Characterization of char derived from various types of solid wastes from the standpoint of fuel recovery and pretreatment before landfilling

Abstract

Carbonization is a kind of pyrolysis process to produce char from organic materials under an inert atmosphere. In this work, chars derived from various solid wastes were characterized from the standpoint of fuel recovery and pretreatment of waste before landfilling. Sixteen kinds of municipal and industrial solid wastes such as residential combustible wastes, non-combustible wastes, bulky wastes, construction and demolition wastes, auto shredder residue, and sludges were carbonized at 500 o C for 1 h under nitrogen atmosphere.In order to evaluate the quality of char as fuel, proximate analysis and heating value were examined. The composition of raw waste had a significant influence on the quality of produced char. The higher the ratio of woody biomass in waste, the higher heating value of char produced. Moreover, an equation to estimate heating value of char was developed by using the weight fraction of fixed carbon and volatile matter in char.De-ashing and chlorine removal were performed to improve the quality of char.The pulverization and sieving method seems to be effective for separation of incombustibles such as metal rather than ash. Most char met a 0.5 wt% chlorine criterion for utilization as fuel in a shaft blast furnace after it was subjected to repeated water-washing.Carbonization could remove a considerable amount of organic matter from raw waste. In addition, the leaching of heavy metals such as chrome, cadmium, and lead appears to be significantly suppressed by carbonization regardless of the type of raw waste. 2From these results, carbonization could be considered as a pre-treatment of waste before landfilling as well as for fuel recovery.

Characteristics of leachate from pyrolysis residue of sewage sludge

“…250 to 300 g h -1 of dry SS was loaded to a laboratory-scale rotary kiln-type reactor (φ 0.15 m × 1.2 m) with using a screw feeder and it was pyrolyzed at 500 °C (Hwang et al, 2007). Nitrogen was used as the carrier gas at a rate of 11 l min -1 to maintain an inert atmosphere.…”

“…In contrast, alkali metals tended to be released readily compared to heavy metals. The high acid-buffering pH of incineration ash and the surface properties of pyrolysis residue might be the reasons for the immobilization of heavy metals (Kistler et al, 1987;Inguanzo et al, 2002;Hwang et al, 2007).…”

“…Previously, we characterized chars derived from various solid wastes, including sewage sludge (Hwang et al, 2007). As sewage sludge char produced at 500 °C had a high ash content and low heating value, it was considered landfill material rather than an alternative fuel.…”

Pretreatment of automobile shredder residue (ASR) for fuel utilization

“…Figure 4 shows the various product yields and qualities obtained by pretreatment. We estimated ASR HHV using HHV data from individual components as listed in (Hwang et al, 2007). By the end of the series of pretreatments, product yield had decreased to 0.5 g g5.6-mm mesh is a simple method to remove ash.…”

Distribution and Contamination Hazards of Heavy Metals in Solid Residues from the Pyrolysis and Gasification of Wastewater Sewage Sludge

“…He et al [24] determined the chemical composition and thermal stability of solid residues, as well as migration and transformation of HMs during SS pyrolysis. Hwang et al [25][26] found that most HMs was completely retained by solid residue after SS pyrolysis treatment and the composition of raw SS had a significant influence on the quality of the resulting residue and thus, the mobility of HMs. Lu et al [27] also studied the influence of pyrolysis temperature on physical and chemical properties of pyrolysis residue.…”