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Fabrication of materials and the adsorption of arsenic.

Phytoextraction using Celosia argentea Linn. by Mn pretreatment can potentially decontaminate Cd-contaminated soils. However, the mechanism that accelerates the Cd bioaccumulation is still unknown. In order to study the effect and mechanism of Mn pretreatment on Cd bioaccumulation in C. argentea, the hydroponic experiments were set to determine the chlorophyll content, antioxidant enzyme activity, malondialdehyde content, and root exudation of C. argentea. The results indicated that after seven days of Mn pretreatment, both the biomass and Cd concentrations in plants increased compared to the control group. One of the mechanisms for this was the improvement in the physiological resistance of C. argentea following pretreatment with Mn. Compared with Cd stress alone, Mn pretreatment increased photosynthesis and reduced membrane lipid peroxidation. Meanwhile, the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) were significantly reduced in leaves of C. argentea after Mn pretreatment through the reduction in the production of reactive oxygen species. In addition, Mn promoted the exudation of organic acids in the roots of C. argentea. The contents of citric and malic acids increased by 55.3% and 26.4%, respectively, which may be another important reason for Mn pretreatment increasing Cd bioaccumulation in C. argentea. Therefore, the present work shows that the pretreatment of seedlings with Mn can provide a meaningful strategy to improve the remediation efficiency of Cd-contaminated soils by C. argentea.

Cr(VI) is toxic to the human body and environment. As a suitable wastewater treatment with low energy requirement technology, constructed wetland-microbial fuel cells (CW-MFCs) can treat Cr(VI) wastewater while generating electricity. In this study, CW-MFC and constructed wetland systems were developed to purify Cr(VI) wastewater. The removal mechanism of Cr(VI) was examined by electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy. The results demonstrated that the average pollutant removal efficiency of the CW-MFC system is 2.99–8.13% higher than that of the constructed wetland system, and the maximum power density is 505.61 mW m−2. Moreover, the XPS and EPR analyses demonstrated that Cr in substrates and Leersia hexandra Swartz primarily is in the form of Cr(III). Moreover, in plants and substrates, the Cr(III) content of the CW-MFC system was higher than that of the control, and the bioconcentration and translocation factors were 0.23 and 0.05 higher than those in the control group, respectively. Therefore, the CW-MFC system can efficiently remove Cr(VI) and promote the accumulation and transport of Cr. Microbial community diversity in the CW-MFC was significantly higher than CW. The abundance of electrogenic bacteria Geobacter and metal dissimilatory reducing bacteria Acinetobacter in CW-MFC is higher than that in CW. To summarize, the study results provide a theoretical basis for the mechanism study of Cr(VI) wastewater treatment using CW-MFC systems.

Understanding the molecular mechanism of tolerance to heavy metals in hyperaccumulators is important for improving the efficiency of phytoremediation and is interesting for evolutionary studies on plant adaption to abiotic stress. Celosia argentea Linn. was recently discovered to hyperaccumulate both manganese (Mn) and cadmium (Cd). However, the molecular mechanisms underlying Mn and Cd detoxification in C. argentea are poorly understood. Laboratory studies were conducted using C. argentea seedlings exposed to 360 μM Mn and 8.9 μM Cd hydroponic solutions. Plant leaves were analyzed using transcriptional and metabolomic techniques. A total of 3960 differentially expressed genes (DEGs) in plants were identified under Cd stress, among which 17 were associated with metal transport, and 10 belonged to the ATP transporter families. Exposures to Mn or Cd led to the differential expression of three metal transport genes (HMA3, ABCC15, and ATPase 4). In addition, 33 and 77 differentially expressed metabolites (DEMs) were identified under Mn and Cd stresses, respectively. Metabolic pathway analysis showed that the ABC transporter pathway was the most affected in Mn/Cd exposed seedlings. Conjoint transcriptome and metabolome analysis showed that the glutathione (GSH) metabolic pathway was over-represented in the KEGG pathway of both DEGs and DEMs. Our results confirm that the ABC transporter and GSH metabolic pathways play important roles in Mn and Cd detoxification. These findings provide new insight into the molecular mechanisms of tolerance to Mn and Cd toxicity in plants.

