From prospecting to mining: A review of enabling technologies, LCAs, and LCCAs for improved construction and demolition waste management.

Knowledge gained from anthropogenic resource prospecting can shed light on the theoretical potential of secondary resources stored in anthropogenic systems. Among others, secondary resources accumulated in the built environment account for a big fraction of anthropogenic resources, indicating great potential for urban mining. However, realizing these opportunities and developing urban mining strategies will require a comprehensive understanding of the technical viability of urban mining technologies, and how their implementation will affect the technical, economic, and environmental performance of a construction and demolition waste (C&DW) management system. To address these important issues, this review summarizes (1) current and emerging technologies that can enable the transition from anthropogenic resource prospecting to anthropogenic resource mining, (2) Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA) results to date on various C&DW management systems, (3) key parameters that govern the technical, economic, and environmental performance of a C&DW management system, and (4) opportunities for improving the methodology of LCAs and LCCAs for future C&DW management. We find that enhancing the utility of extant LCAs and LCCAs in guiding technology deployment and policy decisions can be achieved by considering key parameters governing the techno-economic and environmental performance of C&DW management. In addition, it is critical to adopt and upscale emerging technologies to increase the added value of materials or products recovered from C&DW.

Synthesis of Phenylboronic Acid-Functionalized Magnetic Nanoparticles for Sensitive Soil Enzyme Assays.

Soil enzymes, such as invertase, urease, acidic phosphatase and catalase, play critical roles in soil biochemical reactions and are involved in soil fertility. However, it remains a great challenge to efficiently concentrate soil enzymes and sensitively assess enzyme activity. In this study, we synthesized phenylboronic acid-functionalized magnetic nanoparticles to rapidly capture soil enzymes for sensitive soil enzyme assays. The iron oxide magnetic nanoparticles (MNPs) were firstly prepared by the co-precipitation method and then functionalized by (3-aminopropyl)triethoxysilane, polyethyleneimine and phenylboric acid in turn, obtaining the final nanoparticles (MNPPBA). Protein-capturing assays showed that the functionalized MNPs had a much higher protein-capturing capacity than the naked MNPs (56% versus 6%). Moreover, MNPPBA almost thoroughly captured the tested enzymes, i.e., urease, invertase, and alkaline phosphatase, from enzyme solutions. Based on MNPPBA, a soil enzyme assay method was developed by integration of enzyme capture, magnetic separation and trace enzyme analysis. The method was successfully applied in determining trace enzyme activity in rhizosphere soil. This study provides a strategy to sensitively determine soil enzyme activity for mechanistic investigation of soil fertility and plant-microbiome interaction.

Regional water pollution management pathways and effects under strengthened policy constraints: the case of Tianjin, China.

In recent years, China has attached great importance to pollution control, and national and many provinces have introduced water pollution management policies in the hope that improvements can be made. However, there is currently a lack of objective and adequate assessment of the effectiveness of water pollution management (WPM) at the regional level, especially a lack of in-depth research on the causes of improvement, key measures, and pathways of action. This paper constructs an evaluation index system based on the driver, pressure, state, impact and response (DPSIR) model and evaluates the WPM performance of Tianjin based on the five aspects comprising the DPSIR model. The results show that WPM performance in Tianjin has been commendable, improving from 76.15 points out of 100 in 2014 to 90.93 points out of 100 in 2018. The score increased more rapidly from 2016 to 2018 after the regional policy was implemented. The main reason for this encouraging phenomenon is the significant improvement in water quality. From 2016 to 2020, the closure of high pollution industrial enterprises and the regulatory management of aquaculture have significantly reduced pollutant emissions. At the same time, under the constraints of the river chief system, pollutant discharge permits, discharge standards, ecological compensation agreements on water pollution and other policies in Tianjin, the effect of pollution source control is obvious, with improved water quality and high public satisfaction.

Self-Assembled Peptide Nano-Superstructure towards Enzyme Mimicking Hydrolysis.

The structural arrangement of amino acid residues in native enzymes underlies their remarkable catalytic properties, thus providing a notable point of reference for designing potent yet simple biomimetic catalysts. Herein, we describe a minimalistic approach to construct a dipeptide-based nano-superstructure with enzyme-like activity. The self-assembled biocatalyst comprises one peptide as a single building block, readily synthesized from histidine. Through coordination with zinc ion, the peptide self-assembly procedure allows the formation of supramolecular ß-sheet ordered nanocrystals, which can be used as basic units to further construct higher-order superstructure. As a result, remarkable hydrolysis activity and enduring stability are demonstrated. Our work exemplifies the use of a bioinspired supramolecular assembly approach to develop next-generation biocatalysts for biotechnological applications.

