Treatment Of Municipal Solid Waste 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.

A pilot-scale study of the integrated phycoremediation-photolytic ozonation based municipal solid waste leachate treatment process

Municipal solid waste (MSW) leachate is a highly polluted liquid that accumulates in the landfill and contains a high concentration of toxic pollutants which can pollute the surrounding surface water and groundwater as well, if not treated properly. In this study, an integrated approach of phycoremediation with photolytic ozonation was employed for the leachate collected from the MSW dumpsite which has high Chemical Oxygen Demand (COD) and ammonium (NH4+) levels. Photolytic ozonation treatment was employed as a pre-treatment step under operating parameters of pH: 9.0; Ozone dosage: 5 g/h; UV-C: λ = 254 nm; and contact time: 60 min, in which the COD and NH4+ in the leachate was reduced up to 81% and 95%, respectively. The selected algae Chlorella vulgaris (C.vulgaris) was employed in a lab-scale study to optimize the inoculum conditions in the photolytic ozonated leachate (POL). The specific growth rate of C.vulgaris was observed as 0.14/d in the POL at the optimized condition (inoculum size of 25% (T25)) during the study period of 11 days. High-rate algal pond (HRAP) was employed for the pilot-scale study in controlled environmental conditions as in the T25 experimental run for the assessment of POL treatment and biomass production. C.vulgaris reduced the concentration of pollutants COD, NH4+, and heavy metals (Cu, Fe) in the POL up to 93%, 94%, and 71%, respectively, with the dry biomass productivity of 0.727 g/L/d which is 3 times higher than the biomass productivity of C.vulgaris in freshwater conditions. The biochemical composition (carbohydrates, proteins, and lipids) of the harvested biomass has higher lipid production with lipid productivity of 120 mg/L/d which can be used as a feedstock for the production of value-a dded products.

Exploratory analysis of the microbial community profile of the municipal solid waste leachate treatment system: A case study

Studies on the degradation dynamics of landfill leachate indicate that the microbial community profile is a valuable and sensitive tool for landfill monitoring programs. Although knowledge about the microbial community can improve the efficiency of leachate treatment systems, little is known about the microbial profile changes that occur throughout the leachate attenuation process. In the present work, an exploratory analysis of the microbial community profile of the MSW leachate treatment system in the municipality of Osório (Brazil) was conducted. In this way, a comprehensive analysis of chemical parameters, isotopic signature and microbial profile data were applied to monitor the changes in the structure of the microbial community throughout the leachate attenuation process and to describe the relationship between the microbial community structure and the attenuation of chemical and isotopic parameters. From data analysis, it was possible to assess the microbial community structure and relate it to the attenuation of chemical and isotopic parameters. Based on massive parallel 16S rRNA gene sequencing, it was possible to observe that each leachate treatment unit has a specific microbial consortium, reflecting the adaptation of different microorganisms to changes in leachate characteristics throughout treatment. From our results, we concluded that the structure of the microbial community is sensitive to the leachate composition and can be applied to study the municipal solid waste management system.

Municipal solid waste leachate treatment using ultrasonication microwave & Ozonation combined Fenton process

ABSTRACT This work focus on the effect of Microwave power, Ozonation and Fenton reagent in microwave coupling Ozonation and Fenton oxidation process for the disintegration of COD of leachate. The experimental parameters like pH, COD, temperature, Oxidant dosage, microwave power and reaction time were varied. The results showed that 70% of COD removal efficiency was achieved at 450 W within 10 minutes interval in microwave process, 57.4% of COD removal efficiency was achieved at 60 minutes, ozone dosage 159 mg/L, pH 11. In Fenton Process, 52.91% COD removal efficiency at 60 minutes with H2O2 66.47 mµ/L and Fe2+ 80 mµ/L. Individual process showed an adverse reaction time consumption. On comparison of three processes, microwave achieved higher COD removal with shorter reaction time. In O3+ Fe process 83% COD removal was achieved at 75 minutes of reaction time. The experiment revealed the combined process of M+ O3+ Fe induces to the disintegration of COD in Leachate with a shorter reaction period.

