Mulch film to plastic debris: A survey of agricultural soils of Hebei Province, North China

A significant amount of residual plastic film fragments (RPFF) accumulate in soil because of the widespread use and insufficient recycling of mulch films, substantially contaminating the ecosystem with plastic waste. However, information on RPFF abundance in agricultural soils that use long-term plastic film mulch is limited. In this study, 304 soil samples from 11 cities in Hebei Province, China, were used to examine the presence of RPFF in agricultural soils. We discovered that the main recycling techniques used in Hebei Province were manual picking (48.00%) and manual-mechanical recycling (31.90%), with the majority of recovered mulch (63.15%) disposed as waste. Residual plastic film fragment concentrations ranged from 0.48 to 155.33 kg/ha, with an average of 25.23 kg/ha. The north-central portion of Hebei Province has a more severe residual film pollution problem than the other regions. Notable variations in RPFF amounts were observed among plots planted with different crops and with years of mulching, peaking at 29.50 kg/ha after 5-10 years of mulching. Consequently, to reduce the amount of plastic waste that continues to accumulate in soils owing to agricultural needs, the management of plastic mulch, including its use, recycling, and disposal must be improved.

A review on management of waste three-way catalysts and strategies for recovery of platinum group metals from them

Platinum group metals (PGMs), especially platinum (Pt), palladium (Pd), and rhodium (Rh), are widely used in automotive three-way catalysts (TWCs). PGM resources are scarce and unevenly distributed, with global reserves of 69,000 t in 2020, of which more than 99% are concentrated in South Africa, Russia, Zambia, and the United States. However, the demand for PGMs worldwide is growing continually, especially in China. The recovery of PGMs from spent TWCs not only can alleviate the contradiction between supply and demand but also have good economic and environmental benefits. This paper briefly analyzes the market demand for Pt, Pd, and Rh in the global automotive industry in recent years, emphasizing the importance of waste TWC recycling. It also presents the current status of waste TWC management in some countries, especially China, and critically reviews the main recycling strategies for waste TWCs. On this basis, suggestions for strengthening the management of waste TWCs in China are put forward, and the future development trend of recycling technology is foreseen. The purpose of this paper is to provide some valuable references for the decision-makers of waste TWC management, and hopefully to provide inspiration for related scholars on the future research direction of waste TWC recycling technology.

Recycling strategies for polyhydroxyalkanoate-based waste materials: An overview

The plastics market is dominated by fossil-based polymers, but their gradual replacement by bioplastics (e.g., polyhydroxyalkanoates) is occurring. However, recycling strategies need to be developed to truly unveil the impact of bioplastics on waste accumulation. This review provides a state of the art of recycling strategies investigated for polyhydroxyalkanoate-based polymers and proposes future research avenues. Research on mechanical and chemical recycling is dominated by the use of extrusion and pyrolysis, respectively, while that on biodegradation of polyhydroxyalkanoates is related to soil and aquatic samples, and to anaerobic digestion towards biogas production. Research gaps exist in the relationships between polymer composition and ease of use of all recycling strategies investigated. This is of utmost importance since it will influence the need for separation at the source. Therefore, research emphasis needs to be given to the area to follow the continuous improvement of the process economics towards widespread commercial production of polyhydroxyalkanoates.