Landfill Soil Research Articles

Application of agrotechnical techniques in the reclamation of a solid waste landfill

The work examined the existing solid waste landfill in the city of Uralsk with a total area of 36 hectares. In 2020-2022, a project for a new landfill was developed. Thus, our research proposed alternative solutions for the use of reclamation of the old solid waste landfill using technologies for cultivating perennial grasses. In the experiments, 100% (option 1) and 50% of the landfill body + 50% soil (option 2) were selected. The results of the experiment showed that in option 2, from the landfill body and soil (1:1), seed germination was higher than on samples from 100% of the landfill body. Among the components of perennial herbs, it is recommended to use a grass mixture (wheatgrass, hair grass and sainfoin).

ПИЛОТНЫЙ КАРБОНОВЫЙ ПОЛИГОН: АНАЛИЗ ЗАПАСОВ УГЛЕРОДА В ПОЧВАХ СЕЛЬХОЗУГОДИЙ

The carbon cycle in agroecosystems is determined by the balance between the absorption of carbon dioxide by terrestrial vegetation of agricultural crops to create organic matter and its release during soil respiration. The soil cover is a powerful source of carbon dioxide and serves as a reservoir accumulating soil organic carbon. Organic carbon accumulating in the humus of soils serves as a drain of carbon dioxide, methane into the atmosphere for hundreds of years. The research was carried out in order to analyze the reserves of organic carbon in the soils of agroecosystems and assess the emission of CO2 and CH4 gases. The work was carried out in 2022-2023 at the site of a pilot carbon landfill (arable land) in the Republic of Bashkortostan. In field and laboratory experiments, technologies for controlling carbon dioxide emissions on agricultural lands were developed and tested. In the field, full-profile soil sections and digs were laid in accordance with GOST R58595-2019 with the determination of morphological properties and the selection of soil samples for laboratory analysis. Agrochemical analysis of the soil for the content of organic matter, the density of addition, the content of mobile phosphorus and potassium, the pH value allowed us to estimate the carbon stock of the soil of the carbon landfill according to the methodology of the Ministry of Natural Resources of the Russian Federation. The total reserves of organic carbon of the arable horizon at the carbon-new landfill amount to 503.8 t/ha, which vary and depend on the employment of the field and the characteristics of the agricultural crop. Measurement of the destructive part of the carbon cycle using a portable LI-COR 7810 camera showed that the fields occupied by crops differ in the intensity of the release of soil carbon dioxide ‒ in the field under pure steam, CO2 emissions were 2.18 times lower than under perennial grasses. The availability of data on the spatial distribution of organic soil carbon makes it possible to introduce carbon-dependent crop rotations with a set of crops that contribute to the maximum absorption of atmospheric CO2 and other greenhouse gases into the practice of agriculture.

Biodegradation of Low-Density Polyethylene (LDPE) by Aspergillus niger

The current study focused on the ability of Aspergillus niger to biodegrade low-density polyethylene, while studying some of the factors affecting the biodegradation process, including pH and temperature. Samples were collected from the soil of the waste landfill (sanitary landfill) of Dhi Qar Governorate, located 20 kilometers south of the center of the governorate, and using the dilution method. The genus Aspergillus niger had the highest appearance rate, reaching 100%, as it appeared in all samples, and the colony diameters in the solid medium were calculated. The fungus showed the ability to adapt and grow in the medium containing low-density polyethylene, with the a concentration of (0.1, 0.5, 1)%, and temperature of (15, 25, 35) ᵒC, also pH (2, 4, 6), and the addition of a carbon source of glucose, maltose and a nitrogen source (NH4Cl, NaNo3), the decomposition metabolites and the remaining concentration were identified by using Fourier – transform Infrared Spectroscopy and Gas – Mass Spectroscopy, and later a confirmatory test was conducted to determine the ability of Aspergillus niger to biodegrade low-density polyethylene in the medium of mineral salts.

