Leachate Treatment Technologies Research Articles

Effects of evolving quality of landfill leachate on microbial fuel cell performance.

Microbial fuel cell (MFC) is a novel technology for landfill leachate treatment with simultaneous electric power generation. In recent years, more and more modern landfills are operating as bioreactors to shorten the time required for landfill stabilization and improve the leachate quality. For landfills to operate as biofilters, leachate is recirculated back to the landfill, during which time the organics of the leachate can be decomposed. Continuous recirculation typically results in evolving leachate quality, which chronologically corresponds to evolution stages such as hydrolysis, acidogenesis, acetogenesis, methanogenesis, and maturation. In this research, variable power generation (160 to 230 mW m-2) by MFC was observed when leachate of various evolutionary stages was used as the feed. The power density followed a Monod-type kinetic model with the chemical oxygen demand (COD) equivalent of the volatile fatty acids (VFAs) ( p < 0.001). The coulombic efficiency decreased from 20% to 14% as the leachate evolved towards maturation. The maximum power density linearly decreased with the increase of internal resistance, resulting from the change of the conductivity of the solution. The decreased conductivity boosted the internal resistance and consequently limited the power generation. COD removal as high as 90% could be achieved with leachate extracted from appropriate evolutionary stages, with a maximum energy yield of 0.9 kWh m-3 of leachate. This study demonstrated the importance of the evolving leachate quality in different evolutionary stages for the performance of leachate-fed MFCs. The leachate extracted from acidogenesis and acetogenesis were optimal for both COD reduction and energy production in MFCs.

Multistage biological contact oxidation for landfill leachate treatment: Optimization and bacteria community analysis

Landfill leachate is a wastewater contained solid waste and is hard to treat due to its complex composition. The most effective treatment is biological method among leachate transfer, biological treatment, and physical and chemical methods, however, the chemical oxygen demand (COD) removal efficiency of present biological treatment has not been more than 90% at influent COD concentration of 2000 mg/L to 5000 mg/L. In this study, the multistage biological contact oxidation (MBCO) is performed for treating landfill leachate. The optimized parameters as followed achieve 91.28% COD removal efficiency: influent COD landfill leachate concentration of 4000 mg/L; 0.1 L/min·L (reactor volume) aeration rate; temperature (T) of 35 °C and hydraulic retention time (HRT) of 24 h and also obtained 318.64 mg/L ammonium nitrogen (NH3-N) effluent concentration, Besides, biofilm community structure show that Proteobacteria, Bacteroidetes and Firmicutes are identified as the dominant in phylum. All the results indicate that the MBCO is an effective technology for landfill leachate treatment.

Pine-derived Biochar as Option for Adsorption of Сu, Zn, Cr, Pb, Ni and Decreasing of BOD5 in Landfill Leachate

Landfill leachate is a highly toxic and hazardous form of wastewater due to its complex composition characteristics, e.g. ammonia, metals, organic compounds. Landfill leachate treatment technologies, such as flotation, coagulation/flocculation, precipitation, oxidation, micro-, ultra-, nanofiltration, reverse osmosis, are too expensive, because they require frequent regeneration of the media or generate secondary brine wastes that may pose a disposal problem. In the present study removal of Zn, Ni, Cr, Pb, Cu from Kazokiškės landfill leachate was studied. Kazokiškės landfill is the main site for disposal of Vilnius region municipal wastes. Operator of the landfill is interested in the alternative ways for the primary treatment of the landfill leachate for reducing the load on the expensive reverse osmosis. One of the proposed options for the primary landfill leachate treatment was adsorption by biochar. Due to the high specific surface area, well-developed porous structure and surface functionality biochar has been used as low-cost adsorbent for adsorption of PTEs from aqueous solutions. Biochar was produced from Scots pine (Pinus sylvestris L.) trunk wood (after debarking) by pyrolysis at the highest heating temperature of 700 °C for 45 min in the low-oxygen environment. Laboratory analysis showed that PTEs, such as Zn, Ni, Cr, Pb, Cu, were present in the landfill leachate before water treatment plant. Thus, the aim of the study was to evaluate PTEs (Zn, Ni, Cr, Pb, Cu) removal efficiency by adsorption by pine-derived biochar. Factors, affecting adsorption efficiency, such as biochar particle size (1, 2.5, 4, 5 mm) and dosage of the biochar (1.01, 3.5, 6.05, 9.45, 13.25, 17.82 g/100 ml of leachate) were studied. Effects of the biochar on pH of the landfill leachate, BOD5, PTEs adsorption were analyzed. The findings showed that optimal parameters for decreasing of BOD5 and retention of Cr and Pb were particle size 1 mm and dosage 6.05 g/100 ml of leachate and 1 mm and more than 13.25 g/100 ml of leachate, respectively. No positive effect on Cu and Zn was observed.

