Journal of Hazardous, Toxic, and Radioactive Waste

Bioelectrochemical system (BES)–based microbial electrosynthesis is a viable production route for various industrial commodities. In the last decade, BES has emerged as a sustainable technology for treating wastewater and the simultaneous production of bioelectricity. Currently, more focus is being placed on producing high-value chemicals from these systems instead of wastewater. BES-based microbial electrosynthesis can also be utilized to produce different industrial commodities sustainably by replacing existing chemical-based production streams. Using the bioelectrochemical production route for useful industrial chemicals provides a new route of sustainable production. The present review puts forth the production strategies used for different industrial commodities along with the pitfalls of using ${\mathrm{CO}}_2$ as a substrate through BES-based microbial electrosynthesis. Moreover, particular emphasis is placed on a discussion of the technological enhancements in the commercialization of BES-based microbial electrosynthesis.

Kitchen wastewater (KWW), a type of gray wastewater has garnered significant attention because of organic pollutants and oil and grease. It has hazardous effects on the environment, such as eutrophication in water bodies and choking of pipes in the sewer system. Stagnant KWW invites serious diseases like malaria, filarial, and dengue. The present water crisis demands the reuse of KWW for nonpotable purposes. This paper is mainly focused on the harmful impact of KWW on the environment, various methods used for its treatment, and its applications in different areas. It is found that phytoremediation is a low-cost method for the treatment of KWW. Reuse of KWW in various fields helps to convert its zero value to a valuable resource. Further exploration of KWW is required for determining its sustainable uses.

A sustainable biogeochemical cover system consisting of a biochar-amended soil layer overlain by a basic oxygen furnace (BOF) slag layer is being developed to mitigate fugitive emissions of methane (${\mathrm{CH}}_4$) and carbon dioxide (${\mathrm{CO}}_2$) at municipal solid waste (MSW) landfills. The effectiveness of such a cover system is highly dependent on the survival and activity of methanotrophs in the soil under highly alkaline conditions induced by the presence of slag. In this paper, laboratory microcosm tests were conducted to investigate the effect of BOF slag-infiltrated water on ${\mathrm{CH}}_4$ oxidation in soil and enrichment culture. The effects of BOF slag-infiltrated water at different proportions in soil (0%, 5%, 20%, 60%, and 100%) and in enrichment culture (0%, 11%, 25%, and 100%) were studied. ${\mathrm{CH}}_4$ oxidation rates in the soil were 113, 116, 115, 108, and $97\mathrm{\mu g}{\mathrm{CH}}_4{\mathrm{g}}^{-1}{\mathrm{d}\mathrm{a}\mathrm{y}}^{-1}$ at 0%, 5%, 20%, 60%, and 100% slag-infiltrated water content, respectively. In enrichment culture, the ${\mathrm{CH}}_4$ oxidation rates were 36, 27, 20, and $17\mathrm{\mu g}{\mathrm{CH}}_4{\mathrm{mL}}^{-1}{\mathrm{d}\mathrm{a}\mathrm{y}}^{-1}$ at 0%, 11%, 25%, and 100% slag-infiltrated water content, respectively. The results showed a significant decrease in ${\mathrm{CH}}_4$ oxidation rates with an increase in slag-infiltrated water content ($>11\%$) in enrichment culture and a marginal decrease in soil microcosm. Furthermore, no substantial change in microbial community composition was noted in soil microcosms across all of the slag-infiltrated water content, and they were generally dominated by the Methylobacter luteus species. However, the enrichment culture, which was dominated by Methylobacter at 0% slag-infiltrated water content, showed a decrease in the abundance of Methylobacter and an increase in the abundance of Methylosinus, with an increase in the slag-infiltrated water content.