Distribution of biphenyl degraders in soil samples in Mosul-Iraq

This work aimed to study the distribution of biphenyl degrading isolates from different soils in Nineveh governorate. Fifty five soil samples were collected from reeds soil, sandy soil, landfill soil, oil refinery soil, agricultural soil, sulfur station soil, garden soil, and sewage contaminated soil. Nine isolates were diagnosed based on their cultural characteristics and 16S rRNA gene sequence. Five isolates belonged to Rhodococcus, and the other four were diagnosed as Extensimonas perlucida, Achromobacter sp., Microbacterium barkeri, and Pseudomonas luteola. The sequences were submitted to NCBI and given the initials RM. Our results showed that the soil samples with the highest source of biphenyl degraders was Mishraq sulfur station soil (33.33%) followed by sewage soil (28.57%). On the other hand no biphenyl degraders were isolated from oil refinery soils, agricultural soils and garden soils. Growth rates of the nine biphenyl degraders varied with different strains reflecting the efficiency of their enzymes in degrading biphenyl. Two sets of primers were used to detect dioxygenases used by the isolates. The primer BPHD-f3 and BPHD-r1 was used to amplify a 524bp DNA fragment from the Rieske non-heme iron dioxygenase gene expected to be used in the initial step of biphenyl degradation and was found in 5/9 biphenyl degrading isolates. The second set of primers (DOalpha-2 and DOalpha-3) was designed to target angular dioxygenase genes involved in the first step of aromatic hydrocarbon degradation other than biphenyl. Interestingly, our results showed that E. perlucida and Pseudomonas luteola RM9 contains an angular dioxygenase gene that is probably involved in degrading other aromatic compounds besides biphenyl.

Degradation and potential metabolism pathway of polystyrene by bacteria from landfill site

Microplastics pollution has garnered significant attention in recent years. The unique cross-linked structure of polystyrene microplastics makes them difficult to biodegrade. In this study, we investigated the microbial community in landfill soil that has the ability to degrade polystyrene, as well as two isolated strains, named Lysinibacillus sp. PS-L and Pseudomonas sp. PS-P. The maximum weight loss of polystyrene film and microplastic in 30 days is 2.25% and 6.99% respectively. The water contact angle of polystyrene film decreased by a maximum of 35.70% during biodegradation. The increase in hydrophilicity is attributed to the oxidation reaction and formation of hydroxyl groups during the degradation of polystyrene. The carbon and oxygen element contents of polystyrene decreased and increased by a maximum of 3.81% and 0.79% respectively. The peak intensity changes at wavelengths of 3285–3648 cm−1 and 1652 cm−1 in Fourier transform infrared spectroscopy confirmed the formation of hydroxyl and carbonyl groups. Furthermore, quantitative PCR revealed the gene expression levels of alkane monooxygenase and alcohol dehydrogenase were upregulated by 8.8-fold and 8.5-fold respectively in PS biodegradation. Additionally, genome annotation of Pseudomonas sp. PS-P identified nine genes associated with polystyrene metabolism. These findings highlight Pseudomonas sp. PS-P as a potential candidate strain for polystyrene degradation enzymes or genes. Thus, they lay the groundwork for understanding the potential metabolic mechanisms and pathways involved in polystyrene degradation.

Carbon reduction potential of a rain garden: A cradle-to-grave life cycle carbon footprint assessment

With emphasis on constructing low-carbon cities, the renovation of old communities highlights the importance of renewing rainwater management facilities. Rain garden is an exceptional Nature-based Solution for rainwater management. When applying them to renovate old communities, the carbon footprint should be considered. This study focused on renovating facilities in the Greater Bay Area and utilized the Energy Expert platform to calculate rain garden carbon footprint with the Life Cycle Assessment. The carbon reduction benefits during the operation were estimated. This study accounting the life cycle carbon footprint of the 5455 m2 rain garden was 1117.42 tCO2e. The carbon footprint contribution, from highest to lowest was the end-of-life phase, materials production phase, construction phase, use and maintenance phase. Regarding carbon emission inventory, waste soil landfill, fertilizer acquisition, and waste soil recycling ranked high. Transportation also accounted for a remarkable carbon emission. The rain garden showed great potential for climate change mitigation, with a total and net carbon reduction of 1927.41 and 809.99 tCO2e, respectively. To reduce the carbon footprint of the rain garden, we should focus on waste soil treatment and transportation. Recommendations included increasing waste soil recycling, in situ recycling and green transportation.