The excessive discharge of dye wastewater is a great threat to human health and environment with the development of industry. And it is of great significance to use biomass materials to remove dyes from wastewater with the low cost, renewability and environmental friendliness. In this study, the amine-modified passion fruit peel (ACPFP) was prepared by amination reaction, which exhibited highly efficient removal for anionic dyes (methyl orange (MO) and amaranth (ART)). The adsorption capacities of ACPFP for MO and ART were 1530.81 and 970.87 mg⋅g−1, respectively. And the adsorption conditions (pH, ionic strength, temperature, initial dye concentration, and contact time) and mechanism (kinetic and isotherm models) were investigated. The results revealed that 99% of MO and ART was removed in the best adsorption conditions: pH=5, an adsorbent dose of 1 g⋅L−1, 600 mg⋅L−1of MO and ART initial concentration. The adsorption process correlated well with the pseudo-second-order kinetic model and the Langmuir isotherm. And ACPFP had good adsorption selectivity, stability and recyclability for anionic dyes. In conclusion, ACPFP has broad application prospects in actual water treatment.

Extreme mining activities can risk human life and the environment via potentially toxic elements (PTEs) in road dust, thus making their quantification and assessment unavoidable. For this purpose, we collected 50 fine road dust samples from the Chehe mining area, China, to quantify the level of contamination and ecological and health risks of PTEs comprising As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, and Zn, and their quantitative source apportionment using the positive matrix factorization model (PMF). Results indicated that the average values of Cd, Sb, As, Zn, Pb, and Cu in road dust were 1555.21, 586.78, 429.68, 429.43, 72.88, and 26.61 times higher than their background values. Pollution indices of PTEs revealed a strong level of contamination by Cd, Sb, As, Zn, and Pb, which were extremely polluted in the study area. The average values of the Nemerow integrated risk index (NIRI) and potential ecological risk index (RI) were 104.09 and 86.49 times the highest risk limit, respectively, which are extremely high ecological risks. Based on PMF for quantitative source identification, mining activities and fuel combustion were the main sources of PTEs in road dust contributing 57.25% and 35.95%, respectively. Furthermore, the health risk assessment indicated that Sb, As, Cr, Cd, and Pb in the Chehe road dust could lead to significantly serious carcinogenic and non-carcinogenic risks to both children and adults. The results of this study could be used to opt for strategies to mitigate the ecological and human health risk in the mining area of Hechi, China.

To select suitable plants for phytoextraction of Cd-contaminated soils, we evaluated the phytoextraction potential of five local Cd-accumulators: Amaranthus hypochondriacus L., Solanum nigrum L., P...

In this study, the contribution of substrates microorganisms in three different constructed wetlands (CWs) to Cr(VI) purification was discussed. In addition, the microbial communities in the substrate of different CWs were characterized, and rhizosphere Cr(VI) reducing bacteria was also identified. The results showed that microorganisms could improved Cr(VI) removal to 76.5%, and result in that more Cr(VI) was reduced to Cr(III). The dominant strains in the substrates of different CWs were Sphingomonas sp., Cystobacter sp., Acidobacteria bacterium, Sporotrichum and Pellicularia species. The Cr(VI) reducing bacteria from Leersia hexandra Swartz rhizosphere was identified as Bacillus cereus. Furthermore, under suitable conditions, the removal rate of Cr(VI) by Bacillus cereus was close to 100%.

