Fines migration from soil daily covers in Hong Kong landfills

Laboratory tests using 240 mm diameter columns were conducted to study fines migration in conditions that simulate daily soil covers in Hong Kong municipal solid waste landfills. Five factors suspected to affect fines migration were examined: moisture content at soil compaction, overburden pressure, pumping rate, cover thickness, and soil-waste interface condition. The results show that moisture content at compaction, cover thickness, and soil-waste interface are the most influential parameters on fines migration in completely decomposed granite daily covers. The measured equivalent sizes of migratory fines from the soil covers were in the range of 4–140 μm. The majority of migratory fines migrated during first permeations, representing 64–86% of the total by mass. Larger particles tended to migrate from the soil mass during the saturation process. In a typical run, about 0.0018% of the total cover soil (by dry weight) was washed out during a typical 1 h rainfall event. The results of the laboratory studies point to important engineering implications on the operation of local MSW landfills regarding the use of sandy daily covers.     

Fenton based remediation of polycyclic aromatic hydrocarbons-contaminated soils

This paper aims to review the applications of Fenton based treatments specifically for polycyclic aromatic hydrocarbons-contaminated soils. An overview of the background and principles of Fenton treatment catalysed by both homogenous (conventional and modified Fenton) and heterogeneous (Fenton-like) catalysts is firstly presented. Laboratory and field soil remediation studies are then discussed in terms of efficiency, kinetics and associated factors. Four main scopes of integrated Fenton treatments, i.e. physical-Fenton, biological-Fenton, electro-Fenton and photo-Fenton are also reviewed in this paper. For each of these integrated remediation technologies, the theoretical background and mechanisms are detailed alongside with achievable removal efficiencies for polycyclic aromatic hydrocarbons in contaminated soils compared to sole Fenton treatment. Finally, the environmental impacts of Fenton based soil treatments are documented and discussed.     

The current municipal solid waste management situation in Tibet

The Tibetan Plateau has an average altitude of more than 4,000 m. The total area of Tibetan Plateau is 2,400,000 km2, which occupies 25% of the area of China. Due to the high altitude, the environment has low atmospheric pressure, low oxygen content, and low temperature, and is also fragile. Investigations concerning MSW generation and characteristics, MSW management, collection and transportation, and treatment and disposal of MSW covered four representative cities, including the urban areas of Lhasa city, Shigatse, Nedong of Lhoka and Bayi of Nyingtri. The results show that MSW generation in the urban areas of Lhasa city and Tibet were 450 t/d and 3,597 t/d, respectively, in 2006. However, accelerated economic development and flourishing tourism caused by the opening of the Qinghai-Tibet Railway (QTR) have greatly increased solid waste generation to a new high. It is predicted that MSW generation in Tibet will reach 4,026 t/d in 2010 and 4,942 t/d in 2020. MSW management and disposal lag behind MSW generation due to a number of factors such as equipment shortage, insufficient maintenance, exhaustion of waste treatment capacity and low recycling efficiency. Still, MSW in most areas is dumped in the open with no controls. Because no appropriate collection and treatment systems for leachate and landfill gas exist, untreated leachate is discharged directly into the environment, causing serious secondary pollution. Some suggestions on improving the MSW management system are presented in this paper.     

Perceptions of implied hazard for visual and auditory alerting signals

Visual and auditory alerts are increasingly important and have many applications, particularly in the presentation of hazard information in transportation and many industrial systems. This paper is concerned with the factors that govern the relative effectiveness of alerting signals involving various combinations of visual and auditory signals. The visual variables were colour, flash rate, and flash mode, combined with or without an auditory alarm. It was found that the subjects associated different levels of hazard with different alerting light colours, flash rates, flashing modes, and with combinations of auditory and visual alerts. A red flashing light was perceived as the most effective hazard warning colour, with yellow and blue warning lights indicative of less hazardous situations. The faster the flash rate, the greater is the hazard perceived. A flash rate of 60 fpm (flashes per minute) was not as effective as the rates of 180 and 240 fpm, and 240 fpm was the most effective. This implies that hazard warning signal should flash at well above 60 fpm. Having a breakup in the flashing pattern so as to provide a double or triple flash mode also increases the effectiveness of the signal. There were significant interactions between the alert variables used. The difference in perceived hazard levels for the colours blue and yellow were statistically non significant, but blue was more effective in conveying hazard message than yellow at the high flash rates. When accompanied with auditory alarms, blue and yellow were perceived to convey the same perception level of hazard as red without auditory alarms. The effect of colour on perceived hazard was also found to vary with flash mode. As compared to either visual signal alone or a visual signal with other types of acoustic alarms, a siren type of auditory alarm was found more effective for eliciting perception of hazards. There was evidence that presenting alerting signal in triple-flash mode and at high flash rate could be annoying and might not help improving hazard awareness.     