Перспективи впровадження практичного заняття «Визначення зон забруднення ґрунтів тпв та розрахунок енерговитрат їхнього очищення» з дисципліни Безпека життєдіяльності

In this paper, a method of engineering calculations is proposed, which is necessary for the implementation of the practical lesson “Definition of soil contamination zones of municipal solid waste and calculation of energy costs of their cleaning” from the normative discipline of life safety in order to promote the deepening of knowledge on the protection of the lithosphere, as a component of the natural environment, of future specialists.
 The purpose of the article is the development of the engineering calculation methodology necessary for the implementation of the practical exercise “Definition of zones of soil contamination by municipal solid waste and calculation of energy costs of their cleaning” from the discipline of life safety to promote the deepening of knowledge on the protection of the lithosphere of future specialists.
 The proposed method of engineering calculations includes the calculation of: the size of the zones of soil contamination by pollutants (heavy metals, benzapyrene, petroleum products) around municipal solid waste landfills, the specific energy consumption of landfill soil cleaning by electrochemical remediation from heavy metal contamination, the energy consumption of soil cleaning of municipal solid waste disposal landfills of municipal solid waste both by individual heavy metals and general. The specific energy costs of cleaning the soil of municipal solid waste landfills by the method of electrochemical remediation from pollution were determined depending on the required level of heavy metal concentrations. The energy costs of cleaning the soil of municipal solid waste landfills by the electrochemical remediation method of pollution were determined taking into account the size of the pollution zones and the size of the municipal solid waste landfill. Based on the comparison and comparison of the experimental data obtained as a result of the research, it was established that the success rate of the students of both experimental groups according to the stobal scale was significantly higher than the success rate of the students of the control groups, which means the introduction of the proposed practical lesson from the regulatory discipline “Life Safety” into the educational process is promising. The construction of methods of engineering calculations for the protection of the atmosphere and hydrosphere require further research.

Microplastics as carriers of antibiotic resistance genes and pathogens in municipal solid waste (MSW) landfill leachate and soil: a review.

Microplastics as carriers of antibiotic resistance genes and pathogens in municipal solid waste (MSW) landfill leachate and soil: a review.

Speciation and Pollution Assessment of Chromium and Zinc in Landfill Soils of Brazzaville: Physico-Chemical Analyses and Heavy Metal Contamination

Speciation and Pollution Assessment of Chromium and Zinc in Landfill Soils of Brazzaville: Physico-Chemical Analyses and Heavy Metal Contamination

Assessment of heavy metal pollution in the soil of a construction and demolition waste landfill

Construction industry has a significant effect on the environment and human health. In developing countries including Iran, the waste generated through construction and demolition is disposed in landfills, posing further harms to the environment by increasing the amounts of heavy metals (HMs). In order to tackle the mentioned issue, the first step is to assess the landfill soil’s contamination and risk. To date, no study has examined the status of heavy metal pollution and risk assessment of construction and demolition waste (CDW) landfills in Shiraz, Iran, although a large amount of CDW is disposed in this city. In order to fulfil the mentioned gap within the body of knowledge, a novel study was conducted in which a case study CDW landfill within Shiraz, Iran, was investigated carefully. 420 samples were collected, which was followed by various types of assessment techniques including geo-accumulation index, pollution load index, enrichment factor, and potential ecological risk assessment. The results obtained from pollution assessment methods illustrated considerable levels of contamination within the landfill, with Cd as the main contaminant (PLI value of 14.15, and significant enrichment for 92.7% of the collected samples). Risk assessment also showed a high-level risk of HMs for 84.16% of the samples extracted from the landfill soil, and the most prominent contributors were Cd and Pb with average ecological risks of 712.2 and 57, respectively. The results of this study can have a great impact on future policies and strategies regarding the disposal of CDW in Shiraz, Iran.

