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A proper management of leachates, including their treatment and pretreatment, constitutes a challenge for the operators of landfills. A known method of the treatment of leachates is the adsorption. Responding to the need for reasonable management of raw materials and energy, waste is used as substitutes of commercial sorbents. The laboratory tests on the pretreatment of leachates from the landfill in Janczyce included the following compounds: zeolite (Z), activated carbon (AC), shungite (S), walnut shells (WS), spent coffee grounds (SCG) and sewage sludge (SS). The research allowed to determine the influence of the contact time (10, 20, 40, 80 and 160 min) on the chemical oxygen demand (COD), the colour, the dissolved organic compounds and heavy metals at adsorption dosage (5, 10, 20, 40 and 80 g·L–1). The kinetics and isotherms of the adsorption were determined. Better effectiveness of the activated carbon was discovered for the removal of the colour of the leachate and the reduction of the COD in comparison to the shungite and zeolite. Satisfactory effectiveness of sewage sludge, spent coffee grounds and walnut shells was not found for the remediation of landfill leachates. The highest effectiveness of the removal of the COD (13.5% for SS and t = 10 and 20 min; 19.9% for WS and t = 160 min; 12.9% for CG and t = 10 min) and the colour (34.9% for SS and t = 10; 26.6% for WS and t = 20 min) for alternative sorbents was obtained for 5 g·L–1 dose. Higher doses and longer time cause the deterioration of the initial parameters of the landfill leachates. More favourable effects of the removal of the COD were obtained for shungite (76% for D = 80 g·L–1 and t = 160 min), activated carbon (75.5% for D = 80 g·L–1 and t = 10 min) and zeolite (57.5% for D = 40 g·L–1 and t = 80 min). In the aspect of the elimination of UVA(254), the greatest results were obtained for activated carbon (99.97%, D = 40 g·L–1, t = 160 min), shungite (74%, D = 80 g·L–1, t = 40 min) and zeolite (14.5%, D = 80 g·L–1, t = 160 min). In the aspect of the elimination of the colour, the greatest results were obtained for activated carbon (99.14%, D = 80 g·L–1, t = 60 min), while slightly weaker effects were obtained for shungite (80.5%, D = 80 g·L–1 and t = 80 min) and zeolite (69.25%, D = 80 g·L–1, t = 80 min). An improvement of the adsorption properties of sewage sludge, spent coffee grounds and walnut shells can be realised by proper conditioning. [ABSTRACT FROM AUTHOR]

Potassium ferrate was used in the decontamination of leachate from the landfill in Janczyce, which is part of the Municipal Waste Treatment Plant in Janczyce and has been operating since 2003. The aim of the research is to assess the effectiveness of pre-treatment of landfill leachate with the use of potassium ferrate(VI) (K2 FeO4 ). The potassium ferrate(VI) (K2 FeO4 ) used acts as an oxidant and coagulant. The effects of the K2 FeO4 dose, the duration of the oxidation process and pH were modelled. Analysis of the test results indicates a high elimination efficiency for colour and UVA254. The elimination of pollutants measured by the chemical oxygen demand (COD) index is slightly worse. Based on the results obtained, a mathematical model was developed for the oxidation process of landfill leachate with K2 FeO4 as oxidant and coagulant. The best COD elimination results (45%) were obtained for a potassium ferrate(VI) dose equal to 2.0 g·L–1, pH = 4.5 and after 90 min of landfill leachate oxidation. The best leachate pre-treatment effects were achieved in terms of colour elimination, where managed to reduce the colour by 97% and UV absorbance by approx. 60% at a potassium ferrate(VI) dose equal to 4.5 g·L–1 and, pH = 5.01 and landfill leachate oxidation duration of 60 min. [ABSTRACT FROM AUTHOR]

In this study, a new second-order reaction kinetics model was developed for the elimination of chemical oxygen demand (COD) in landfill leachate treatment with Fenton reagent. The objective of the reaction was to reduce COD, UVA(254) and color in the process of landfill leachate treatment with Fenton reagent. The model was verified on sample data obtained experimentally. Oxidation concerns landfill leachate organic pollutants in the presence of Fe(II) for different oxidant and catalyst concentrations. The results of experiments demonstrated that the use of Fenton reaction have brought the expected outturns. As a result of using the Fenton reaction, the content of COD was lowered from 1.742 to 0.177 g·L–1. On the basis of the investigations, the values of the reaction rate constants k2 were estimated from 0.0018 to 0.0023 L·g–1·min–1. It was shown that the conversion degree can become a useful tool for the assessment of the oxidation reaction kinetics. [ABSTRACT FROM AUTHOR]

Landfill leachate is a major hazard for the surrounding ambience as it detrimentally contaminates the soil and groundwater. In the present study, sulfate radical based advanced oxidation process (SR-AOP) was adopted for the treatment of stabilized/mature landfill leachate (SLL) using pyrite (FeS 2) as a heterogeneous catalyst. The FeS 2 catalyst was characterized using XRD, FT-IR, SEM and EDX spectroscopy techniques to evaluate its structural, functional groups, morphological features, and chemical composition, respectively. The effect of various operating parameters on SR-AOP such as initial pH, FeS 2 dosage, Na 2 S 2 O 8 concentration, and temperature on COD and TOC removal was also studied. The FeS 2 (1000 mg/L), Na 2 S 2 O 8 (1000 mg/L) concentrations at pH 8.8 were found optimal, and COD and TOC removals were found as 78.5% and 74.2%, respectively. After the treatment of SR-AOP, BOD 5,20 /COD ratio of landfill leachate was improved from 0.023 to 0.41. Scavenging tests revealed that the primary oxidative species in SR-AOP are •OH and SO 4 •-; however, SO 4 •- plays a major role while •OH is also involved in the process. Intriguingly, no significant change in the catalytic efficiency and characteristic nature of FeS 2 was observed even after four sequential treatments of the same FeS 2 catalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

Aerobic granular sludge (AGS) systems treating effluents with a C:N:P ratio similar to real old landfill leachate were evaluated on simultaneous C, N and P removals, and to reduce the main problems encountered, such as nitrite accumulation, biomass loss, and granule disintegration. Therefore, six sequential batch reactors (SBR) were operated with different anaerobic (A), anoxic (An), and aerobic (O) configurations: A/O (R1 and R2), O/An with conventional feeding and well-defined anoxic phase (R3), O/An with step-feeding and well-defined anoxic phase (R4), and O/An (R5 and R6). The O/An with step-feeding reactor (R4) had the highest biomass retention/settleability (SVI 30 < 50 mL/g), the best nitrification rates (99%), and chemical oxygen demand (COD) (97%), total nitrogen (91%) and total phosphorous (55%) removals. Furthermore, there was no nitrite accumulation, and granules' disintegration was insignificant. The most abundant phylum in the reactors O/An was Planctomycetota, composed mainly of organisms from the Pirellulaceae and Legionellaceae families. In these reactors, the abundance of phosphorus-accumulating organisms (PAOs) and denitrifying bacteria were similar, while the abundance of glycogen-accumulating organisms was much higher than PAOs. Therefore, the type of cycle directly influences performance, granule characteristics, and system stability, being important for future investigations applying the AGS technology to leachate treatment. [Display omitted] • Effect of cycle type was studied in aerobic granular sludge (AGS) systems. • Oxic (O)/anoxic (An)-type reactor with a well-defined An phase was the best cycle configuration. • The highest COD, TN, and P removals were achieved at the O/An cycle with step-feeding. • The intercalation of the feast/famine and anoxic periods minimized nitrite accumulation. • Planctomycetota was the most abundant phylum in the reactors with a well-defined anoxic phase and step-feeding. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this study was to measure the environmental impact of five different laboratory-scale constructed wetland (CW) treatment systems with varying design approaches, which have been employed to treat different types of wastewater. Moreover, the present study also assessed the feasibility of treating landfill leachate using four different hybrid wetlands built outdoors, and analyzed the environmental viability based on the life cycle assessment (LCA). Primarily, the choice of media materials has been the focus of evaluating the sustainability of the systems, as for each system the media materials cover major material consumption and define treatment performance. Methods: This study applied a life cycle assessment using the SimaPro software tool to quantify the environmental impacts from the constructed wetland systems. Primarily, the LCA has been applied by adopting the ReCiPe 2016 method with cross-validation using the Impact 2002+ method. Moreover, an uncertainty analysis has been performed to determine any uncertainties involved in the datasets, along with sensitivity analysis on the inventory. Results and discussions: As the results suggest, the systems employed for wastewater treatment using cement mortar have the highest environmental burden. In contrast, the natural media choices, sugarcane bagasse and coco-peat, have proved to be environmentally favorable. Media employment from recycled materials like brick and steel slag could significantly redeem the previous environmental burdens of these materials, providing treatment efficiency. However, the systems employed for landfill leachate treatment revealed the CW using brick chips as the most vulnerable system with regards to environmental concerns, implying that the media brick chips are certainly the major contributor behind this high leap in the scale. However, both the systems worked very well in the carcinogenic category, providing good treatment performance, and eventually exerting lesser impact. Conclusion: The overall assessments suggested choice of media materials are essential to deciding the sustainability of a CW design. However, the CW is more beneficial and environmentally friendly than the other treatment methods, until the design scale has a high capacity. Nevertheless, the choice of the LCA method is also significant, while measuring impact scales. [ABSTRACT FROM AUTHOR]

