Treatment Efficiency Of Leachate Research Articles

Enhancing municipal solid waste leachate treatment efficiency: AI-based prediction of electrocoagulation/flocculation recovery using iron electrodes

ABSTRACT This study addresses a gap in municipal leachate (MUPL) treatment by introducing a pioneering application of artificial intelligence (AI) in the electrocoagulation/electroflocculation (EC/EF) process utilizing iron electrodes. The overarching aim is to demonstrate the efficacy of AI, particularly a multi-layer perceptron (MLP)-based feed-forward artificial neural network (ANN) incorporating the Levenberg-Marquardt (LMb) algorithm, in predicting and optimizing EC/EF outcomes for turbidity (TDY) removal. The research methodology involved experimentation and robust ANN data modeling. The significance of this work emerges from the successful integration of AI, showcasing its potential in advancing wastewater, demonstrated through a strong positive correlation (0.994) between the ANN model predictions and experimental outcomes. The study achieves a remarkable 99.4% TDY removal at an electrolysis time of 10 min and contributes valuable insights into the critical parameters influencing the EC/EF process. Results from the ANN modeling exhibit high predictive accuracy, supported by elevated R-squared values and minimal mean square error. Statistical analyses underscore the significance of key process parameters, highlighting the influential roles of current intensity and settling time. The study emphasized the favourable impact of maintaining an acidic pH range, as it reduced electrostatic repulsion between particles, facilitating pollutant agglomeration, and identified electrolysis time as a key factor in enhancing treatment efficiency, supported by a strong positive correlation between electrolysis time and TDY reduction. Energy cost savings were realized by not requiring temperature elevation. Achieving a 99.4% TDY removal translates to substantial reductions in other pollutants present in the MUPL, thereby elevating water quality and ensuring compliance.

Reduction of the environmental and health consequences of cigarette butt recycling by removal of toxic and carcinogenic compounds from its leachate.

Cigarette butt is a hazardous waste, and its management faces many challenges. The generation of leachate containing many pollutants including heavy metals is one of the limitations of recycling cigarette butts. The aim of this study was to reduce organic compounds and heavy metals in leachate resulting from cigarette butt recycling in an electrocoagulation reactor. For this purpose, two samples, including freshly smoked cigarette butts and littered cigarette butts, were processed and the treatment of leachate resulting from them was studied in an electrocoagulation reactor. The efficiency of leachate treatment was investigated in the treatment time of 10-40min and current intensity of 20-100mA. The results showed that the minimum reduction of chemical oxygen demand and turbidity was 25.3% and 33.4%, respectively. Increasing the current intensity and treatment time increased the efficiency of removing turbidity and chemical oxygen demand up to 47.1% and 41.2%, respectively, in optimum conditions. The reduction of nickel, chromium, cadmium, and lead in the lowest current density and minimum treatment time was more than 90%, which increased to more than 99% with the increase of the current density and treatment time. The use of electrocoagulation is a suitable solution to reduce heavy metals in leachate resulting from cigarette butt recycling, while the proper reduction of organic compounds in this type of leachate requires further treatment processes.

Physiochemical and biological characteristics of fouling on landfill leachate treatment systems surface

Fouling of landfill leachate, a biofilm formation process on the surface of the collection system, migration pipeline and treatment system causes low efficiency of leachate transportation and treatment and increases cost for maintenance of those facilities. In addition, landfill leachate fouling might accumulate pathogens and antibiotic resistance genes (ARGs), posing threats to the environment. Characterization of the landfill leachate fouling and its associated environmental behavior is essential for the management of fouling. In this study, physicochemical and biological properties of landfill leachate fouling and the possible accumulation capacity of pathogens and ARGs were investigated in nitrification (aerobic condition) and denitrification (anaerobic condition) process during landfill leachate biological treatment, respectively. Results show that microbial (bacterial, archaeal, eukaryotic, and viral) community structure and function (carbon fixation, methanogenesis, nitrification and denitrification) differed in fouling under aerobic and anaerobic conditions, driven by the supplemental leachate water quality. Aerobic fouling had a higher abundance of nitrification and denitrification functional genes, while anaerobic fouling harbored a higher abundance of carbon fixation and methanogenesis genes. Both forms of leachate fouling had a higher abundance of pathogens and ARGs than the associated leachate, suggesting the accumulation capacity of fouling on biotic pollutants. Specifically, aerobic fouling harbored three orders of magnitude higher multidrug resistance genes mexD than its associated leachate. This finding provides fundamental knowledge on the biological properties of leachate fouling and suggests that leachate fouling might harbor significant pathogens and ARGs.