Humins, as solid-phase redox mediators, are important for enhancing anaerobic biotransformation processes. Although humins are broadly distributed in estuarine and marine sediments, to date, their electron transfer capacity (ETC) from marine sediments has been poorly characterized. This study determined the potential of humins as redox mediators for microbial redox metabolic reactions in sediments along a transect from the Yangtze Estuary to the adjacent East China Sea and analyzed their electron-mediating characteristics. Comparative analyses of humins in sediments along this transect were conducted to investigate their ETC as redox mediators for microbial redox metabolic reactions, namely dissimilatory iron reduction (DIR) and dissimilatory nitrate reduction to ammonium (DNRA), using Shewanella oneidensis MR-1. Elemental composition, electrochemical, and Fourier transform infrared analyses were performed to better understand the functional redox groups in humins. All the humins functioned as solid-phase redox mediators and enhanced DIR and DNRA by Shewanella oneidensis, although with varying efficacy. The humins extracted from sampling site P1 (P1-HM), located close to the Yangtze Estuary, most effectively enhanced iron and nitrate reduction without nitrite accumulation. Electrochemical analysis confirmed the highest redox activity and ETC in P1-HM and a weakening trend of ETC with increasing distance from the estuary. Fourier transform infrared analysis suggested that quinone moieties might serve as key redox functional groups in humins. Considering their high yield and ETC, P1-HM could be important redox mediators that influence microbial redox metabolic reactions in sedimentary ecosystems of the Yangtze Estuary. Thus, this study provides insights into the distribution of humins, their ECT, and their potential role as redox mediators for microbial redox reactions, which could improve understanding of elemental biogeochemical cycling processes involving microorganisms in the Yangtze Estuary and East China Sea sedimentary ecosystems and provide important reference information for researches on other estuary areas.

The Lijiang River is of great ecological and environmental importance for Guilin City, which is located in the karst area of southeast China. Given its importance, a detailed evaluation of the heavy metals (HMs) in the river sediment is required. For the first time, 61 sediment samples were collected along the entire Lijiang River to determine pollution level and ecological risk posed by 10 HMs (Co, Cr, Cu, Mn, Ni, Pb, Zn, As, Hg, and Cd). These were assessed using the geo-accumulation index, potential ecological risk index, and modified degree of contamination. The results showed that the mean concentrations of the majority of HMs exceeded their corresponding background values and followed the trend: midstream > downstream > upstream. Based on the spatial distributions and pollution indices of the 10 HMs, the Lijiang River was found to have a high accumulation of Cd, Hg, Zn, and Pb in the sediments. The midstream area was the most polluted with respect to Cd and Hg, and also posed a relatively higher potential ecological risk than the downstream and upstream areas. The sources of the assessed HMs were inferred based on a correlation analysis and principal component analysis, which identified both natural and anthropogenic sources. A higher pollution potential was associated with Cd, Hg, Pb, and Zn in the midstream and downstream areas due to higher organic and carbonate content, urbanization, agricultural activities, and leisure activities (e.g., boating and cruises). In contrast, natural erosion and weathering processes were responsible for the HM concentrations in the upstream area. The findings of this study will help the local authorities to protect the important water resource of the Lijiang River.

A biosurfactant (BS) is a surface-active metabolite that is secreted by microbial metabolism, and can be used as a substitute for chemically synthesized surfactants. The first and most critical step to the successful application of BSs is to isolate bacterial strains with strong BS-producing capabilities. In this study, a BS-producing Serratia marcescens ZCF25 was isolated from the sludge of an oil tanker. Through polyphasic characterization using Fourier-transform infrared spectroscopy, thin layer chromatography, and gas chromatography-mass spectrometry, the produced BS was classified as a lipopeptide; it can decrease the water surface tension from 72.0 to 29.50 mN m

Photocatlytic decomplexation provides an effective way to tackle the problem of heavy metal contamination. By far, the exploration of more efficient photocatalysts with low environmental risk is still an important but challenging issue. In this study, the feasibility of using metal-free carbon nitride as environmental-friendly catalysts for photocatalytic decomplexation was demonstrated, using Cu(II)-EDTA as a model contaminant. A facile oxygen doping strategy could significantly enhance the interfacial separation of photogenerated holes, which was determined to be the most effective reactive species for decomplexation reactions. Compared to pristine g-C3N4, oxygen doped sample exhibited 2.5-fold enhanced photoactivity. The hypothesis of using decomplexation solution as sustainable resource for fabricating copper modified photocatalysts was further investigated. The in-situ formation of Cu or Cu2O resulted in the significantly improved activity for hydrogen evolution over recycled photocatalysts. According to the component analysis, chemical reduction strategy was beneficial for the sufficient recovery of copper ions, while the photoreduction method led to the most efficient utilization of copper metals. This study not only presents a promising method for the treatment of heavy metal-contaminated water, but also provides a sustainable way to utilize decomplexation solution as valuable resource for clean energy production.