Oxidative degradation of landfill leachate by catalysis of CeMnOx/TiO2 in supercritical water: Mechanism and kinetic study

Landfill leachate is a typical refractory wastewater that contains high concentration of organic pollutants. In this work, we investigated the treatment of landfill leachate by supercritical water oxidation (SCWO) in a batch reactor. The effects of temperature (T, 450–600°C), oxidation coefficient (OC, 1.2–3.4), reaction time (t, 60–600s) and pH (4.13–8.05) on total organic carbon (TOC) removal efficiency (TRE,%) and ammonia nitrogen (NH3-N) removal efficiency (NRE,%) were analyzed. TRE and NRE increased remarkably with increasing temperature and OC. At 3.4 OC and 600°C, 92.5% TRE and 50.9% NRE were achieved after 600s. A modified kinetic model on TRE and NRE considering the induction time was developed and accurately correlated the experimental results. A significant co-oxidation effect of methanol and landfill leachate in SCWO was detected. Furthermore, heterogeneous catalysts were added to SCWO of landfill leachate to improve the removal rate of organic contaminants. A series of composite catalysts (CeMnOx/TiO2) which consisted of the cerium, manganese and titanium oxides were prepared by impregnation method with varying Ce/Mn ratio. Compared with the SCWO of leachate without catalyst, the CeMnOx/TiO2 catalyst with Ce/Mn ratio of 1:2 exhibited high catalytic activity and stability. Additionally, a catalytic reaction mechanism was proposed. It was assumed that MnOx is the active component and CeO2 is the additive and oxygen supplier. The results obtained from this work suggest the SCWO with high-efficiency and stable catalyst could be a promising technology for landfill leachate treatment.

Determination of Cod and Color Reduction of Stabilized Landfill Leachate by Fenton Process

The Fenton process on landfill leachate was done in a batch reactor. The application of Fenton treatment technology for landfill leachate treatment greatly depends on the optimum Fenton operating conditions. The present study investigated the chemical oxygen demand (COD) and color removal efficiency of a non-biodegradable leachate by Fenton process. Determining optimum Fenton conditions requires multiple experiments using variable reaction parameters (pH, temperature, and H2O2 and Fe2+ doses).The treatment showed that the leachate organics can be broke down by the use of Fenton?s reagent. The result showed that with increasing H2O2 dosage, H2O2/Fe2+ ratio and decreasing the pH and contact time, the COD and color removal increased. The laboratory result determined that the best functional situation to catch the goals _ (i.e., BOD5/COD =0.1) resulted; pH=3, Contact time=30 minutes, H2O2 concentration= 40000 mgL-1 and the favorable H2O2/Fe2+ ratio = 10.

EWS:AOx™ as Next Generation Leachate Treatment Technology.

EWS:AOx™ as Next Generation Leachate Treatment Technology.

Membrane bioreactor technology for leachate treatment at solid waste landfills

Controlled landfilling remains a commonly applied method for municipal solid waste disposal with leachate generation being an inevitable consequence of the decomposition of the waste and the percolation of water through decomposing waste. The membrane bioreactor (MBR) technology has evolved into an effective process in treating such high strength wastewater streams because of its ability to retain high biomass concentration through membrane separation. This paper presents a critical review of the application of the MBR technology for the treatment of leachate and evaluates its performance in this context while highlighting factors affecting MBR operation. The paper concludes with outlining existing gaps and future research needs to improve the understanding and performance of the MBR technology for leachate treatment.