Leachate, a toxic and complex liquid, is a growing problem for municipal solid waste landfills. This study investigated non-catalytic and homogeneous catalytic (1 g/L MoO3 and CuO) wet oxidation (WO) for leachate treatment and examined the performance and reusability of the economical catalysts. Leachate was subjected to a 60-min WO at 180–240 °C. Catalysts' performance was evaluated through a reduction in chemical oxygen demand (COD) and total nitrogen content (TN), production and degradation of volatile fatty acids (VFAs), colour change, and surface characterisation. The breakdown of organic matter, such as humic and fulvic substances, benefited from increased reaction time, temperature and the presence of the catalysts. The catalysts' contribution to degradation was found to be greater with increasing temperature. A maximum reduction in COD and TN of approximately 50% was obtained at 240 °C with CuO. However, the catalysts experienced fouling, decreasing the performance by up to 50%, limiting its reusability. [ABSTRACT FROM AUTHOR]

In this study, a modified coagulation sludge (MCS) from a real landfill leachate coagulation pretreatment was first prepared with polymerized ferric sulfate (PFS) as the activator for PMS to degrade bisphenol A (BPA). The results showed that 43.34% of BPA was adsorbed by MCS when [BPA]0 = 20 mg/L, [MCS]0 = 0.8 g/L, and time = 80 min. Thereafter, by adding 3000 mg/L PMS to initiate the oxidation process, complete BPA removal, i.e. 100%, was achieved in 60 min. In addition, in tap water and municipal wastewater scenarios, 100% and 90.07% removal of BPA were obtained, respectively, and MCS exhibited outstanding performance after repeated use. MCS displayed an excellent adsorption capacity in which chemical adsorption was the main effect, and hydroxyl radicals were the major contributor to BPA degradation. Characterizations of fresh and reacted MCS were conducted, and the results showed that the MCS structure was stable after repeated use, and the surface functional groups, surface defect sites, and iron oxides participated in PMS activation. Overall, this study demonstrated successful recycling of coagulation sludge from landfill leachate pretreatment to activate PMS for environmental pollution control, which is in accordance with the goal of using waste to control waste. [ABSTRACT FROM AUTHOR]

Leachate generated in a landfill may not be treated by conventional biological treatment due to its nature and complexity. The process of forming aerobic granules in batch sequencing reactors having features such as; reducing the settling process time and saving energy consumption and high decomposition rate have been noticed by researchers. In the present study, the structure of sequencing batch reactors (SBRs) was evaluated for the formation of granules, which were subsequently utilized for the treatment of landfill leachate. The experiment was initiated by using the GSBR, containing 1200 ml with different apparatuses, to develop granular sludge, and synthetic wastewater was added to reinforcement. The selected parameters for the operational hydraulic retention time (HRT) of the wastewater (6‐h cycles) included feeding, idle, aeration, settling, and discharge. Furthermore, the controlled conditions were the dissolved oxygen (DO) range of 2–2.2 mg/L, temperature range of 20–23℃, and pH of 7.5–8.3. The chemical oxygen demand (COD), mixed liquor suspended solids (MLSS), and sludge volume index (SVI) daily were measured at the influent and effluent of GSBR reactor. The main properties of aerobic granular sludge were identified during the research procedures, and the remarkable settling and potent, high‐density microbial structure of the granules were confirmed. The mean size of the formulated granules was estimated at 7.46 ± 1.8 mm, and the volume of the biomass also increased from approximately 1607 to 4137 mg/L through the granulation process. Moreover, 98% of the influent chemical oxygen demand (COD) could be removed by the formulated granular sludge, and the final‐stage organic loading rate was estimated at 5.65 COD/m3/day. According to the results, GSBRs could be employed for the formulation of aerobic granular sludge for the treatment of landfill leachate. [ABSTRACT FROM AUTHOR]

In this study, the effects of the combination of classical Fenton (CFP) and modified Fenton (MFP) processes with UV light on the treatment of sanitary landfill leachate have been investigated. Iron (Fe2+ and Fe0) dosage, hydrogen peroxide dosage, reaction time, pH and different UV lamps have been optimized to achieve high COD removal. In addition, zeroth, first and second order kinetic models are applied for all processes under optimum conditions. For CFP and MFP; optimum pH 3, reaction time 30 min, 4 g/kg TS Fe2+ and Fe0 and 5 g/kg TS H2O2 have been determined. The COD removal efficiency is determined as 48.86% for CFP and 59.27% for MFP under optimum conditions. COD removal efficiencies increased in photo Fenton application under UV light. The efficiency is found to increase under UVA light source from 48.86% to 49.17% and from 59.27% to 70.72% in in CFP and MFP, respectively. In the kinetic study, the highest R2 values are obtained in the CFP/UV process, while CFP and MFP are found to fit the 0th order kinetic model. In this study, it has been concluded that Fenton and photo Fenton applications are effective in reducing the COD values of landfill leachate. [ABSTRACT FROM AUTHOR]

This study focused on the investigation of physicochemical characterization and metal(oid)s in landfill leachate of Bushehr port along the Persian Gulf. TDS, BOD5, COD, Hg, and Cd concentrations in fresh leachate were above leachate discharge standards. Significant differences were detected among alkalinity, EC, COD, and Na+ levels in various seasons. Furthermore, the high leachate pollution index (LPI) value showed a significant amount of pollutants present in landfill leachate. The results of this study help in understanding the pollution potential of landfill leachate of Bushehr port along the Persian Gulf. Thus, decision-makers should manage landfill leachate to reduce further environmental pollution. [ABSTRACT FROM AUTHOR]