Identification of key surfactant in municipal solid waste leachate foaming and its influence mechanism

Serious foaming problems and the excessive consumption of defoamer have undoubtedly become one of the most critical problems that hinder municipal solid waste (MSW) leachate treatment efficiency and industry development. Since there is limited research penetrating the foaming mechanism and identification of the key surfactants, current defoaming and surfactant removal techniques lack pertinence and orientation. In this study, a foaming characterization device was developed and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC/MS/MS) was optimized to accurately identify the key surfactants affecting leachate foaming and offer a glimpse into their interaction mechanisms. This study collected leachate samples from 9 typical landfills and waste-to-energy facilities of various waste compositions, climatic conditions, ages, and geographical locations. The foaming problem of leachate was mainly centered on raw leachate and nanofiltration membrane concentrate (NFC). Fresh leachate performed with relatively low foaming capacity and foam stability, associated with low surfactant concentration. The pH value of the system was positively correlated with the concentration of anionic surfactants, indicating significant impacts on surfactant release in MSW. Since the distribution characteristics of linear alkylbenzene sulfonate (LAS) in leachate were consistent with the variety of foaming performances, LAS proved to be an indispensable surfactant in the leachate involved in this study, and its content proportion escalated to 92.87% in aged leachate.

The Effects of Agitation Method on the Food Waste Leachate Treatment Efficiency of an Anaerobic Digester

The Effects of Agitation Method on the Food Waste Leachate Treatment Efficiency of an Anaerobic Digester

Microbial Treatment of Raw and Primary Treated Sanitary Landfill Leachate by Indigenous Strain Brevibacillus agri.

Landfill leachate is a potential environmental threat. Sanitary landfills are model sites which contains a leachate collection pool and a processing facility to treat it up to environmental standards before discharge. The present study is the very first endeavor to establish leachate treatment efficiency of indigenous microbial strain Brevibacillus agri. Leachate samples were inoculated with isolated strain and incubated for 41days in an orbital shaker. Percent reduction in major water quality parameters was assessed after 0, 7, 21, and 41days of incubation, for understanding the degradation kinetics. Results of the study demonstrate that Brevibacillus agri was effective in improving the wastewater quality of both raw and primary treated leachate. Overall reduction for different water quality parameters was found to be 50% higher for primary treated leachate than that for raw leachate within 21days of incubation. Microbial degradation followed first-order kinetics with rate constants in the range of 0.0047-0.03 and 0.0061-0.074day-1 for raw and primary treated leachate respectively. Calculated half-life of each pollutant parameter was significantly higher in the raw sample (23-147days) as compared to the primary treated one (27-112days). The leachate pollution index (LPI) value of the raw leachate was also found to be > 25% higher than primary treated leachate sample after microbial treatment. Hence, it can be concluded that on site application of primary treatment technology followed by secondary microbial degradation by indigenous microflora, viz., Brevibacillus sp., may prove effective to achieve desirable water quality for safe environmental discharge.

