Utilization of industrial by-products for the production of controlled low strength materials (CLSM)

Industrial by-products were used for the production of controlled low-strength material (CLSM). CLSM, also known as 'flowable fill' is used as a replacement of compacted soil in cases where the application of the latter is difficult or impossible. The low mechanical requirements (compared with structural concrete) enable the use of industrial by-products for the production of CLSM. In this study cement kiln dust, asphalt dust, coal fly ash, coal bottom ash and quarry waste were tested for the possibility of producing CLSM with large proportions of those wastes. The results showed that in most cases, CLSM with good properties could be made with significant amounts of dust (25-50%w), especially when the dust has some cementing or pozzolanic potential as do fly ash and cement kiln dust.     

A grey-relation-based method (GRM) for thermogravimetric (TG) data analysis

Journal of Material Cycles and Waste Management - Thermogravimetric analyzer was applied to analyze 22 solid materials and their mixtures at a heating rate of 10 K min−1...     

A novel method for the preparation of silver/chitosan-O-methoxy polyethylene glycol core shell nanoparticles

Uniformly sized silver/chitosan-O-methoxy polyethylene glycol (chitosan-O-MPEG) core shell nanoparticles with different degree of substitution were synthesized. Thus, N-phthaloyl chitosan is reacted with polyethylene glycol monomethyl ether iodide in the presence of silver oxide by the following steps. At first, amino groups of chitosan are protected by fourfold excess of phthalic anhydride. Then N-phthaloyl chitosan is reacted with an appropriate amount of monomethyl ether iodide in the presence of silver oxide and lastly N-phthaloyl groups are removed to yield silver/chitosan-O-MPEG core shell nanoparticles. Structure of prepared silver/chitosan-O-MPEG core shell nanoparticles have been characterized by UV/Vis spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), X-ray diffraction, and scan electron microscopy (SEM-EDX). Experimental results revealed that the prepared silver core particles had the size 18?±?2?nm. Core shell structure with chitosan-O-MPEG-coating had the size 40?±?2?nm.     

A novel mechanical plant compression system for biomass fuel and acquisition of squeezed liquid with water-soluble lignin as anti-virus materials

Journal of Material Cycles and Waste Management - Plant biomass could be a viable alternative renewable resource, but the moisture content must be reduced to use it as fuel. Mechanical compression...     

聚乙烯亚胺改性UiO-66-NH2对水中U(Ⅵ)的吸附

采用聚乙烯亚胺(PEI)改性氨基化锆基金属有机骨架材料(UiO-66-NH₂)制备了UiO-66-NH₂/PEI,利用XRD、SEM和FTIR对产物进行了表征,并将其用于吸附水中的U(Ⅵ)。考察了UiO-66-NH₂/PEI吸附U(Ⅵ)的影响因素,并研究了吸附动力学和等温线。实验结果表明:UiO-66-NH₂/PEI对U(Ⅵ)具有良好的吸附效果,PEI与UiO-66-NH₂质量比为30%、溶液pH为6、吸附剂投加量为80 mg/L、吸附时间为120 min、初始U(Ⅵ)质量浓度为10 mg/L时,UiO-66-NH₂/PEI对U(Ⅵ)的去除率达98.2%(303 K下);UiO-66-NH₂/30%PEI对U(Ⅵ)的吸附在60 min内达到平衡,吸附过程符合准二级动力学模型和Langmuir模型,最大吸附量达452.49 mg/g。     

Photocatalytic Degradation of Poly(Vinyl Alcohol) on Pt/TiO<Subscript>2</Subscript> with Fenton Reagent

In this research Fenton reagent (Fe²⁺/H₂O₂) was investigated as oxidants to degrade poly (vinyl alcohol) (PVA). The role of nano-TiO₂ photocatalyst was discussed as an additive in Fenton reagent (Fe²⁺/H₂O₂). Pt/TiO₂ composites were also synthesized by photo-reaction to be used as additive in Fenton reagent. The rapid degradation of PVA was obtained when Pt/TiO₂ composites served as photocatalyst. The different photocatalytic efficiency of Pt/TiO₂- Fenton reagent (Fe²⁺/H₂O₂) was studied compared with TiO₂- Fenton reagent (Fe²⁺/H₂O₂) during the degradation of PVA.     

A novel additive for the reduction of acid gases and NO(x) in municipal waste incinerator flue gas.