Objective: In this work, polyvinyl alcohol (PVA) and sodium alginate (SA) were used as entrapped carriers and Artemisia argyi stem biochar (ABC) was used as an absorption carrier to immobilize aerobic denitrifying bacteria screened from landfill leachate, thus a new carbon-based functional microbial material (PVA/SA/ABC@BS) was successfully prepared. Methods: The structure and characteristics of the new material were revealed by using a scanning electron microscope and Fourier transform infrared spectroscopy, and the performance of the material for treating landfill leachate under different working conditions was studied. Results: ABC had abundant pore structures and that the surface contained many oxygen-containing functional groups, carboxyl groups, and amide groups, etc. and it had good absorbing performance and strong acid and alkali buffering capacity, which was beneficial to the adhesion and proliferation of microorganisms. After adding ABC as a composite carrier, the damage rate of immobilized particles was decreased by 1.2%, and the acid stability, alkaline stability, and mass transfer performance were increased by 9.00, 7.00, and 56%, respectively. When the dosage of PVA/SA/ABC@BS was 0.017g/ml, the removal rates of nitrate nitrogen (NO3−-N) and ammonia nitrogen (NH4+-N) were the highest, which were 98.7 and 59.4%, respectively. When the pH values were 11, 7, 1, and 9, the removal rates of chemical oxygen demand (COD), NO3−-N, nitrite nitrogen (NO2−-N) and NH4+-N reached the maximum values, which were 14.39, 98.38, 75.87, and 79.31%, respectively. After PVA/SA/ABC@BS was reused in 5 batches, the removal rates of NO3−-N all reached 95.50%. Conclusion: PVA, SA and ABC have excellent reusability for immobilization of microorganisms and degradation of nitrate nitrogen. This study can provide some guidance for the great application potential of immobilized gel spheres in the treatment of high concentration organic wastewater. [ABSTRACT FROM AUTHOR]

Partial nitrification‐anammox (PN/A) is an energy‐efficient technology for nitrogen removal in landfill leachate treatment. Numerous studies have reported successful implementation of the PN/A process and its stable operation under laboratory conditions. One of the primary challenges in PN/A engineering applications is the mass of the seed sludge required for start‐up. This study examined the PN/A using a sequence batch reactor (SBR) inoculating a common mixture to treat landfill leachate. After 70 days of operation, the system successfully realized a one‐stage PN/A process and maintained a stable ammonium NH4+$$ \left({NH}_4^{+}\right) $$ removal efficiency of 97.65% ± 1%, where the effluent of NH4+$$ {NH}_4^{+} $$ and nitrate (NO3−$$ {NO}_3^{-} $$) were less than 4 ± 1.5 mg L−1 and 10 mg L−1. In addition, the relative abundances of Ca. Kuenenia and Ca. Brocadia, which are typical anaerobic ammonia‐oxidizing bacteria (AnAOB), increased from 0.08% to 3.99% (70 days) and 0.01% to 0.45%, respectively. The relative abundances of ammonia‐oxidizing bacteria (AOB) Nitrosomonas and Nitrosospira increased from 0.9% to 2.89% and 0.007% to 0.1% (70 days), respectively. Both AnAOB and AOB are important niches of the system. Practitioner Points: The research realized PN/A rapidly by inoculating common mixture sludge.The experiment successfully enriched AnAOB from 0.09% to 3.89% within 70 days.The article revealing the ecological roles of AOB and AnAOB in the landfill leachate treatment. [ABSTRACT FROM AUTHOR]

The direct biological treatment of high concentrations of toxic organics in landfill leachate represents a formidable challenge. Given the excellent performance of adsorption and catalytic oxidation of sulfonated cobalt phthalocyanine / activated carbon (CoSPc/AC), this study investigated the removal of chemical oxygen demand (COD) from landfill leachate by CoSPc/AC under different conditions of temperatures, carrier particle sizes and concentrations. The response surface model further optimized the experimental conditions. Under conditions of 60 °C temperature, 50 mesh carrier particle size, and 14,697 mg/L influent COD, the predicted COD removal efficiency reached a maximum of 79.25%. The catalysts were characterized by X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy. It was revealed that the adsorption of COD in landfill leachate by activated carbon was primarily by physical adsorption, and the adsorbed organic matters were attached to a fixed point outside the activated carbon until the adsorption equilibrium was reached. The catalytic oxidation of COD mainly depends on CoSPc-O2−, CO3+ and sulfonic acid groups which had strong oxidizing properties after activation. The carrier-catalyst prepared in this study had high adsorption capacity of activated carbon as well as a good chemical oxidation capacity.Article Highlights: CoSPc/AC is more suitable for the pretreatment of landfill leachate. The adsorption mainly proceeded via physical adsorption. The catalytic oxidation mainly depended on CoSPc-O2-, Co3+ and sulfonic acid groups. [ABSTRACT FROM AUTHOR]

The physical and bacteriological evaluation of raw landfill leachate from Gosa Landfill in FCT, Abuja, Nigeria was carried out in this study using standard procedures. The probable bacteria identified from the biochemical tests of isolated samples were Streptococcus pneumoniae with Pseudomonas aeruginosa and Staphylococcus aureus. However, molecular characterization involving sequencing and BLAST further confirmed the bacteria present. This study concludes that the bio filter produced from Coco peat and Ash affects both the physicochemical properties and bacteriological flora of raw landfill leachate through degradation. [ABSTRACT FROM AUTHOR]

Membrane filtration processes have been used to treat landfill leachate. On the other hand, closing the leachate treatment loop and finding a final destination for landfill leachate membrane concentrate (LLMC) – residual stream of membrane systems – is challenging for landfill operators. The re-introduction of LLMC into the landfill is typical; however, this approach is critical as concentrate pollutants may accumulate in the leachate treatment facility. From that, leachate concentrate management based on resource recovery rather than conventional treatment and disposal is recommended. This work comprehensively reviews the state-of-the-art of current research on LLMC management from leachate treatment plants towards a resource recovery approach. A general recovery train based on the main LLMC characteristics for implementing the best recovery scheme is presented in this context. LLMCs could be handled by producing clean water and add-value materials. This paper offers critical insights into LLMC management and highlights future research trends. [ABSTRACT FROM AUTHOR]

The increasing amounts of municipal solid waste and their management in landfills caused an increase in the production of leachate, a liquid formed by the percolation of rainwater through the waste. Leachate creates serious problems to municipal wastewater treatment plants; indeed, its high levels of ammonia are toxic for bacterial cells and drastically reduce the biological removal of nitrogen by activated sludge. In the present work, we studied, using a metagenomic approach based on next-generation sequencing (NGS), the microbial composition of sludge in the municipal wastewater treatment plant of Porto Sant'Elpidio (Italy). Through activated sludge enrichment experiments based on the Repetitive Re-Inoculum Assay, we were able to select and identify a minimal bacterial community capable of degrading high concentrations of ammonium (NH4+-N ≅ 350 mg/L) present in a leachate-based medium. The analysis of NGS data suggests that seven families of bacteria (Alcaligenaceae, Nitrosomonadaceae, Caulobacteraceae, Xanthomonadaceae, Rhodanobacteraceae, Comamonadaceae and Chitinophagaceae) are mainly responsible for ammonia oxidation. Furthermore, we isolated from the enriched sludge three genera (Klebsiella sp., Castellaniella sp. and Acinetobacter sp.) capable of heterotrophic nitrification coupled with aerobic denitrification. These bacteria released a trace amount of both nitrite and nitrate possibly transforming ammonia into gaseous nitrogen. Our findings represent the starting point to produce an optimized microorganisms's mixture for the biological removal of ammonia contained in leachate. [ABSTRACT FROM AUTHOR]

This study aimed to improve the efficiency in methane production of anaerobic digestion of fruit and vegetable waste. For this purpose, two strategies were evaluated: the first was the anaerobic co-digestion with coffee grounds and landfill leachate using different carbon–nitrogen ratios (C/N ratio 25:1 and 12.5:1); the second strategy was the use of two different inoculum sources (digested swine manure and a mixture composed of different inoculums—Mix). The samples were characterized before and after the biochemical methane potential (BMP) tests and methane production was monitored. The modified Gompertz kinetic model was used to predict the process of AD. The Mix inoculum and the co-digestion of FVW and SCG, with a C/N ratio of 25:1, resulted in the highest methane yield (198.1 Nml gVS−1). The results highlight that the choice of co-substrates with different properties than the FVW and the composition of an inoculum adapted to different types of substrates can contribute to the improvement in methane conversion from FVW. The kinetic analysis proved that the modified Gompertz model was adequate to describe the AD process, indicating that the studied conditions were favorable for methane production. [ABSTRACT FROM AUTHOR]

