Effect of co-contaminated soil mixtures as fixed/fluidized bed media on pollutants emission under thermal treatment

Abstract

Thermal treatment of soil polluted by lube oil and heavy metals (cadmium, chromium, copper, and lead) was carried out by using a laboratory-scale incinerator. The effect of co-contaminated soil mixtures as fixed/fluidized bed media was studied with different ratios of sand bed amount to soil feeding. Additionally, the effect of soil moisture content on incineration system was further investigated. The reduction in air input altered the mode of fluidized bed to fixed bed which resulted in an increase in organic pollutants such as benzene, toluene, ethylbenzene, xylene, and polycyclic aromatic hydrocarbons. The combustion efficiency of fixed bed mode was observed to be relatively high at a lower ratio of sand bed amount to soil feeding, whereas high combustion efficiency was found in fluidized bed mode at a higher ratio of sand bed amount to soil feeding. Much higher concentration of organic pollutants in both gas phase and bottom ash is found under a higher soil moisture content. In addition, the increase in moisture content has resulted in an increase in lead, cadmium, and chromium in fly ash while copper was decreased. An important consideration is that the partitioning of heavy metals was randomly distributed in particle sizes of bottom ash. The highest concentration of heavy metals was deposited on fine-sized particle. The distribution of heavy metals in medium-sized and coarse-sized particles to form eutectic species might be produced by the soil-sand aggregation.

Investigation on the fast co-pyrolysis of sewage sludge with biomass and the combustion reactivity of residual char

“…Fluidized-bed reactors can provide high heating rates and shorten the time lag of devolatilization, but the particle dispersion causes very slight or no interactions (Samaksaman et al, 2016). In this work, a drop-tube reactor is used to perform fast pyrolysis experiments.…”

Remediation of oil-based drill cuttings using low-temperature thermal desorption

“…Residual TPH in all treatments decreased with treatment time, and the removal rates increased with treatment temperature. Generally, the addition of sand to OBDCs improved the desorption rates of TPH, which is in agreement with Samaksaman et al (2016a) who showed that a ratio of sand/soil (0.75/1 to 1.5/1) could enhance the elimination of BTEX and PAHs in both fixed bed and fluidized bed reactors.…”

“…In this study, the LTTD treatment of OBDCs artificially spiked with different PHCs content was examined using a bench-scale apparatus. Ottawa sand was mixed with OBDCs with different mixing ratios to enhance the LTTD remediation process, as the additive could improve the texture and pore size of drill cuttings, thus increasing the effective diffusivity in porous media (Falciglia et al, 2011, Samaksaman et al, 2016a. The main objectives of the study were: (1) to analyze the changes of soil properties before and after thermal treatment, and examine the impacts of LTTD process on soil characteristics;…”

“…Moreover, enhanced methods should be investigated. For example, the addition of sand to soil could enhance the effective diffusivity of hydrocarbons in soil (Falciglia et al, 2011) and improve the thermal conductivity of soil (Samaksaman et al, 2016a). Kinetics for different oil fractions removal and energy consumption of LTTD should also be examined to better understand the application OBDCs remediation.…”

Novel treatment and value-added utilization of oily sludge using ionic liquid and pyrolysis

“…Petroleum hydrocarbons (PHCs) and heavy metals are potential persistent environmental toxins (Roy et al, 2005). They could exist at contaminated sites affected by accidental spills and leaks from petroleum, transportation, and mining industries (Samaksaman et al, 2016).…”