Effects of concentrated leachate injection modes on stabilization of landfilled waste

Injection of concentrated leachate to landfills is a simple and cost-effective technology for concentrated leachate treatment. In this study, the effects of injection mode of concentrated leachate and its hydraulic loading rate on the stabilization of landfilled waste were investigated. Compared with the injection of concentrated leachate, the joint injection of leachate and concentrated leachate (1:1, v/v) was more beneficial to the degradation of landfilled waste and mitigated the discharge amount of pollutants at the hydraulic loading rate of 5.9 L m(-2) day(-1). As the hydraulic loading rate of the joint injection of leachate and concentrated leachate was increased from 5.9 to 17.6 L m(-2) day(-1), the organic matter, biologically degradable matter, and total nitrogen of landfilled waste were degraded more rapidly, with the degradation constant of the first-order kinetics of 0.005, 0.004, and 0.003, respectively. Additionally, NO2(-)-N and NO3(-)-N in the concentrated leachate could be well removed in the landfill bioreactors. These results showed that a joint injection of concentrated leachate and raw leachate might be a good way to relieve the inhibitory effect of high concentrations of toxic pollutants in the concentrated leachate and accelerate the stabilization of landfilled waste.

Perspective of harnessing energy from landfill leachate via microbial fuel cells: novel biofuels and electrogenic physiologies.

Organic carbon, nitrogen, and sulfur are highly concentrated in municipal solid waste (MSW) landfill leachate, which usually frustrates conventional leachate treatment technologies from the perspective of energy costs. Therefore, the possibility of converting leachate to a new energy source via microbial fuel cell (MFC) technology has been examined recently. This paper summarizes the power output and energy recovery efficiency of the leachate-fed MFCs according to different feeding patterns, cell structures, and loading rates. Also, we assess potential energy-generating chemicals in leachate like nitrogen and sulfur compounds and propose alternative pathways, which may lift strict ratios between organic carbon and nitrogen content in conventional denitrification of leachate and are expected to achieve a higher voltage than traditional organic-oxygen based cells. Although currently power output of leachate-fed MFCs is limited, it seems well possible that dynamic characteristics of MSW leachates and microbial physiologies underlying some bio-electrochemically efficient activities (e.g., direct interspecies electron transfer) could be stimulated in MFC systems to improve the present status.

Present Conditions and Problems regarding Advanced Leachate Treatment Technologies

Present Conditions and Problems regarding Advanced Leachate Treatment Technologies

Contemporary Environmental Issues of Landfill Leachate: Assessment and Remedies

Landfills are the primary option for waste disposal all over the world. Most of the landfill sites across the world are old and are not engineered to prevent contamination of the underlying soil and groundwater by the toxic leachate. The pollutants from landfill leachate have accumulative and detrimental effect on the ecology and food chains leading to carcinogenic effects, acute toxicity, and genotoxicity among human beings. Management of this highly toxic leachate presents a challenging problem to the regulatory authorities who have set specific regulations regarding maximum limits of contaminants in treated leachate prior to disposal into the environment to ensure minimal environmental impact. There are different stages of leachate management such as monitoring of its formation and flow into the environment, identification of hazards associated with it, and its treatment prior to disposal into the environment. This article focuses on: (i) leachate composition, (ii) plume migration, (iii) contaminant fate, (iv) leachate plume monitoring techniques, (v) risk assessment techniques, hazard-rating methods, mathematical modeling, and (vi) recent innovations in leachate treatment technologies. However, due to seasonal fluctuations in leachate composition, flow rate, and leachate volume, the management approaches cannot be stereotyped. Every scenario is unique and the strategy will vary accordingly. This article lays out the choices for making an educated guess leading to the best management option.