Treatment of a landfill leachate from Casablanca city by a coagulation-flocculation and adsorption process using a palm bark powder (PBP)

The study aims to evaluate the efficiency of a combined landfill leachate treatment (coagulation with ferric chloride coupled with adsorption onto palm bark powder (PBP)) enhance a low cost bioadsorbent. The efficiency of this treatment, was assessed in terms of chemical oxygen demand (COD), color and turbidity removal. This bioadsorbent was subjected to physico-chemical and morphological characterization by different methods (Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), N2 adsorption-desorption isotherms, pH at zero charge point (pHPZC) and Boehm titration method).The coagulation process reduced the turbidity by 90%, the COD by 50%, the color by 80% and the biological oxygen demand (BOD5) by 99% for the optimum dose of ferric chloride of 12 g Fe3+. L−1. Thereafter, the sequential treatment of a landfill leachate based on coagulation as a pre-treatment process and then adsorption onto PBP improves the removal of turbidity, COD and color to 99%, 59% and 90%, respectively.These results demonstrate that combined coagulation-flocculation and adsorption processes could be a useful option for the treatment of solid-waste landfill leachate.

Landfill Leachate Treatment Methods and Its Potential for Ammonia Removal and Recovery - A Review

As a fast-developing country, the population, urbanization and industrialization have developed rapidly in Malaysia. The growth in population increases human activities, leading to a rise in the generation of waste. Municipal solid waste in Malaysia is currently estimated to rise from 23,000 tons/day in 2010 to 30,000 tons/day in 2020. Due to its simplicity and low costs, landfilling is the most common method in the country. However, there are various environmental drawbacks associated with landfills that have attracted social and environmental attention in recent decades. One of the key issues is the generation of leachate from the percolation of rainwater by waste disposal in a landfill. Landfill leachate contains many pollutants including ammonia-nitrogen (NH3-N) which is a particular concern due to its high concentration in leachate. High concentration of ammonia not only causes health and environmental problems but also affects the efficiency of leachate treatment. Therefore, a pre-treatment to remove ammonia is required before downstream treatment to prevent contamination to the surrounding ground and surface water. In general, leachate can be characterized by physico-chemical and biological parameters. Leachate characterization is essential to evaluate the leachate pollution potentials in the landfill site and to determine the treatment methods. Hence, the present review highlights the recent development of landfill leachate treatment methods and its potential for ammonia removal and recovery. Rather than releasing the extracted ammonia directly into the environment that causes air pollution, ammonia from the stripping process can be recovered and used to produce fertilizers. This review also contributes to the body of knowledge of the ammonia stripping treatment in terms of its efficiency and its application for leachate treatment.

LEACHATE TREATMENT BY REVERSE OSMOSIS METHOD- REGIONAL SANITARY LANDFILL “ZELJKOVAC” CASE STUDY

The purpose of this paper is to elaborate a plan for the leachate treatment at the “Zeljkovac” sanitary landfill in Leskovac city. Different processes occur over time at the landfill. The processes of infiltration and transpiration occur continuously, distributing the humidity and affecting the water balance within the body of the landfill. The landfill body acts as a giant sponge, in which water moves, and from which water can be released - both into groundwater and into the atmosphere in the form of water vapour or as a filtrate at the bottom of the landfill. In this paper, particular attention is given to the kind of waterwhich is actually filtrate from a landfill, often called leachate. The efficiency of the most commonly used methods will be presented, depending on the most prevalent pollutants in leachate. As there are many methods for treating this kind of wastewater, the reverse osmosis method will be presented as one of the most widely used . The technological process of a reverse osmosis plant will be described, as well as the result that shows the output quality of the leachate after the treatment process. The major finding of this paper reflects a clear justification for using this method to achieve the desired efficiency of leachate treatment.

Adsorption – Membrane process for treatment of stabilized municipal landfill leachate

