Electrokinetic remediation of heavy metals from municipal solid waste incineration fly ash pretreated by nitric acid

Abstract

Municipal solid waste incineration (MSWI) fly ash has a high concentration of heavy metals (HMs) which are hazardous to the environment. Moreover, it has high pH and buffering capacity which hinders the removal of HMs. Another constraining factor is the considerable fraction of HMs which exist in oxidizable and reducible states. The acid pretreatment of MSWI fly ash is a key solution to this problem. Therefore, the current experiment is carried out to evaluate the effect of acid pretreatment of MSWI fly ash and reaction/proposed time on the removal efficiency of HMs through an electrokinetic experiment. The leaching experiment results show that acid pretreatment has increased the desorption/release of heavy metal ions (Pb2+, Cd2+, Cu2+ and Zn2+). It enhances the migration of HM ions in electrolytic cells which get precipitated at the cathode, thereby increasing the removal efficiency of HMs in the electrokinetic experiment. Moreover, it is found that prolonged proposed time (12 d) has significant effect on the removal efficiency of HMs. Finally, it is concluded that acid pretreatment and prolonged proposed time have enhanced the removal electrokinetic remediation of HMs which is carried out via three processes, i.e. desorption (enhanced by acidification), migration and precipitation.

Waste to energy incineration technology: Recent development under climate change scenarios

“…There are different methods and treatments to reduce leaching and are classified into three groups: physical and chemical separation; solidification and stabilization; and thermal treatment. The separation process consists of washing, electrochemical process, adsorption and distillation (Kirkelund et al, 2015; Li et al, 2018; Zhu et al, 2010). Stabilization and solidification process include accelerated carbonation, hydrothermal solidification and chemical stabilization (Luo et al, 2017; Ni et al, 2017; Vavva et al, 2017; Zhang et al, 2016).…”

Critical Review of Electro-kinetic Remediation of Contaminated Soils and Sediments: Mechanisms, Performances and Technologies

“…When the soil plasticity value exceeds 35, the soil will shrink excessively during the remediation process, leading to soil cracking and disturbing the pollutant removal mechanism (López-Vizcaíno et al 2016a, b). The range of voltage gradient used in laboratory tests is 1-3 V/cm (Li et al, 2018;Zhu et al, 2009). The high current level can increase the total ion concentration and improve the ion electromigration efficiency in the electro-kinetic remediation process (Tang et al, 2020), but it will reduce the overall electroosmotic flow and release a lot of heat (Joule effect), resulting in energy consumption and relatively high costs (Xue et al, 2017).…”

“…1 Soil and Sediment Treatment by Electro-kinetic Remediation Mining, electroplating, and other industrial activities, as well as sewage irrigation, the use of chemical fertilizers, and other agricultural production processes, lead to large amounts of heavy metals and organic pollutants accumulating in the soil and/or sediment. These pollutants can bio-accumulate in living organisms and cause a threat to the health of plants and animals including humans (Forstner, 2004;Li et al, 2018).…”