The migration and transformation of dissolved organic matter (DOM) caused by landfill leachate leakage affected the phylogenetic development of bacterial communities in groundwater around the landfill. Previous studies mainly focused on the hydrochemical properties of DOM in groundwater contaminated by landfill leachate and the relationships between groundwater quality parameters and bacterial communities. However, the changes in DOM components and bacterial communities caused by landfill leachate leakage and their correlations remained unclear. In this work, we analyzed the evolution characteristics of DOM and identified the bacterial communities and their corresponding functions in groundwater around the landfill. The results showed that DOM content in groundwater increased after the diffusion of landfill leachate to groundwater. Significant differences in characteristics between DOM components were presented at different locations in the landfill leachate plume due to the physical dilution and bacterial degradation of DOM. One of the obvious manifestations was the tendency of humic acid-like substances to accumulate at downstream points. Samples from the contaminated aquifer had higher diversity and abundance of bacterial communities than those in the uncontaminated aquifer. Anaerobic or facultative anaerobic bacteria played predominant roles in contaminated groundwater, due to the input of organic matter, nitrate, and ammonia nitrogen. Redundancy analysis indicated that the content of fulvic acid-like DOM had a conspicuous impact on the composition of bacterial communities in the polluted groundwater. Vogesella were the dominant bacteria at the genus level in groundwater around the landfill. Furthermore, Vogesella were significant for microbial utilization and played an important role in the production of fulvic acid-like DOM. These results indicated that landfill leachate pollution posed a potential threat to the structure and function of bacterial communities in groundwater, and provided a basis for exploring the interaction between DOM composition and bacterial communities in groundwater plume contaminated by landfill leachate. [ABSTRACT FROM AUTHOR]

The high pollutant load of sanitary landfill leachates poses a huge challenge in the search for efficient and environment friendly solutions for their treatment. The objective of this work was to study an integrated solution of environmentally friendly technologies — immediate one-step lime precipitation (IOSLP), carbonation (CB), and phytoremediation (Phyt) — to treat a sanitary landfill leachate. In the leachate sample treatment by IOSLP, the influence of CaO concentration (18.2–33.3 gCaO L−1) and stirring time (2–60 min) on the sludge sedimentability and pollutant removal was studied. Organic load and ammonia nitrogen (AN) removal increases with CaO added, as well as sludge volume. Stirring time has a small influence on organic load and AN removal, presenting a minimum for sludge volume. Thus, the best operational conditions were chosen as 27.6 gCaO L−1, and 40-min stirring time, with 64% chemical oxygen demand (COD) removal. Sludge humidity was 2.1%, making dewatering needless. IOSLP supernatant was submitted to CB by atmospheric CO2, and 100% removals in AN and hardness were attained. Effluents from IOSLP and IOSLP + CB were utilized in Phyt tests, with Vetiver (Chrysopogon zizanioides (L.) Roberty). The best COD removal (37%) during Phyt was attained for the samples treated by IOSLP + CB. [ABSTRACT FROM AUTHOR]

Expanded vermiculite was used as an adsorbent to remove ammonia nitrogen from landfill leachate. Bench and pilot-scale adsorption experiments were performed with leachate collected from a closed sanitary landfill located in Curitiba, southern Brazil. At the bench-scale, two different heights of vermiculite and three different flow rates were tested using a fixed-bed column. These tests produced an average uptake capacity of 33.4 mg g−1 for the ammonia nitrogen concentration of 2,560 mg L−1. The Yan model was used to determine the breakthrough and the exhaustion times due to the best fit of the data to this model. At the pilot-scale, the flow rate was determined from the shortest length of the mass transfer zone obtained from bench-scale experiments. Tests were performed using one stainless-steel column filled with 26.2 kg of expanded vermiculite, which resulted in a bed height of 1.6 m. A leachate flow rate of approximately 350 L d−1 was applied to achieve the required contact time of 8.3 h. At this scale, an average uptake capacity of 18.1 mg g−1 was obtained for the ammonia nitrogen concentration of 1,193 mg L−1. It is worth mentioning that the flow rate and the concentration of the adsorbate in the feeding solution are fundamental to improve the operational time of the fixed-bed column. The main goal of this research was the determination of operating conditions to scale-up the adsorption process of ammonia nitrogen onto expanded vermiculite. The contact time was a key parameter to reach this goal. [ABSTRACT FROM AUTHOR]

Microplastics are generated from plastic waste in landfills due to physical, chemical, and biological effects, and eventually enter into the leachate. Leachate is a potential source of environmental microplastics which has not been emphasized. Here, we summarized the investigation of microplastics in leachate in 9 countries from 28 papers, provided a comprehensive review of the sampling, detection, and separation of microplastics in leachate, and elaborated on the quality control in each process. There are more than forty types of microplastics in leachate, with diverse shapes, wide size distribution, and concentrations of 0–25 items/L. Commonly used techniques are FTIR, Raman, SEM, and py-GC–MS for characterizing microplastics, while standardization of micro- or nanoplastics for leachate with a complex composition should be further studied. We also discussed in depth the degradation mechanism of microplastics in advanced oxidation processes (AOPs). Microplastics can be decomposed into small molecules such as aldehydes and ketones, and some can even eventually be degraded into CO2 and H2O in AOPs, which may be further implemented in leachate treatment plants. This review provides the scientific fundamentals for understanding the microplastics in landfill leachate and proposes removal strategies for future research. [ABSTRACT FROM AUTHOR]

The treatment of leachate by vegetative filters composed of short-rotation willow coppice (SRWC) has been shown to be a cost-effective alternative to conventional and costly methods. However, few studies have considered the treatment capability of willow filters at a scale large enough to meet the industrial requirements of private landfill owners in North America. We report here on a field trial (0.5 ha) in which a willow plantation was irrigated with groundwater (D0) or aged leachate at two different loadings (D1 and D2, which was twice that of D1). Additionally, half of the D2-irrigated plots were amended with phosphorus (D2P). The system, which operated for 131 days, was highly efficient, causing the chemical oxygen demand concentration to drop significantly with the total removal of ammonia (seasonal average removal by a concentration of 99–100%). D2P efficacy was higher than that of D2, indicating that P increased the performance of the system. It also increased the willow biomass 2.5-fold compared to water irrigation. Leaf tissue analysis revealed significant differences in the concentrations of total nitrogen, boron, and zinc, according to the treatment applied, suggesting that the absorption capacity of willows was modified with leachate irrigation. These results indicate that the willow plantation can be effective for the treatment of landfill leachate in respect of environmental requirements. [ABSTRACT FROM AUTHOR]

Landfill leachate (LFL) treatment is a severe challenge due to its highly viscous nature and various complex pollutants. Leachate comprises various toxic pollutants, including inorganic macro/nano components, xenobiotics, dissolved organic matter, heavy metals, and microorganisms responsible for severe environmental pollution. Various treatment procedures are available to achieve better effluent quality levels; however, most of these treatments are nondestructive, so pollutants are merely transported from one phase to another, resulting in secondary contamination. Anaerobic digestion is a promising bioconversion technology for treating leachate while producing renewable, cleaner energy. Because of its high toxicity and low biodegradability, biological approaches necessitate employing other techniques to complement and support the primary process. In this regard, pretreatment technologies have recently attracted researchers' interest in addressing leachate treatment concerns through anaerobic digestion. This review summarizes various LFL pretreatment methods, such as electrochemical, ultrasonic, alkaline, coagulation, nanofiltration, air stripping, adsorption, and photocatalysis, before the anaerobic digestion of leachate. The pretreatment could assist in converting biogas (carbon dioxide to methane) and residual volatile fatty acids to valuable chemicals and fuels and even straight to power generation. However, the selection of pretreatment is a vital step. The techno-economic analysis also suggested the high economic feasibility of integrated-anaerobic digestion. Therefore, with the incorporation of pretreatment and anaerobic digestion, the process could have high economic viability attributed to bioenergy production and cost savings through sustainable leachate management options. [ABSTRACT FROM AUTHOR]