Extraction Potential of Lolium perenne L. (Perennial Rye Grass) for Metals in Landfill Soil: Its Tolerance and Defense Strategies

Landfill sites open and close frequently throughout the world, taking over a significant amount of land and leaving it contaminated and unavailable to the surrounding population for use. Different forms of remediation methods have been employed to rehabilitate contaminated land to a state that poses less of a threat to the environment. Phytoremediation is one of the remediation techniques that has proven to be effective, economical and easier to implement compared to other methods. The main aim of this study was to explore the potential use of Lolium perenne L. to remediate and restore metal-contaminated landfill soil and determine its stress tolerance mechanism(s). The metal uptake, determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES) and inductively coupled plasma-mass spectroscopy (ICP-MS), revealed that Lolium perenne accumulate a higher amount of metals in the roots than in leaves, which was further confirmed by the translocation factor (TF) values of all of the metals that were below 1, ranging between 0.2 and 0.8, while Cu, Cr and Pb had a bioaccumulation factor (BCF) > 1. This confirms that L. perenne is capable of absorbing metals into the root matrix but might restrict further movement into other parts of the plant as a defense mechanism against metal toxicity. In response to metal-induced stress, L. perenne displayed an increase in enzyme activity of superoxide dismutase, glutathione S-transferase, peroxidase and amylases in plants grown in landfill soil. Peroxidases displayed the highest level of enzyme activity, while total amylolytic activity had the most significant increase in activity over time. Although not a hyperaccumulator, L. perenne is a potential candidate for the phytoremediation of landfill soil and the phytostabilization of Cu, Cr and Pb.

Multivariate analysis of enriched landfill soil consortia provide insight on the community structural perturbation and functioning during low-density polyethylene degradation

Plastic-enriched sites like landfills have immense potential for discovery of microbial consortia that can efficiently degrade plastics. In this study, we used a combination of culture enrichment, high-throughput PacBio sequencing of 16 S rRNA and the ITS gene, Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) to examine the compositional and diversity perturbations of bacterial and fungal consortia from landfill soils and their impact on low-density polyethylene (LDPE) film biodegradation over a 90-day period. Results showed that enrichment cultures effectively utilized LDPE as a carbon source for cellular growth, resulting in significant weight reduction (22.4% and 55.6%) in the films. SEM analysis revealed marked changes in the micrometric surface characteristics (cracks, fissures, and erosion) and biofilm formation in LDPE films. FTIR analyses suggested structural and functional group modification related to C-H (2831–2943 cm⁻¹), and CH₂ (1400 cm⁻¹) stretching, CO and CC (680–950 cm⁻¹) scission, and CO incorporation (3320–3500 cm⁻¹) into the carbon backbone, indicative of LDPE polymer biodegradation. Enrichment cultures had lower diversity and richness of microbial taxa compared to soil samples, with LDPE as a carbon source having a direct influence on the structure and functioning of the microbial consortia. A total of 26 bacterial and 12 fungal OTU exhibiting high relative abundance and significant associations (IndVal > 0.7, q < 0.05) were identified in the enrichment culture. Bacterial taxa such as unclassified Parvibaculum FJ375498, Achromobacter xylosoxidans, unclassified Chitinophagaceae PAC002331, unclassified Paludisphaera and unclassified Comamonas JX898122, and six fungal species (Galactomyces candidus, Trichosporon chiropterorum, Aspergillus fumigatus, Penicillium chalabudae, Talaromyces thailandensis, and Penicillium citreosulfuratum) were identified as the putative LDPE degraders in the enrichment microbial consortium cultures. PICRUSt2 metagenomic functional profiling of taxonomic bacterial taxa abundances in both landfill soil and enrichment microbial consortia also revealed differential enrichment of energy production, stress tolerance, surface attachment and motility pathways, and xenobiotic degrading enzymes important for biofilm formation and hydrolytic/oxidative LDPE biodegradation. The findings shed light on the composition and structural changes in landfill soil microbial consortia during enrichment with LDPE as a carbon source and suggest novel LDPE-degrading bacterial and fungal taxa that could be explored for management of polyethylene pollution.