The present status of landfill leachate treatment and its development trend from a technological point of view

More and more stringent requirements for pollution control and the implementation of the new discharge standard for landfill leachate make the development and application of landfill leachate treatment a research focus. The aim of the review is to determine appropriate technique for effective treatment of landfill leachate. In the paper, various leachate treatment technologies are presented and summarized, the key control parameters and some main problems are discussed from a technological point of view. It is proposed that the improvement of existing technical and the development and industrial application of a new treatment for landfill leachate are necessary. The development and application of integrated leachate treatment process of different physical, biological and chemical technologies could be a suitable option to reduce the contamination levels of leachate. Particularly, advanced oxidation technologies and an efficient integration between physical–chemical processes and biochemical processes are indicated as a significant research direction of new technology development.

Sustainable treatment of landfill leachate

Landfill leachate is a complex liquid that contains excessive concentrations of biodegradable and non-biodegradable products including organic matter, phenols, ammonia nitrogen, phosphate, heavy metals, and sulfide. If not properly treated and safely disposed, landfill leachate could be an impending source to surface and ground water contamination as it may percolate throughout soils and subsoils, causing adverse impacts to receiving waters. Lately, various types of treatment methods have been proposed to alleviate the risks of untreated leachate. However, some of the available techniques remain complicated, expensive and generally require definite adaptation during process. In this article, a review of literature reported from 2008 to 2012 on sustainable landfill leachate treatment technologies is discussed which includes biological and physical–chemical techniques, respectively.

Research on Leachate Treatment Process Selection of Guangxi Municipal Solid Waste Plant

Based on the research of municipal solid waste leachate treatment technology in China, aiming at several typical leachate treatment technologies in the Guangxi area, this paper has made analyses and studies. It has made comprehensive investigation of materials, and has obtained the final leachate treatment technology scheme applicable in the Guangxi area.

Environmental assessment and sustainable management options of leachate and landfill gas treatment in Estonian municipal waste landfills

PurposeThe purpose of this paper is to compare various landfill gas (LFG) and leachate treatment technologies in a life‐cycle perspective.Design/methodology/approachSince a landfill causes emissions for a very long‐time period, life‐cycle‐based environmental assessment was carried out to compare different technological options for sustainable leachate treatment and LFG collection and utilization. WAMPS, the life‐cycle assessment (LCA) model for waste management planning, was used for the environmental assessment of selected leachate and LFG treatment technologies.FindingsResults of both direct measurements in the studied landfills and LCA support the fact that leachate treatment with reverse osmosis has the best environmental performance compared to aerobic‐activated sludge treatment. Recently, the collection efficiency of LFG in the studied landfills is relatively low. In order to improve the overall environmental performance of LFG management the gas collection rate should be improved. LFG utilisation for energy recovery is an essential part of the system. The results of the study show that the avoided impacts of energy recovery can be even greater than direct impacts of greenhouse gas emissions from landfills. Therefore, measures which combine LFG collection with energy generation should be preferred to treatment in flare.Research limitations/implicationsIt should be noted that the results of this study do not express the total environmental impacts of the entire landfill system, but only the eutrophicating impacts and global warming related to the studied leachate and LFG management options. Therefore, it is recommended that further LCAs investigate also other relevant impact categories.Practical implicationsThe results of LCA modelling show that it is important to ensure the highest collection and treatment efficiency of leachate and LFG, since poor capture compromises the overall environmental performance of a landfill.Originality/valueThe paper provides a site‐specific data on sustainable leachate and LFG management in selected Estonian conventional municipal solid waste landfills. As such, the paper contributes to the development of the regional reference input data for LCA in waste management.

Simultaneous phosphate and COD cr removals for landfill leachate using modified honeycomb cinders as an adsorbent

In this study, honeycomb cinders were employed to remove phosphate and Chemical Oxygen Demand (COD cr) simultaneously for landfill leachate treatment. Operating conditions of honeycomb cinders pretreatment, pH, temperature, honeycomb cinders dosage, reaction time, and settling time, were evaluated and optimized. The results revealed that the removal efficiencies of both phosphate and COD cr could be increased up to 99.9% and 66.7% under the optimal conditions, respectively. Moreover, the structures of raw/modified honeycomb cinders and resulting precipitates were detected by Scanning Electron Microscope (SEM), Energy Dispersive Spectrometers (EDS) analysis and X-ray Diffraction (XRD). The results suggested that the adsorption method using honeycomb cinders might be an effective strategy as a pretreatment technology for landfill leachate treatment.