Atrazine is a kind of triazine herbicide that is widely used for weed control due to its good weeding effect and low price. The study of atrazine removal from the environment is of great significance due to the stable structure, difficult degradation, long residence time in environment, and toxicity on the organism and human beings. Therefore, a number of processing technologies are developed and widely employed for atrazine degradation, such as adsorption, photochemical catalysis, biodegradation, etc. In this article, with our previous research work, the progresses of researches about the treatment technology of atrazine are systematically reviewed, which includes the four main aspects of physicochemical, chemical, biological, and material-microbial-integrated aspects. The advantages and disadvantages of various methods are summarized and the degradation mechanisms are also evaluated. Specially, recent advanced technologies, both plant-microbial remediation and the material-microbial-integrated method, have been highlighted on atrazine degradation. Among them, the plant-microbial remediation is based on the combined system of soil-plant-microbes, and the material-microbial-integrated method is based on the synergistic effect of materials and microorganisms. Additionally, future research needs to focus on the excellent removal effect and low environmental impact of functional materials, and the coordination processing of two or more technologies for atrazine removal is also highlighted.

Constructed wetland-microbial fuel cell coupling system is a new type of bioelectrochemical system that couples constructed wetland and microbial fuel cell. The system plays an important role in biological power generation and sewage purification. The principle is that the bottom of the constructed wetland bed (low ORP) serves as the anode of the microbial fuel cell. The organic matter in the water is degraded under the action of the electricity-producing microorganisms and released during the degradation process. The electrons are transferred along the external circuit to the biocathode on the surface of the bed (higher ORP) to complete the redox reaction. This article summarizes the research progress of the microbial fuel cell-constructed wetland coupling system from two aspects: system structure and factors affecting system operation. The system structure includes electrode materials, substrates, wetland plants and microorganisms. The influencing factors include HRT, DO, organic matter concentration and wastewater composition, electrode structure. Finally, the problems and research directions of the microbial fuel cell-constructed wetland coupling system are summarized, and the research potential of the system is prospected.

In recent years, soil heavy metal pollution has caused serious harm to human beings and the environment. Phytoremediation has become the main means of soil remediation because of its advantages such as low cost, obvious effect and low secondary pollution. In this paper, the status quo and harm of soil cadmium pollution in China and the mechanism of phytoremediation of cadmium were summarized.

Integration possibility and performance of a fixed-bed photo-catalytic reactor, merged with a detention pond, were examined at scale model. The focus of this study is to overcome the key issues of the conventional detention ponds and provide an enhanced surface water quality via nano-TiO2 as a novel hybrid technology. Photo-degradation of detained water nutrients in newly designed fixed-bed reactor pond (FRP) was studied to observe the impacts of heterogeneous reactions under ultraviolet irradiation. Immobilization of nano-titanium dioxide as catalyst, covering the FRP internal surface, was practiced for comparison and control. Rutile with anatase forms of TiO2 nano-powder (P25) was replaced in cement (white cement as well as Portland) at three dosages (30, 10, and 3%) for optimization purpose. Biodegradable pollutant elimination capability of FRP underpinned by the results for lower nitrate (16%), orthophosphate (25%), and COD (18%) in 2 days retention time, comparatively. Within 21 days, detaining time 26%, 58%. and 47% higher elimination was achieved, respectively. Improved catalyst surface area to reactor volume as well as an optimized retention time, based on streamflow pollution level, were achieved via splitting the FRP into two parts using a divider. FRP inlet was equipped with a flow switcher to capture and detain the first flush from the stormwater separately, while the balance is directed to the second part with a different required holding period. The divider walls were coated with cement-based nano-TiO2 and it also retrofitted applying filter media inside, for sediment-bound pollutant omission which the technique emerged with a greater TSS removal potency of up to 43%.