The aim of this study was to investigate the efficiency of removal of difficult-to-biodegrade organic compounds from real stabilized landfill leachate with a membrane process alone and in combination with powdered-activated-carbon (PAC) adsorption. For filtration, ceramic membranes were used. The characteristics of the raw leachate were 788 mg COD/L and color of 0.4458 cm−1. With all combinations of PAC-adsorption and a membrane process (MF, UF, fine-UF) and with fine-UF alone, leachate treatment was highly efficient. For each membrane, treatment was more efficient when the membrane process was combined with PAC addition. This means that adsorption (PAC dose 3 g/L, adsorption time 30 min) made the largest contribution to leachate treatment (COD and color removal efficiency of 73.1% and 94.4%, respectively). In all cases, organic particles bigger than 100 kDa were removed most efficiently, whereas particles smaller than 3 kDa were removed least efficiently. The efficiency of leachate treatment with PAC + MF, PAC + UF and PAC + fine-UF did not differ significantly (>87% COD and > 97% color). With regard to membrane flux, however, these combinations can be ranked in the following order: PAC + MF > PAC + UF > PAC + fine-UF. Therefore, PAC + MF (0.3 MPa) was selected as the most effective solution (COD and color removal efficiencies of 87.8% and 97.2%, respectively; permeate flux of 167.6 L/(m2∙h)), as it combined efficient pollutant removal with low membrane pressure.

Photocatalytic treatment of landfill leachate: A comparison between N-, P-, and N-P-type TiO2 nanoparticles

Abstract Landfill leachate is included in the group of recalcitrant wastewaters and its treatment is a necessary measure for environmental protection and sustainable development. Photocatalytic treatment method using N-, P-, and N-P-type TiO2 nanoparticles under visible light irradiation has been recently considered for the treatment of recalcitrant wastewaters. Since the oxidizing agents in each type of nanoparticles are different, their efficiency for pollutant treatment is different. Therefore, this study aims at comparing the leachate treatment efficiency using N-, P-, and N-P-type TiO2 under visible light irradiation. For this purpose, TiO2 nanoparticles were doped by tungsten (W) and carbon (C) separately and simultaneously (W-C). The effect of leachate pH, dopant content, calcination temperature, and exposure time on the leachate treatment efficiency was experimentally investigated and optimized. Finally, the best nanoparticle type for leachate photocatalytic treatment was determined by performing experiments with same leachate under the optimum conditions of each type of nanoparticles. Based on the results, the COD removal efficiency for leachate with 2,050 mg/L initial COD in the photocatalytic treatment process using W-doped, C-doped, and W-C-codoped TiO2 nanoparticles was 46, 60, and 64%, respectively, after 46 h exposure time. The findings of this study provide researchers with new insights about the most efficient doped TiO2 nanoparticles for leachate treatment under visible light irradiation using slurry and fixed bed reactors.

UPLC Orbitrap MS/MS-based fingerprints of dissolved organic matter in waste leachate driven by waste age

Waste leachate is a pool of complicated metabolites from waste treatment and disposal as a global environmental problem. The recognition of dissolved organic matter (DOM) in leachate is crucial to improve leachate treatment efficiency and comprehend waste stabilization process. The present study acquired the molecular information for DOM in 22 waste leachate samples using ultra-performance liquid chromatography coupled with hybrid quadrupole Orbitrap mass spectrometry (UPLC Orbitrap MS/MS) based on two dimensions of retention time and mass-to-charge ratio. Unique mass peaks occupied more than 20% of the detected mass peaks in each leachate, implying that the molecular information for DOM could be the fingerprint of waste landfills and storage pits. Waste age and composition predominately accounted for this unique DOM. The double-bond equivalent increased and the H/C decreased with waste age. We further found that 57 precursor ion peaks and artificial matter (confirmed as N-butylbenzenesulfonamide) were significantly correlated with waste age by multiple test and non-target screening. These molecular characteristics of raw leachate were first determined to compensate for the evolution of leachate with waste age. The fingerprints of waste leachate can be further applied in environmental monitoring scenarios, e.g., tracing landfill leakage.

