Waste Leachate Research Articles

Hazardous waste leachates induced changes in plant water relation, photosynthetic pigments, heavy metal accumulation and yield of mustard (Brassica juncea L.) plant

Chromium (Cr) contamination by industrial sites in water and agricultural soils is common and responsible for the human body being at risk from this heavy metal. The present study aims to assess the plant growth, yields, photosynthetic pigments, water relation, and heavy metal accumulation to understand the nature of the adaptation of Cr overload in mustard plants. An experiment was conducted at different levels of Basic Chrome Sulphate (BCS) sludge leachates i.e., T1 (control without leachates), T2 (25% leachates+75% DW); T3 (50% leachates + 50% DW); T4 (75% leachates + 25% DW) and T5 (100% leachates) on mustard (Brassica juncea L.) plant in completely randomized design (CRD). The primary leachates were collected from the dumping site of BCS sludge which was situated at 26⁰24′57′' NL and 80⁰3′28′' EL at Khanchandpur Kharanja, Rania, Kanpur Dehat district of Uttar Pradesh, India. Results indicated that the vegetative growth and yield were significantly decreased on increasing the dose of leachates. The linear regression coefficient (R2) values showed that the number of seeds, biomass, and seed yields per plant were more significantly affected (R2 = 0.963, R2 = 0.955, and R2 = 0.872 respectively) than vegetative growth (R2 = 0.706). The photosynthetic pigments like chlorophyll `a' (Chl. a), chlorophyll `b' (Chl. b), and carotenoid contents were significantly increased on increasing the dose of leachates while the Chl.`a'/Chl.`b' ratio decreased but carotenoid/ chlorophyll ratio increases. The leaf surface area and relative water contents (RWC) were significantly decreased while the degree of succulence and specific water content were significantly increased. Maximum Cr concentration was observed in the root up to T4 levels and further sharply declined while shoot and seed, it was not detected up to T4 but further sharply increased which may be due to Cr being restricted in the root up to a certain limit of Cr load in mustard plant and further on increasing the load it enters into the shoot and affects to growth and yields. The accumulation of Cr, Ni, and Pb was increased on increasing leachate dose because leachates also contain these heavy metals. The results of the Pollution Load Index (PLI) indicated that Cr scored maximum (1.792) pollution load and showed descending order as Cr > Zn >Pb>Cu>Cd>Ni.

SARS-CoV-2 surveillance-based on municipal solid waste leachate in Brazil.

Municipal solid waste leachate-based epidemiology is an alternative viral tracking tool that applies fresh truck leachate as an early warning of public health emergencies. This study aimed to investigate the potential of SARS-CoV-2 surveillance based on solid waste fresh truck leachate. Twenty truck leachate samples were ultracentrifugated, nucleic acid extracted, and real-time RT-qPCR SARS-CoV-2 N1/N2 applied. Viral isolation, variant of concern (N1/N2) inference, and whole genome sequencing were also performed. SARS-CoV-2 was detected on 40% (8/20) of samples, with a concentration from 2.89 to 6.96 RNA Log10 100mL-1. The attempt to isolate SARS-CoV-2 and recover the whole genome was not successful; however, positive samples were characterized as possible pre-variant of concern(pre-VOC), VOC Alpha (B.1.1.7) and variant of interest Zeta (P.2). This approach revealed an alternative tool to infer SARS-CoV-2 in the environment and may help the management of local surveillance, health, and social policies.