Sprinkler irrigation systems are widely used in medium and large scale farms in different forms. However less types are available to apply in small farms due to their high costs. The current study was done according to a novel cost effective design for a semi-permanent sprinkler irrigation system for small farm owners. The new layout known as Corner Pivot Lateral (CPL) was examined in irrigation test center at Lijian Scientific and Technological Demonstration Park, at Nanning city, China. CPL was implemented without a main/sub mainline pipe, by applying a single pivoting lateral at the corner of the plot that directly connected to the resource to convey water from the pump. The lateral moves around the corner using a rotating elbow in a quadrant pattern manually to cover the entire farm. A conventional semi-permanent system was applied for the same farm as reference. A cost analysis on the required components as well as annual operational costs was carried out for comparison and control. Results showed that a lower system component would be needed for the CPL method. Overall, more than a 15% capital cost reduction with 7% annual cost decrement was achieved for CPL in this experiment comparatively. The Catch can technique was applied to examine the CPL system&rsquo, s efficiency and 79% water distribution uniformity around the sprinkler was obtained. This new method can encourage small estate holders to switch from traditional to pressurized systems which optimizes water application costs.

This study aimed to prepare surface amino-riched passion fruit peel (DAPFP) by amination reaction with low-cost biomaterials and use it as a biosorbent to adsorb Cr (VI). The specific physicochemical and structural properties of DAPFP were characterized by SEM, EDS, XRD, TG, Zeta, XPS, and FT-IR. The effects of pH value, initial concentration, adsorption time, coexisting ions, and temperature on the adsorption of Cr (VI) were systematically investigated. The results showed that within 90 min, DAPFP could reduce the concentration of Cr (VI) solution (1 mg/L−1) to an allowable safe level of drinking water (0.05 mg/L−1) specified by the World Health Organization. The adsorption process complies with pseudo-second-order kinetics and the Langmuir isotherm model. The adsorption capacity of the prepared biosorbent could reach 675.65 mg/g−1. The results of thermodynamic studies confirmed that the adsorption process was a self-discharging heat process. DAPFP also showed good reusability, even after being used repeatedly five times, it still showed excellent adsorption performance. FT-IR and XPS analyses showed that electrostatic attraction and reduction were the main reasons for the adsorption. By virtue of its low cost and excellent adsorption performance, DAPFP has a potential practical application as an adsorbent in treating Cr (VI) containing wastewater.

Nitrogen, as a common substance in water pollution, can easily cause eutrophication of water when it is excessive. Constructed wetland, as a water treatment method that combines the common actions of plants, microorganisms, and substrates, has positive significance for the removal of nitrogen. This article reviews the nitrogen removal mechanism of each component in constructed wetlands, and the effects of temperature, carbon-nitrogen ratio, dissolved oxygen, pH, and HRT on denitrification, and proposes existing problems and research directions in constructed wetlands.

Phytoremediation is a low cost and green remediation technology, which is widely used in remediation of soil polluted by heavy metals such as cadmium and manganese. However, with the extension and implementation of phytoremediation technology in soil remediation, the disposal of a large number of hyperaccumulator plant harvests has become a hot topic in the field of phytoremediation. These harvests generally contain high concentrations of heavy metals, which can cause secondary contamination if improperly disposed of. This paper reviews the traditional disposal techniques that can be processed by composting process, compaction landfill, Liquid phase extraction, incineration, Ashing and Pyrolysis as well as emerging resource disposal technologies such as phytomining and supercritical water technology and identifies current issues with phytoremediation plants disposal. The possible research directions in the future are also prospected.

Soil heavy metal pollution is an important environmental problem threatening people’s health and sustainable economic development. Phytoremediation has become an important technology for the treatment of heavy metal contaminated soil with the characteristics of economy and environmental protection. This paper mainly analyzed the role of microbial community in heavy metal contaminated soil remediation process. Bacterias mainly strengthen the remediation effect of plants on heavy metal contaminated soil in two ways: first, bacterias have adsorption effect on heavy metals and reduce the toxicity of heavy metals to plants in soil; Two is to secrete organic acids and nutrients needed for plant growth to promote the absorption of heavy metals by hyperaccumulators.