Dyadobacter pollutisoli sp. nov., isolated from plastic waste landfill soil.

A Gram-stain-negative, yellow-pigmented and facultatively aerobic bacterium, designated strain U1T, was isolated from plastic dumped soil sampled in the Republic of Korea. Cell of strain U1T were non-motile rods showing catalase-negative and oxidase-positive activities. Strain U1T was shown to grow at 10-37 °C (optimum, 25-30 °C) and pH 6.0-9.0 (optimum, pH 8.0), and in the presence of 0-0.5 % (w/v) NaCl (optimum, 0 %). Strain U1T contained iso-C15 : 0, C16 : 0, C16 : 1 ω5c and summed feature 3 (comprising C16 : 1 ω6c and/or C16 : 1 ω7c) as the major cellular fatty acids (>5 %) and menaquinone-7 as the sole respiratory quinone. Phosphatidylethanolamine, two unidentified aminolipids and three unidentified lipids were identified as the major polar lipids. The DNA G+C content of strain U1T calculated from the whole-genome sequence was 45.5 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain U1T formed a distinct phylogenetic lineage within the genus Dyadobacter. Strain U1T has the highest 16S rRNA sequence similarity to Dyadobacter bucti QTA69T (97.9 %). Average nucleotide identity and digital DNA-DNA hybridization values between strain U1T and D. bucti QTA69T were 74.6 % and 18.9 %, respectively. Based on phenotypic, chemotaxonomic and molecular features, strain U1T represents a novel species of the genus Dyadobacter, for which the name Dyadobacter pollutisoli sp. nov. is proposed. The type strain is U1T (= KACC 22210T=JCM 34491T).

Comparative evaluation of the results of chemical analysis of the solid municipal waste filtrate at the Irkutsk landfill

Heavy metals are widespread chemical elements, many of which are toxic components polluting the biosphere. They include more than 40 are priority pollutants. Every year the danger of their getting them into the soil is increasing. A powerful source of release of harmful heavy metals into the environment are municipal solid waste (MSW) dumps. There are dozens of such these landfills in Irkutsk region, including the largest landfill in Irkutsk. In 2014 and 2019, on the territory of this landfill the landfill leachate was analyzed for the content of general chemical and toxic components. The comparative analysis showed that the landfill soil is extremely dangerous. The excess of MPC of heavy metals in the filtrate ranged from 2.4 to 67.6. The article presents the results of the analysis of landfill leachate taken in 2021 in the sanitary protection zones, and compared with the previously obtained data. It was established that the chemical and biochemical processes between various components of landfill leachates cause the formation of toxic compounds and become sources of infection. Precipitation forms a large amount of leachate which has significant concentrations of especially toxic substances, which inevitably enter the groundwater. In addition to harmful compounds and heavy metals, wastewater also contains pathogenic microorganisms.

