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Stochastic optimisation of organic waste-to-resource value chain
2021
Robles, Ivan | Durkin, Alex | Guo, Miao
Organic fraction municipal solid waste (OFMSW) has a high potential for energy and value-added product recovery due to its carbon- and nutrient-rich composition; however, traditional value chains have treated OFMSW as an undesired by-product. This study focuses on value chain optimisation to assist the transition to resource recovery value chains. To achieve this, this work combined two stage stochastic mathematical optimisation with geographical spatial analysis and time series waste generation analysis. Existing infrastructure in England, including anaerobic digestion plants and road transportation networks, were included in the model. To account for uncertainty in waste generation, multiple scenarios and their associated probabilities were developed based on environmental variables. The optimisation problem was solved to further advance the understanding of economically optimal waste-to-resource value chains under waste generation variability. The pertinent decision variables included sizing, technology selection, waste flows and location of thermochemical treatment sites. The model highlights the potential reduction in system profitability as a result of different operating constraints, such as minimum plant operating capacity factors and landfill taxation. The latter was shown to have the largest impact on profitability as overconservative systems designs were implemented to hedge against the waste variability. Such computer-aided models offer opportunities to overcome the challenges posed by waste generation variability and waste to resource value chain transformation.
Показать больше [+] Меньше [-]Effects of seawater pH and temperature on foraging behavior of the Japanese stone crab Charybdis japonica
2017
Wu, Fangli | Wang, Ting | Cui, Shuaikang | Xie, Zhe | duPont, Sam | Zeng, Jiangning | Gu, Huaxin | Kong, Hui | Hu, Menghong | Lu, Weiqun | Wang, Youji
We examined prey selection and foraging behaviors of the crab Charybdis japonica exposed to four combinations of pH (7.3 and 8.1) and temperature (18°C and 25°C). The order of prey selection by C. japonica was Potamocorbula laevis, Ruditapes philippinarum, Tegillarca granosa and Mactra veneriformis. Under high pCO2, times for searching, breaking, eating and handling were all significantly longer than those at the normal pCO2, and the prey profitability and predation rate under high pCO2 were significantly lower than normal pCO2. Moreover, temperature significantly influenced the foraging behaviors, but its effects were not as strong as those of pH; times for searching, eating and handling under high temperature were significantly lower than the low temperature, and the prey predation rates under high temperature was significantly higher than low temperature. In conclusion, high pCO2 negatively affected the foraging behavior, but high temperature actively stimulated the foraging behaviors of crabs.
Показать больше [+] Меньше [-]Reduction of CO2 emissions with automatic mooring systems. The case of the port of Santander
2017
Ortega Piris, Andrés | Díaz-Ruiz-Navamuel, Emma | Pérez-Labajos, Carlos A. | Oria Chaveli, Jesús
The revolutions in the maritime industry resulting from the implementation of integrated transport systems (bulk) and containerization (regular lines) at first had little effect on traditional mooring systems for ships in port. However, the research into innovation in automated mooring systems with increasingly advanced technologies carried on regardless.The so-called “Automatic Mooring Systems” (AMS), automatic systems that allow vessels to be moored without ropes, are being increasingly implemented in numerous ports in many different countries in the world, particularly in those whose traffic volumes have allowed the threshold of profitability of these infrastructures to be reached. But besides the financial benefits, the implantation of the AMS is having positive effects on the environment by reducing CO2 emissions in many commercial ports.The present work aims to measure for the first time the reduction in the CO2 emissions of merchant vessels as a consequence of the substitution of traditional mooring systems with the new automatic systems, continuing along the lines of previous works in the field of the reduction in CO2 emissions in ports.The estimation is made by applying the EPA and ENTEC “bottom-up” methodologies to the traffic in the port of Santander (Spain) in the year 2014.The implementation of the AMS, when compared to the traditional mooring systems, leads to a reduction in CO2 emissions of 76.78% calculated using the EPA method and 76.63% using the ENTEC method. Hence, the Port Authorities in their long-term planning decisions should promote the introduction of automatic mooring systems wherever the profitability thresholds of traffic allow it, as this will lead to significant environmental benefits by substantially reducing CO2 emissions during the maneuvers of merchant ships in maritime commercial ports.
