Microwave pyrolysis treatment of sewage sludge: Performed at laboratory and full-scale conditions

Abstract

This paper describes the current applied research of microwave pyrolysis (MP) treatment of sewage sludge at laboratory and full-scale conditions at University of Pavia (UNIPV) and Brno University of Technology, AdMaS research centre (BUT AdMaS). Disposal of sewage sludge is becoming one of the most important issues in waste water management in EU, particularly thermal treatment and reuse of sludge. Thermal treatment is often associated with incineration, but there are alternative methods such as gasification or pyrolysis, which produce biochar, pyrolysis oil and pyrolysis gas (Syngas), that may be used for further applications. Current applied research of sludge disposal shows that MP as one of the thermal methods is a suitable solution in terms of circular economy, carbon footprint reduction, HM fixation, energy recovery and water retention. The thermal MP of sewage sludge is applied at a laboratory scale MP unit at UNIPV and laboratory, and full-scale MP units at BUT AdMaS. The MP units use different 3 kW magnetrons with the frequency of 2.45 GHz, at atmospheric and low atmospheric pressure. The research is focused on monitored pre-treatment of sewage sludge MP, catalysts, optimization process of MP units and reusing of biochar and pyrolysis oil. To date the research at UNIPV and BUT AdMaS focused on the microwave treatment of sewage sludge, pyrolysis oil and biochar has been conducted separately, but currently, both universities as partners, prepare a proposal project of a mobile MP container unit for sewage sludge disposal which will be relocated and seasonally treat dry sludge at selected wastewater treatment plants.