14 Oct 2019, 1:59 am
Waste Management & Research
Waste Management &Research, Ahead of Print.
In this study, we examine the economic and environmental significance associated with the implementation of an EU waste-separated collection scheme in a developing context – Lebanon. Two scenarios, S1 and S2, representing different intensities of source segregation were analysed. In S1, the average source segregation intensity reached 25% and 13% for the Italian test area and Lebanese test area, respectively. In S2, source segregation intensity increased to 48% and 68% for the Italian and Lebanese test areas, respectively. Passing from S1 to S2 increased collection costs significantly, up to 44% with greater increases in the Italian test area where labour cost is higher. In both areas, environmental impacts decreased with greater source segregation intensity. Savings in the climate change impact and stratospheric ozone depletion potential were lower under the Lebanese test area in comparison with the Italian test area. In contrast, savings in freshwater eutrophication and acidification impact were lower for the Italian test area. The increase in the source segregation intensity resulted in maximum savings for the depletion of abiotic resources, 74% to 77% and 79% to 80% in a developing and developed context, respectively.
14 Oct 2019, 1:58 am
Waste Management & Research
Waste Management &Research, Ahead of Print.
14 Oct 2019, 1:55 am
Waste Management & Research
Waste Management &Research, Ahead of Print.
Carcass waste recycling exerts an important influence on preventing epidemic diseases, improving the ecological environment, and promoting sustainable development of the livestock industry although it has rarely aroused widespread attention throughout the world. Based on the data of 470 households engaged in breeding pigs in Hebei, Henan, and Hubei, China, and considering dead pigs as an example, this study employed the Double Hurdle model to assess impact of risk perception on household dead pig recycling behaviour and further tested the moderating effects of environmental regulation on the impact of risk perception on household dead pig recycling behaviour. The results show that: (1) Risk perception has a positive and significant influence on household dead pig recycling behaviour; however, this influence is mainly caused by households’ production and public health safety risk perceptions. Food and ecological safety risk perceptions have no significant influence on household dead pig recycling behaviour. (2) Environmental regulation has enhanced moderating effects on the impact of risk perception on household dead pig recycling behaviour, but the moderating effects mainly arose from imperative, guiding, and voluntary regulations. A moderating effect of incentive regulation is not obvious. (3) The moderating effects of environmental regulations present strong heterogeneity when different breeding scales and recycling technical attributes are considered. Finally, some policy implications, such as improving households’ risk perception level, enhancing environmental regulation intensity, and classifying to formulate measures, are proposed.
14 Oct 2019, 1:48 am
Waste Management & Research
Waste Management &Research, Ahead of Print.
Septic systems are typically designed to treat domestic wastewater from households without access to centralized facilities. The installation of a food waste disposer (FWD) may increase the discharge of food waste (FW) into the wastewater; therefore, the installation of a FWD is discouraged in households that have a septic system. This study was conducted to determine how a typical dose of FW from a FWD can affect the performance of a septic system in terms of sewage treatment and solids accumulation. A 20-L control tank was compared with an experiment tank to which FW was added, increasing the amount of total suspended solids (TSS) by 31.3% and total chemical oxygen demands by 46.3% for a period of 110 days. Although the influent water quality changed dramatically, the effluent from the experiment tank had a substantially lower percentage increase in water quality parameters compared with the effluent from the control. It was found that in the experiment tank, 75.8% of FW TSS was degraded, whereas only 36.7% of sewage TSS was degraded, and that 18.8% of FW TSS and 44.9% of sewage TSS accumulated in the experiment tank. The addition of FW increased the scum accumulation, even though the dry matter of the scum layer was much less in quantity than the sludge layer. It also increased the lipid content in the sludge. The increase in the scum layer was mainly due to the increase in protein from the addition of the FW. Overall, compared with sewage TSS, FW TSS tends to be more biodegradable, which indicates that the impact on pumping frequency from adding FW will be insignificant.
10 Oct 2019, 7:29 pm
Waste Management & Research
Waste Management &Research, Ahead of Print.
Thermal treatment offers an alternative method for the separation of aluminum foil and cathode materials during spent lithium-ion batteries recycling. In this work, the combustion kinetic of cathode was studied based on six model-free (isoconversional) methods, namely Flynn–Wall–Ozawa (FWO), Friedman, Kissinger–Akahira–Sunose, Starink, Tang, and Boswell methods. The possible decomposition mechanism was also probed using a master-plots method (Criado method). Thermogravimetric analysis showed that the whole thermal process could be divided into three stages with temperatures of 37–578°C, 578–849°C, and 849–1000°C. The activation energy (Eα) derived from these model-free methods displayed the same trend, gradually increasing with a conversion range of 0.002–0.013, and significantly elevating beyond this range. The coefficients from the FWO method were larger, and the resulted Eα fell into the range of 10.992–40.298 kJ/mol with an average value of 20.228 kJ/mol. Comparing the theoretical master plots with an experimental curve, the thermal decomposition of cathode could be better described by the geometric contraction models.
10 Oct 2019, 7:28 pm
Waste Management & Research
Waste Management &Research, Ahead of Print.
Cyanide is among the most toxic chemicals widely employed in the cyanidation process to leach precious minerals, such as gold and silver, by the minerals processing companies worldwide. This present article reviews the determination and detoxification of cyanide found in gold mine tailings. Most of the cyanide remains in the solution or the slurries after the cyanidation process. The cyanide species in the gold tailings are classified as free cyanide, weak acid dissociation, and metallocyanide complexes. Several methods, such as colorimetric, titrimetric, and electrochemical, have been developed to determine cyanide concentrations in gold mine effluents. Application of physical, natural, biological, and chemical methods to detoxify cyanide to a permissible limit (50 mg L−1) can be achieved when the chemical compositions of cyanide (type of species) present in the tailings are known. The levels of cyanide concentration determine the impact it will have on the environment.