A devised methodology presented here allows the determination of di-n-butyl phthalate in environmental samples (water and landfill leachate) using solid-phase extraction (SPE) and gas chromatography. It is developed based on the use of a gas chromatograph with an FID detector. Preliminary testing has also provided extraction parameters and conditions for chromatographic determination, with calibration applied by reference to an internal standard. The linearity of the calibration curve has been tested in DBP concentrations ranging from 0 to 7.5 mg/L, with the data obtained showing that, throughout this range, the detector readings as a function of the DBP concentrations remain linear (R2 coefficient >0.99). The average levels of recovery of DBP from aqueous solutions of phthalates are in the range of 97-109%, while the corresponding figures for leachates are 85-101%. The values of the coefficients of variation associated with the results obtained do not exceed 5%. The results, therefore, indicate that the applied extraction method is effective as regards DBP extraction from both water and landfill leachate, while numerous other substances present in the leachate from landfill sites apparently do not affect the correct determination of di-n-butyl phthalate by the method developed. [ABSTRACT FROM AUTHOR]

The final disposal of municipal solid waste (MSW) in dumpsites is still a reality worldwide, especially in low- and middle-income countries, leading to leachate-contaminated zones. Therefore, the aim of this study was to carry out soil and leachate physicochemical, microbiological, and toxicological characterizations from a non-operational dumpsite. The L-01 pond samples presented the highest physicochemical parameters, especially chloride (Cl; 4101 ± 44.8 mg L−1), electrical conductivity (EC; 10,452 ± 0.1 mS cm−1), and chemical oxygen demand (COD; 760 ± 6.6 mg L−1) indicating the presence of leachate, explained by its close proximity to the landfill cell. Pond L-03 presented higher parameters compared to pond L-02, except for N-ammoniacal and phosphorus levels, explained by the local geological configuration, configured as a slope from the landfill cell towards L-03. Seven filamentous and/or yeast fungi genera were identified, including the opportunistic pathogenic fungi Candida krusei (4 CFU) in an outcrop sample. Regarding soil samples, Br, Se, and I were present at high concentrations leading to high soil contamination (CF ≤ 6). Pond L-02 presented the highest CF for Br (18.14 ± 18.41 mg kg−1) and I (10.63 ± 3.66 mg kg−1), while pond L-03 presented the highest CF for Se (7.60 ± 1.33 mg kg−1). The most severe lethal effect for Artemia salina was observed for L-03 samples (LC50: 79.91%), while only samples from L-01 were toxic to Danio rerio (LC50: 32.99%). The highest lethality for Eisenia andrei was observed for L-02 samples (LC50: 50.30%). The applied risk characterization indicates high risk of all proposed scenarios for both aquatic (RQ 375–909) and terrestrial environments (RQ > 1.4 × 105). These findings indicate that the investigated dumpsite is contaminated by both leachate and metals, high risks to living organisms and adjacent water resources, also potentially affecting human health. [ABSTRACT FROM AUTHOR]

The revised leachate pollution index (r‐LPI) developed using the fuzzy Delphi analytical hierarchy process (FDAHP) is a technique to quantify the contamination potential of landfill leachate. The steps involved in the formulation of the r‐LPI were the selection of parameters using the fuzzy Delphi method (FDM), computing relative weights of the parameters using the fuzzy analytic hierarchy process (FAHP), development of sub‐index curves, and finally, aggregation of sub‐indices. The calculation of the weights of the parameters has been one of the most crucial steps in the formulation of any index. The analytical hierarchy process (AHP) has been one of the most widely used methods for weight calculation. However, it was observed that the traditional AHP is inadequate to deal with the imprecise or ambiguous nature of linguistic evaluation. It also involves human subjectivity, which induces ambiguity and entails the use of decision‐making with uncertainty. The fuzzy AHP method was used in this study to overcome this difficulty. Three significant issues pertinent and essential to fuzzy AHP were addressed: contradictions in expert judgment, deriving priorities from inconsistent fuzzy judgment matrices, and group decision‐making. In this study, three FAHP methods: Chang's extent analysis (EA) method, fuzzy preference programming (FPP), and logarithmic fuzzy preference programming (LFPP) were used to calculate the weights of the r‐LPI parameters. The results of these methods were then compared, and it was determined that LFPP was the most suitable method for calculating the weights of the r‐LPI parameters. [ABSTRACT FROM AUTHOR]

Phytoremediation is considered an effective and economical method for metal recovery along with removing toxic chemicals from contaminated soil. The studies done so far concentrate on the factors responsible for uptake of a single heavy metal from the soil. However, in nature, pollutants are generally found as a mixture of various heavy metals. Furthermore, research related to phytoremediation of mixed contaminant sites such as landfills are focused on the selection of plants rather than heavy metal uptake pattern. Thus, it becomes important to understand how phytoremediation processes change in remediating a mixed pollutant with respect to removing single metal contamination. In the present study, the phytoremediation potential of Indian marigold is compared when the soil–metal concentration is individually spiked with Cd, Pb, Ni, and Cr salt solution against the remediation potential of marigold when the soil–metal concentration is spiked by landfill leachate (mixture of heavy metal) collected from the Gazipur landfill site, New Delhi, India. The result shows that the rate of metal accumulation is highly sensitive to metal concentration and metal interactions. When the soil–metal concentration is spiked with metal salts, their respective total uptake by marigold follows the order Cd > Pb > Cr > Ni with BCF > 1, TF > 2, and ECf > 1 for Cd and Cr making marigold a hyperaccumulator and with BCF < 1, TF > 2, and ECf < 1 showing an avoidance toward uptake of Pb and Ni. When the heavy metal accumulation pattern is studied for soil–metal concentration spiked by landfill leachate, the order of accumulation follows Cd > Cr > Pb > Ni with BCF > 1, TF > 2, and ECf > 1, and marigold is an accumulator for Cr. BCF > 1, TF < 2, and ECf < 1 stabilizes Cd and Pb add by leachate and there is no uptake of Ni after reaching a tolerance level of 555 µg/kg. The study is useful for understanding change in heavy metals uptake from heterogeneous sites for better landfill management. [ABSTRACT FROM AUTHOR]

This article presents the results of optimizing microalgae Chlorella sp. cultivation to obtain a higher amount of biomass and to use cheaper suitable waste for algae cultivation. It has been found that the most suitable waste for growing microalgae is landfill leachate, which can replace the source of nitrogen in the cultivation medium. The largest concentration of microalgae Chlorella sp. biomass is obtained in the medium containing 0.08 g·L−1 nitrogen acquired from the landfill leachate. For fertilizer production, the microalgae biomass suspension was centrifuged and analyzed. The chemical composition of microalgae biomass was found to be sufficiently good to produce granular nitrogen fertilizer with bioactive materials because it contains primary nutrients (3.49% nitrogen, 2.10% phosphorus, and 0.50% potassium) along with secondary nutrients (13.42% calcium and 3.69% magnesium) and 75.33% organic matter and trace elements. Also, microalgae biomass does not contain any heavy metals. The use of a microalgae suspension allows to reduce the amount of moisture used in the production of fertilizers. If optimal conditions are chosen, it is possible to granulate bioactive nitrogen fertilizer that satisfies all the criteria.

