Application of Zn-contaminated soil: Feasibility study on the removal of H2S from hot coal-derived gas

In this study, zinc-contaminated soils were chosen as a candidate material for the removal of hydrogen sulfide (H₂S) from hot coal-derived gas. Laboratory experiments showed that H₂S was decreased to less than 10 ppm when the zinc-contaminated soils were reacted with H₂S. The best removal temperature of H₂S was found to be at 550°C in the operating conditions. In addition to zinc species, free iron oxides in contaminated soils also performed an active species to react with H₂S and enhanced the sulfur capacity. Through the XPS analysis, iron sulfide (FeS) and zinc sulfide (ZnS) were the major products after removal experiments. Regeneration experimental results indicated that the zinc-contaminated soils can be regenerated by pass diluted air and thus be reused on the removal of H₂S for many times.     

Effects of ozonation and coagulation on effluent organic matter characteristics and ultrafiltration membrane fouling

Effluent organic matter （EfOM） is the major cause of fouling in the low pressure membranes process for wastewater reuse. Coagulation and oxidation of biological wastewater treatment effluent have been applied for the fouling control of microfiltration membranes. However, the change in EfOM structure by pre-treatments has not been clearly identified. The changes of EfOM characteristics induced by coagulation and ozonation were investigated through size exclusion chromatography, UV/Vis spectrophotometry, fluorescence spectrophotometry and titrimetric analysis to identify the mechanisms in the reduction of ultrafiltration （UF） membrane fouling. The results indicated that reduction of flux decline by coagulation was due to modified characteristics of dissolved organic carbon （DOC） content. Total concentration of DOC was not reduced by ozonation. However, the mass fraction of the molecules with molecular weight larger than 5 kDa, fluorescence intensity, aromaticity, highly condensed chromophores, average molecular weight and soluble microbial byproducts decreased greatly after ozonation. These results indicated that EfOM was partially oxidized by ozonation to low molecular weight, highly charged compounds with abundant electron- withdrawing functional groups, which are favourable for alleviating UF membrane flux decline.