Microplastics and mesoplastics as emerging contaminants in Tehran landfill soils: The distribution and induced-ecological risk

Environmental pollution with microplastics (MPs) and mesoplastics (MEPs) and their potential risks to human health and ecosystem quality have aroused the concern of communities. Therefore, the pioneering study was conducted on Tehran landfill soil contamination with MPs and MEPs. 56 shallow and deep soil samples were collected from different landfill areas in the wet and dry seasons. The physical and chemical characteristics of MPs and MEPs were measured using a stereomicroscope and FTIR-ATR spectroscopy, respectively. The results showed that the average MP abundance in shallow and deep soil was 863 ± 681 and 225 ± 138 particles/kg soil, and for MEPs, it was 29.8 ± 6.4 and 18.1 ± 8.3 particles/kgsoil. The low-density plastic particles were separated completely by flotation with H2O, NaCl, and ZnCl2 solutions, but PVC was only separated by 90%. Over 90% of MPs and MEPs were LDPE, PP, and PS polymers, explained by their widespread applications in single-use products and their consumption in Iran. Films, white and black, and 0.1–0.5 mm were the dominant shapes, colors, and sizes of MPs, respectively. The prevailing MEPs were film-shaped and in white and yellow colors, with a size of 0.5–1.0 cm. Canonical correlation analysis indicated that total organic matter and moisture were highly correlated with MP shapes. The calculated polymer hazard index values have a wide range at different sampling points, and this index yielded hazard levels III-IV and II-IV for MPs and MEPs, respectively, while according to the pollution load index category, the hazard level of MPs and MEPs was I-II and I. The potential ecological risk index from combined polymers has been estimated to be of minor to extreme danger for MPs and of minor risk for MEPs. Our findings provided baseline data on MPs contamination in Tehran landfill soil and its associated ecological risk, which aids policymakers in implementing risk-reduction measures.

Impact of Solidified Municipal Sludge as Temporary Covering Soil on the Stability of Landfill Slope

Solidified municipal sludge is widely used as temporary covering soil in landfill. Due to the complex leachate of landfill, solidified municipal sludge has the problems of stagnant water and strength degradation. In order to investigate the influence of solidified municipal sludge on the stability of landfills, a landfill slope model with SEEP/W and SLPOE/W was established, using the actual infiltration as the boundary condition. Based on the changes in permeability and strength of the intermediate overburden layer, the migration law of leachate in a landfill under the condition of an intermediate overburden layer was analyzed. The relationship between landfill slope safety, climatic conditions and deterioration of the intermediate overburden layer was further explored. The results show that the permeability of the intermediate overburden layer affects the distribution of leachate and the height of stagnant water. During the rainstorm period, the safety factor of the landfill slope decreased rapidly from 1.4 to 1.0 or even lower. With the decrease in the shear strength of the intermediate overburden, the safety factor of the landfill slope was reduced to less than 1.0. Therefore, maintaining the permeability and strength of solidified municipal sludge at a certain level is required to ensure the safety and stability of landfill slopes.

Biodegradation of polylactic acid by a mesophilic bacteria Bacillus safensis

A mesophilic bacterial strain, Bacillus safensis PLA1006, was isolated from landfill soil and was tested for growth on polylactic acid (PLA) emulsion medium. The strain formed clear zones on the medium and produced protease and lipase. The macroscopic morphology of the PLA films was not changed significantly after treatment with Bacillus safensis PLA1006 but the films were whitened. Weight loss of PLA films was about 8% after 30 days of incubation with Bacillus safensis PLA1006 in mineral salt medium. Scanning electron microscopy revealed etching on the surface of PLA film treated by Bacillus safensis PLA1006. This also caused an increase in hydrophilicity of the PLA films surface. Attenuated total reflectance - Fourier transform infrared spectroscopy analysis of PLA films after treated by Bacillus safensis PLA1006 showed no new absorption peaks but a decrease in the intensity of all absorption peaks. The hydrolysis products of PLA by the strain contained monomers and oligomers of lactic acid. Zymogram detection showed that proteases may play a role in the degradation of PLA.