Treatment of Leachate from Open Dumpsite of Municipal Solid Waste by Ozone Based Advanced Oxidation Process

ABSTRACT Open dumping of Municipal Solid Waste (MSW) results in generation of leachate that contains large amounts of organic matter, ammonia, heavy metals, chlorinated organics, phenolic compounds, phthalates, and pesticide residues which irreparably contaminate both surface and groundwater. Advanced Oxidation Processes (AOP) have been reported as one of the effective treatment methods, especially in improving the biodegradability of the leachate as well as effective in removing recalcitrant organics. With AOP pre-treatment rendered the leachate becomes more amenable to further treatment using biological treatment, adsorption, or ion-exchange processes. The study reported in this paper mainly aims at assessing the suitability of ozone and peroxone (O3+H2O2) based advanced oxidation processes (AOP) for the treatment of MSW leachate from the open dumpsite. The effect of reaction time, impact of O3 dose, and H2O2 concentration on the efficiency of COD removal, improvement in the biodegradability of the leachate, and pH change were determined as the performance parameters for the treatment process. The maximum COD removal efficiency was found to be 46% and 82% with ozone alone (3975 mg/L) and with ozone (9275 mg/L) + 50 mg/L H2O2 each with 120 min. reaction time. It is also found that the BOD5/COD ratio has been increased from 0.09 to 0.58 at optimum O3 + 50 mg/L H2O2 treatment would offer as an effective method for increasing the biodegradability.

A feasibility study on optimization of combined advanced oxidation processes for municipal solid waste leachate treatment

Municipal solid waste (MSW) leachate, mostly comprised of organic and inorganic substances originated from discarded organic matters, chemicals, and liquors at MSW dumpsite. Pollutant composition and toxic compounds of leachate necessitate the effective treatment before its disposal. In the current study, advanced oxidation processes; ozonation, peroxone process and photolytic ozonation were employed for the treatment of complex MSW leachate. Central Composite Design (CCD) of Response Surface Methodology (RSM) was applied to optimize the various operating parameters in the treatment system. The optimized condition of pH: 9.0; contact time: 60 min and Ozone dose: 5 g/h for a litre of leachate provided the maximum COD and NH3–N reduction of 72 % and 80 % respectively for photolytic ozonation (under 15 W–UVC; λ:254 nm) whereas under the same operating conditions, ozonation process provided 45 % of COD removal and 50 % of NH3-N removal. Peroxone process with H2O2 concentration of 800 mg/L, showed the maximum COD and NH3-N removal efficiencies of 61 % and 59.7 % respectively. The developed models have confirmed the interaction between the selected parameters; have good agreement with each other; have the best fit. The present approach provided the knowledge to adopt an efficient way of treatment to the complex MSW leachate to proceed further for pilot-scale treatment.

Dynamics of Antibiotic Resistance Genes During the Municipal Solid Waste Leachate Treatment

Antibiotic resistance genes (ARGs) are considered to be emerging environmental contaminants. ARGs are frequently detected in municipal solid waste landfill and its leachate. In this study, high-throughput quantitative PCR techniques were used to investigate the dynamics of ARGs during the treatment process of landfill leachate. The results showed that ARGs in leachate were diverse and abundant, and leachate treatment could effectively reduce their abundance; the absolute abundance of ARGs was reduced to 9.2×1010 copies·L-1, which was five orders of magnitude less than the abundance of the influent. However, the range and abundance of antibiotic resistance genes in the leachate effluents were still high compared to the natural environment. Therefore, the secondary contamination of ARGs might be caused by leachate being directly discharged into municipal sewage system. In this regard, ecological and environmental risk is an inconvenient truth. Furthermore, strong correlations indicate that heavy metals and mobile genetic elements (MGEs) in landfill leachate might influence the transfer of ARGs.

Treatment of concentrated leachate with low greenhouse gas emission in two-stage membrane bioreactor bio-augmented with Alcaligenes faecalis no. 4

ABSTRACTMethane (CH4) and nitrous oxide (N2O) emissions from two-stage membrane bioreactor (MBR) bio-augmented by Alcaligenes faecalis no. 4 during municipal solid waste leachate treatment were investigated. The system was operated at hydraulic retention time (HRT) of 2.5 and 1 days in each reactor under the presence and absence of sludge recirculation. Alcaligenes faecalis no. 4 bio-augmentation helped improving organic carbon and nitrogen removals while reducing CH4 and N2O emissions. CH4 and N2O emissions were decreased by 46% and 85% when A. faecalis no. 4 was introduced at HRT of 2.5 days. Under the presence of A. faecalis no. 4, the operation of two-stage MBR with sludge recirculation could reduce CH4 and N2O emissions by 51% and 54% as compared to its operation without sludge recirculation. An operation under short HRT of 1 day also yielded high organic carbon and nitrogen removals of more than 85% while emitting lower CH4 and N2O emission of 6.7% C and 0.04% N when operated with sludge recirculation.Implications: A two-stage membrane bioreactor was effectively applied to the treatment of concentrated leachate (BOD~20,000 mg/L) at a short hydraulic retention time of 2.5 days and 1 day. About 80% of CH4 and N2O was emitted from the anaerobic and aerobic reactors, respectively. Introduction of Alcaligenes faecalis no. 4 reduced CH4 and N2O emissions in both reactors as it became the predominant microorganism under an elevated pH condition. Lower CH4 and N2O emissions were achieved under a sludge recirculation operation, as Alcaligenes faecalis no. 4 could suppress methanogenic activities in the anaerobic reactor and converted a majority of nitrogen into its cell mass, thus reducing N2O production through a biological nitrification–denitrification pathway.

