaterability limit and energy efficiency. Analysis of horizontal layers after 15-min ED suggests electro-osmotic flow reversal, as evidenced by a shifting of the point of minimum moisture content from the anode toward the cathode. This flow reversal was also confirmed by the pH at the anode being below the isoelectric point, as ascertained by pH titration. The important role of pH on ED was further studied by adding acid/base solutions to biosolids prior to ED. An acidic pH reduced the biosolids charge while simultaneously increasing the dewatering efficiency. Thus, process optimization depends on trade-offs between speed and efficiency, according to physicochemical properties of the biosolids microstructure.
authors.affiliation: †Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke Street West, Montreal, Quebec H3A 0C3, Canada.
authors.forename: Tala
authors.initials: T
authors.lastname: Navab-Daneshmand
authors.affiliation: †Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke Street West, Montreal, Quebec H3A 0C3, Canada.
authors.forename: Raphaël
authors.initials: R
authors.lastname: Beton
authors.affiliation: ‡Department of Chemical Engineering, McGill University, 3610 University Street, Montreal, Quebec H3A 0C5, Canada.
authors.forename: Reghan J
authors.initials: RJ
authors.lastname: Hill
authors.affiliation: †Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke Street West, Montreal, Quebec H3A 0C3, Canada.
authors.forename: Dominic
authors.initials: D
authors.lastname: Frigon
mesh_terms: D004566:Electrodes; D006361:Heating / Q000295:instrumentation / Q000379:methods*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D012722:Sewage / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014866:Waste Products; D014867:Water / Q000737:chemistry
chemical_list: D012722:Sewage; D014866:Waste Products; D014867:Water