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Plant response to the leakage of stored CO 2 is a key concern for safe carbon capture and storage (CCS). An understanding of plant tolerance to high soil CO 2 concentrations is urgently required to facilitate bio-indicator selection for both long-term environmental monitoring and prevention of stored CO 2 leakage. In this study, we propose a new index, the Leaking CO 2 Tolerance Index, LCTI, which assesses plant CO 2 tolerance using the change (downward shift) in index values under leakage treatments. The calculated LCTI reveals that, of the four studied plants, clover was the most tolerant (0.42), followed by alfalfa (0.4), teosinte (0.33), and finally maize (0.29). Our results suggest that clover, along with other high-LCTI species, should be selected as species that can potentially adapt and respond to CCS leakage. Furthermore, plants such as maize appear suitable as bio-indicators to monitor carbon storage fields, allowing early detection of CO 2 leakage.

Chlorine dioxide (ClO2) has proven its efficiency as a fumigant toward bacteria and viruses. However, it still has challenges on its portability and simplicity of ClO2 generation to meet the demand for disinfection in public and medical sectors. In this study, ClO2 stripping process via a rotating packed bed (RPB) from the commercial ClO2 solution was developed to a non-chemical-reaction ClO2 generation for air sterilization in a hospital. The ClO2 stripping efficiency (η) and the volumetric liquid mass-transfer coefficient (KLa) were examined under various operating variables, such as initial liquid concentration (CLi), rotational speed (ω), gas-to-liquid flow rate ratio (QG/QL), and liquid flow rate (QL). The results indicated that the gaseous ClO2 can be rapidly and continuously generated via stripping using RPB with η varied above 97% in the certain range of CLi (100–2000 mg/L) and QL (0.04–0.250 L/min). The overall KLa depends on the change of QL and ω, varied from 0.009 s−1 to 0.027 s−1. The output concentration of gaseous ClO2 (CG) can be adjusted from around 10 ppm to over 1000 ppm based on the established prediction model and controlling CLi, QL, QG, and ω. The results of the on-site disinfection test in the Mycobacterium Tuberculosis Laboratory in a hospital have shown effective elimination of all sites of E. coli and 2 of 5 sites of G. stearothermophilus with a CT value at the gas monitoring point of 642 ppm-h and humidity of 81%.

In this study, the approach of stimulating the production of volatile fatty acids (VFAs) during food wastes (FW) fermentation by linear alkylbenzene sulphonates (LAS) is proposed and the underlying mechanisms from a metagenomic perspective are analyzed. The results show that with an appropriate level of LAS (50 mg/L), VFA production is greatly enhanced (11854 versus 1825 mg COD/L) with the increased proportions of high-value long-chain ones. Mechanistic explorations indicate that LAS contributes to the solubilization/hydrolysis of the main organic components in FW (i.e., carbohydrates, proteins and lipids) due to the amphipathic features. Besides, LAS would interact with the cell membranes and increase the cell permeability to promote the membrane transport of substrates into the functional microorganisms for further metabolisms. The metagenomic analysis demonstrates that the critical genes involved in hydrolase secretion (i.e., bglX, pepD and lip), ABC transporter (i.e., rfbA and lolD), main substrate metabolism (especially the proteins and lipids, i.e., glsA and glpK) and fatty acid biosynthesis (i.e., accA, accC and accD) all highly expressed in LAS-conditioned reactors. The upregulation of these encoding genes stimulates microbial metabolic activities and improves the production rates of VFAs. Besides, the distribution of functional microbial populations and their associations with genetic expressions in different reactors were investigated. This study provides profound information on the stimulating effects of LAS on FW fermentation for VFA production from genetic and functional perspectives.

Efficient, convenient, economical and environmentally friendly materials have always been the first choice for solving environmental problems. In this work, stable carbonized and ordered hollow nanofiber aerogels were obtained under the action of directional freezing and calcination. The benzoxazine monomer (BA) in the nanofiber was polymerized in situ under the action of high temperature to crosslink the nanofibers, thereby further stabilizing the aerogel structure. The plastic deformation of the carbonized aerogel after oil absorption with 100 cycles of compression was 30%. The carbonized hollow nanofiber aerogels were superhydrophobic and oleophilic, which allowed selective absorption of oil upon contact with oily wastewater. As a similar density, the oil absorption performance of the hollow nanofiber aerogels was higher than that of the normal nanofiber aerogels, implying high efficiency of the hollow nanofiber aerogels. After compression, the dry sample could recover its shape in oil, indicating the resilience of the hollow nanofiber aerogel. Moreover, the cycle absorption experiment illustrated that low-toxicity ethanol could remove most of the oil adsorbed in the aerogels, and ensure stable performance during recycling. After five cycles, the hollow nanofiber aerogel still retained its the original shape without fiber falling off, reducing the secondary pollution to the environment. The present study provides a strategy for the design and fabrication of ordered hollow nanofiber aerogels for wastewater treatment and other potential applications.

Heavy metal(loid)s and organic pollutants have garnered global concern due to their potential for bioaccumulation and carcinogenic effects. The aquatic environment is one of the most important receiving compartments for these pollutants. Therefore, researchers are committed to developing inexpensive and highly efficient technologies for the removal of these recalcitrant contaminants from water. Zero-valent iron (ZVI), which has a strong reduction ability, low cost and can be recycled, has been considered as an environmentally benign element for removal of heavy metal(loid)s and organic chlorinated pollutants. However, some factors limit the ZVI application, with passivation of ZVI considered as the main limitation. Recent research has focused on methods to eliminate or alleviate these interferences and maximize ZVI performance. This review summarizes recent findings for the removal of typical heavy metal(loid)s and organic pollutants in the aquatic environment by ZVI-based technologies. Different combinations of chemical, physical, biological, or other methods with ZVI and their operating conditions and influencing factors are presented and discussed. Finally, we also present the removal mechanisms of ZVI-based technologies and recommendations for future research. This review provides an up-to-date perspective on the removal of pollutants using ZVI-based technologies and collates references for future large-scale application to wastewater treatment.