Behavior Study of Migration and Transformation of Heavy Metals during Oily Sludge Pyrolysis

Abstract

This paper studied the migration, transformation, leaching toxicity, and risk assessment of heavy metals when oily sludge was pyrolyzed at multiple pyrolysis temperatures and residence times. Results indicated that heavy metals were enriched in char, while less than 3% of heavy metals were distributed to gas and liquid products. By the modified European Community Bureau of Reference sequential extraction method, it was found that the most immobilized Cr, Ni, and Pb were obtained under conditions of 600 °C for 30 min, 400 °C for 60 min, and 500 °C for 60 min, respectively. However, pyrolysis reduced the percentage of stable fractions in Cu and Zn. Similarly, the leaching concentrations of Cr, Ni, and Pb decreased through pyrolysis, while that of Zn increased. Risk assessment code results suggested that pyrolysis reduced the environmental risk of Pb but increased that of Zn. Meanwhile, the mechanism of heavy metal migration and transformation was explored by characterizing with proximate analysis, ultimate analysis, X-ray fluorescence, Fourier transform infrared spectroscopy, and X-ray diffraction. The results indicated that aromatization and mineral crystals in chars influenced the immobilization of heavy metals.

Recent Advances and Perspectives of Copyrolysis of Biomass and Organic Solid Waste

“…Therefore, it is necessary to properly dispose of OS to reduce its harmful effect on the environment. 122 TDS is an inevitable byproduct of textile dyeing. Compared with MS, TDS usually contains more toxic organic compounds and heavy metals.…”

“…The main components of OS are cycloalkanes, benzene series, PAHs, and other toxic substances. Therefore, it is necessary to properly dispose of OS to reduce its harmful effect on the environment . TDS is an inevitable byproduct of textile dyeing.…”

Techno-Economic Assessment and Sensitivity Analysis of Glycerol Valorization to Biofuel Additives via Esterification

“…In continuation of our group’s interest in environmental catalysis, the aim of this work is to provide a feasibility study with a techno-economic analysis for the valorization of crude glycerol into acetins. − This analysis has been done on Aspen Plus for process optimization followed by the techno-economic analysis by Aspen Process Economic Analyzer (APEA). The first part consists of a preliminary process development and a preliminary conceptual flowsheet with the mass and energy transfer schemes.…”

Investigation of N Migration during Municipal Sludge/Coal Co-Pyrolysis via ReaxFF Molecular Dynamics

“…Additionally, traditional sludge disposal techniques, including sanitary landfills and ocean dumping, have been subject to major limitations and restrictions due to their negative impacts on soil and groundwater. Compared to conventional methods, thermal treatment of sludge has been extensively applied as it enables energy recovery under environmentally friendly conditions. − As a critical first step in different thermal treatment technologies, sludge pyrolysis has attracted widespread attention. − However, the high moisture and ash content of sludge lead to pyrolysis products of suboptimal quality . In this regard, sludge/coal co-pyrolysis has the potential to enhance the quality of these products, considering the physical and chemical characteristics of both sludge and coal .…”