Study of the PM<Subscript>10</Subscript> concentration variations along two intra-urban roads within a compact city

Eighty-five measurement campaigns were performed repeatedly to compare the concentration variation profiles along two intra-urban roads—one with open configuration and the other with street canyon effect. Fixed-effects panel data analysis was applied for formulating a model to express the PM₁₀ concentrations along intra-urban roads in terms of parameters like nearby central monitoring data, traffic counts and meteorological conditions with an objective to analyze the PM₁₀ concentration variation patterns along the two roads. Our findings reveal that traffic intensity and metrological conditions exert influence on concentration variation for both types of road configurations while wind velocity only affect the pollutants removal effectiveness of open road configuration. Further analysis unveils that the PM₁₀ concentration distribution profiles within a compact city environment are not always uniform and are dependent on the road configuration. Considerable PM₁₀ concentration differences were observed along the street canyon, and 70% of their variations are attributed to variations in their road aspect ratios. By contrast, no significant concentration difference is observed at open road configurations.     

评估可离子化有机化合物的生物累积潜力：当前的认知和研究的重点

本研究的目的是回顾目前关于可离子化有机化合物(IOCs)的生物累积潜力的认知,重点讨论鱼类经验数据的有效性。IOCs在鱼体内的生物积累潜力可以很好地表征为：依赖pH的鳃摄取和排泄,肠道吸收和磷脂吸附(膜-水分区)。关键的挑战包括缺乏关于IOCs生物转化和血浆结合的经验数据。鱼拥有多种蛋白质,可以在细胞膜上传输IOCs。然而,除了少数情况下,这种传输对环境污染物的吸收和积累的意义是未知的。本文提出了2个研究案例。第一个描述了pH值和生物转化对有机酸和碱的生物富集的建模作用,而第二个则采用了一个更新的模型来研究导致全氟烷基酸积累的因素。全氟化烷基酸个案研究是值得关注的,因为它说明了膜转运蛋白在肾脏中可能具有的重要性,并强调了交叉比对方法(read-across approaches)的潜在价值。认识到当前需要对IOCs进行生物累积危害评估和生态风险评估,作者提供了一个分层策略,从保守的假设(模型和相关数据)到需要化学特定信息的更复杂的模型。
精选自Armitage, J. M., Erickson, R. J., Luckenbach, T., Ng, C. A., Prosser, R. S., Arnot, J. A., Schirmer, K. and Nichols, J. W. (2017), Assessing the bioaccumulation potential of ionizable organic compounds: Current knowledge and research priorities. Environmental Toxicology and Chemistry, 36: 882–897. doi: 10.1002/etc.3680
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3680/full
     

Single-Plant Biocomposite from Ricinus Communis: Preparation, Properties and Environmental Performance

A single-plant biobased composite material was prepared from fibre and matrix constituents produced from the castor plant, ricinus communis. It is shown that the mechanical properties of the castor plant fibres are comparable to those of other bast fibres and that the stiffness and strength characteristics of the castor fibre/polyamide 11 biocomposite compare well with those of other natural fibre composites. By using a biobased thermoplastic matrix material the reliance on non-renewable feedstock sources is reduced and end-of-lifetime recyclability is improved. The analysis of the environmental performance of the new castor plant composite suggests that the biobased material has great potential as a sustainable alternative replacing glass fibre-reinforced plastics.     