Potential of fungus Trichoderma harzianum for toxicity reduction in municipal solid waste leachate

The purpose of this research was to test the ability of selected fungus Trichoderma harzianum for municipal solid waste leachate treatment. The research carried out by inoculating the enzyme produced by T. harzianum with different ratio (10% up to 80% v/v) of solid waste leachate. The findings clearly indicated that the enzymatic addition was effectively acted (86.09% of chemical oxygen demand removed), and the rate of chemical degradation amended treatment enhanced as compared to control. Also, the enzymatic addition excellently reduced the inhibition of germination (35.8 ± 0.7) of seed (Zea mays L.) and improved the environmental quality of treated leachate. Therefore, these results can be use to articulate the preliminary feedstock for pilot to field-scale application.

Inhibitory effect of high calcium concentration on municipal solid waste leachate treatment by the activated sludge process.

This research focused on the inhibitory effects of Ca on the aerobic biological treatment of landfill leachate containing extremely high Ca concentrations. When the Ca concentration in leachate to be treated was more than 4500 mg l-1, the total organic carbon removal rate was significantly reduced and the processing time to achieve the same removal efficiency was 1.4 times that in the control treatment without added Ca. In contrast, the total nitrogen and ammonia nitrogen (NH4+-N) removal efficiencies were positively related to the Ca concentration, increasing from 65.2% to 81.2% and from 69.2% to 83.7%, respectively, when the dosage of added Ca increased from zero to 8000 mg l-1. During aerobic treatment, the reductions of solution Ca concentration were in the range of 1003-2274 mg l-1 and were matched with increases in the Ca content in the residual sludge. The inhibition threshold of Ca in the leachate treated by the activated sludge process appeared to be 4500 mg l-1, which could be realized by controlling the influent Ca concentration and using an appropriate sludge return ratio in the activated sludge process.

POPULATION ANALYSIS IN HIGH-NITRATE WASTEWATER TREATMENT IN SEQUENCING BATCH REACTORS

The pickling liquor used in the stainless steel manufacturing process is a mixture of nitric and hydrofluoric acid which generates wastewater with nitrate concentrations ranging between 500 and 6000 mgNO3--N/L. In the present study, laboratory-scale anoxic Sequencing Batch Reactors (SBRs) were used to treat high nitrate wastewaters. Two different sludge inocula were tested: one from a Municipal Solid Waste Leachate Treatment Plant (LTP), and the other from a Sewage Treatment Plant (STP). Methanol and sugar-rich wastewater were assayed as alternative carbon sources for denitrification. The best results (removal of 700 mg NO3-N/L in 6 hours of operating) were obtained when using methanol as external carbon source and inoculum from the LTP. Phylogenetic analysis of the bacteria present in the bioreactors using 16S rDNA sequences showed the presence of members of three bacterial phyla: Proteobacteria (Alfa, Gamma and Beta classes), Bacteroides and Actinobacteria. Bacteria belonging to the genera Pseudomonas, Aeromonas, Comamonas, Flavobacterium and Tessaracoccus were identified, Paracoccus being the most conspicuous denitrifying genus. Although most of the isolated bacteria harbour the nosZ denitrification gene, three of them, Paracoccus sp R-24665, Paracoccus denitrificans ATCC19367 and Paracoccus sp WB1, stood out in terms of their denitrifying capacity in both the synthetic and original wastewater, employing methanol as the carbon source. The results open the way to implementing and optimizing the full-scale treatment of industrial wastewater contaminated with nitrate.

Removal of refractory organics in nanofiltration concentrates of municipal solid waste leachate treatment plants by combined Fenton oxidative-coagulation with photo--Fenton processes.