Catalytic oxidation pretreatment is a significant focus in the field of membrane fouling control; however, traditional catalytic materials are plagued by limitations in catalytic sites and challenges in recovery. In this study, a novel catalyst, B-doped NiFe 2 O x , was prepared with magnetic recovery capabilities and abundant oxygen vacancies to address landfill leachate treatment and mitigate membrane fouling. The results demonstrated the efficient activation of persulfate (PS) by the catalytic sites on B-NiFe 2 O x , which significantly degraded the complex organic pollutants like conjugated double bonds and aromatic compounds in landfill leachate. A large amount of humic acid and soluble microbial products in the landfill leachate were efficiently degraded upon contact with sulfate and hydroxyl radicals produced by B-NiFe 2 O x /PS, thereby resulting in achieving a chemical oxygen demand removal efficiency of up to 72 % and more than a twofold enhancement in filtration flux. Moreover, the characteristics of the fouled layer reveal that the B-NiFe 2 O x /PS system facilitated the formation of a porous cake layer, maximizing the retention of functional groups on the NF270 membrane surface. Notably, a minor presence of B-NiFe 2 O x is uniformly distributed within the cake layer, indicating the in-situ occurrence of weak catalytic oxidation reactions. This study provides an effective and innovative approach utilizing catalytic oxidation for membrane fouling control. [Display omitted] • B-NiFe 2 O x /PS was used for the first time to mitigate membrane fouling. • The production of·OH and·SO 4 2- were the main oxidation and antifouling mechanisms. • B-NiFe 2 O x /PS reduced the membrane foulants and formed the loose cake layer. • Abundant humic substances and SMPs were efficiently degraded by B-NiFe 2 O x /PS. • A small amount of B-NiFe 2 O x participated in the in-situ catalytic oxidation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microbial diversity and composition changed during process upgrade. • Key biomarkers like Nitrosomonas were identified. • Process upgrade and floc size affect microbial community assembly. • Upgrade led to denser, more homogeneous microbial networks with closer interactions. • A deep learning model was developed for predicting nitrogen removal efficiency. Upgrading processes to reduce biodegradable organic substance addition is crucial for treating landfill leachate with high pollutant concentrations, aiding carbon emission reduction. Aggregate size in activated sludge processes impacts pollutant removal and sludge/water separation. This study investigated microbial community succession and driving mechanisms in different floc-size aggregates during nitrogen removal progress upgrade from conventional to partial nitrification–denitrification in a full-scale landfill leachate treatment plant (LLTP) using 16S rRNA gene sequencing. The upgrade and floc sizes significantly influenced microbial diversity and composition. After upgrading, ammonia-oxidizing bacteria were enriched while nitrite-oxidizing bacteria suppressed in small flocs with homogeneity and high mass transfer efficiency. Larger flocs enriched Defluviicoccus , Thauera , and Truepera , while smaller flocs enriched Nitrosomonas , suggesting their potential as biomarkers. Multi-network analyses revealed microbial interactions. A deep learning model with convolutional neural networks predicted nitrogen removal efficiency. These findings guide optimizing LLTP processes and understanding microbial community dynamics based on floc size. [ABSTRACT FROM AUTHOR]

[Display omitted] In this study, bauxite tailings were innovatively employed as the coagulant resource in the treatment of nanofiltration concentrated landfill leachate (NCLL) via bipolar membrane electrodialysis (BMED). The employment of H 2 C 2 O 4 as the leaching acid, in lieu of HNO 3 , not only promoted the leaching of metal ions but also minimized the competitive migration of free H+, attributable to its chelating effect. The COD removal increased from about 40.4 % to about 49.9 %, while the energy consumption (EC) decreased to about 0.05 kWh/g COD when the acid is replaced by H 2 C 2 O 4. An optimal dosage of bauxite tailing is crucial for effective COD removal. An increase in the initial concentration of H 2 C 2 O 4 benefits metal leaching, while, an excessive concentration thereof augments the competition of H+ ions, thereby impeding the coagulation process. Furthermore, the current density exerted a notable impact on both COD removal and EC, with an optimal density identified at 5 mA/cm2. Connecting more treatment units still maintains COD removal efficiency at approximately 50 %, with a significant reduction in EC of about 24 %, necessitating only 0.038 kWh/g COD. Humic-like and fulvic-like acids are efficiently coagulated, which represent the principal biorefractory substances in NCLL. Consequently, this research delineates a novel approach for the utilization of bauxite tailings and the treatment of NCLL. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anoxic-aerobic (low DO)-DMBR process was proposed for landfill leachate treatment. • High COD and TN removal of 87% and 79% were achieved under COD/N ratio of 3.5. • One filtration cycle lasted for over 20 days in the DMBR at the flux of 10 LMH. • The genus Anaerolinea and Caldilinea were mainly enriched in the DM layer. • Genes related with QS, EPS and biofilm formation were up regulated in the DM layer. This study proposed a novel anoxic/4-stage aerobic/self-forming dynamic membrane bioreactor (DMBR) process for treating landfill leachate with low carbon-to-nitrogen ratio (COD/N). When the influent COD and NH 4 +-N were 3689 ± 425 and 1042 ± 96 mg/L, high removal efficiencies of 87 % for COD and 79 % for TN can be achieved. The mature dynamic membrane (DM) was rapidly established within 1 h, allowing one operational cycle to last over 20 days with the permeate turbidity below 5 NTU. The primary cause of biofouling was identified as the accumulation of small particles, proteins, polysaccharides, and inorganic components such as Ca2+ and Mg2+ in the DM layer. In addition, significant up-regulation of genes associated with quorum sensing signaling molecules (such as pac , trpE , dgcB), extracellular polymeric substances secretion (exoP , exoQ , algA), and biofilm formation (lasA) were observed in the DM layer, while some genus, like Thauera, Anaerolinea and Caldilinea were highly enriched in DM layer. These findings indicate that DMBR offers cost-effective and technically advantageous operations, making it a promising candidate for the treatment of high-strength landfill leachate. [ABSTRACT FROM AUTHOR]

[Display omitted] • A hybrid electro-biosystem for SCFAs production from LL was proposed. • As high as 80 % strong-toxic organics in LL was degraded during electrochlorination. • Cl- availability played key role on LL detoxification and decoloration. • Output energy of 4.38 kJ/L was achieved in the forms of SCFAs production. Upcycling of hidden energy and resources from landfill leachate (LL) into short-chains fatty acids (SCFAs) represents a substantially unexploited opportunity to handle environmental issue and achieve a circular economy. Due to high biotoxicity and poor biodegradability, efficient conversion of LL into SCFAs remains a great challenge. Herein, a hybrid electro-biosystem that coupling spatially separate LL electrochlorination, photo-remediation and dark fermentation was constructed to realize LL toxicity alleviation, resource recovery and SCFAs production in cascade. During LL electrochlorination, macromolecular organics evolution and LL toxicity alleviation mechanisms were revealed, in which available Cl- concentration played key role on LL properties amendment. During microalgae photo-remediation, resources recovery efficiency demonstrates that suitable LL electrochlorination can enhance microalgal photosynthesis and stimulate intracellular energy accumulation. Finally, SCFAs were produced from microalgae biomass via dark fermentation with butyric acid and acetic acid as major products, outputting total energy of 4.38 kJ/L. The work provides a paradigm shift of low-cost LL disposal with extra benefit of SCFAs production. [ABSTRACT FROM AUTHOR]