Transcription profiling-guided remodeling of sulfur metabolism in synthetic bacteria for efficiently capturing heavy metals.

Heavy metal contamination is becoming a global problem threatening human health. Heavy metal removal by engineered microbes by cellular adsorption and uptake is a promising strategy for treatment of heavy metal contamination. However, this strategy is confronted with limited heavy metal-capturing elements. In this study, we performed a transcription profiling-guided strategy for construction of heavy metal-capturing synthetic bacteria. Transcription profiling of a heavy metal-tolerating Cupriavidus taiwanensis strain revealed up-regulation of sulfur metabolism-related operons (e.g., iscSAU and moaEDAB) by Pb2+ and Cd2+. A synthetic Escherichia coli strain, EcSSMO, was constructed by design of a synthetic sulfur metabolism operon (SSMO) based on iscSAU/moaEDAB. Biochemical analysis and X-ray photoelectron spectroscopy (XPS) revealed that the synthetic bacteria had remodeled sulfur metabolism and enhanced heavy metal-tolerating capacity, with higher surviving EcSSMO cells than the surviving control cells Ec0 (not containing SSMO) at 50 mg/L of Pb2+ and Cd2+ (>92 % versus <10 %). Moreover, EcSSMO exhibited much higher heavy metal-capturing capacity than Ec0, removing>90 % of Pb2+ and Cd2+ at 5 mg/L of Pb2+ and Cd2+, and >40 % of both heavy metals even at 50 mg/L of Pb2+ and Cd2+. This study reveals emphasizes feasibility of transcription profiling-guided construction of synthetic organisms by large-scale remodeling metabolic network.

Honeycombed Au@C-TiO2-Xcatalysts for enhanced photocatalytic mineralization of Acid red 3R under visible light.

The mineralization of organic pollutants under visible light is challenging, limiting the practical application of photocatalytic technology in wastewater treatment. To achieve the efficient mineralization of Acid red 3R (AR3R), a series of honeycombed catalysts (TiO2, C-TiO2-X, Au@TiO2 and Au@C-TiO2-X) were prepared via a facile in situ synthetic method and characterized by XRD, TEM, BET, XPS and DRS, respectively. The introduction of C and Au species promote the simultaneous generation of •O2- and •OH over Au@C-TiO2-X under visible light radiation. The Au@C-TiO2-X catalyst showed superior performance for the deep mineralization of AR3R, affording a TOC removal rate larger than 90 % within 240 min under visible light (> 420 nm). The photocatalytic degradation mechanism of AR3R is proposed according to UV-vis and in situ DRIFTS analysis. The superior photocatalytic activity of Au@C-TiO2-X is attributed to the synergistic effect of •O2- and •OH owing to C doping and Au deposition.

Study on the long-term effects of DOM on the adsorption of BPS by biochar.

Bisphenol S (BPS), regarded as a valid alternative to Bisphenol A (BPA), has been found to induce acute toxicity, genotoxicity. In this paper, BPS pollution was repaired by corn straw biochar, and the effect of dissolved organic matter (DOM) on the remediation mechanism was investigated. Different DOMs were obtained by decomposing corn straw in red soil, yellow soil and brown soil. The DOMs were characterized by Elemental analysis, Fourier infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (Uv-vis) spectroscopy, Three-dimensional excitation-emission matrix (3D-EEM). Different kinds of DOMs were added into the biochar adsorption system to determine the optimal pH, optimal dosage, equilibrium adsorption capacity, adsorption kinetics, adsorption isotherms, thermodynamic characteristics, and explore the influence mechanism of DOM on the adsorption of BPS by biochar. The results of the adsorption experiments showed that DOM would suppress the BPS adsorption capacity on biochar. In addition, the DOM, produced by decomposition of corn straw with brown soil, had the strongest inhibitory effect on adsorption, and red soil was the soil with the lowest inhibitory effect on organic pollution removal by biochar.

Effect of operating parameters on hydrothermal liquefaction of corn straw and its life cycle assessment.