Synthesis of graphite/PbO2 anode: electrodeposition process modeling for improved landfill leachate treatment using RSM and ANN approach

Based on the hypothesis that the electrodeposition conditions may have effects on the developed electrode’s oxidation performance, the present study aimed at investigating the effects of a graphite/PbO2 anode preparation conditions (current intensity, Pb(NO3)2 concentration, HNO3 concentration, and temperature) on leachate treatment efficiency. Synthesis conditions were varied to improve the performance of the electrode, and leachate treatment efficiencies were evaluated using anodes prepared at different conditions. The Box–Behnken design was used as an experimental design for achieving the goal. The effect of variables on the system’s outcome was modeled by response surface methodology and artificial neural network. The variation in chemical oxygen demand (COD) removal efficiency from 7.81 to 24.58% for 2 h of electrolysis demonstrates significant influences of anode preparation conditions on its performance. The optimum conditions were attained as 0.64 A of current intensity, 0.16 mol L−1 of Pb(NO3)2, 0.16 mol L−1 of HNO3, and 76.98 °C of temperature. The PbO2 electrode developed at optimum conditions yielded 79 ± 1.7% COD removal efficiency of leachate at 8 h. The study results show that electrode synthesis conditions affect the oxidation ability of the electrode, and optimization of the same can significantly improve the treatment performance.

Assessing landfill leachate quality and leachate treatment efficiency using good sampling practices

A number of the compounds detected in landfill leachates have proved to be harmful to humans and to the natural environment. As a result, appropriate landfill leachate treatment methods must be developed, with the aim to reduce harmful concentrations of pollutants to levels which do not impose a threat to the natural environment. The complex nature of the leachates makes it difficult to select the most appropriate set of treatment methods for a specific landfill, and the actual efficiency of a treatment plant is measured in situ by comparing the quality of the water entering the plant with the quality of the water leaving the plant. The complex nature of the leachates puts high demands on the sampling, handling of sample before analyses, and analyses, as the character of the sample must not be altered. The demands increase with decreasing concentrations of the targeted compounds (µg/1 level or less). Despite this, no standard protocols for sampling and handling of leachate samples exist. The purpose of this study was to give examples of good sampling practices. Important aspects to consider during sampling and handling of samples are; i) sampling of nonhomogenized water bodies, ii) contamination, and iii) alterations of samples during collection and storage. It was found that a number of substances are enriched in the surface layer of a water body, why it was concluded that the surface layer is an important matrix to consider, both concerning the presence and the transport of harmful compounds. The risk of contamination during sampling was evaluated with the use of a field water blank, which was handled as a true water sample. It was found that despite careful handling contaminants were found at low concentrations (µg/1 level) in the field water blank, which indicated a severe risk of contamination during leachate sampling, handling of sample and/or analyses. Also in this study, the alteration of leachate samples during transport and storage was assessed. The results showed that preservation with 0.2 weight-% sodium azide immediately after sampling and storing at 48° C for a maximum of seven days in borosilicate glass bottles, resulted in the lowest loss of organic compounds from the samples. It has been evident since long that the reported character of sampled landfill leachates varies significantly. The variations can been assumed to sometimes origin from the sampling procedures used. In conclusion, the choice of sampling, transport, storage, and sample preparation before analyses is more crucial for the outcome of leachate characterisation studies than sometimes conceived.

Influence of operations on leachate characteristics in the Aerobic-Anaerobic Landfill Method

Landfill aeration is an effective technique for the controlled and sustainable conversion of conventional anaerobic landfills into a biologically stabilized state associated with a significantly lowered or the near elimination of the landfill gas emission potential. For in-situ leachate treatment recycling back the generated leachate in the bioreactor is also a promising technique for reducing pollutants and cost of ex-situ treatment as well. This research has been conducted to ascertain the in-situ treatment of leachate in Aerobic Anaerobic Landfill Method (AALM) compared with aerobic landfill and evaluated the impacts of various leachate recirculation regimes on MSW degradation and to provide data for successful operation in landfill sites. The experiment was conducted using six Plexiglass® landfill simulation reactors with a height of 100 cm and a diameter of 15 cm. Air was injected at the rates of 1.6 l/kg DM/h (Low aeration rate) for reactors R-LA, R-LAA (recirculatory) and LAA (non-recirculatory) and 4.8 l/kg DM/h (High aeration rate) in R-HA, R-HAA (recirculatory), and HAA (non-recirculatory) until day 242. It has been evaluated that R-HAA at high aeration rate achieved higher leachate quantity reduction (36.9%) than low aeration rate reactor R-LAA (19.6%) and AALM provides a better solution to control the temperature within the landfill body. The final NH4+-N concentration in R-HA (214.5 mg/l) was eight times lower than in the R-LA (1741.0 mg/l) reactor, and R-HAA (842.5 mg/l) was about three times lower than R-LAA (2315.4 mg/l) reactor on day 242. The change in leachate recirculation amount at varying moisture content positively affected the stabilization process and in-situ leachate treatment efficiency. The combination of both technologies (intermittent aeration and leachate recirculation) is a feasible way for in-situ leachate treatment, decrease the cost of further ex-situ leachate treatment as well as a viable and cost-saving alternative to continuous aeration.