10 Oct 2019, 7:25 pm
Waste Management & Research
Waste Management &Research, Ahead of Print.
This study presents the results of a seasonal municipal solid waste composition campaign, that took place over the period of September 2017 to June 2018 in the capital city of Kazakhstan, Astana. Four sampling campaigns were conducted in order to identify the seasonal variation of municipal solid waste composition, recyclables and energy potential materials, such as combustible fraction, useful for the evaluation of waste-to-energy potential. The combustible fraction was analysed for thermal fuel properties, such as proximate and elemental analyses and gross calorific value. The results over the four different seasons showed that the average recyclable fraction of municipal solid waste on a wet basis of 33.3 wt.% and combustibles fraction was 8.3 wt.%. The largest fraction was the organics (47.2 wt.%), followed by plastic (15.4 wt.%) and paper (12.5 wt.%). Small seasonal variations were observed for organics, paper, plastic and glass fractions. The highest values were found in summer for the organic waste, in spring for paper and plastic and autumn for glass. The recyclables fraction showed an absolute seasonal variation of 5.7% with a peak in the winter season (35.4%) and the combustibles fraction showed a seasonal variation between 8.3 wt.% to 9.4 wt.%. Finally, the average calorific value of the combustible fraction was estimated to be 21.6 MJ kg-1 on a dry basis.
10 Oct 2019, 2:53 am
Waste Management & Research
Waste Management &Research, Ahead of Print.
Thermal treatment offers advantages of significant volume reduction and energy recovery for the polyurethane foam from waste refrigerators. In this work, the pyrolysis kinetics of polyurethane foam was investigated using the model-fitting, model-free and distributed activation energy model methods. The thermogravimetric analysis indicated that the polyurethane foam decomposition could be divided into three stages with temperatures of 38°C–400°C, 400°C–550°C and 550°C–1000°C. Peak temperatures for the major decomposition stage (<400°C) were determined as 324°C, 342°C and 344°C for heating rates of 5, 15 and 25 K min-1, respectively. The activation energy (Eα) from the Friedman, Flynn–Wall–Ozawa and Tang methods increased with degree of conversion (α) in the range of 0.05 to 0.5. The coefficients from the Flynn–Wall–Ozawa method were larger and the resulted Eα values fell into the range of 163.980–328.190 kJ mol-1 with an average of 206.099 kJ mol-1. For the Coats–Redfern method, the diffusion models offered higher coefficients, but the E values were smaller than that from the Flynn–Wall–Ozawa method. The Eα values derived from the distributed activation energy model method were determined as 163.536–334.231 kJ mol-1, with an average of 206.799 kJ mol-1. The peak of activation energy distribution curve was located at 205.929 kJ mol-1, consistent with the thermogravimetric results. The Flynn–Wall–Ozawa and distributed activation energy model methods were more reliable for describing the polyurethane foam pyrolysis process.
1 Oct 2019, 3:56 am
Waste Management & Research
Waste Management &Research, Ahead of Print.
Industrial solid waste management encompasses a vital part of developed and developing countries strategies alike. It manages waste generated from vital industries and governs the hazardous waste generated as a major component of integrated waste management strategies. This article reviews the practices that govern the management approaches utilized in the developed world for industrial spent catalysts. It critically assesses the current situation of waste management within the developing world region focusing on the industrial waste component, in a novel attempt to crucially develop a strategy for a way forward based on best practices and future directions with major European industries. The review also draws parallels with European countries to compare their practices with those of the State of Kuwait, which rely solely on landfilling for the management of its industrial waste. Spent catalysts recovery methods are discussed at length covering conventional methods of valuable metals and chemicals recovery (e.g., hydrometallurgical, solid–liquid and liquid–liquid extraction) as well as biological recovery methods. A major gap exists within regulations that govern the practice of managing industrial waste in Kuwait, where it is essential to start regulating industries that generate spent catalysts in-view of encouraging the establishment of valorization industries for metal and chemical recovery. This will also create a sustainable practice within state borders, and can reduce the environmental impact of landfilling such waste in Kuwait.
27 Sep 2019, 11:46 pm
Waste Management & Research
Waste Management &Research, Ahead of Print.
Catalytic pyrolysis of three different agricultural and forestry wastes (pinewood, peanut shell, rice straw) was performed in a fixed-bed reactor heated slowly under a stream of purging argon in the temperature range from 300 °C to 700 °C using K2CO3 as the catalyst. The aim of this study is to investigate the gaseous, liquid, and solid products derived from three different biomasses, and to ascertain the effects of K2CO3 on the pyrolysis behaviours. The products’ yields correlated with the composition of the biomasses and the addition of catalyst in the biomasses. The addition of K2CO3 described a strong catalysis in all three phases of the products: The liquid yield decreased obviously in contrast to the increase in gas yield. The liquid yields of pinewood and peanut shell demonstrated a remarkable decrease, while that of rice straw demonstrated the least decrease owing to a significant difference between the fibre composition of rice straw and those of the other two biomasses. This catalytic pyrolysis procedure was observed to produce low yields of liquid that contained high proportions of ketones and phenols, with minor acids, aldehydes, and furans. Among the three, the phenols of rice straw indicated the most obvious increase, while guaiacols decreased significantly, indicating that K2CO3 facilitated the secondary decomposition of guaiacols. Generally, for K2CO3 catalyst, the order of catalytic effect was pinewood > peanut shell > rice straw.