Phytoremediation technology has become the frontier and hot research of soil heavy metal pollution areas of resource, environmental and biological sciences internationally. In view of current problems of phytoremediation technology, this paper summarizes research progress for phytoremediation technology of heavy metal contaminated soil, discussing physics, chemistry, biotechnology methods of increasing plant biomass and heavy metal accumulation. This paper focuses on the mechanism and application effects of genetic engineering technology, chelate induced technology and microbial combined phytoremediation and the future research direction of phytoremediation was also prospected.

Environmental pollution has long been a hot topic in the world, and soil heavy metal pollution is particularly prominent. In recent years, many scholars have found that the heavy metal antimony (Sb) has been widely found in the soil, which has shown many problems that cannot be ignored and has attracted widespread attention in the academic community. Article summarizes the related accumulator plant of Sb and the physical remediation technology, chemical remediation technology and phytoremediation technology of Sb contaminated soil. It is expected to provide reference for heavy metal soil remediation, and hope to find a hyperaccumulator plant that can efficiently absorb heavy metal antimony, to promote green with permanent governance effect, economical, and completely repair technology application and promotion.

s: From the beginning of the last century, the sugar industry has been undergoing reform and advance. In the global economy, the traditional sugar industry chain has been unable to promote economic development, and this development is not based blindly on raise sugar content and sugar yield of sugarcane. We should combine development with current increasingly serious environmental pollution situation. Sugar waste water and sludge and other waste contains high concentrations of organic matter and high acidity (1). According to the concept of cleaner production, make targeted help in the press, clarification, filtration, evaporation, boiling sugar crystals each step of sugar production can improve efficiency both of technology and equipment. Through closed circuit process such as condensation and cooling recycled water supply system to achieve water-saving and reducing emission, it could also help the sugar industry to achieve sustainable development.

Immobilized microorganism technology is one technique of the effective biotechnology for wastewater treatment.It has the advantages of the seed culture of bacteria with high activity and stability the reaction easily controlled low amount of sludge produced and removal the organic matter and substances difficultly degraded. The application research development of immobilized microorganism technology on wastewater treatment was analyzed through the introduction of immobilized technology and the different selection of carriers. It reviews the recent application of immobilized microorganism technology in difficult degrades wastewater, toxicity heavy metals wastewater organism wastewater, N and P wastewater.

This paper mainly summarizes the current situation of aquaculture and biological treatment technology, and summarizes the application of water treatment process and biological engineering in aquaculture wastewater treatment. Pointing that using the biochemical reaction characteristics of microbial in the purification of water quality to establish a variety of biological systems will have great research value and broad market prospects.

Biochar as a new type of adsorbent, its physical and chemical characteristics and adsorption of heavy metal has been widely studied. Based on the current studies, the article reviewed the main characteristics of biochar, its influencing factors (preparation temperature, feed stocks, functional group et.) on adsorption of heavy metals in water and its mechanism of adsorption (ion exchange adsorption, complexation, precipitation sedimentation et.). Briefly summarize unresolved issues for potential applications of biochar in the future.

Based on current literature, the article reviewed the mechanism and route of nitrogen removal, discussed the microbial species associated with nitrogen metabolism in constructed wetlands. Key unresolved issues were concluded for classical and novel nitrogen removal routes.

This paper analyzes heavy metal content in the soil of abandoned tailings and dominant plants, and absorption and bioconcentration capability as well as cumulative characteristics of the four kinds of dominant plants such as Phragmites australis, Typha angustifolia, Miscanthus sinensis, Equisetum fluviatile for heavy metals Pb, Zn, Sb, Cu, Cr, Cd, As and Mn through investigating samples of the zinc antimony ore abandoned tailings. The results manifest that investigated eight heavy metals contents in the abandoned tailings all exceed soil background values of both Guangxi and the whole nation. Abandoned tailings soil is polluted most seriously by Mn, Sb and Cd, followed by As, zinc and Pb.