Long-term Performance of Conductive-backed multilayered HDPE Geomembranes

The long-term performance of three multilayered textured white conductive-backed geomembranes (GMBs) is compared to the comparable textured nonconductive GMBs and their smooth edge/equivalent to investigate the effect of the conductive layer on their longevity. Oven immersion in synthetic municipal solid waste leachate is used at a range of temperatures to accelerate the ageing during an incubation period of 50 months. It is shown that the conductive layer can antagonistically or synergistically affect the antioxidant depletion of conductive-backed GMBs relative to nonconductive GMBs produced by the same GMB manufacturer and formulated using the same nominal resin and antioxidant package. However, their relative degradation at 85 °C does not necessarily follow their relative antioxidant depletion times implying that the manufacturing process and the interaction between the additive packages of these GMBs can affect their relative degradation beyond the antioxidant depletion stage. Arrhenius modelling predicts the antioxidant depletion stage at field temperatures ranging between 180 and 1400 years at 20 °C for two different conductive-backed GMBs produced by two different manufacturers. With such variation in the long-term performance of conductive-backed GMBs currently available in the market, their durability should be investigated before their use in barrier systems to ensure they can meet the required design life of the desired geoenvironmental application.

Hydrochemistry and groundwater quality assessment around solid waste landfill sites in peri-urban Jaipur, NW India.

Jaipur, the capital city of Rajasthan State in northwestern India, is one of the fastest-growing urban centers in the country. The city and the region around it have documented a substantial drop in the water table due to the over-abstraction of groundwater resources to cater to the increasing water demands of the growing population. Consequently, the entire Jaipurdistrict has been categorized as a "dark zone," prohibiting any further groundwater development activity. Besides its dwindling availability, water quality is also a matter of concern. In places, the water is geogenically contaminated and unsuitable for drinking purposes due to high levels of undesired elements in groundwater, such as high fluoride in the southern part and high chloride in the southwestern part of the district. Groundwater contamination can also occur through several anthropogenic factors, such as industrialization and excessive use of insecticides and pesticides. Water pollution through sewage disposal in open land-fill sites is also an important factor, especially in the growing urban centers. In this study, the water quality evaluation around three landfill sites in the Jaipur district, namely Mathura Das Pura and Langadiyawas (east of the city) and Sewapura (northwest of the city), was carried out. The cation-anion analysis of 45 groundwater samples collected around these sites reveals a wide variation in the abundance of constituent parameters. In a majority of cases, most of the parameters are within acceptable limits prescribed by the national and international agencies (Bureau of Indian Standards and World Health Organization). The fluoride content is more than the prescribed limit of 1.5mg/l in several cases. This could be an intrinsic property of deeper aquifers. The majority of Mathura Das Pura and Langadiyawas samples classify as Na + K - CO3 + HCO3 to Mg - CO3 + HCO3 types in the Piper classification scheme, while a small proportion shows mixed water type characteristics, i.e., with no dominant parameter. Most of the samples have heavy metal abundances within the permissible limits while slightly elevated Cd and Pb levels were observed in some samples. A positive correlation between these two metals can be attributed to a common pollutant, possibly sourced from solid waste. The percent pollution index of Sewapura samples shows lower pollution levels (PPI < 40%) and a dominant chemical weathering trend while the majority of Mathura Das Pura-Langdiyawas samples show a high pollution effect (PPI 40 to 80%). In general, the chemical parameters of Sewapura (relatively new landfill site) samples define a more coherent group while water quality parameters in Mathura Das Pura and Langdiyawas (old landfill sites) samples show a wide variation, unsystematic distribution, and significantly higher than prescribed values for most of the hydrochemical parameters. The study shows that some of the water quality issues may be geogenic, while municipal waste dumping and leachate infiltration have adversely affected the groundwater quality.

Evaluating barrier performance of geomembranes against 1,4-dioxane and bisphenol a in landfill leachates

Previous studies have shown that within a month benzene easily passes through geomembranes (PVC, LDPE, and HDPE geomembranes). This study uses diffusive permeation tests to clarify the barrier performance of geomembranes against bisphenol A and 1,4-dioxane, which have been detected in some Japanese waste leachates. Although dissolved bisphenol A can be adsorbed on the geomembranes, it does not pass through them during the testing period (at least 400 days are required for it to completely pass through 0.5-mm-thick PVC geomembranes). In addition, dissolved 1,4-dioxane is not adsorbed on any geomembranes and hardly passes through any of them (at least five years are required for it to completely pass through 0.5-mm-thick PVC geomembranes). Thus, geomembranes exhibit a good barrier performance against these two organic compounds, especially 1,4-dioxane.