Efficiency of landfill leachate treatment in a MBR/UF system combined with NF, with a special focus on phthalates and bisphenol A removal

In this study, a pilot-scale membrane bioreactor (MBR) was operated at a municipal solid waste plant (MSWP) to treat a mixture of landfill leachates (LLs) obtained from modern (MP-LLs) and previous (PP-LLs) waste cells. The MBR unit combined anoxic and aerobic zones with external ultra- and nanofiltration (MBR/UF and MBR/UF/NF, respectively). In addition to the removal of macropollutants, special attention was given to phthalates (PAEs) and bisphenol A (BPA). According to the obtained results, the MBR/UF system with acclimated biomass was effective for treating LLs, and the obtained effluent was generally similar in quality to raw municipal wastewater. The MBR biomass showed high potential for BPA and PAEs biodegradation/biotransformation as confirmed by a metagenomic approach. Only a high chloride concentration (1960 mg Cl−/L), which was twice the value acceptable by Polish regulations for industrial wastewater entering the municipal wastewater system, justifies the additional usage of the NF unit. Notably, a decreasing amount of biodegradable organic matter in MBR influent is expected with time because of changes in the biochemistry of modern waste cells; therefore, an external carbon source would probably be needed to support denitrification. However, the cooccurrence of an aerobic and anaerobic ammonia-oxidizing community with denitrifying bacteria provides the opportunity for advanced removal of nitrogen and organic carbon.

Comparing young landfill leachate treatment efficiency and process stability using aerobic granular sludge and suspended growth activated sludge

The treatment of young landfill leachate was investigated using two 3L sequencing batch reactors (SBR) with different biomass: aerobic granular sludge (GSBR) and the suspended growth activated sludge (ASBR). According to the nature of aerobic granular sludge, high settling velocities were expected in the GSBR and it was confirmed with 60ml/gVSS of 5-min sludge volume index (SVI5). However, the activated sludge required 30min for the ASBR to achieve a SVI of 42ml/gVSS. Compared to the ASBR, the GSBR was also more efficient in nitrogen and carbon removal. During the steady period of the experiment, 99% of total ammonium nitrogen (TAN) was removed through nitritation and nitrification in the GSBR with an average influent TAN concentration of 498mg/L. With high influent TAN concentration, the GSBR could achieve a full nitrification efficiency of 56±12% without accumulating nitrite. On the contrary, complete nitrification was not achieved in the ASBR as it was exposed to high concentrations of free ammonia (FA) and free nitrous acid (FNA), 16 and 0.2mg/L respectively. Partial nitrification (nitritation) with the efficiency of 77±10% was observed in the ASBR. The GSBR also presented higher efficiency in denitrification compared to the ASBR. 23% denitrification was observed in the GSBR during the anaerobic phase. Moreover, higher chemical oxygen demand (COD) removal efficiency was observed in GSBR than ASBR. Phosphorus removal efficiency was almost identical in both reactors. Overall, compared with the activated sludge, the aerobic granular sludge showed the best nutrients removal performance and higher tolerance to toxic compounds in young landfill leachate.

