Fate of phthalate esters in landfill leachate under subcritical and supercritical conditions and determination of transformation products

Phthalate esters pollution in the leachate, soil, and water around a landfill near the sea, Iran

This investigation aimed to scrutinize the level of phthalate esters (PEs) in the landfill leachate of a coastal city in the north of the Persian Gulf and the sensitive ecosystem (soil and water) around it. Soil (two depths) and water samples were prepared from 5 stations in wet and dry seasons. The studied landfill leachate contained 114-303 μg/L of phthalates. The highest concentration of phthalates was related to bis (2-ethylhexyl) phthalate (3257 ng/g) in the wet season at surface soil (0-5 cm) in the landfill site, while the lowest one (6 ng/g) belonged to dimethyl phthalate at sub-surface soil at 700 m from the landfill in the dry season. A significant change in the level of Σ6PEs in the dry (303 μg/L) and wet (114 μg/L) seasons (P ≤ 0.05) was observed for water samples. The PE concentrations in wet times were higher in all soil depths than in dry times. With increasing depth, the content of phthalates decreased in all studied environments. A direct relationship was observed between the phthalates concentration and the pH value of leachate/water and soil. The PEs concentration was linked to electrical conductivity (leachate: R2 = 0.65, P < 0.01 and surface soil: R2 = 0.77, P < 0.05) and the soil organic content. The ecological risk of di-n-butyl phthalate, benzyl butyl phthalate, bis (2-ethylhexyl) phthalate, and di-n-octyl phthalate in the wet season was greater than one. The results showed that significant levels of phthalate esters are released from landfills to the surrounding environment, which requires adequate measures to maintain the health of the ecosystem and nearby residents.

Landfill leachates as a significant source for emerging pollutants of phthalic acid esters: Identification, occurrence, characteristics, fate, and transport

Phthalic acid esters (PAEs) are byproducts released from various sources, including microplastics, cosmetics, personal care products, pharmaceuticals, waxes, inks, detergents, and insecticides. This review article provides an overview of the literature on PAEs in landfill leachates, exploring their identification, occurrence, characteristics, fate, and transport in landfills across different countries. The study emphasizes the influence of these substances on the environment, especially on water and soil. Various analytical techniques, such as GC-MS, GC-FID, and HPLC, are commonly employed to quantify concentrations of PAEs. Studies show significant variations in levels of PAEs among different countries, with the highest concentration observed in landfill leachates in Brazil, followed by Iran. Among the different types of PAE, the survey highlights DEHP as the most concentrated PAE in the leachate, with a concentration of 89.6 μg/L. The review also discusses the levels of other types of PAEs. The data shows that DBP has the highest concentration at 6.8 mg/kg, while DOP has the lowest concentration (0.04 mg/kg). The concentration of PAEs typically decreases as the depth in the soil profile increases. In older landfills, concentrations of PAE decrease significantly, possibly due to long-term degradation and conversion of PAE into other chemical compounds. Future research should prioritize evaluating the effectiveness of landfill liners and waste management practices in preventing the release of PAE and other pollutants into the environment. It is also possible to focus on developing efficient physical, biological, and chemical methods for removing PAEs from landfill leachates. Additionally, the effectiveness of existing treatment processes in removing PAEs from landfill leachates and the necessity for new treatment processes can be considered.

Full life cycle and sustainability transitions of phthalates in landfill: A review

Phthalates (PAEs) are added to various products as a plasticizer. As these products age and are disposed of, plastic waste containing PAEs enters the landfill. The landfill environment is complicated and can be regarded as a "black box". Also, PAEs do not bind with the polymer matrix. Therefore, when a series of physical chemistry and biological reactions occur during the stabilization of landfills, PAEs leach from waste and migrate to the surrounding environmental media, thereby contaminating the surrounding soil, water ecosystems, and atmosphere. Although research on PAEs has achieved progress over the years, they are mainly concentrated on a particular aspect of PAEs in the landfill; there are fewer inquiries on the life cycle of PAEs. In this study, we review the presence of PAEs in the landfill in the following aspects: (1) the main source of PAEs in landfills; (2) the impact of the landfill environment on PAE migration and conversion; (3) distribution and transmedia migration of PAEs in aquatic ecosystems, soils, and atmosphere; and (4) PAE management and control in the landfill and future research direction. The purpose is to track the life cycle of PAEs in landfills, provide scientific basis for in-depth understanding of the migration and transformation of PAEs and environmental pollution control in landfills, and new ideas for the sustainable utilization of landfills.