MICROWAVE TECHNIQUE IN WASTEWATER AND SLUDGE PROCESSING University of Szeged, Faculty of Engineering Department of Process Engineering Moszkvai krt. 5-7, H-6725 Szeged, Hungary Sándor Beszédes

INTRODUCTION water microorganisms (viruses, pathogens) organic particles organic compounds heavy metals micro pollutants (pharmaceuticals, endocrin disruptors) Sludge: semi-solid residual from wastewater Heavy degradable compounds are concentrated into the sludge

 Sludge handling technology determines the capacity and economical parameters of WWTP  Common alternatives of sewage sludge treatments: using in agriculture (cropland application) incineration composting Main aim of sludge handling:  volume reduction (thickening, dewatering)  elimination of pathogens  modify sludge structure (stabilization)  recycling and recovery (fertiliser, composting, biogas) (fertiliser, composting, biogas)

MICROWAVE APPLICATIONS IN WASTEWATER AND SLUDGE TECHNOLOGIES

MW-induced pyrolysis Soil, sludge and sediments are poor absorbers - slow heating up Solution: mixing with carbon,metal-oxides microwave-hybrid heating (MHH) Sludge conditioning MW destroy EPS and cell walls – bound water releasing Improve sludge dewatering, but increase organic matter content of sludge liquor (MW treatment – polyelectrolyte dosing – filtration) Improving digestibility EPS with divalent ions form compact sludge flocks MW cause the breakage of EPS network and the hydrogen bounds

Sludge sanitation MW irradiation is more effective for inactivation of fecal coliforms than conventional heating MW enhanced stabilization of heavy metals Reduce the leachable Cu 2+ and Pb 2+ from hydroxyde sediment of printed circuit board manufactoring sludge Enhance the binding of metal ions with dipolar polymeric molecules MW-assisted regenaration of activated carbon Enlargement of narrow microspores under MW irradiation result in slower deposit forming Adsorption capacity is stable during 8-10 regeneration cycle

.. MWPUVD: Microwave powered UV disinfection use of MW energy to power electrodeless quartz UV lamps Compare to conventional UV systems Less frequent lamp change/longer lamp life Quicker start-up Increased efficiency Minimized fouling Lower operational cost/less energy lost More economical in partially-filled water channels Kent County Regional Wastewater Treatment Plant (WWTP), Delaware, U.S. MW enhanced advanced oxidation techniques

Microwave technique in demulsification processes  Energy absorption is influenced by dielectric properties  Dielectric loss of oil is small  Effect of MW irradiation on water in oil (W/O) emulsions viscosity decreasing faster than density difference (temperature effect) when viscosity decreases size of oil droples increases efficiency of coagulation process increases if viscosity is higher coalescence of water molecules is easier, because boundary layer around water molecules is ruptured in oscillating EM field

 rapid and selective heating  high dissipated energy level  affect the structure of macromolecules  enhances chemical reactivity (via thermal and athermal effects) improves pathogen destruction transforms suspended solids into soluble compounds leads to disruption of EPS and sludge flocs broken cell-liquor and extracellular organic matter release into the soluble phase proteins release more quickly than carbohydrates, but the total change of sCarb i higher than sProt Effects of MW irradiation on sludge

RESULTS OF MW SLUDGE PRE-TREATMENT OF FOOD INDUSTRY SLUDGE

ORGANIC MATTER SOLUBILITY R 2 = R 2 (adj) = 0,996 Q 2 = 0,994

BIODEGRADABILITY R 2 = R 2 (adj) = 0,996 Q 2 = 0,995

CH and MW treatment prior to AD process

Daily biogas product

MPWS DWS

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