As the shortage of non-renewable fossil fuels, the renewable fuels should be further developed. Biomass energy has emerged the great utilization potential, and liquefaction of biomass is a typical technology. This paper studied the effect of the operation parameters on the hydrothermal liquefaction of corn straw using a batch reactor, including liquefaction temperature, initial pressure, retention time, solvent, and catalyst. The optimal liquefaction conditions for corn straw were 300 °C under 4 MPa for 15 min using the mixture of water and methanol as the solvent. After the addition of catalyst, NKC-11 catalyst showed the excellent performance, and the primary components were phenol and derivatives, alkane, furan, and the low concentration of organic acids. Lastly, the life cycle assessment on the hydrothermal liquefaction of corn straw for bio-oil production was executed. The results of LCA suggested that a net 1.31 kg of CO2 equivalent was produced for 1 kg of bio-oil product without considering syngas, while the value changed to 13.03 kg with considering syngas. Moreover, the results of sensitivity analysis further suggested that the syngas was a key factor on the environmental impacts in the hydrothermal liquefaction of corn straw process.

Pattern of microbial community composition and functional gene repertoire associated with methane emission from Zoige wetlands, China-A review.

The Hindu-Kush Himalaya region extends over 4 million km2 across the eight countries. Knowingly, the Qinghai-Tibetan Plateau (QTP) is considered the principal altitudinal permafrost constituent on earth and is deemed as the third 'pole'. Among which, the Zoige wetlands are located in the northeastern boundary of QTP, wrapping a total area of 6180 km2 with an average altitude of 3500 m. This entire region is the hotspot for methane emission since the last decade. Given the importance of methane emission, many studies have focused on the effect of environmental fluctuations on the overall methane profile and, more recently on the methanogenic community structure. The current review summarizes recent advancements of the methanogenic community and methane profile and outlines a framework for better understanding of the microbial ecology of the Zoige wetlands, China. Moreover, as microorganisms are indispensable to biogeochemical cycles, especially for methane, they are believed to be the best indicators to identify the condition of wetlands. Hence, we suggest that, underpinning the microbial profile could help understand the status of a wetland.

Construction of Recycling Photocatalytic Gels for the Disinfection of Pathogens and Degradation of Organic Pollutants.

Bismuth oxybromide (BiOBr) nanosheets are exciting photocatalysts for microbial disinfection and organic dye degradation. However, it remains a great challenge to easily recycle these nanomaterials and improve their photocatalytic ability. Herein, we constructed a novel photocatalytic BiOBr@PAG gel containing BiOBr nanosheets and polyacrylamide gel (PAG), based on peroxydisulfate-induced polymerization reaction. The photocatalytic gel had equally distribution of BiOBr nanosheets on the surface, and could be easily recycled from water. More strikingly, the gel could also rapidly kill all tested pathogenic bacteria (i. e., Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) under irradiation. Its disinfection activity is attributed to remarkable intracellular ROS production and oxidative cell damage. Furthermore, the gel had higher photocatalytic activity than BiOBr nanosheets alone during degradation of organic dyes. This study developed a novel strategy for preparation of easy-recycling and high-efficiency photocatalytic systems for practical application in environmental treatment and medicinal disinfection.

Anaerobic digestion.

Worldwide waste generation has become a topic of interest since the accumulation of this waste has prompted environmental hazards. Among which, anaerobic digestion provides green and efficient alternate solution for removal of toxic waste and energy production. Therefore, this review emphasizes on the recent data published in 2018 on topics related to anaerobic process, enhancement of biogas production, and fermentation efficiency. Furthermore, more focus was made on the factors influencing anaerobic digestion and the effect of trace elements as ionic salts as well as nanoparticles on overall biogas production, respectively. PRACTITIONER POINTS: Anaerobic digestion provide green and efficient alternate solution to deal with. This review focused on the conditions related to anaerobic process to improve biogas production and fermentation efficiency. The trace elements were focused on how to influence biogas production during anaerobic digestion.

Liquefaction of Biomass and Upgrading of Bio-Oil: A Review.

The liquefaction of biomass is an important technology to converse the biomass into valuable biofuel. The common technologies for liquefaction of biomass are indirect liquefaction and direct liquefaction. The indirect liquefaction refers to the Fischer-Tropsch (F-T) process using the syngas of biomass as the raw material to produce the liquid fuel, including methyl alcohol, ethyl alcohol, and dimethyl ether. The direct liquefaction of biomass refers to the conversion biomass into bio-oil, and the main technologies are hydrolysis fermentation and thermodynamic liquefaction. For thermodynamic liquefaction, it could be divided into fast pyrolysis and hydrothermal liquefaction. In addition, this review provides an overview of the physicochemical properties and common upgrading methods of bio-oil.