Microbial Treatment of di (2-ethyl hexyl) Phthalate by Lysinibacillus xylanilyticus Isolated from Landfill Soil

The bacterial strains were isolated from landfill soil contaminated with phthalate, collected from dump yard near Byepass, Patna. Thestrain named T23 was chosen among the isolated strains due to its high efficacy towards the degradation. We observed the effects ofvarious environmental and chemical factors for optimising the conditions for degradation. The strain T23 was identified as Lysinibacillusxylanilyticus based on its phenotypic as well as phylogenetic characteristics by performing 16S rRNA gene sequencing and for thedetermination of the metabolic end products after degradation. Gas chromatography and mass spectrometry (GC-MS) analysis was doneand the degradable intermediates obtained were 7, 10, 13-Hexadecatrienoic acid, Cyclotrisiloxane, n-Hexadecanoic acid, Oleic Acid andErucic acid. The strain T23 showed maximum degradation at pH 8.5 and temperature was 10.5 and it could tolerate up to 0-15% NaCl.Maximum degradation was exhibited at the carbon source, dextrose, and nitrogen source, casein. The 23 strain was having maximumpotential for degradation which can be used for various remediation purposes.

Exploring Potent Fungal Isolates from Sanitary Landfill Soil for In Vitro Degradation of Dibutyl Phthalate.

Di-n-butyl phthalate (DBP) is one of the most extensively used plasticizers for providing elasticity to plastics. Being potentially harmful to humans, investigating eco-benign options for its rapid degradation is imperative. Microbe-mediated DBP mineralization is well-recorded, but studies on the pollutant's fungal catabolism remain scarce. Thus, the present investigation was undertaken to exploit the fungal strains from toxic sanitary landfill soil for the degradation of DBP. The most efficient isolate, SDBP4, identified on a molecular basis as Aspergillus flavus, was able to mineralize 99.34% dibutyl phthalate (100 mg L-1) within 15 days of incubation. It was found that the high production of esterases by the fungal strain was responsible for the degradation. The strain also exhibited the highest biomass (1615.33 mg L-1) and total soluble protein (261.73 µg mL-1) production amongst other isolates. The DBP degradation pathway scheme was elucidated with the help of GC-MS-based characterizations that revealed the formation of intermediate metabolites such as benzyl-butyl phthalate (BBP), dimethyl-phthalate (DMP), di-iso-butyl-phthalate (DIBP) and phthalic acid (PA). This is the first report of DBP mineralization assisted with A. flavus, using it as a sole carbon source. SDBP4 will be further formulated to develop an eco-benign product for the bioremediation of DBP-contaminated toxic sanitary landfill soils.

Dielectric barrier discharge plasma for the remediation of microplastic-contaminated soil from landfill

The huge amount of plastic waste accumulated in landfills has caused serious microplastic (MP) pollution to the soil environment, which has become an urgent issue in recent years. It is challenging to deal with the non-biodegradable MP pollutants in actual soil from landfills. In this study, a coaxial dielectric barrier discharge (DBD) system was proposed to remediate actual MP-contaminated landfill soil due to its strong oxidation capacity. The influence of carrier gas type, applied voltage, and air flow rate was investigated, and the possible degradation pathways of MP pollutants were suggested. Results showed the landfill soil samples contained four common MP pollutants, including polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC) with sizes ranging from 50 to 1500 μm. The MP pollutants in the soil were rapidly removed under the action of reactive oxygen species (ROS) generated by DBD plasma. Under the air flow rate of 1500 mL min−1, the maximum remediation efficiency represented by mass loss reached 96.5% after 30 min treatment. Compared with nitrogen, when air was used as the carrier gas, the remediation efficiency increased from 41.4% to 81.6%. The increased applied voltage from 17.5 to 24.1 kV could also promote the removal of MP contaminants. Sufficient air supply was conducive to thorough removal. However, when the air flow rate reached 1500 mL min−1 and continued to rise, the final remediation efficiency would be reduced due to the shortened residence time of ROS. The DBD plasma treatment proposed in this study showed high energy efficiency (19.03 mg kJ−1) and remediation performance (96.5%). The results are instructive for solving MP pollution in the soil environment.