Assessment of Treatment Efficiency of Lysimeter Leachate using Leachate Pollution Index

This study illustrates the leachate treatment efficiency based on leachate pollution index (LPI) of pre- treatment leachate as well as post-treatment leachate with chemical coagulants. Leachate samples were collected at regular intervals of time from the leachate collection chamber of the landfill lysimeter at KUET campus, Bangladesh to compute its pollution potential. The landfill lysimeter consists of one open dump lysimeter-A with leachate detection (A1) and collection system (A2) as well as two sanitary landfill lysimeters B and C having two different types of cap liner. The relevant parameters of leachate sample were measured in the laboratory to evaluate sub-pollution (sub-LPIs) in terms of LPI in organic pollutant (LPIor), inorganic pollutant (LPIin) and heavy metal (LPIhm) as well as the overall LPI. Moreover, the values of LPI in pre-treatment leachate were to be found 19.53, 25.33, 23.48 and 23.74 for the A1 and A2 systems of open lysimeter-A, as well as the collection systems of sanitary lysimeters- B and C, respectively. It reveals significantly the higher values than that of LPI of 5.77, 7.38 and 7.38 for the maximum leachate discharge standards of Bangladesh, India and Hong Kong, respectively. The leachate was then treated with ferric chloride (FeCl3), poly alluminum chloride (PAC), ferrus sulphate (FeSO4) and aluminum sulphate (Al2(SO4)3) in various dosages and pH values. The concentrations in post-treatment leachate by using FeCl3 at optimum dosage were to be found below the limit of maximum leachate discharge standards. Study also reveals the values of LPI of 5.32, 5.69, 5.32 and 5.24 in post-treatment leachate for the A1 and A2 systems of open lysimeter-A, as well as the collection systems of sanitary lysimeters-B and C, respectively belowthe values of LPI in leachate of maximum discharge standards. Finally, it can be concluded that differences in the level of contaminants of pre- treatment and post-treatment leachate indicated the role of leachate treatment system in minimizing the level of contaminants and lowering the risk of leachate contamination based on LPI.

Application of multiple toxicity tests in monitoring of landfill leachate treatment efficiency.

Leachate from a closed landfill used for co-disposal of municipal and tannery waste was submitted to coagulation treatment, air stripping, adsorption on granular activated carbon, and Fenton oxidation with the aim to reduce toxicity of the leachate. Optimal operational conditions for each process were identified. The performance of the treatment was monitored by determination of organic matter (COD, DOC, BOD5), inorganic components (N-NH4(+), Cl(-), alkalinity, metals), organic compounds (BTEX, PAHs, PCBs, OCPs) while changes in toxicity were followed by multiple toxicity tests. Among the applied treatment techniques, adsorption on granular activated carbon was the most efficient method for removal of organic matter and metals while air stripping was the most efficient for removal of N-NH4(+) and reduction of toxicity. Lower reduction of organic matter content and toxicity was obtained during coagulation treatment. Fenton oxidation was effective for removal of COD; however, it negatively affected toxicity reduction. The combination of adsorption on granular activated carbon and air stripping led to an appreciable reduction of organic and inorganic pollutants and to leachate detoxification. Application of bioassays was helpful for assessing suitability of treatment methods and demonstrated that they are, together with physicochemical parameters, an indispensable part for monitoring of treatment efficiency.

Ceramic Raschig Rings—Improving Removal of Organic Compounds from Landfill Leachate by Perozone (O3/H2O2)

For improving the treatment of landfill leachate by combination O3/H2O2, ceramic Raschig rings (CRR) with different surface areas were added to enhance mass transfer of ozone into liquid phase. To determine optimal conditions of reaction, pH and reaction time was also studied. The optimal pH range of 8–9, optimal reaction time of 80 min was identified in this research. CRR contribute to the significant improvement of efficiency of landfill leachate treatment by O3/H2O2 systems. With added CRR of 728 m2/m3 surface area, color, COD and TOC removal was increased in comparison with experiment without CRR is 8%, 14%, and 9%, respectively. In this condition, the ozone utilization efficiency was also higher than that of experiment without CRR. Content of O3 was also identified uses 3.441 kg O3/kg COD.