Interactions of waste disposal site leachate with the Merida karst aquifer, Mexico

Hydrogeochemical tools were applied to evaluate the effect caused by the presence of municipal waste leachate on the balance of a karstic aquifer. The system evaluated correspond to the aquifer underlying the area of the old municipal waste disposal site (MWDS) in the city of Merida, Mexico. A contaminant plume identified with chloride ion concentrations was detected. Groundwater samples were collected from boreholes located along a flow line, starting at the downstream boundary of the dump site. The parameters involved in the carbonate system were analyzed, obtaining a decline in calcium (Ca2+) and magnesium (Mg2+) concentrations for high pCO2 values. This behavior is explained by the presence of high bicarbonate (HCO3–) content, as a result of the waste decomposition reactions. The bicarbonate ions behaved as a buffer preventing pH reduction. In addition to this, the calcium and magnesium species indicate that the formation of complexes affected the mineral solubility where leachate has the greatest influence. The transport of minerals, in moles, between boreholes located along the groundwater flow line, was determined through inverse modeling. It is concluded that the leachate affects the carbonate balance, as determined by the transfer of minerals along the flow line; it was observed that mixed waters with a higher percentage of leachate tend to dissolve carbonate minerals. This is the analogous to findings reported in other leachate contaminated aquifers.

Machine-learning-aided application of high-gravity technology to enhance ammonia recovery of fresh waste leachate

Stripping is widely applied for the removal of ammonia from fresh waste leachate. However, the development of air stripping technology is restricted by the requirements for large-scale equipment and long operation periods. This paper describes a high-gravity technology that improves ammonia stripping from actual fresh waste leachate and a machine learning approach that predicts the stripping performance under different operational parameters. The high-gravity field is implemented in a co-current-flow rotating packed bed in multi-stage cycle series mode. The eXtreme Gradient Boosting algorithm is applied to the experimental data to predict the liquid volumetric mass transfer coefficient (KLa) and removal efficiency (η) for various rotation speeds, numbers of stripping stages, gas flow rates, and liquid flow rates. Ammonia stripping under a high-gravity field achieves η = 82.73% and KLa = 5.551 × 10−4 s−1 at a pH value of 10 and ambient temperature. The results suggest that the eXtreme Gradient Boosting model provides good accuracy and predictive performance, with R2 values of 0.9923 and 0.9783 for KLa and η, respectively. The machine learning models developed in this study are combined with experimental results to provide more comprehensive information on rotating packed bed operations and more accurate predictions of KLa and η. The information mining behind the model is an important reference for the rational design of high-gravity-field-coupled ammonia stripping projects.

Method for establishing soil contaminant discharge inventory: An arsenic-contaminated site case study

The existing method to survey site pollution is generally based on soil-groundwater sampling and instrumental analysis, which enables us to access the detailed soil pollution status while lacking quantitative association with industrial activities. It is urgent to understand contaminant discharge modes and establish a discharge inventory for achieving process-targeted pollution control. This study took a 40-year phosphate fertilizer-sulfuric acid site as an example and constructed a contaminant tracing method based on on-site investigations and detailed industrial data. These investigations and data were combined to determine the characteristic pollutant of this site, arsenic. And the calculation process of four-pathway pollution modes (atmospheric deposition, wastewater, solid waste leaching, and storage dripping) is derived from the existing acceptance criteria and risk assessment guidelines. They are set to calculate the arsenic's factory-to-soil discharge flux. The absent process contaminant release information and parameters, such as discharge coefficient, were obtained from soil-groundwater pollution control standards and discharge handbooks. It was found that the high concentration of arsenic (around 1930 mg g−1) was preponderantly caused by sulfur-iron slag and tailing leaching (96.19%), while the other pathways accounted for only 0.13% (atmospheric deposition), 3.59% (wastewater) and 0.09% (storage tank). Results were verified by the measured arsenic concentration, and the difference was +16.29%, which was acceptable. Finally, a contaminant discharge inventory was established with high-resolution spatial distribution and time-scale (historical discharge) evolution. The innovation of this study lies in the preliminary construction of a method for formulating soil discharge inventory. This study would contribute to the refined management of site pollution and reduction of source contaminants discharge. In addition, it will help infer the pollution condition of sites that are difficult to sample so as to help the government achieve precise source control.

