Browsing by Author "Cai, Chao"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
Item Open Access Enhanced bioremediation of aged polycyclic aromatic hydrocarbons in soil using immobilized microbial consortia combined with strengthening remediation strategies(MDPI, 2023-01-18) Zhou, Haixuan; Gao, Xiurong; Wang, Suhang; Zhang, Youchi; Coulon, Frederic; Cai, ChaoMicrobial biodegradation is considered as one of the most effective strategies for the remediation of soil contaminated with polycyclic aromatic hydrocarbons (PAHs). To improve the degradation efficiency of PAHs, PAH-degrading consortia combined with strengthening remediation strategies was used in this study. The PAH biodegrading performance of seven bacterial consortia constructed by different ratios of Mycobacterium gilvum MI, Mycobacterium sp. ZL7 and Rhodococcus rhodochrous Q3 was evaluated in an aqueous system containing phenanthrene, pyrene, benzo[a]pyrene and benzo[b]fluoranthene. Bacterial consortium H6 (Q3:ZL7:MI = 1:2:2) performed a high degrading efficiency of 59% in 8 days. The H6 was subsequently screened to explore its potential ability and performance to degrade aged PAHs in soils from a coking plant and the effects of strengthening strategies on the aged PAH degradation, including the addition of glucose or sodium dodecyl benzene sulfonate (SDBS) individually or as a mixture along immobilization of the inoculant on biochar. The highest degradation efficiencies, which were 15% and 60% for low-molecular-weight (LMW) PAHs and high-molecular-weight (HMW) PAHs, respectively, were observed in the treatment using immobilized microbial consortium H6 combined with the addition of glucose and SDBS after 24 days incubation. This study provides new insights and guidance for future remediation of aged PAH contaminated soils.Item Open Access Field verification of low-level biochar applications as effective ameliorants to mitigate cadmium accumulation into Brassica campestris L from polluted soils(Frontiers, 2023-01-16) Zhang, Youchi; Liu, Shuang; Lin, Shanna; Reid, Brian J.; Coulon, Frederic; Cai, ChaoIntroduction: Cadmium (Cd) has been recognized as a significant contributor to the pollution of farmland soils in China, and biochars have been reported to be effective in mitigating soil Cd pollution. However, most studies have been conducted in laboratory or greenhouse settings, not at a field scale, and the biochars used have been applied at unrealistically high amounts (>10 t/ha). Methods: In this research, three biochars: rice straw biochar (RSB), pig manure biochar (PMB) and rice husk biochar (RHB) were produced from readily available farm residues. Then the effects at low-level application (1.8 and 3.6 t/ha) on Cd were investigated in a field experiment cropped with rape (Brassica campestris L.). Results: Batch adsorption experiments indicated Cd adsorption capacity of three biochars followed the order of RSB (43.5 mg/g) > PMB (33.3 mg/g) > RHB (24.4 mg/g). Field experiment indicated biochar amendments could slightly change soil pH and cation exchange capacity (CEC); yet led to considerable and significant decreases in extractable Cd concentrations [reductions of: 43%–51% (PMB), 29%– 35% (RSB) and 17%–19% (RHB)]. Reduced extractable Cd correlated with lower Cd concentrations in rape plants. PMB and RSB were more effective in decreasing Cd phytoaccumulation into edible parts of rape (>68% reduction) than RHB. Discussion: Low-level application of PMB or RSB could efficiently decrease the phytoaccumulation of Cd from soils into crops. These results demonstrate the reality of biochar-based remediation solutions to contribute to the mitigation of diffuse Cd contamination in farmland. The results also highlight the need to trail biochars in the presence of the soil to be targeted for remediation.Item Open Access In vitro model insights into the role of human gut microbiota on arsenic bioaccessibility and its speciation in soils(Elsevier, 2020-04-16) Chi, Haifeng; Hou, Yanwei; Li, Guofeng; Zhang, Youchi; Coulon, Frederic; Cai, ChaoThe bioaccessibility of arsenic and its speciation are two important factors in assessing human health risks exposure to contaminated soils. However, the effects of human gut microbiota on arsenic bioaccessibility and its speciation are not well characterized. In this study, an improved in vitro model was utilized to investigate the bioaccessibility of arsenic in the digestive tract and the role of human gut microbiota in the regulation of arsenic speciation. For all soils, arsenic bioaccessibility from the combined in vitro model showed that it was <40% in the gastric, small intestinal and colon phases. This finding demonstrated that the common bioaccessibility approach assuming 100% bioaccessibility would overestimate the human health risks posed by contaminated soils. Further to this, the study showed that arsenic bioaccessibility was 22% higher in the active colon phase than that in the sterile colon phase indicating that human colon microorganisms could induce arsenic release from the solid phase. Only inorganic arsenic was detected in the gastric and small intestinal phases, with arsenate [As(V)] being the dominant arsenic species (74%–87% of total arsenic). Arsenic speciation was significantly altered by the active colon microbiota, which resulted in the formation of methylated arsenic species, including monomethylarsonic acid [MMA(V)] and dimethylarsinic acid [DMA(V)] with low toxicity, and a highly toxic arsenic species monomethylarsonous acid [MMA(III)]. Additionally, a high level of monomethylmonothioarsonic acid [MMMTA(V)] (up to 17% of total arsenic in the extraction solution) with unknown toxicological properties was also detected in the active colon phase. The formation of various organic arsenic species demonstrated that human colon microorganisms could actively metabolize inorganic arsenic into methylated arsenicals and methylated thioarsenicals. Such transformation should be considered when assessing the human health risks associated with oral exposure to soil.Item Open Access Promoting Sino-UK Collaboration on Developing Low Carbon and Sustainable Methodologies for Brownfields and Marginal Land Re-use in China(2017-01) Coulon, Frederic; Campo