水平型浸透性反応層(HPRB)による有害物質捕捉技術の長期性能評価

水平型浸透性反応層(HPRB)による有害物質捕捉技術の長期性能評価

Statistical optimization of process parameters for landfill leachate treatment using electro-Fenton technique

Mature landfill leachate is typically non-biodegradable and contains high concentration of refractory organics. The aim of this research was to optimize operating parameters in electro-Fenton process, for the removal of recalcitrant organics from semi-aerobic landfill leachate using response surface methodology (RSM). Effectiveness of important process parameters H 2O 2/Fe 2+ molar ratio, current density, pH and reaction time were determined, optimized and modeled successfully. Significant quadratic polynomial models were obtained ( R 2 = 0.9972 and 0.9984 for COD and color removals, respectively). Numerical optimization based on desirability function were employed; in a 43 min trial 94.07% of COD and 95.83% of color were removed at pH 3 and H 2O 2/Fe 2+ molar ratio 1, while current density was 49 mA/cm 2. The results indicate that E-Fenton process was an effective technology for semi-aerobic landfill leachate treatment.

Optimizing the treatment of landfill leachate by conventional Fenton and photo-Fenton processes

Landfill, a matured and economically appealing technology, is the ultimate approach for the management of municipal solid wastes. However, the inevitable generation of leachate from landfill requires further treatment. Among the various leachate treatment technologies available, advanced oxidation processes (AOPs) are among powerful methods to deal with the refractory organic constituents, and the Fenton reagent has evolved as one promising AOPs for the treatment of leachates. Particularly, the combination of UV-radiation with Fenton's reagent has been reported to be a method that allows both the photo-regeneration of Fe 2+ and photo-decarboxylation of ferric carboxylates. In this study, Fenton and photo-Fenton processes were fine tuned for the treatment of leachates from the Colmenar Viejo (Madrid, Spain) Landfill. Results showed that it is possible to define a set of conditions under which the same COD and TOC removals (≈ 70%) could be achieved with both the conventional and photo-Fenton processes. But Fenton process generated an important quantity of iron sludge, which will require further disposal, when performed under optimal COD removal conditions. Furthermore conventional Fenton process was able to achieve slightly over an 80% COD removal from a “young” leachate, while for “old” and ”mixed” leachates was close to a 70%. The main advantage showed by the photo-assisted Fenton treatment of landfill leachate was that it consumed 32 times less iron and produced 25 times less sludge volume yielding the same COD removal results than a conventional Fenton treatment.

Characterization and removal of dissolved organic matter (DOM) from landfill leachate rejected by nanofiltration

Dissolved organic matter (DOM) from wastewater rejected by nanofiltration from a landfill leachate treatment plant was fractionated into humic acid (HA), fulvic acid (FA) and hydrophilic (HyI) fractions. It was found that humic substances (HA and FA) composed 75% of the total dissolved organic carbon (DOC) concentration of the DOM, with an average molecular weight of about 1000 Da. Elemental analysis, infrared spectroscopy, UV-visible spectroscopy and acid-base titration observations showed that the HA and FA of the DOM exhibited lower fractions of condensed aromatic functional groups but larger fractions of acidic groups compared with other aquatic DOMs. The properties of HA and FA were similar, but HA exhibited more complete humification, while the HyI fraction had more acidic groups. An aminated polymeric adsorbent NDA-8 was used to adsorb the DOM in the wastewater along with primary coagulation. Results of bench-scale experiments indicated that the treatment process could effectively remove the DOM and heavy metals while desorption liquid was 10 times more condensed than raw wastewater. Results of desorption and reproducibility tests consolidated the strong application potential of this treatment process as an advanced landfill leachate treatment technology.