Removal of the refractory organic matters in leachate brines generated from nanofiltration unit in two full-scale municipal solid waste landfill leachate treatment plants was investigated by Fenton oxidative-coagulation and ultraviolet photo - Fenton processes in this study. Fenton oxidative-coagulation was performed under the condition of an initial pH of 5.0 and low H2O2/Fe(2+) ratios. After precipitate separation, the remaining organic constituents were further oxidized by photo - Fenton process. For both leachate brines with varying pollution strength, more than 90% COD and TOC reductions were achieved at H2O2/Fe(2+) dosages of 35 mM/8 mM and 90 mM/10 mM, respectively. The effluent COD ranged 120-160 mg/L under the optimal operating conditions, and the biodegradability was increased significantly. Fenton oxidative-coagulation was demonstrated to contribute nearly 70% overall removal of organic matters. In the combined processes, the efficiency of hydrogen peroxide varied from 216 to 228%, which may significantly reduce the operating cost of conventional Fenton method. Six phthalic acid esters and thirteen polycyclic aromatic hydrocarbons were found in leachate brines, and, on the average, around 80% phthalic acid esters and 90% polycyclic aromatic hydrocarbons were removed by the combined treatments.

Removal and transformation of dissolved organic matter (DOM) during the treatment of partially stabilized leachate in membrane bioreactor

The removal of dissolved organic matter (DOM) during municipal solid waste leachate treatment in a membrane bioreactor (MBR) was investigated. The MBR was operated with fouled and cleaned membranes, at a time. DOM, mixed liquor, and effluent were characterized by fractionation and fluorescence excitation-emission matrix (EEM) spectroscopy. Results showed DOM removals of 82% during the MBR operation with the fouled membrane. The DOM characterization indicated that most of the hydrophilic compounds and protein-like substances could be significantly removed by microbial activities in the treatment processes. Furthermore partial removal or transformation of organic substances was observed during membrane filtration. The fouled membrane improved DOM rejection by only about 2% when compared to the cleaned membrane, which demonstrated the significance of irreversible foulants on DOM rejection. There were insignificant differences in DOM fractionation and EEM fluorescence spectra between water samples filtered through the fouled and cleaned membranes.

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.

Performance of tubular reverse osmosis for the desalination/concentration of a municipal solid waste leachate

Municipal solid waste leachate (MSWL) has the potential to pollute the water environment and to affect biological treatment processes adversely if not properly handled. Reverse osmosis (RO) has the ability to remove both organics and inorganics effectively from effluents. Therefore, RO was evaluated for the treatment of MSWL. It was found that both cellulose acetate and polyamide RO membranes should function effectively for the treatment of the leachate and that it should be possible to control membrane fouling with chemical cleaning. The polyamide membranes, however, performed somewhat better than the cellulose acetate membranes for the treatment of the leachate. The quality of the treated leachate with the exception of ammonia-nitrogen and COD should comply with the quality requirements for discharge into the water environment. Biological treatment processes are effective in complete removal (to only traceable levels) of ammonia-nitrogen and biodegradable COD. The quality of the treated effluent further complies with the quality requirements (chloride and heavy metals) for discharge into the municipal biological treatment system. The capital and operational cost of a 250 m3/d tubular reverse osmosis (TRO) plant is estimated at R1.95 m. and R11.45/m3, respectively.

Important aspects of long-term production and treatment of municipal solid waste leachate

Less than 30 out of a total of 250 active municipal solid waste (MSW) landfills in Norway use on-site biological leachate treatment systems. One of the most important aspects with regard to landfills is the treatment of the expected polluting leachate emissions, requiring simple and low-cost systems. A combination of aeration, dams and filtering techniques is likely to result in the best treatment options. Biological treatment systems, like aerated lagoons or sequenced batch reactors in combination with natural systems like soil infiltration, spray irrigation, filtration or constructed wetlands can be cost-effective systems for MSW leachate treatment in Norway. Aerated lagoons appeared to be an efficient treatment stage for landfill leachate treatment in cold climates. The hydraulic retention time should be >20 d to keep the nitrifiers in the lagoon during periods with low temperatures. Landfills can be grouped into categories depending on landfill size, age, hydrology and climate before evaluating sampling programmes prior to treatment system installation and during operation. Simple filtration techniques with bark and crushed concrete can significantly improve leachate quality during treatment and remove nitrogen, colour, heavy metals and pesticides, buffer the pH and add phosphorous.