Moreno, Pablo; Jiang, Ying; Longhurst, Phil; Bardos, Paul; Li, Xiaonuo; Harries, Nicola; Jones, Kevin; Li, Hong; Li, Fasheng; Cao, Yunzhe; Hu, Qing; Gao, Jingyang; Chen, Mengfang; Zhu, Yong-Guan; Cai, ChaoRapid urbanisation and changes in land use resulting from industrial change has left a legacy of vast polluted industrial and commercial areas (also called brownfields) and marginal land areas. Recent evidence from the UK, EU and USA indicate that these land areas may have considerable potential for renewables production, for example from solar, wind or biomass. In parallel there are opportunities for carbon storage in rehabilitated soil, as well as substitution by the production of renewables. The UK is also leading the understanding in the wider parallel benefits that can be achieved from ecosystem services and public health benefits from improved provision of green space. These multiple services can be provided together, in synergy, from soft re-uses of post-industrial sites, and in this way the post-industrial regeneration areas in China should be seen as a major opportunity for new enterprise, society and the wider environment. The improving bankability of renewable energy projects, and the possibility of creating a voluntary carbon offset business, means that revenue streams may be sufficient to pay for ongoing land management over time as a profit generating activity. In terms of fastest benefit to UK PLC and China, the likelihood is that combination of renewable energies with “dual use” for habitat will provide both more readily commercial brownfield re-use opportunities for cities in China in the short term, and also create better carbon management opportunities, as well as a variety of wider sustainability benefits. Thus this type of re-uses will create a platform for rapid commercial exchange and development between Chinese and UK companies. Considering that China is preparing an action plan for managing soil pollution and remediation across the country estimated to be RMB 7tn which is equivalent to one-third of the national exchange reserves, this report on developing low carbon and sustainable methodologies for brownfields and marginal land re-use in China provides timely information that will support the decision making for sustainable remediation opportunities in China. The report is intended to serve as a tool and resource guide to stakeholders involved in land remediation willing to engage in sustainable remediation implementation for renewable energy and carbon management applications. It is intended to inform remediation stakeholders unfamiliar with sustainable remediation about the concept, practices, and available resources. The report capitalises on UK leadership positions on the sustainable rehabilitation of brownfields land (SURF-UK), the soft re-use of brownfields (e.g. for energy or amenity rather than buildings); effective end-use directed risk management for contaminated land, and sustainable remediation.Item Open Access Recent advances in biochar engineering for soil contaminated with complex chemical mixtures: remediation strategies and future perspectives(Elsevier, 2020-12-29) Anae, Jerry; Ahmad, Nafees; Kumar, Vinod; Thakur, Vijay Kumar; Gutierrez, Tony; Yang, Xiao Jin; Cai, Chao; Yang, Zhugen; Coulon, FredericHeavy metal/metalloids (HMs) and polycyclic aromatic hydrocarbons (PAHs) in soil have caused serious environmental problems, compromised agriculture quality, and have detrimental effects on all forms of life including humans. There is a need to develop appropriate and effective remediation methods to resolve combined contaminated problems. Although conventional technologies exist to tackle contaminated soils, application of biochar as an effective renewable adsorbent for enhanced bioremediation is considered by many scientific researchers as a promising strategy to mitigate HM/PAH co-contaminated soils. This review aims to: (i) provide an overview of biochar preparation and its application, and (ii) critically discuss and examine the prospects of (bio)engineered biochar for enhancing HMs/PAHs co-remediation efficacy by reducing their mobility and bioavailability. The adsorption effectiveness of a biochar largely depends on the type of biomass material, carbonisation method and pyrolysis conditions. Biochar induced soil immobilise and remove metal ions via various mechanisms including electrostatic attractions, ion exchange, complexation and precipitation. PAHs remediation mechanisms are achieved via pore filling, hydrophobic effect, electrostatic attraction, hydrogen bond and partitioning. During last decade, biochar engineering (modification) via biological and chemical approaches to enhance contaminant removal efficiency has garnered greater interests. Hence, the development and application of (bio)engineered biochars in risk management, contaminant management associated with HM/PAH co-contaminated soil. In terms of (bio)engineered biochar, we review the prospects of amalgamating biochar with hydrogel, digestate and bioaugmentation to produce biochar composites.Item Open Access Remediation of cadmium and lead polluted soil using thiol-modified biochar(Elsevier, 2020-01-07) Fan, Jiajun; Cai, Chao; Chi, Haifeng; Reid, Brian J.; Coulon, Frederic; Zhang, Youchi; Hou, YanweiThiol-modified rice straw biochar (RS) was prepared by an esterification reaction with β-mercaptoethanol and used for the remediation of Cd and Pb polluted soils. Modified biochar was characterized through elemental analysis, BET analysis, FE-SEM, FT-IR and XPS. These analytical results revealed that thiol groups were successfully grafted onto the surface of the biochar and were involved in metal ion complexation. Batch sorption experiments indicated that Cd2+ and Pb2+ sorption onto RS described well by a pseudo second order kinetic model and a Langmuir isotherm. The maximum adsorption capacities for Cd2+ and Pb2+, in the single-metal systems, were 45.1 and 61.4 mg g−1, respectively. In the binary-metal systems, RS selectively adsorbed Cd2+ over Pb2+. Cd2+ and Pb2+ were removed mainly through surface complexation. In the soil incubation experiments (28 days), RS reduced the available Cd by 34.8–39.2 %; while, RS reduced the available Pb by 8.6 %–11.1 %. This research demonstrates RS as a potentially effective amendment for the remediation of heavy metal polluted soils.