New Developments in Material Preparation Using a Combination of Ionic Liquids and Microwave Irradiation.

During recent years, synthetic methods combining microwaves and ionic liquids became accepted as a promising methodology for various materials preparations because of their high efficiency and low energy consumption. Ionic liquids with high polarity are heated rapidly, volumetrically and simultaneously under microwave irradiation. Hence, combination of microwave irradiation as a heating source with ionic liquids with various roles (e.g., solvent, additive, template or reactant) opened a completely new technique in the last twenty years for nanomaterials and polymers preparation for applications in various materials science fields including polymer science. This review summarizes recent developments of some common materials syntheses using microwave-assisted ionic liquid method with a focus on inorganic nanomaterials, polymers, carbon-derived composites and biomass-based composites. After that, the mechanisms involved in microwave-assisted ionic-liquid (MAIL) are discussed briefly. This review also highlights the role of ionic liquids in the reaction and crucial issues that should be addressed in future research involving this synthesis technique.

Coupling Plasmonic and Cocatalyst Nanoparticles on N⁻TiO2 for Visible-Light-Driven Catalytic Organic Synthesis.

The use of the surface plasmon resonance (SPR) effect of plasmonic metal nanocomposites to promote photocarrier generation is a strongly emerging field for improving the catalytic performance under visible-light irradiation. In this study, a novel plasmonic photocatalyst, AuPt/N⁻TiO2, was prepared via a photo-deposition⁻calcination technique. The Au nanoparticles (NPs) were used herein to harvest visible-light energy via the SPR effect, and Pt NPs were employed as a cocatalyst for trapping the energetic electrons from the semiconductor, leading to a high solar-energy conversion efficiency. The Au2Pt2/N⁻TiO2 catalyst, herein with the irradiation wavelength in the range 460⁻800 nm, exhibited a reaction rate ~24 times greater than that of TiO2, and the apparent quantum yield at 500 nm reached 5.86%, indicative of the successful functionalization of N⁻TiO2 by the integration of Au plasmonic NPs and the Pt cocatalyst. Also, we investigated the effects of two parameters, light source intensity and wavelength, in photocatalytic reactions. It is indicated that the as-prepared AuPt/N⁻TiO2 photocatalyst can cause selective oxidation of benzyl alcohol under visible-light irradiation with a markedly enhanced selectivity and yield.

Bisphenol S Adsorption Behavior on Ferralsol and Biochar Modified Soil with Dissolved Organic Matter.

Bisphenol S (BPs) has been found in a variety of common consumer products surrounding human living, despite the fact that it could damage the human digestive system and genital system. In China, straw-returning to the field is a common soil improvement technology used to increase the concentration of dissolved organic matter (DOM), which plays an important role in the natural environment as a microreactor of contaminants. Additionally, the biochar obtained by the straw is an effective soil conditioner. DOM is a key influencing factor when biochar is employed as the conditioner of BPs contaminated soil. However, the BPs adsorption behavior on the Ferralsol affected by DOM and biochar is also unclear. Hence, DOM was prepared and the effect of DOM on the BPs adsorption behavior on soil and biochar modified soil was investigated. DOM was characterized by Elemental analysis, Fourier transforming infrared spectra (FT-IR), and three-dimensional excitation-emission matrix spectra (3D-EEM). The results of the adsorption experiments indicated that both biochar and DOM could improve the BPs adsorption capacity in Ferralsol, while DOM suppressed the BPs adsorption capacity of biochar modified soil, indicating that DOM and BPs could not be applied at the same time for BPs adsorption.

Efficient Synthesis of Furfural from Biomass Using SnCl4 as Catalyst in Ionic Liquid.

Furfural is a versatile platform molecule for the synthesis of various chemicals and fuels, and it can be produced by acid-catalyzed dehydration of xylose derived from renewable biomass resources. A series of metal salts and ionic liquids were investigated to obtain the best combination of catalyst and solvent for the conversion of xylose into furfural. A furfural yield of 71.1% was obtained at high xylose loading (20 wt%) from the single-phasic reaction system whereby SnCl4 was used as catalyst and ionic liquid 1-ethyl-3-methylimidazolium bromide (EMIMBr) was used as reaction medium. Moreover, the combined catalyst consisting of 5 mol% SnCl4 and 5 mol% MgCl2 also produced a high furfural yield (68.8%), which was comparable to the furfural yield obtained with 10 mol% SnCl4. The water⁻organic solvent biphasic systems could improve the furfural yield compared with the single aqueous phase. Although these organic solvents could form biphasic systems with ionic liquid EMIMBr, the furfural yield decreased remarkably compared with the single EMIMBr phase. Besides, the EMIMBr/SnCl4 system with appropriate water was also efficient to convert xylan and lignocellulosic biomass corn stalk into furfural, obtaining furfural yields as high as 57.3% and 54.5%, respectively.