Hundreds of millions of people in the world regularly intake groundwater that has a high-risk arsenic level. In several parts of Asia, the arsenic concentration reaches up to $\mathrm{1,000}\mathrm{\mu g}/\mathrm{L}$, which is above the drinking water standards of the World Health Organization ($10\mathrm{\mu g}/\mathrm{L}$). The present study discusses the arsenic removal from groundwater using a mixed-valent iron [Fe(II)-Fe(III)] oxide, commonly known as magnetite. Mixed-valent iron [Fe(II)-Fe(III)] oxide particles were synthesized from iron oxide waste that was obtained from the steel industry. Six column reactors were operated based on different operational variables, such as amount of adsorbent, particle size, initial arsenic concentration, empty bed contact time (EBCT), and flow rate. Four columns were continuously operated for 44 days, and two columns were operated for 80 days. The adsorption profile was maintained well for all the reactors with more than 98% arsenic removal efficiency from influent water. The shorter breakthrough curve was achieved for the columns operated with a higher influent arsenate concentration as compared with the columns operated with a low influent arsenate concentration. Moreover, the longer breakthrough curve was achieved for the column packed with a higher quantity of adsorbent. The column operated with a low EBCT and high flow rate resulted in the earlier breakthrough because arsenate ions did not get adequate time to bind at the adsorption sites and, subsequently, excited the column before it reached the state of equilibrium.

Concentrations of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes are determined in atmospheric aerosol samples collected from an academic campus, Department of Chemistry, National Institute of Technology, Jamshedpur, India. The sampling work carried out for the present study was carried from June to September 2018. The maximum concentration of PAHs and n-alkanes was observed to be $6.02\mathrm{ng}/{\mathrm{m}}^3$ (June) and $23.02\mathrm{ng}/{\mathrm{m}}^3$ (September), and the minimum concentration was observed to be $5.36\mathrm{ng}/{\mathrm{m}}^3$ (July) and $10.13\mathrm{ng}/{\mathrm{m}}^3$ (June), respectively. The average concentration level of $\sum 17$ n-alkanes and $\sum 13$ PAHs was estimated to be $15.62\pm 5.51$ and $5.69\pm 0.33\mathrm{ng}/{\mathrm{m}}^3$, respectively, during the study periods. To better understand the ring variations in PAHs, it was found that the concentration of four-ring PAHs was 35.28%, that of five-ring PAHs was 34.18%, that of six-ring PAHs was 22.76%, and that of three-ring PAHs was 7.78%. Phenanthrene (Phn) was the most abundant PAH with fine particulate matter (${\mathrm{PM}}_{2.5}$) in the study. The concentration level of PAHs and n-alkanes varied with season. Pearson’s correlation coefficient method was applied for source apportionment of PAHs and n-alkanes. It was reported by using principal component correlation (PCC) that the source of emissions may be industrial activity, automobiles, wood, coal, or dung cake burning.

The declining trends in water levels and degrading water quality in most parts of India are major concerns which need to be addressed. A hydrochemical study was carried out in parts of southwest Punjab, India to understand the groundwater quality and its suitability for drinking and agriculture under changing hydrogeological conditions and land-use patterns. The hydrochemical results suggest that most locations have water quality that is unfit for its use for both drinking and irrigational activities; 20% of samples from Muktsar were fit for drinking in both seasons, whereas in Faridkot district 39% of samples were fit for drinking purposes, which increased to 63% in the postmonsoon season with respect to total dissolved solids (TDS). Based on the hardness, 95% of samples from both seasons were unfit for drinking purposes in Muktsar district, whereas all samples were unfit for drinking in both seasons in Faridkot district. Based on the electrical conductivity (EC), more than 20% of samples were in the doubtful category and 57% were unfit for drinking during the premonsoon season in Muktsar district. During the postmonsoon season the percentage of samples in the permissible category increased from 19% to 35%, which could be attributed to dilution by rain water. In Faridkot district, drinking water suitability decreased from 52% to 42%. The groundwater in these two districts has high salinity, sodium hazards, and is contaminated by nitrate and sulfate. The study highlights the need to monitor the contaminant spread periodically and optimize the cropping pattern as well as exploitation of water resources to achieve sustainable water quality and quantity in this region.