Co-Extraction of Uranium and Mercury Using Ion Exchange from Cemented Radioactive Waste Sulfuric Leachate in Iodide Media

The production of medical isotopes in Chalk River Laboratories facilities (Chalk River, ON, Canada) has resulted in a large quantity of cemented radioactive waste (CRW) containing valuable elements such as uranium. From the perspective of recovering and ultimately recycling valuable elements from CRW, the solubilization of key constituents such as uranium, mercury, and cesium has been previously investigated using H2SO4/KI. However, to achieve recycling of these elements, separation must be performed as they are co-solubilized. In this study, the extraction of uranium and mercury by chelating resin Lewatit TP260 from surrogate cemented radioactive waste (SCRW) leaching solution in sulfuric media and in the presence of iodide was investigated. Extraction of U and Hg was assessed as a function of the concentration of KI (0.12 M to 0.24 M) used during the SCRW dissolution process. Continuous experiments showed that the Lewatit TP260 functional group, aminomethylphosphonic acid, had a high affinity for U. Mercury was also extracted onto the Lewatit TP260. However, the presence of iodide in the SCRW leaching solution increased the competition between the adsorbed mercury of the stationary phase and the iodide–mercury complexes of the mobile phase. Additionally, the reusability of the resin was tested through extraction and desorption cycles. Due to the presence of trivalent cation, the capacity of Lewatit TP260 for U and Hg decreases with the number of cycles.

Dissemination of sulfonamide resistance genes in digester microbiome during anaerobic digestion of food waste leachate

The preeminence of sulfonamide drug resistance genes in food waste (FW) and the increased utilization of high-strength organic FW in anaerobic digestion (AD) to enhance methane production have raised severe public health concerns in wastewater treatment plants worldwide. In this regard, the dissemination patterns of different sulfonamide resistance genes (sul1 and sul2) and their impact on the digester core microbiota during AD of FW leachate (FWL) were evaluated. The presence of various sulfonamide antibiotics (SAs) in FWL digesters improved the final methane yield by 37 % during AD compared with FWL digesters without SAs. Microbial population shifts towards hydrolytic, acidogenic, and acetogenic bacteria in the phyla Actinobacteriota, Bacteroidota, Chloroflexi, Firmicutes, Proteobacteria, and Synergistota occurred due to SA induced substrate digestion and absorption through active transport; butanoate, propanoate, and pyruvate metabolism; glycolysis; gluconeogenesis; the citrate cycle; and pentose phosphate pathway. The initial dominance of Methanosaeta (89–96 %) declined to 47–53 % as AD progressed and shifted towards Methanosarcina (40 %) in digesters with the highest SA concentrations at the end of AD. Dissemination of sul1 depended on class 1 integron gene (intl1)-based horizontal gene transfer to pathogenic members of Chloroflexi, Firmicutes, and Patescibacteria, whereas sul2 was transmitted to Synergistota independent of intl1. Low susceptibility and ability to utilize SAs during methanogenesis shielded methanogenic archaea against selection pressure, thus preventing them from interacting with sul or intl1 genes, thereby minimizing the risk of antibiotic resistance development. The observed emergence of cationic antimicrobial peptide, vancomycin, and β-lactam resistance in the core microbiota during AD of FWL in the presence of SAs suggests that multidrug resistance caused by bacterial transformation could lead to an increase in the environmental resistome through wastewater sludge treatment.

