MICROWAVE TECHNIQUE IN WASTEWATER AND SLUDGE PROCESSING

1. MICROWAVE TECHNIQUE IN WASTEWATER AND SLUDGE PROCESSING Sándor Beszédes University of Szeged, Faculty of Engineering Department of Process Engineering Moszkvai krt. 5-7, H-6725 Szeged, Hungary E-mail:beszedes@mk.u-szeged.hu

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

3. 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)

4. MICROWAVE APPLICATIONS IN WASTEWATER AND SLUDGE TECHNOLOGIES

5. 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

6. Sludge sanitation • MW irradiation is more effective for inactivation of fecal coliforms • than conventional heating • MW enhanced stabilization of heavy metals • Reduce the leachable Cu2+ and Pb2+ 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

7. . . MW enhanced advanced oxidation techniques • 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.

8. 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

9. Effects of MW irradiation on sludge • 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 disruptionof EPS and sludge • flocs broken • cell-liquor and extracellularorganic • matter release into thesoluble phase • proteins release more quickly than carbohydrates, but the total change of sCarb i higher than sProt

10. RESULTS OF MW SLUDGE PRE-TREATMENT OF FOOD INDUSTRY SLUDGE

11. ORGANIC MATTER SOLUBILITY R2 = 0.997 R2(adj) = 0,996 Q2 = 0,994

12. BIODEGRADABILITY R2 = 0.998 R2(adj) = 0,996 Q2 = 0,995

13. CH and MW treatment prior to AD process

14. Daily biogas product

15. MPWS DWS

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