Replacing Traditional Plastics with Biodegradable Plastics:Impact on Carbon Emissions

In recent years, a great deal of attention has been focused on the environmental impact of plastics, including the carbon emissions related to plastics, which has promoted the application of biodegradable plastics. Countries worldwide have shown high interest in replacing traditional plastics with biodegradable plastics. However, no systematic comparison has been conducted on the carbon emissions of biodegradable versus traditional plastic products. This study evaluates the carbon emissions of traditional and biodegradable plastic products (BPPs) over four stages and briefly discusses environmental and economic perspectives. Four scenarios—namely, the traditional method, chemical recycling, industrial composting, and anaerobic digestion—are considered for the disposal of waste biodegradable plastic product (WBBPs). The analysis takes China as a case study. The results show that the carbon emissions of 1000 traditional plastic products (plastic bags, lunch boxes, cups, etc.) were 52.09–150.36 carbon emissions equivalent of per kilogram (kg CO2eq), with the stage of plastic production contributing 50.71%–50.77%. In comparison, 1000 similar BPPs topped out at 21.06–56.86 kg CO2eq, approximately 13.53%–62.19% lower than traditional plastic products. The difference was mainly at the stages of plastic production and waste disposal, and the BPPs showed significant carbon reduction potential at the raw material acquisition stage. Waste disposal plays an important role in environmental impact, and composting and anaerobic digestion are considered to be preferable disposal methods for WBBPs. However, the high cost of biodegradable plastics is a challenge for their widespread use. This study has important reference significance for the sustainable development of the biodegradable plastics industry.</p

Adaptive Wall-Based Attachment Ventilation : A Comparative Study on Its Effectiveness in Airborne Infection Isolation Rooms with Negative Pressure

The transmission of coronavirus disease 2019 (COVID-19) has presented challenges for the control of the indoor environment of isolation wards. Scientific air distribution design and operation management are crucial to ensure the environmental safety of medical staff. This paper proposes the application of adaptive wall-based attachment ventilation and evaluates this air supply mode based on contaminants dispersion, removal efficiency, thermal comfort, and operating expense. Adaptive wall-based attachment ventilation provides a direct supply of fresh air to the occupied zone. In comparison with a ceiling air supply or upper sidewall air supply, adaptive wall-based attachment ventilation results in a 15%–47% lower average concentration of contaminants, for a continual release of contaminants at the same air changes per hour (ACH; 10 h−1). The contaminant removal efficiency of complete mixing ventilation cannot exceed 1. For adaptive wall-based attachment ventilation, the contaminant removal efficiency is an exponential function of the ACH. Compared with the ceiling air supply mode or upper sidewall air supply mode, adaptive wall-based attachment ventilation achieves a similar thermal comfort level (predicted mean vote (PMV) of −0.1–0.4; draught rate of 2.5%–6.7%) and a similar performance in removing contaminants, but has a lower ACH and uses less energy

Strategy for Assuring Water Security in the Haihe River Basin by 2035

Water security in the Haihe River Basin is an important component of China's ecological civilization and is vital for highquality national development of the country. Considering the development requirement for water security in the Haihe River Basin, we analyzed the problems regarding water security assurance from the perspectives of water resources, water environment, water ecology, and flood disasters. Subsequently, we predicted the development trend of water security in the Haihe River Basin by 2035 through data simulation. On this basis, an overall idea was proposed, that is, assuring water security in the Haihe River Basin by reinforcing measures for protecting water ecology, and highlighting the role of water resources carrying capacity. Focus should be placed on developing capacities regarding (1) systematic allocation and efficient utilization of water resources, (2) comprehensive improvement in water environment, (3) governance and restoration of basin ecology, and (4) prevention and emergency response of flood disasters. Furthermore, we proposed the following suggestions from a technological perspective: (1) implementing new strategies for the conservation and efficient utilization of water resources, (2) ensuring drinking water safety and improving water governance capacities, (3) establishing a water ecological pattern that features people-water harmony, and (4) developing a flood disaster prediction and response mechanism

Vortex characteristics of a gas cyclone determined with different vortex identification methods

This paper characterizes the vortex flow field in a gas cyclone based on different vortex identification methods, including vorticity method, Q criterion, λ2 criterion, Ω method and Liutex method. Analysis and comparison of isosurfaces of different vortex identification methods indicate that except vorticity method, the vortex core, the eddy flow and the short-circuit flow can be identified directly by other methods. But the small scale vortices, such as top ash ring, can only be fully recognized by Liutex method. The contours demonstrate that the magnitude of five vortex parameters is the largest in the vortex core, followed by the short-circuit flow, and the eddy flow is the smallest. But only Liutex method can predict the vortex core center and identify the most severe vortex eccentricity is in the bottom of vortex finder, the lower part of the cone and the hopper. The work not only improves the understanding of the vortex structure in a gas cyclone, which can critically affects cyclone performance, but also reveals the differences in the commonly used vortex characterization methods