Screening of pharmaceutical and personal care products (PPCPs) along wastewater treatment system equipped with root zone treatment: A potential model for domestic waste leachate management

We present the use of root zone treatment (RZT) based system for the removal of pharmaceutical and personal care products (PPCPs) from domestic wastewater. The occurrence of more than a dozen PPCPs were detected in an academic institution wastewater treatment plant (WWTP) at three specific locations, i.e., influent, root treatment zone, and effluents. The comparisons of observed compounds detected at various stages of WWTP suggest that the presence of PPCPs, like homatropine, cytisine, carbenoxolone, 4,2′,4′,6′-tetrahydroxychalcone, norpromazine, norethynodrel, fexofenadine, indinavir, dextroamphetamine, 3-hydroxymorphinan, phytosphingosine, octadecanedioic acid, meradimate, 1-hexadecanoyl-sn-glycerol, and 1-hexadecylamine, are unusual than the usual reported PPCPs in the WWTPs. In general, carbamazepine, ibuprofen, acetaminophen, trimethoprim, sulfamethoxazole, caffeine, triclocarban, and triclosan are often reported in wastewater systems. The normalized abundances of PPCPs range between 0.037–0.012, 0.108–0.009, and 0.208–0.005 in main influent, root zone effluent, and main effluents, respectively, of the WWTP. In addition, the removal rates of PPCPs were observed from −200.75% to ∼100% at RZT phase in the plant. Interestingly, we observed several PPCPs at later stages of treatment which were not detected in the influent of the WWTP. This is probably owing to the presence of conjugated metabolites of various PPCPs present in the influent, which subsequently got deconjugated to reform the parent compounds during the biological wastewater treatment. In addition, we suspect the potential release of earlier absorbed PPCPs in the system, which were absent on that particular day of sampling but have been part of earlier influents. In essence, RZT-based WWTP was found to be effective in removing the PPCPs and other organic contaminants in the study but results in stress the need for further comprehensive research on RZT system to conclude the exact removal efficacy and fate of PPCPs during treatment in the system. As a current research gap, the study also recommended RZT to be appraised for PPCPs in-situ remediation from landfill leachates, an underestimated source of PPCPs intrusion in the environment.

Effects of Pore Fluid and Surface Roughness on Geomembrane - Soil Interface Behavior

In this study, direct shear tests were conducted on soil - geomembrane interfaces. Sand/bentonite mixture and crushed sand were tested in contact with two geomembranes of the same type. To examine the effect of leachate on the mechanical properties of the geomembrane, acidic mine drainage, coal combustion product, and municipal solid waste leachates were prepared in the laboratory. The initial void ratio and internal friction angles of sand/bentonite and crushed sand were 0.34, 0.52, and 23⁰, 35⁰, respectively. In the smooth geomembrane - soil interface, the minimum interface friction angle (18⁰) was obtained on acidic mine drainage cured geomembrane – sand/bentonite, while the maximum (31⁰) interface friction angle was obtained on uncured geomembrane - crushed sand. In the textured geomembrane - soil interface, the minimum interface friction angle (17⁰) was obtained on acidic mine drainage cured geomembrane – sand/bentonite, while the maximum (43⁰) interface friction angle was obtained on uncured geomembrane - crushed sand. The friction angle of the crushed sand - geomembrane surface is higher than the friction angle of the sand/bentonite - geomembrane surface. While acidic mine drainage is the leachate that affects the shearing behavior of the geomembrane in the most negative way, coal combustion product is the leachate that has the least negative impact.