Показать больше [+] Меньше [-]Potential ameliorative role of Spirulina platensis in powdered or extract forms against cyclic heat stress in broiler chickens
2022
Elbaz, Ahmed M. | Ahmed, Ayman M. H. | Abdel-Maqsoud, Ahmed | Badran, Aml M. M. | Abdel-Moneim, Abdel-Moneim Eid
Global warming has become intensified and widespread, threatening the world with causing acute heatwaves that adversely affect poultry production and producers' profitability. Spirulina platensis is a precious and promising mitigating strategy to combat the detrimental impacts of heat stress due to its high contents of nutrients and bioactive components. The current study was designed to compare the incorporation impact of S. platensis powder or aqueous extract on the growth and physiological responses of heat-stressed broiler chicks. Six hundred 1-day-old Ross 308 male broiler chicks were allocated into five experimental groups with six replicates of 20 chicks each. The control group fed the basal diet without additives, SPP1 and SPP2 groups fed the basal diet with 1 g/kg and 2 g/kg S. platensis powder, respectively, while SPE1 and SPE2 groups received 1 ml/L and 2 ml/L S. platensis aqueous extract in the drinking water, respectively. All birds were exposed to cyclic heat stress (34 ± 2 °C for 12 h) for three successive days a week from day 10 to day 35. In vitro analysis showed that total phenols, flavonoids, and antioxidant activity of S. platensis were remarkably decreased (P < 0.001) in the aqueous extract compared to the powder form. Body weight, weight gain, and feed conversion ratio were improved (P < 0.001) in all treated groups, while carcass yield and dressing percentage were increased only in SPP1 and SPP2. Feed and water intake and blood biochemical parameters were not affected. Both forms of S. platensis enhanced the lipid profile, redox status, and humoral immune response of heat-stressed chicks superior to the powder form. Conclusively, the powder form of S. platensis was more effective in enhancing the productivity of broilers and alleviating the negative impacts of heat stress than the aqueous extract form.
Показать больше [+] Меньше [-]A comparative study of national variations of the European WEEE directive: manufacturer’s view
2022
Andersen, Terje
We are facing the challenge of rapid growth in waste from electrical products (e-waste). In Europe, handling e-waste is regulated by the European Waste Electrical and Electronic Equipment (WEEE) directive, which is based on the extended producer responsibility (EPR) model as a regulatory tool forcing manufacturers and importers to take responsibility for their products throughout their lifecycles. However, the directive allows for great variations in implementations in each country, causing e-manufacturers and e-waste handling operators to face challenges in their transition to more sustainable operations. To identify the challenges involved, this study investigates the effect of the WEEE directive from a manufacturer’s perspective. A case study of an e-manufacturer operating subsidiaries in several European countries and the associated producer responsibility organizations (PROs) is presented. The case study includes interviews from 17 stakeholders in 12 organizations in eight European countries. Key findings are as follows. First, the WEEE data reported are not harmonized. Second, the calculations of the environmental fee differ across countries. Third, following up on different national WEEE obligations sometimes leads to over-reporting to avoid negative effects on environmental corporate social responsibility, brand reputation, and profitability. Fourth, outsourcing end-of-life (EoL) treatment responsibility to PROs is seen as positive by the manufacturer but results in a decoupling of the EPR and the operational EoL treatment, which may reduce efforts to transfer to a higher circularity level of its EEE products. Fifth, WEEE is considered a way for e-manufacturers to handle waste not to adopt a circular focus. This paper contributes to both practitioners and researchers within reverse logistics and sustainability by adding knowledge from real-life context of how EPR is implemented in WEEE.
Показать больше [+] Меньше [-]Can the social trust promote corporate green innovation? Evidence from China
2021
Pan, Zicheng | Liu, Liang | Bai, Shuyuan | Ma, Qianting
Corporate green innovation has played a crucial role in balancing profitability and environmental protection. The existing research on determinant factors of green innovation has its main defects in emphasizing excessively enterprise’s formal institutional environment and neglecting the informal institutional environment, causing an incomplete understanding of the relationship between institutional environments and corporate green innovation. To bridge this gap, using a sample of Shanghai and Shenzhen A-share listed firms in manufacturing industry during the period of 2010–2016, we investigate how social trust, an important informal institutions, affects corporate green innovation. Our results show that social trust is positively associated with green innovation, remaining valid after applying endogenous and robustness tests. In addition, the positive relationship between social trust and green innovation is more prominent when the enterprise is non-state-owned or locates in a looser command-and-control (CAC) environmental regulations region. Further analysis shows that social trust boosts corporate green innovation via promoting knowledge sharing, decreasing financing constraints, and fulfilling more corporate social responsibility (CSR). This paper enriches the literature concerning social trust and green innovation and draws back more public attention on the role of informal institutions play in promoting green innovation.
