Sewage sludge, the inevitable by-product of municipal wastewater treatment plant operation, is a key issue in many countries due to its increasing volume and the impacts associated with its disposal. Thermochemical processing offers a new way of managing sewage sludge, not only by providing effective volume reduction, but also enabling transformation of carbon-rich organic fraction into valuable energy and fuel. Owing to some unique properties, sewage sludge differs from other solid fuels such as lignocellulosic biomass and coal, making its thermochemical conversion application somewhat complicated and challenging. This paper reviews the options of converting sewage sludge to energy and fuel via three main thermochemical conversion processes namely pyrolysis, gasification and combustion. The fundamental aspects of sewage sludge and its behaviour in each of thermochemical process are summarised. The challenges in adopting thermochemical conversion technology in sewage sludge management are addressed, and various alternative approaches deserving further consideration, such as the incorporation of pre-processing and co-utilisation, are discussed.

Thermochemical processing of sewage sludge to energy and fuel: Fundamentals, challenges and considerations

Arsenic removal technologies and future trends: A mini review

Fly ash-based geopolymers containing added silicate waste. A review

Fate and distribution of heavy metals during thermal processing of sewage sludge

Municipal solid waste (MSW) incineration fly ash as an important source of heavy metal pollution in China.

Stabilization of chromium-bearing electroplating sludge with MSWI fly ash-based Friedel matrices.

With the growing application of sludge incineration, the thermal behavior of heavy metals during this process is increasingly a concern. This work was conducted to determine the speciation evolutio...

Speciation Evolutions of Heavy Metals during the Sewage Sludge Incineration in a Laboratory Scale Incinerator

Reducing volatilization of heavy metals in phosphate-pretreated municipal solid waste incineration fly ash by forming pyromorphite-like minerals.

The present work focused on the effects of different reagents on the remediation of arsenic and chromium co-contaminated soil by electrokinetic technology coupled with permeable reactive barrier (EK-PRB). In a running of EK-PRB, reductant (ascorbic acid, sodium citrate) and chelating agent (EDTA-2Na) were used to pretreat contaminated soil together with CaAl-LDH as reactive materials for PRB. As a result, the chelating agent improved the removals of As and Cr in co-contaminated soil. However, the reducing agent only increased As removal. When 0.05 M sodium citrate was used in pretreatment, the As removal attained the maximum of 50.5%, although Cr removal was only 44.1% at the same time. When the contaminated soil was pretreated with 0.01 M EDTA-2Na, the Cr removal increased to 54.28%, although As removal was only 26.3%. After EK-PRB, the As and Cr were efficiently captured by CaAl-LDH, resulting in maximal fixed amounts of 126.5 mg/kg (As) and 1507.6 mg/kg (Cr). The XRD and FITR analyses of LDH indicated that As was mainly adsorbed on the surface of LDH. As for Cr, it was mainly intercalated into interlayer of LDH.

Ying Sun

Papers

Stabilization of chromium-bearing electroplating sludge with MSWI fly ash-based Friedel matrices.

Speciation Evolutions of Heavy Metals during the Sewage Sludge Incineration in a Laboratory Scale Incinerator

Reducing volatilization of heavy metals in phosphate-pretreated municipal solid waste incineration fly ash by forming pyromorphite-like minerals.

Enhanced remediation of arsenic and chromium co-contaminated soil by eletrokinetic-permeable reactive barriers with different reagents.

Migration and transformation of phosphorus in municipal sludge by the hydrothermal treatment and its directional adjustment.