Impacts of garbage classification and disposal on the occurrence of pharmaceutical and personal care products in municipal solid waste leachates: A case study in Shanghai

Leachate generated during the treatment and disposal of municipal solid wastes (MSWs) can be an important source of pharmaceutical and personal care products (PPCPs) in the environment. With the implementation of garbage classification policy in China, the disposal methods of MSWs have changed, while its impacts on the occurrence of PPCPs in the generated leachate remain unknown. In this study, we investigated 49 target PPCPs in the leachates of classified MSWs, i.e. residual waste leachate (RWL) and food waste leachate (FWL), and revealed the influence of garbage classification implementation on the occurrence of PPCPs in leachates to be treated. The results showed the concentration and mass load of target PPCPs in the RWL samples (median values: 34.9 ng/L and 52.3 mg/d, respectively) were significantly higher than those in the FWL samples (median values: 19.3 ng/L and 14.5 mg/d, respectively). Macrolide (ML) antibiotics were the predominant PPCPs in the RWL samples, while in the FWL samples, quinolone (QL) antibiotics exhibited the highest concentration and mass load. The implementation of garbage classification policy led to the reduction of PPCP mass load (from 739 g/d to 262 g/d) in leachates to be treated. The findings are helpful for better designing or managing MSW treatment and disposal processes to minimize the emission of PPCPs from MSW leachates.

A comparison of reactor configuration using a fruit waste fed two-stage anaerobic up-flow leachate reactor microbial fuel cell and a single-stage microbial fuel cell

Food waste generation and its consequent environmental impacts are increasing due to rapid urbanization, the global population, and associated food demand. Microbial fuel cells (MFCs) are a sustainable technology through which this food waste can be treated and used to produce bioelectricity. This study used two MFC configurations, a two-stage anaerobic up-flow leachate reactor MFC and a single-stage MFC, comparing the potential to treat solid fruit waste and fruit waste leachate. The two-stage MFC showed a higher potential to remove substrate at a shorter time compared to single-stage MFC. In 30 days, the two-stage anaerobic up-flow leachate reactor had a power density of 221 mW/m2. It was able to remove more total solids (by 95 %), volatile solids (by 70 %), total chemical oxygen demand (by 83 %), soluble chemical oxygen demand (by 87 %), and carbohydrates (by 33 %) compared to the single-stage MFC. However, the single-stage MFC showed higher coulombic efficiency (by 86.7 %) compared to the two-stage MFC. The efficiency of single-stage MFC improved by adding buffer and maintaining a neutral pH level of the substrate. The results of this study emphasize the importance of reactor design and demonstrate that MFC can be a viable technology to generate bioenergy from food waste.

Processing of Phosphoric Solid Waste by Humic Acid Leaching Method

This article presents the results of research on the leaching of solid phosphorus-containing waste with humic acid. Such waste includes the by-products of the electrothermal processing of phosphate raw materials—phosphorus sludge and cottrel dust. Chemical and X-ray diffraction analyses have been used to study their composition and phase structure, according to which these substances have an amorphous structure. The leaching of phosphoric sludge and cottrel dust was investigated by varying the main parameters. The obtained data were processed using the method of formal kinetics to study the features of the process. The reaction rate constants and the apparent activation energy were calculated, and the values found made it possible to determine that the process under study is limited by diffusion. The scientific novelty of the article is the use of humic acid for leaching phosphoric solid waste as opposed to traditional methods. This new method may offer improved efficiency, reduced environmental impact, and a potential alternative solution for the processing of phosphoric waste.

Interfacial Coordination Bonding-Assisted Redox Mechanism-Driven Highly Selective Precious Metal Recovery on Covalent-Functionalized Ultrathin 1T-MoS2.

