Reconstruction of microbiome and functionality accelerated crude oil biodegradation of 2,4-DCP-oil-contaminated soil systems using composite microbial agent B-Cl

COF-derived porous nitrogen-doped carbon for removal of emerging organic contaminants and efficient uranium extraction from seawater

The development of adsorbents for efficient and highly selective seawater extraction of uranium was instrumental in fostering sustainable progress in energy and addressing the prevailing energy crisis. However, the complex background composition of the marine environment, including radionuclides, organic pollutants, and a large number of co-existing heavy metal ions, were non-negligible obstacles to the extraction of uranium from seawater. The present investigation successfully employed a self-templated approach to synthesize porous nitrogen-doped carbon (PNC) derived from COF, which exhibited tremendous potential as an adsorbent for pollutant removal in environmental treatment. LZU1@PNC not only retained the structural features of the original COF-LZU1, but also overcame the acid-base instability problem commonly found in COFs. Subsequently, the removal process of two typical water pollutants on the material was investigated using 2,4-DCP and [UO2(CO3)3]4-. The results demonstrated that LZU1@PNC exhibited superior removal performance for the target pollutants compared to COF-LZU1, owing to its larger specific surface area and abundant defect structure. After six desorption-regeneration cycles, LZU1@PNC still maintained a high removal rate of the target contaminants, demonstrating the stability of this material and its excellent recyclability. In addition, based on various characterization techniques, the removal mechanism of 2,4-DCP was presumed to be mainly electrostatic attraction, hydrogen bonding, and π-π stacking interactions. Conversely, the elimination process of [UO2(CO3)3]4- predominantly relied on surface complexation phenomena. The present investigation provided new perspectives and stimulated a broader study of other COF-derived carbon materials and their modifications as adsorbents for uranium extraction from seawater and other applications.

Effect of dissolved oxygen on the peroxymonosulfate activation pathway in an electrochemical Co/P/CA cathode system

Although dissolved oxygen plays an important role in electro-Fenton-like processes, few investigations have revealed its underlying effects in such processes. Herein, the effect of dissolved oxygen on peroxide activation in an electro-Fenton-like system comprising electrochemical cells and peroxymonosulfate (PMS) was investigated. Cobalt phosphide-modified carbon aerogel (Co/P/CA) was used as the cathode material owing to the high conductivity and catalytic activity of Co/P/CA. Several free radicals and their effects on organic pollutant removal were observed using electron paramagnetic resonance spectrometry and quenching experiments, respectively. The observations revealed that in the presence of O2, hydroxyl radical (·OH), superoxide (O2-·), and singlet oxygen (1O2) served as the primary active species in the PMS activation process, while in the presence of N2, ·OH and sulfate radical (SO4-·) served as the dominant active species in this process. The factor responsible for the difference in the PMS activation pathways available under O2 and N2 conditions was investigated using rotating disk electrode tests and free energy calculations. The tests indicated that O2 facilitates PMS activation to form ·OH instead of SO4-·. The dissolved oxygen subsequently underwent a single-electron-reduction reaction and was converted into O2-·, which could serve as a source of 1O2. When N2 was introduced, Co species, particularly Co(II), played a key role in activating PMS. The free radicals ·OH and SO4-· were generated during the PMS activation process. This study clearly demonstrates the mediating catalysis role of dissolved oxygen in electro-Fenton-like system through experimental data and theoretical calculations, thereby positively contributing to future studies regarding the continuous activation of peroxides in composite systems and improvement of the efficiency of waterbody remediation.

An immobilized composite microbial material combined with slow release agents enhances oil-contaminated groundwater remediation

Microbial remediation of oil-contaminated groundwater is often limited by the low temperature and lack of nutrients in the groundwater environment, resulting in low degradation efficiency and a short duration of effectiveness. In order to overcome this problem, an immobilized composite microbial material and two types of slow release agents (SRA) were creatively prepared. Three oil-degrading bacteria, Serratia marcescens X, Serratia sp. BZ-L I1 and Klebsiella pneumoniae M3, were isolated from oil-contaminated groundwater, enriched and compounded, after which the biodegradation rate of the Venezuelan crude oil and diesel in groundwater at 15 °C reached 63 % and 79 %, respectively. The composite microbial agent was immobilized on a mixed material of silver nitrate-modified zeolite and activated carbon with a mass ratio of 1:5, which achieved excellent oil adsorption and water permeability performance. The slow release processes of spherical and tablet SRAs (SSRA, TSRA) all fit well with the Korsmeyer-Peppas kinetic model, and the nitrogen release mechanism of SSRA N2 followed Fick's law of diffusion. The highest oil removal rates by the immobilized microbial material combined with SSRA N2 and oxygen SRA reached 94.9 % (sand column experiment) and 75.1 % (sand tank experiment) during the 45 days of remediation. Moreover, the addition of SRAs promoted the growth of oil-degrading bacteria based on microbial community analysis. This study demonstrates the effectiveness of using immobilized microbial material combined with SRAs to achieve a high efficiency and long-term microbial remediation of oil contaminated shallow groundwater.

Sustainable management and valorization of biomass wastes using synthetic microbial consortia

In response to the persistent expansion of global resource demands, considerable attention has been directed toward the synthetic microbial consortia (SMC) within the domain of microbial engineering, aiming to address the sustainable management and valorization of biomass wastes. This comprehensive review systematically encapsulates the most recent advancements in research and technological applications concerning the utilization of SMC for biomass waste treatment. The construction strategies of SMC are briefly outlined, and the diverse applications of SMC in biomass wastes treatment are explored, with particular emphasis on its potential advantages in waste degradation, hazardous substances control, and high value-added products conversion. Finally, recommendations for the future development of SMC technology are proposed, and prospects for its sustainable application are discussed.