• DBD/Fenton process was used to treat landfill leachate and mitigate membrane fouling. • DBD/Fenton system overcame the pH limitation of the Fenton reaction. • 1O 2 , •OH, and O 2 •− were mainly involved in contaminant degradation by DBD/Fenton. • The degradation mechanism of PFOA entailed the cyclic elimination of CF 2 groups. • DBD/Fenton system promoted the formation of a loose and porous cake layer. This study investigated a sustainable approach through dielectric barrier discharge (DBD) enhanced Fenton technology coupling nanofiltration (NF) process for landfill leachate treatment. The DBD/Fe(II)/H 2 O 2 system exhibited significant synergistic effects, removing 55.07 % of TOC and 53.79 % of UV 254 within 60 min, respectively. Additionally, the DBD/Fe(II)/H 2 O 2 system demonstrated exceptional performance in removing fluorescent substances and large molecular organic compounds, thereby reducing the formation of cake layer on the nanofiltration membrane. Moreover, membrane flux increased by 2.34 times, with reversible and irreversible resistances decreasing by 75.79 % and 81.55 %, respectively. Quenching experiments revealed ·OH as the primary active species for perfluorooctanoic acid (PFOA) degradation in the DBD/Fe(II)/H 2 O 2 process. The degradation pathway of PFOA was also elucidated via capillary electrophoresis-quadrupole time-of-flight mass spectrometry analysis. Correlation analysis indicated that TOC and EEM were the primary fouling factors. Lastly, through an assessment of energy consumption, economic costs, and carbon dioxide emissions, the advantages and practical application potential of the DBD/Fe(II)/H 2 O 2 system were demonstrated. In summary, the DBD/Fe(II)/H 2 O 2 system emerges as a feasible strategy for NF pretreatment, holding immense potential for treating landfill leachate. [Display omitted] [ABSTRACT FROM AUTHOR]

Electrocoagulation of landfill leachate has been widely investigated, however, only few reports include the reuse of the treated water. In this work, treated leachate is evaluated as irrigation water. The main obstacle is the high Sodium Absorption Ratio (S A R = N a + / ( C a 2 + + M g 2 + ) / 2 . Reducing this indicator involves decreasing Na+ and increasing Mg2+ or Ca2+. Sodium concentration reduction is difficult by electrochemical methods (E 0 = −2.71 V); Ca2+ increasing is not feasible as it precipitates. Hence, the use of different Al-Mg anodes was tested tending to increase Mg2+ concentration in the treated water The alloy 88%wtAl-12%wtMg was able to remove 52.9% of COD, 98.1% of turbidity, 97.9% of color, obtaining a SAR of 8.2 meq·L−1, total hardness (TH) of 64.2 meq·L−1 and a soluble sodium percentage (SSP) of 75.8 meq·L−1. This was achieved by working at a current density of 15 mA cm−2, a treatment time of 15 min and a pH 5.0. The phytotoxicity of the treated leachate was evaluated by the germination index using Lactuca Sativa L., reaching a value of 83.2%, which is considered excellent for irrigation water. During growth, 3–4 primary leaves were observed in seedings after 21 days, similar to when potable water was used. The results demonstrate that electrocoagulation is an adequate treatment technique for the reuse of landfill leachate if appropriated materials are used as anodes working in well selected operational variables. [Display omitted] • Al-Mg alloys are introduced has anodes in electrocoagulation of landfill leachate. • Treated leachate composition comply with international standards for irrigation water. • Phytotoxicity diminish after treatment. Lactuca Sativa L germination rate was 95.8%. • Seeding growth was identical when treated leachate or potable water was used. • The research opens a new perspective for the reuse of landfill leachate. [ABSTRACT FROM AUTHOR]

The recycling of food waste (FW) through anaerobic fermentation into lactic acid (LA), with two isomers L-LA and D-LA, aligns with the principles of a bio-based circular economy. However, FW fermentation is often limited by competing pathways, acidification inhibition, and trace metals deficiency. This study investigates the introduction of landfill leachate, containing buffering agents (ammonia) and trace metals, into FW fermentation. Various dosages of landfill leachate, ranging from 90 (LN-90) to 450 mg/L (LN-450) based on inclusive ammonia calculation, were employed. Results showed that LA production peaked at 43.65 ± 0.57 g COD/L in LN-180 on day 6, with a high optical activity of L-LA at 92.40 ± 1.15 %. Fermentation pathway analysis revealed that landfill leachate amendment enhances hydrolysis (as evidenced by increased activity of amylase, α-glucosidase, and protease) and glycolysis (resulting in enhanced utilization of carbohydrates and glucose). The inclusive ammonia in leachate plays a crucial role as a buffer, maintaining optimal pH conditions (5–7), thereby reducing volatile fatty acid production and thus intensifying LA orientations. The increased activity of L-lactate dehydrogenase (L-LA generation) and decreased NAD-independent lactate dehydrogenase (LA consumption) in properly dosed leachate further explained the high accumulation of L-LA. Dominance of lactic acid bacteria, including Streptococcus , Enterococcus , Klebsiella , Bifidobacterium , Bavariicoccus , and Lacticaseibacillus, accounted for 91.08% (LN-90), while inhibitory effects were observed in LN-450 (4.45%). Functional gene analysis further supported the enhanced glycolysis, L-lactate dehydrogenase, and nitrogen assimilation. Finally, a network analysis indicates a beneficial effect on the genus Enterococcus and Klebsiella by landfill leachate addition. This study demonstrates the efficiency of utilizing landfill leachate to enhance LA recycling from FW fermentation, aligning with the concept of circular economy by transforming waste into valuable resources. [Display omitted] • Optimal addition of landfill leachate (LL) on lactic acid (LA) production is 180 mg/L. • LA production peaked at 43.65 g COD/L with optical activity of L-LA at 92.40%. • LL amendment could enhance the processes of hydrolysis and glycolysis. • Lactic acid bacteria accounted for 91.08% at LL dosage of 90 mg/L. • Inhibitory effects of LL on Lactic acid bacteria (4.45%) at LL dosage of 450 mg/L. [ABSTRACT FROM AUTHOR]

Landfill leachate-containing per- and polyfluoroalkyl substances (PFAS) is both an important 'sink' and a 'source' of secondary pollution, posing serious threaten to surrounding environments. To date, the pollution characteristics of PFAS in landfill leachate, and the coexistence and interaction between PFAS and other leachate contaminants, such as dissolved organic matter (DOM) and toxic metals remains unclear. Herein, our results showed that 17 target PFAS, with concentrations ranged from 1804 to 43309 ng/L, were detected in landfill leachates. The main PFAS were short-chain and even-chain substances represented by perfluorobutanoic acid (PFBA) and perfluorobutane sulfonic acid (PFBS). Leachate derived DOM is mainly composed of protein-like and humic-like substance, among which the total contribution of protein-like substance is as high as 73.7%. Correlation analysis results showed that the distribution of PFAS was strongly correlated with the substituted functional groups (e.g., carboxyl and hydroxyl) on the aromatic ring of humic-like substance (C2 and E 253 /E 203) and autochthonous metabolism by microbial activities (FI). Furthermore, Mn element showed a significantly strong correlation with PFAS. Both organic and inorganic substances positively correlated with toxic metals. Our findings are helpful to understand the environmental fate of PFAS, and contribute to decision-making regarding DOM, toxic metals, and PFAS management in landfill. [Display omitted] • Seventeen target PFAS were detected in landfill leachate. • The main PFAS were short- and even-chain substances represented by PFBA and PFBS. • DOM mainly derived protein-like matter, with the total contribution as high as 74%. • PFAS was mainly affected by substitutes of DOM aromatic ring and autochthonous metabolism by microbial activities. • Mn element showed a significantly strong interaction with PFAS. [ABSTRACT FROM AUTHOR]