Rational design of functional material interfaces with well-defined physico-chemical-driven forces is crucial for achieving highly efficient interfacial chemical reaction dynamics for resource recovery. Herein, via an interfacial structure engineering strategy, precious metal (PM) coordination-active pyridine groups have been successfully covalently integrated into ultrathin 1T-MoS2 (Py-MoS2). The constructed Py-MoS2 shows highly selective interfacial coordination bonding-assisted redox (ICBAR) functionality toward PM recycling. Py-MoS2 shows state-of-the-art high recovery selectivity toward Au3+ and Pd4+ within 13 metal cation mixture solutions. The related recycling capacity reaches up to 3343.00 and 2330.74 mg/g for Au3+ and Pd4+, respectively. More importantly, above 90% recovery efficiencies have been achieved in representative PMs containing electronic solid waste leachate, such as computer processing units (CPU) and spent catalysts. The ICBAR mechanism developed here paves the way for interface engineering of the well-documented functional materials toward highly efficient PM recovery.

Characterization of the microbiological effects of pomegranate, banana, and mandarin peels on water under laboratory conditions

The protection of natural resources, especially water resources, is attracting international attention by researchers in order to achieve sustainable development. Inadequate treatment of waste from the food industry leads to pollution of ground and surface water through leachate or direct discharge of waste. To understand the impact of inappropriate discharge of these wastes, the microbial groups (bacteria, yeasts, and moulds) of pomegranate peel (PP), banana peel (BP), mandarin peel (MP) and the water in which each waste is decomposed were studied. The microbial groups were isolated, quantified, and purified by elective media at 30 °C. The fungal microbial isolates were identified by their macro and microscopic characteristics. The findings show that the highest density of bacteria (3.95 ± 0.48 × 105 CFU/ml) was obtained in the water in which the BP is decomposed, the highest density of yeasts (4.59 ± 0.52 × 105 CFU/ml) and moulds (4.10 ± 0.34 × 105 CFU/ml) was recorded in the water in which the PP is decomposed compared to the microbial density of the initial and the final control water. The fungal microbial groups were more diverse between the decomposition waters; the waters in which PP and BP are decomposed showed a higher diversity with 9 and 8 species respectively, compared to the water in which MP is decomposed with 7 species, and compared to the initial and the final control water with 3 and 5 species respectively. Conclusively, direct dumping or landfilling of food waste in general, PP, BP, and MP in particular can cause pollution of surface and groundwater by microorganisms that can be harmful.

Leaching of Sm, Co, Fe, and Cu from Spent SmCo Magnets Using Organic Acid

In this study, the Taguchi method was used to investigate the effect of citric acid and malic acid on the leaching of SmCo magnet waste. First, we used a L16(45) orthogonal table to conduct experiments. Second, we conducted a factor effect analysis on the experimental results of the orthogonal table to understand the influence of temperature, acid concentration, solid–to–liquid ratio, time, and hydrogen peroxide on the leaching efficiency and we obtained the priority order of the factors affecting the leaching efficiency. The priorities of citric acid and malic acid were H2O2 &gt; temperature &gt; S/L &gt; time &gt; acid and temperature &gt; time &gt; S/L &gt; H2O2 &gt; acid, respectively. Finally, the optimal leaching parameters were obtained through confirmation experiments. For optimal leaching rates with citric acid, the amount of hydrogen peroxide (H2O2) added was 2.0 vol.%, the temperature was 90 °C, the S/L ratio was 5 g L−1, the time was 135 min and the acid concentration was 1.0 mol L−1, resulting in leaching efficiencies of Sm, Co, Fe, and Cu of 87.62, 93.82, 97.10, and 92.84%, respectively. For optimal leaching rates with malic acid, the temperature was 80 °C, the time was 75 min, the S/L ratio was 7.5 g L−1, the amount of hydrogen peroxide added was 3.5 vol.%, and the acid concentration was 1.5 mol L−1, resulting in leaching efficiencies of Sm, Co, Fe, and Cu of 75.18, 74.58, 82.42, and 1.35%, respectively.