Показать больше [+] Меньше [-]The environmental impact of shrimp aquaculture and the coastal pollution in Mexico
1998
Paez-Osuna, F. | Guerrero-Galvan, S.R. | Ruiz-Fernandez, A.C. (Estacion Mazatlan, Instituto de Ciencias del Mar y Limnologia, Universidad Nacional Autonoma de Mexico, Apdo. Postal 811, Mazatlan 82000, Sinaloa (Mexico))
Optimized ratoon rice system to sustain cleaner food production in Jianghan Plain, China: a comprehensive emergy assessment
2022
Ding, Zijuan | Hu, Ren | Styles, David | Wang, Xiaolong | Tian, Yingbing | Cao, Yuxian | Hou, Jun
Ratoon rice (RR) is regarded as a labor-saving and efficient approach to rice cultivation; however, sub-optimal production techniques (fertilization, irrigation, harvesting) may lead to serious environmental problems and unsustainable agriculture. In this study, emergy analysis was combined with indicators of soil fertility, global warming potential (GWP), and profitability to comprehensively assess the sustainability performance of three cultivation modes: (i) traditional farm practice (TRA), (ii) optimized mode (OPT), and (iii) OPT plus green manure planting (OPTM). Over 2 years, compared with the TRA mode, OPT and OPTM modes increased total rice yield by 10% and 19% on average and improved profit by 233.7 and 456.5 Yuan ha⁻¹, respectively. Single emergy analysis results showed that, compared with the TRA mode, OPT and OPTM (2-year average value) modes increased production efficiency by 10% and 8%, reduced renewable fraction and emergy sustainability index by 14–19% and 18–23%, respectively, and increased environmental loading ratio by 31% and 22%. Multiple EMA analysis results showed that, compared with the TRA mode, OPT and OPTM (2-year average value) modes reduced UEVNₘᵢₙ by 23% and 21% and increased UEVGWP 32% and 51%, respectively. The UEVTₒₜₐₗ ᵣₑᵥₑₙᵤₑ and UEVBₑₙₑfᵢₜ of OPT and OPTM increased by 8–29% and 4–37%, respectively, compared with TRA mode. The comprehensive assessment indicated that, despite OPT and OPTM modes have a range of improvements and dis-improvements versus the TRA mode, OPTM was the more sustainable mode of RR production overall. However, some sustainability indicators remained poor, and there remains scope for further optimization via, e.g., precision application of enhanced-efficiency fertilizers, application of a straw-decomposing inoculant to improve soil fertility, and use of new improved rice varieties with high regenerative ability to improve the yield of ratoon crops.
Показать больше [+] Меньше [-]Increase energy use efficiency and economic benefit with reduced environmental footprint in rice production of central China
2022
Yuan, Shen | Zhan, Xuewu | Xu, Le | Ling, Xiaoxia | Peng, Shaobing
Identifying an energy-efficient system with low energy use, low global warming potential (GWP), and high profitability is essential for ensuring the sustainability of the agro-environment. Given the global importance of China’s rice production, this study determines energy, environmental, and economic performances of transplanted (TPR) and direct-seeded rice system (DSR) in central China. The results showed that total energy inputs for TPR and DSR were 31.5 and 22.8 GJ ha⁻¹ across two growing seasons, respectively. Higher energy input for TPR primarily resulted from extra energy use of the nursery beds and transplanting. Higher energy output of DSR (202.5 GJ ha⁻¹) over that of TPR (187.7 GJ ha⁻¹) was due to a slightly higher yield from DSR. Therefore, DSR exhibited significantly higher energy use efficiency than that of TPR. Lower specific energy for DSR (2.78 MJ kg⁻¹) relative to TPR (4.02 MJ kg⁻¹) indicated that the energy used to produce per unit of rice grain could be reduced by 30.8% by adopting DSR. On average, GWP of DSR was reduced by 5.6% compared with TPR. Moreover, DSR had a 55.8% higher gross return and a 25.7% lower production cost than those of TPR. Overall, compared with TPR, DSR has the potential to increase gross economic return and energy output with reduced energy input and emissions. Therefore, this study suggests that DSR is an environmentally-sound and economically-viable production system. As such, DSR is noted as an energy-efficient and climate-smart production system that could be used by policymakers and farmers to achieve not only improvements in the environment but also financial benefits.
Показать больше [+] Меньше [-]Economic benefits of construction waste recycling enterprises under tax incentive policies
2022
Liu, Jingkuang | Gong, Engqing | Wang, Xuetong
To further explore the development of construction waste recycling enterprises and promote the recycling of construction waste resources in China, a system dynamics model of the economic benefits of construction waste recycling enterprises is established using the system dynamics method and taking the tax incentive of the Guangzhou Municipal Government as an example. The economic benefits of construction waste recycling enterprises are analyzed from the perspective of the total cost, total revenue, and total recycling amount. The results of the MATLAB simulation and numerical analysis show that (1) by simulating the effects of different taxes such as value-added tax (VAT), education surcharge, urban construction tax, and enterprise income tax on the economic benefits of construction waste recycling enterprises, it is found that when tax incentives reach 70%, the VAT favorable policies bring the highest gains, followed by enterprise income tax, whereas favorable education surcharge policies and urban construction tax have the least impact on economic benefits. (2) Taking the monetary subsidy of the Guangzhou municipal government as an example, it is estimated that the total revenue of construction waste recycling enterprises will increase by 33.56% annually in 2030. When the new production technology is adopted, the return on investment (ROI) will reach 46.8% in 2030 compared to previous technological improvements. In the simulation scenario, the ROI will be 42.2%, which has a good incentive effect on the cost control of enterprises. (3) Increasing the available power to VAT and corporate income tax can improve the profitability of construction waste recycling enterprises in China; however, tax incentive policy will no longer be the main factor affecting the benefits of enterprises when a certain time is reached. (4) It is suggested that the government improves the relevant tax laws incentive policies, increase tax incentives, and add equipment tax incentive policies, actively change the tax mode, and increase indirect tax models to improve the economic benefits of enterprises. The research results provide a decision-making reference for the government to formulate laws and policies related to the economic benefits of construction waste recycling and promote the development of the construction waste recycling industry, the development of new industries, such as waste recycling and treatment, and the formation of industrial chains, to achieve the strategic goal of sustainable development.
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