Mercury adsorption to aged biochar and its management in China.

Biochar is frequently applied for the reduction of mercury (Hg) migration in soil; however, most of the studies only focused on the adsorption capacity evaluation of fresh biochar. We investigated the Hg adsorption capacities of biochar prepared from wheat straw, corn straw, and sunflower seed shells. Biochar aging was simulated via natural aging, high-temperature aging, and freeze-thaw aging. The adsorption capacities of all the aged biochar were increased, and wheat straw biochar and seed shells biochar treated with high-temperature aging (wBC-Ha500 and sBC-Ha600) and corn straw biochar treated with freeze-thaw aging (cBC-Fta500) showed an observable improvement on the equilibrium adsorption amounts. The kinetics of the fresh biochar samples fitted the pseudo-first-order kinetic model and the pseudo-second-order kinetic model, while the kinetics of the aged biochar samples fitted the pseudo-second-order kinetic model. Biochar adsorption capacity increased with higher initial concentrations and increasing temperatures. Elemental analysis, Fourier-transform infrared spectroscopy (FT-IR) spectra, cation-exchange capacity (CEC), surface area (SA), zeta potential, and X-ray photoelectron spectroscopy (XPS) showed that the aging mechanism consisted of hydroxylation and carboxylation caused by the functional groups on the biochar surface. According to the different climatic zones in China, wheat straw biochar and seed shell biochar are suitable for the tropical zone and the subtropical zone, while corn straw biochar is more suitable for the cold and the mid-temperate zones.

Effective removal of Cr(vi) from aqueous solution by biochar supported manganese sulfide.

In order to remove hexavalent chromium (Cr(vi)) efficiently and simplify the adsorbent preparation process, we employed a single step method to prepare a new biochar supported manganese sulfide material. The nanoscale MnS particles were highly soldered on the biochar support surface, and this adsorbent displayed the effective removal of Cr(vi) (98.15 mg L-1) via synergistic effect between adsorption and reduction/precipitation under weak acid conditions (pH = 5.0-6.0). The adsorption kinetic data were described well by the pseudo second-order kinetic model, suggesting that the reaction process was a chemisorption process. The adsorption isotherm data were described well by the Redlich-Peterson model, further suggesting that this reaction was a hybrid chemical reaction-sorption process. In addition, the Dubinin-Radushkevich isotherm model with 8.28, 8.57, and 12.91 kJ mol-1 adsorption energy also suggests that it was a chemisorption process. The simple and eco-friendly preparation process, low-cost, and the high removal efficiency could make it a promising material for the purification of Cr(vi)-contaminated wastewater.

Analysis of soil risk characteristics by comprehensive assessment in an industrial area of China.

Soil pollution in industrial areas poses a major challenge for China's environmental protection. In this study, comprehensive assessment methodologies for soil risk in industrial areas were developed. The comprehensive assessment covered ecological and human health risks of soil pollution, as well as vulnerability of different types of risk receptors. Comprehensive ecological risk assessment integrated potential ecological risk assessment and landscape vulnerability assessment. Comprehensive social risk assessment specialized human health risk assessment by introducing spatial distribution of population. A typical industrial area in China was studied, and the quantitative and spatial assessments of the comprehensive soil risk were presented. The results showed that the spatial distribution of soil comprehensive ecological and social risks differed. High-risk areas of soil comprehensive ecological risk in the study area were mainly farmlands and nature reserves. Inhabited areas and industrial zones were less affected by comprehensive ecological risk of soil. By contrast, the spatial distribution of soil comprehensive social risk and human activities showed a clear trend of convergence. Vulnerability assessment of the risk receptors provided a suitable complement to the risk assessment of soil pollution.

Anaerobic Process.

A review of the literatures published in 2017 on topics relating to anaerobic process issues in the improvement of biogas production and fermentation efficiency of various kinds of organic waste. New process methodology and technology of digestion is also presented. This review is divided into the following sections: pretreatment, organic waste and co-digestion, multiple-stage process, process methodology and technology.