The reduction of SO2, HCl, and NO(x) concentrations using calcium magnesium acetate (CMA) as a novel sorbent in a simulated municipal waste incinerator flue gas was investigated. The reduction of individual SO2, HCl, and NO(x) concentrations was tested at 850 degrees C and it was found that CMA could reduce the SO2 concentration by 74%, HCl concentration by 64%, or NO(x) concentration by 94%. It was observed that individual SO2 or HCl capture increased with increasing initial oxygen concentration in the reacting gas or increasing sorbent input. NO(x) reduction decreased with increasing initial oxygen concentration in the reacting gas. The simultaneous reduction of SO2, HCl, and NO(x) concentrations by CMA was also investigated. It was found that CMA could simultaneously capture 60% SO2 and 61% HCl and reduce NO(x) concentrations by 26%, when the initial oxygen concentration in the reacting gas was 4%. During the simultaneous reduction of SO2, HCl, and NO(x), it was noted that as the initial oxygen concentration in the reacting gas increased, the efficiency of SO2 capture increased too, but the efficiency of HCl capture and the efficiency of NO(x) destruction decreased.     

Poly (Vinyl Alcohol) Composite Membrane with Polyamidoamine Dendrimers for Efficient Separation of CO2/H2 and CO2/N2

Journal of Polymers and the Environment - Although polyvinyl alcohol (PVA) membranes are commonly used for CO2 separation, there is still large development space in mechanical properties and high...     

Development of a simple and sensitive method for the characterization of odorous waste gas emissions by means of solid-phase microextraction (SPME) and GC-MS/olfactometry

A solid-phase microextraction (SPME) method has been developed for the extraction of odorous compounds from waste gas. The enriched compounds were characterized by gas chromatography-mass spectrometry (GC-MS) and gas chromatography followed by simultaneous flame ionization detection and olfactometry (GC-FID/O). Five different SPME fiber coatings were tested, and the carboxen/polydimethylsiloxane (CAR/PDMS) fiber showed the highest ability to extract odorous compounds from the waste gas. Furthermore, parameters such as exposure time, desorption temperature, and desorption time have been optimized. The SPME method was successfully used to characterize an odorous waste gas from a fat refinery prior to and after waste gas treatment in order to describe the treatment efficiency of the used laboratory scale plant which consisted of a bioscrubber/biofilter combination and an activated carbon adsorber. The developed method is a valuable approach to provide detailed information of waste gas composition and complements existing methods for the determination of odors. However, caution should be exercised if CAR/PDMS fibers are used for the quantification of odorous compounds in multi-component matrices like waste gas emissions since the relative affinity of each analyte was shown to differ according to the total amount of analytes present in the sample.     

Pseudomonas sp. (Strain 10–1B): A potential inoculum candidate for green and sustainable remediation

Soil pollution caused by polycyclic aromatic hydrocarbons (PAHs) is a consequence of various industrial processes which destabilizes the ecosystem. Bioremediation by bacteria is a cost‐effective and environmentally safe solution for reducing or eliminating pollutants in soils. In the present study, we artificially polluted agricultural soil with used automobile engine oil with a high PAH content and then isolated bacteria from the soil after 10 weeks. Pseudomonas sp. strain 10–1B was isolated from the bacterial community that endured this artificial pollution. We sequenced its genomic DNA on Illumina MiSeq sequencer and evaluated its ability to solubilize phosphate, fix atmospheric nitrogen, and produce indoleacetic acid, in vitro, to ascertain its potential for contribution to soil fertility. Its genome annotation predicted several dioxygenases, reductases, ferredoxin, and Rieske proteins important in the ring hydroxylation initiating PAH degradation. The strain was positive for the soil fertility attributes evaluated. Such combination of attributes is important for any potential bacterium partaking in sustainable bioremediation of PAH‐polluted soil.     

Model simulations for describing water transport in a landfill with bottom ash from a municipal solid waste incinerator (MSWI): model validation and scenarios.