The management of reverse osmosis (RO) concentrate remains a challenging task for operators of Landfill Leachates Treatment Plants. In this article we suggest an integrated treatment scheme for RO concentrate that combines solar distillation, struvite precipitation to reduce ammonia content of the distillate and biological treatment of the supernatant either with mixed cultures of bacteria or with microalgae. Experiments in a pilot-scale solar still, equipped with underfloor heating system, showed that the production rate of the distillate ranged up to 3.17 L/d m2. The distillate was characterized by elevated average concentrations of ammonium nitrogen; 2028 mg/L and 1358 mg/L in the two experiments conducted, respectively. A decreasing trend on concentrations of NH 4 +-N was noticed during these experiments, while the opposite was observed for COD. Struvite recovery experiments showed that the optimum Mg:NH 4 :PO 3 ratio was that of 2:1:5.8. Under these conditions, the NH 4 +-N removal reached 88%. Further treatment of the process supernatant into a 4-L hybrid sequencing batch reactor with biocarriers and activated sludge achieved NH 4 +-N removal higher than 98% in Phases C and D, where 450 and 600 mL of supernatant were added, respectively. Similar removal was also observed in a 2-L bioreactor with microalgae Chlorella sorokiniana when 150 mL of struvite supernatant were added (Phase B) while further increase of the amount of added supernatant to 200 mL resulted to a sharp stop of NH 4 +-N consumption (Phase C). Calculations for a landfill serving 20,000 inhabitants and a daily RO concentrate production of 6 m3/d showed that the required area for the construction of the solar still was 1893 m2 and the volumes of the hybrid and the microalgae reactor were 54 m3 and 60 m3, respectively. The recovered solid material of struvite process, after characterization for heavy metals and organic micropollutants, could be reused to the fertilizers industry. [Display omitted] • Solar distillation coupled with different processes for RO concentrate management. • The production rate of solar distillate ranged up to 3.17 L/d m2. • The distillate characterized by elevated average concentrations of NH 4 –N. • NH 4 –N removal reached 88% at the optimum Mg:NH 4 :PO 3 ratio in struvite experiments. • Further treatment of struvite supernatant achieved in MBBR and microalgae systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel heterogeneous Fenton system based on Cu species was established. • Significant role of pH adjustment in removing HA and FA from Landfill Leachate was revealed. • Removal efficiency of HA component reached 100% according to PARAFAC. Mature landfill leachate contains large quantities of a wide range of hazardous and refractory pollutants, especially humic acid-like (HA) and fulvic acid-like (FA) substances. These have poor biodegradability and a considerable ultraviolet-light quenching capacity, severely inhibiting the performance of wastewater treatment and post ultraviolet-light disinfection, but this aspect has attracted little previous research. The Fenton reaction has proved to be a feasible method for removing ultraviolet-quenching substances (UVQSs) but in conventional systems it is unable to completely mineralize organic contaminants. In this study, a novel electro-oxidation process was developed consisting of a flow-through reactor with a Cu 2 O cathode to catalyze Fenton-type reactions, and oxidation at a RuO 2 anode. The combination of pH adjustment and electro-oxidation was evaluated for the treatment of real ultrafiltration (UF) filtrate of mature landfill leachate. A series of analytical techniques were used to determine the performance for the removal of HA and FA. Under optimal conditions, the elimination of fluorescence characteristics of HA and FA reached 100 % and 99.3 %, respectively, according to PARAFAC results based on EEM spectra. TOC was removed by 25.5 %∼30.4 % during the pH adjustment step and 51 % by electrochemical oxidation. Changes in the molecular weight distribution and fluorescence content showed that pH adjustment played an important and significant role in removing UVQSs, and the remaining TOC after electrochemical oxidation was attributed to bioavailable amino acid-like substances. Overall, the results have demonstrated the successful development of an effective method of treating the UF filtrate from mature landfill leachate, with particular respect to the removal of the problematic HA and FA content. [ABSTRACT FROM AUTHOR]

[Display omitted] • High biomass induced ammonia assimilation to remove nitrogen. • Assimilation pathway nitrogen removal achieved 82.00 ± 0.96 % TN removal. • The production of proteins and amino acids were promoted by high biomass. • glnA and gltD were the main nitrogen cycle functional genes. The AO (Anoxic/oxic) process for treating high-strength ammonia in landfill leachate requires external carbon source and alkalinity. Alternatively, the processes of partial nitrification-Anammox (PNA) and partial denitrification-Anammox (PDA) with less or no carbon source have been developed, but enabled modulation difficulty due to nitrogen valence transformation. Ammonia assimilation for nitrogen removal immobilize ammonia (NH 4 +-N) as organic nitrogen, without nitrogen valence conversion and reducing greenhouse gases emission. This study offers a novel approach for nitrogen removal from low chemical oxygen demand (COD) to nitrogen (C/N) ratio leachate. The nitrogen removal response of biomass to ammonia assimilation in landfill leachate was established. Results demonstrated that the nitrogen removal contribution of ammonia assimilation and organics utilization by microorganisms significantly increased with biomass. When the initial mixed liquor suspended solid (MLSS) was 11200 mg/L, the removal efficiency of total nitrogen (TN) and COD in the landfill leachate achieved 98.42 ± 0.12 % and 80.60 ± 0.35 % after 30 days of operation, respectively. The corresponding assimilation contributions for TN and COD removals were 82.00 ± 0.96 % and 52.24 ± 0.82 %, respectively. Cell protein analysis showed that higher biomass significantly increased the production of intracellular and extracellular proteins or amino acids. The enrichment of bacterial genera such as Defluviicoccus , Aequorivita , Truepera , and Proteiniphilum played a crucial role in organics removal and NH 4 +-N assimilation. Functional gene analysis further demonstrated that most NH 4 +-N and organics were removed through bacterial assimilation. This research offered a green, efficient, and economical solution for the treatment of low C/N ratio landfill leachate. [ABSTRACT FROM AUTHOR]

The significant increase in global Landfill Leachate is a pressing challenge directly linked to the growing global population. Among the strategies for landfill leachate treatment, advanced oxidation processes using sulfate radical (SR-AOP) have gained considerable interest, despite the challenge of nitrate generation during ammonia oxidation. This study introduces a sequential treatment method that combines adsorption and a UV/PMS/Fe2+ system to assess its impact on COD (Chemical Oxygen Demand) and ammonia removal efficiencies. The results show that the sequential process achieves optimal COD and ammonia removal rates of 88 % and 88.3 % respectively. The increase in UV 254 absorbance removal during the adsorption phase indicates the removal of UV quenching substances (UVQS), supporting the effectiveness of using adsorption as a pretreatment for the UV-assisted systems (UV/PMS/Fe2+). Additionally, analysis using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) reveals that the adsorption treatment before the SR-AOP process not only enhances COD and ammonia removal efficiencies, but also eliminates heavy metals such as vanadium (V), titanium (Ti), zinc (Zn), and aluminum (Al) present in leachate. Moreover, the higher BOD/COD ratio suggests improved biodegradability of the effluent. When compared to other systems at optimal conditions, the sequential adsorption and UV/PMS/Fe2+ systems demonstrate superior performance, focusing on removing refractory matter and reducing ammonia content, especially effective at a pH level of 7.25. Analysis using Excitation-Emission Matrix (EEM) shows a shift from primary peaks in raw leachate spectra associated with humic and fulvic acid-like compounds to lower-intensity peaks from fulvic-like small molecule materials in the treated effluent. [Display omitted] • Sequential adsorption and UV/PMS/Fe2+ treatment removes 88 % COD and 88.3 % ammonia from leachate. • The best system performance is in neutral environmental conditions. • The process also eliminates heavy metals like V, Ti, Zn, and Al, improving overall treatment efficiency. • EEM fluorescence spectra changes indicate removal of humic and fulvic compounds, enhancing effluent biodegradability. [ABSTRACT FROM AUTHOR]