Evaluation of per- and polyfluoroalkyl substances (PFAS) in leachate, gas condensate, stormwater and groundwater at landfills

Per- and polyfluoroalkyl substances (PFAS), found in many consumer products, are commonly disposed of in landfills at the end of their service lives. To identify landfill liquids that should be prioritized for treatment, this study aimed to evaluate PFAS levels in different aqueous samples from landfills and identify relationships between PFAS and landfill characteristics. Twenty-six PFAS including 11 perfluoroalkyl carboxylic acids (PFCAs), 7 perfluoroalkyl sulfonates (PFSAs), and 8 perfluoroalkyl acid precursors (PFAA-precursors) were measured in municipal solid waste (MSW) leachate, construction and demolition debris (CDD) leachate, municipal solid waste incineration (MSWI) ash leachate, gas condensate, stormwater, and groundwater from landfills. Based on the median, results show that PFAS levels in MSW leachate were the highest (10,000 ng L−1), CDD leachate were intermediate (6200 ng L−1), and MSWI ash leachate were the lowest (1300 ng L−1) among the leachates evaluated. PFAS levels in gas condensate (7000 ng L−1) were similar to MSW leachate. PFAS in stormwater and groundwater were low (medians were less than 500 ng L−1). Dominant subgroups included PFCAs and PFAA-precursors in all leachates. PFSAs were also found in CDD leachate, PFAA-precursors in gas condensate, and PFCAs in stormwater and groundwater. Landfill characteristics significantly correlated with ∑26PFAS included waste proportions (percentage of MSWI ash in landfill, |rs| = 0.22), operational status (active or not, |rs| = 0.27) and rainfall (30-d cumulative rainfall, |rs| = 0.39). The results from this study can be used to prioritize which landfills and which reservoir of liquids (and corresponding subgroup of PFAS) to target for PFAS management.

Wastewater Treatment of Solid Waste Leachate and Production of Proteinaceous Biomass Using Duckweed Vegetation ( Lemna minor )

Tekoğul, H., 2023. Wastewater treatment of solid waste leachate and production of proteinaceous biomass using duckweed vegetation (Lemna minor). Journal of Coastal Research, 39(2), 296–302. Charlotte (North Carolina), ISSN 0749-0208. Phytoremediation provides cost–effective wastewater treatment and recovery of wastewater as rich biomass by aquatic plants and produces bioenergy and various important by-products. This study was carried out to treat solid waste leachate with Lemna minor L. and convert wastewater nutrients into protein-rich biomass by this aquatic plant. To create the experimental setups, L. minor was produced in wastewater at six dilution ratios: 100% (T1), 75% (T2), 50% (T3), 25% (T4), Hoagland medium with Lemna (T5c), and 100% wastewater without Lemna (T6). At the end of the 45-day study,the pH 7.00 (T5c) and 8.81, the protein yield rate (crude protein) in the trial groups was found to be T1 = 40.10%, T2 = 67.53%, T3 = 75.24%, T4 = 42.72%, and T5c = 85.00%. In the study, the T3 group showed the best performance in terms of initial weight, final weight, total biomass, specific growth rate, relative growth rate, and protein ratio in wastewater groups. The highest and lowest removal rates in leachate ranged between 85.40% (T4) and 56.50% (T1) for the NH4 +-N value, 14.20% (T4) and 4.73% (T2) for NO2-N, 16.96% (T4) and 6.53% (T3) for NO3-N, and 23.10% (T3) and 16.08% (T1) for PO4–3-P. The total biomass of the trial groups showed an average 50.55% increase from the baseline level. Although 46% biomass was obtained in the Hoagland medium with vegetative growth, a very high biomass of 61% was obtained in the T3 group of solid waste leachate containing dilute wastewater. As a result, phytoremediation is recommended as a solid option for the management of wastewater resources. This efficiency has shown that aquatic plants can be used in the treatment of wastewater and the obtained high protein biomass can be used in various ways, such as animal feed and bioenergy.