A hybrid approach for environmental impact evaluation of design options

The strengthened environmental regulatory requirements and general awareness of the need for environmental conservation worldwide, design for environment has become a key design criterion in new product development processes. Due to their resources-consuming attribute and the prerequisite expert knowledge in environmental sciences for the impacts interpretations, the existing forms of product-oriented environmental impact assessment methods are impractical to be adopted by product designers in small-and-medium enterprises. Life Cycle Assessment (LCA) is a generally accepted quantitative approach to assess a product’s environmental impact. However, a full LCA study often requires a considerable amount of data and therefore, it is regarded as not a handy tool for product design evaluations particularly at the initial design stage. This leads to our intention to develop an immediately applicable approach for decision-makers to evaluate the design options. The proposed approach integrates Analytic Hierarchy Process and Fuzzy Theory, with Evidential Reasoning (ER) to support the environmental impact evaluations of design options. A case study is carried out to demonstrate its applicability to prioritize the environmental impact of various design options. A symmetrical triangular distribution is introduced for calculating the expected utility and for testing the sensitivity of results.     

Concentrations of cyclic volatile methylsiloxanes in biosolid amended soil,influent, effluent,receiving water,and sediment of wastewater treatment plants in Canada

A comprehensive surveillance program was conducted to determine the occurrence of three cyclic volatile methylsiloxanes (cVMS) octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) in environmental compartments impacted by wastewater effluent discharges. Eleven wastewater treatment plants (WWTPs), representative of those found in Southern Ontario and Southern Quebec, Canada, were investigated to determine levels of cVMS in their influents and effluents. In addition, receiving water and sediment impacted by WWTP effluents, and biosolid-amended soil from agricultural fields were also analyzed for a preliminary evaluation of the environmental exposure of cVMS in media impacted by wastewater effluent and solids. A newly-developed large volume injection (septumless head adapter and cooled injection system) gas chromatography – mass spectrometry method was used to avoid contamination originating from instrumental analysis. Concentrations of D4, D5, and D6 in influents to the 11 WWTPs were in the range 0.282–6.69 μg L⁻¹, 7.75–135 μg L⁻¹, and 1.53–26.9 μg L⁻¹, respectively. In general, wastewater treatment showed cVMS removal rates of greater than 92%, regardless of treatment type. The D4, D5, and D6 concentration ranges in effluent were <0.009–0.045 μg L⁻¹, <0.027–1.56 μg L⁻¹, and <0.022–0.093 μg L⁻¹, respectively. The concentrations in receiving water influenced by effluent, were lower compared to those in effluent in most cases, with the ranges <0.009–0.023 μg L⁻¹, <0.027–1.48 μg L⁻¹, and <0.022–0.151 μg L⁻¹ for D4, D5, and D6, respectively. Sediment concentrations ranged from <0.003–0.049 μg g⁻¹ dw, 0.011–5.84 μg g⁻¹ dw, and 0.004–0.371 μg g⁻¹ dw for D4, D5, and D6, respectively. The concentrations in biosolid-amended soil, having values of <0.008–0.017 μg g⁻¹ dw, <0.007–0.221 μg g⁻¹ dw, and <0.009–0.711 μg g⁻¹ dw for D4, D5, and D6, respectively, were lower than those in sediment impacted by wastewater effluent in most cases. In comparison with the no-observed-effected concentrations (NOEC) and IC50 (concentration that causes 50% inhibition of the response) values, the potential risks to aquatic, sediment-dwelling, and terrestrial organisms from these reported concentrations are low.     

Hydrous ferric oxide nanoparticles hosted porous polyethersulfone adsorptive membrane: chromium (VI) adsorptive studies and its applicability for water/wastewater treatment

In this present study, adsorptive membranes for Cr(VI) ion removal were prepared by blending polyethersulfone (PES) with hydrous ferric oxide (HFO) nanoparticles (NPs). The effects of HFO NPs to PES weight ratio (0–1.5) on the physicochemical properties of the resultant HFO/PES adsorptive membranes were investigated with respect to the surface chemistry and roughness as well as structural morphologies using different analytical instruments. The adsorptive performance of the HFO NPs/PES membranes was studied via batch adsorption experiments under various conditions by varying solution pH, initial concentration of Cr(VI), and contact time. The results showed that the membrane made of HFO/PES at a weight ratio of 1.0 exhibited the highest adsorption capacity which is 13.5 mg/g. Isotherm and kinetic studies revealed that the mechanism is best fitted to the Langmuir model and pseudo-second-order model. For filtration of Cr(VI), the best promising membranes showed improved water flux (629.3 L/m² h) with Cr(VI) ion removal of 75%. More importantly, the newly developed membrane maintained the Cr(VI) concentration below the maximum contamination level (MCL) for up to 9 h.