Removing Hydrogen Sulfide Contamination in Biogas Produced from Animal Wastes

Extraction, Purification, Characterization and Application in Livestock Wastewater of S Sulfur Convertase

Sulfide is a toxic pollutant in the farming environment. Microbial removal of sulfide always faces various biochemical challenges, and the application of enzymes for agricultural environmental remediation has promising prospects. In this study, a strain of Cellulosimicrobium sp. was isolated: numbered strain L1. Strain L1 can transform S^2-, extracellular enzymes play a major role in this process. Next, the extracellular enzyme was purified, and the molecular weight of the purified sulfur convertase was about 70 kDa. The sulfur convertase is an oxidase with thermal and storage stability, and the inhibitor and organic solvent have little effect on its activity. In livestock wastewater, the sulfur convertase can completely remove S^2-. In summary, this study developed a sulfur convertase and provides a basis for the application in environmental remediation.

Density functional theory analysis for H2S adsorption on pyridinic N- and oxidized N-doped graphenes

Biomass discharged from primary industries can be converted into methane by fermentation. This methane is used for generating electricity with solid oxide fuel cells (SOFCs). This methane fermentation provides H2S, which reduces the efficiency of SOFCs even at a level as low as a few parts per million. It has been experimentally reported that a nitrogen (N)-doped graphene-based material known as pyridinic N removes H2S via an oxidation reaction compared with another graphene-based material known as oxidized N. To understand this experimental result, we investigated H2S adsorption on pyridinic N and oxidized N by a density functional theory analysis and further examined the activation barrier of dissociation reactions. We found that the adsorption of H2S on pyridinic N is more stable than that on oxidized N. In addition, the H2S dissociation reaction occurs only on pyridinic N.

The role of soils in the regulation of air quality

Soils play a key role in meeting the UN Sustainable Development Goals (SDGs). In this study, we review the contribution of soils to the regulation of air quality, which is one of 'Nature's Contributions to People' identified by the Intergovernmental-Policy Platform on Biodiversity and Ecosystem Services (IPBES). This is particularly relevant for SDG3 (health and well-being) and 11 (sustainable cities and well-being) but also impacts other SDGs. Soils can act as both a source and a sink of air pollutants (and their precursors). In addition, soils support plant growth which plays a major role in regulating air quality. The scale of the soil impacts on air quality range from global (e.g. greenhouse gas fluxes, stratospheric ozone depletion) to local (e.g. odours, particulates, pathogen transport). Harmful emissions from soil can be increased or decreased by anthropogenic activity, while climate change is likely to modify future emissions patterns, both directly and in response to human mitigation and adaption actions. Although soils are not the only source of these pollutants, it is worthwhile managing them to reduce erosion and nutrient losses to maintain soil health so we may continue to benefit from the contributions to good quality of life they provide. This article is part of the theme issue 'The role of soils in delivering Nature's Contributions to People'.