In the present study the water movement in a bottom ash landfill from a municipal solid waste incinerator (MSWI) was investigated. The pore regime of such landfills consists of macropores (with diameter > 50 microm), which make up about two-thirds of the total porosity and micropores. The program MACRO, which describes flow through porous media and takes both macro- and micropore flows into account, was applied. The model was calibrated with a time series from the landfill Riet, near Winterthur in Switzerland. In the present study the model was recalibrated at a time series for 1 year. With this scenario the influence of an expected reduction or increase of the porosity on leachate behaviour of such landfills over a long time (> 100 years) was studied ('long-term behaviour'). It has been shown that reliable information about water percolation can only be provided by obtaining more information about the hydraulic structure of such landfills. In particular, the number of macropores and the porosity exert great influence on the water movement.     

PFAS Experts Symposium: Statements on regulatory policy,chemistry and analytics,toxicology, transport/fate,and remediation for per‐ and polyfluoroalkyl substances (PFAS) contamination issues

Sixty leading members of the scientific, engineering, regulatory, and legal communities assembled for the PFAS Experts Symposium in Arlington, Virginia on May 20 and 21, 2019 to discuss issues related to per‐ and polyfluoroalkyl substances (PFAS) based on the quickly evolving developments of PFAS regulations, chemistry and analytics, transport and fate concepts, toxicology, and remediation technologies.  The Symposium created a venue for experts with various specialized skills to provide opinions and trade perspectives on existing and new approaches to PFAS assessment and remediation in light of lessons learned managing other contaminants encountered over the past four decades. The following summarizes several consensus points developed as an outcome of the Symposium:

• Regulatory and policy issues: The response by many states and the US Environmental Protection Agency (USEPA) to media exposure and public pressure related to PFAS contamination is to relatively quickly initiate programs to regulate PFAS sites. This includes the USEPA establishing relatively low lifetime health advisory levels for PFAS in drinking water and even more stringent guidance and standards in several states. In addition, if PFAS are designated as hazardous substances at the federal level, as proposed by several Congressional bills, there could be wide‐reaching effects including listing of new Superfund sites solely for PFAS, application of stringent state standards, additional characterization and remediation at existing sites, reopening of closed sites, and cost renegotiation among PRPs.
• Chemistry and analytics: PFAS analysis is confounded by the lack of regulatory‐approved methods for most PFAS in water and all PFAS in solid media and air, interference with current water‐based analytical methods if samples contain high levels of suspended solids, and sample collection and analytical interference due to the presence of PFAS in common consumer products, sampling equipment, and laboratory materials.
• Toxicology and risk: Uncertainties remain related to human health and ecological effects for most PFAS; however, regulatory standards and guidance are being established incorporating safety factors that result in part per trillion (ppt) cleanup objectives. Given the thousands of PFAS that may be present in the environment, a more appropriate paradigm may be to develop toxicity criteria for groups of PFAS rather than individual PFAS.
• Transport and fate: The recalcitrance of many perfluoroalkyl compounds and the capability of some fluorotelomers to transform into perfluoroalkyl compounds complicate conceptual site models at many PFAS sites, particularly those involving complex mixtures, such as firefighting foams. Research is warranted to better understand the physicochemical properties and corresponding transport and fate of most PFAS, of branched and linear isomers of the same compounds, and of the interactions of PFAS with other co‐contaminants such as nonaqueous phase liquids. Many PFAS exhibit complex transport mechanisms, particularly at the air/water interface, and it is uncertain whether traditional transport principles apply to the ppt levels important to PFAS projects. Existing analytical methods are sufficient when combined with the many advances in site characterization techniques to move rapidly forward at selected sites to develop and test process‐based conceptual site models.
• Existing remediation technologies and research: Current technologies largely focus on separation (sorption, ion exchange, or sequestration). Due to diversity in PFAS properties, effective treatment will likely require treatment trains. Monitored natural attenuation will not likely involve destructive reactions, but be driven by processes such as matrix diffusion, sorption, dispersion, and dilution.

The consensus message from the Symposium participants is that PFAS present far more complex challenges to the environmental community than prior contaminants. This is because, in contrast to chlorinated solvents, PFAS are severely complicated by their mobility, persistence, toxicological uncertainties, and technical obstacles to remediation—all under the backdrop of stringent regulatory and policy developments that vary by state and will be further driven by USEPA. Concern was expressed about the time, expense, and complexity required to remediate PFAS sites and whether the challenges of PFAS warrant alternative approaches to site cleanups, including the notion that adaptive management and technical impracticability waivers may be warranted at sites with expansive PFAS plumes. A paradigm shift towards receptor protection rather than broad scale groundwater/aquifer remediation may be appropriate.