Treatment of mature landfill leachate by biofilters and Fenton oxidation

Novel Treatment of Sugar Mill Wastewater in a Coupled System of Aged Refuse Filled Bioreactors (ARFB): Full-Scale

Sugar is the most important food supplement of our daily diet. During the production, sugar mills use a large volume of water and produce a significant amount of wastewater polluted with high organic compounds. Therefore, it is necessary to treat the wastewater before their disposal. For this reason, this article presents the results obtained from the monitoring of a coupled system of aged refuse filled bioreactors (ARFB) in full scale to treat wastewater from a sugar mill. The coupled system consists of two bioreactors (a primary one -ARFB1- and a rectification one -ARFB2-) arranged in a series with identical geometries. The ARFB1-ARFB2 system was evaluated in two stages. The first stage (maintenance period) for 28 weeks, and second stage (Zafra season) for 29 weeks. The system was fed with sugar mill wastewater (SMW) with a chemical oxygen demand (COD) of 2787 ± 1552 mg/L and 2601 ± 722 mg/L, respectively. As results, we observed a rapid stabilization of the system over 2 months. In addition, we found the ARFB1-ARFB2 system achieved an average COD removal of 94.9%, with a final effluent (E2) concentration below the maximum permissible limits of Mexican and international regulations for all analyzed parameters. Finally, the results of this study show that the ARFB1-ARFB2 full-scale novel technology is an efficient process for removal of the main contaminants that affect the wastewater from the sugar mills.

A review and perspective of recent research in biological treatment applied in removal of chlorinated volatile organic compounds from waste air

Chlorinated volatile organic compounds (Cl-VOCs) waste air is a kind of typical recalcitrant organic compounds, which poses a great threat to the ecological environment and human health. At present, the biotechnology is considered as a potential strategy for the Cl-VOCs removal due to the advantages of low energy consumption and less possibility of secondary pollution. This work summarizes the recent researches on strains, bioreactors and technology integration. The dominant pure strains for biodegradation of Cl-VOCs are first outlined with a special focus on the co-metabolism of multi-components. It then summarizes two bioreactors (optimized airlift reactor (ALR) and two-phase partitioning bioreactor (TPPB)) and strategy (addition of surfactant) for improvement of biotrickling filter (BTF), which are benefit to achieve the mass transfer enhancement in the removal of hydrophobic Cl-VOCs from waste air. After that, the integration technologies, such as magnetic field (MF)-BTF, non-thermal plasma (NTP)/ultraviolet light (UV)-BTF, and microbial electrolytic cells (MEC), are elucidated, which provide opportunities for complete mineralization of Cl-VOCs in a more efficient, energy-saving and economical way. Finally, current challenges and a perspective of future research on biotechnology for Cl-VOCs removal are thoroughly discussed.

Recovery of efficient treatment performance in a semi-aerobic aged refuse biofilter when treating landfill leachate: Washing action using domestic sewage

Semi-aerobic aged refuse biofilters (SAARB) are known to efficiently remove organic matter, nitrogenous substances, and anions from landfill leachate. However, long-term recirculation of mature landfill leachate inevitably leads to accumulation of pollutants and decreases treatment capacity. In this study, the washing action provided by domestic sewage was used to recover and even enhance the treatment performance of SAARBs treating mature landfill leachate. Three SAARB columns were operated for 300 d after which a "Recirculation-Washing-Recirculation" sequence was followed. In the first recirculation period (22 d), removal of chemical oxygen demand (COD) and total nitrogen (TN) decreased from ca. 90% and 60%, respectively, initially to about 75% and less than 20%, respectively. Thereafter, washing (20 d) of the SAARBs was accomplished by applying domestic sewage. In the subsequent second recirculation period (30 d), the SAARBs were operated at the same hydraulic loading as used initially, but achieved high (ca. 90%) COD and relatively high (ca. 59%-76%) TN removal, including degradation of refractory organic matter such as humic- and fulvic-like substances. Overall, the mechanisms of the treatment performance recovery (including organics degradation and nitrification-denitrification) using domestic sewage can be attributed to three main effects: (1) some accumulated pollutants were washed out, thereby leading to recovery of the adsorption ability of aged refuse; (2) the inhibition of bio-refractory organics stress on microbial activities was mitigated by domestic sewage washing; and (3) the wash out of some accumulated salts (e.g., chloride and sulfate ions) probably helped the microbial activity recover.

Treatment of a Mature Landfill Leachate: Comparison between Homogeneous and Heterogeneous Photo-Fenton with Different Pretreatments

This study focuses on the treatment of a mature landfill leachate by coagulation and photo-Fenton at different conditions. Optimal coagulation is carried out with ferric chloride in acid conditions; and with alum in near-neutral conditions, to minimize the use of sulphuric acid for pH adjustment (1 g/L vs. 7.2 g/L), the generation of sludge and the increase of conductivity in the final effluent. In both cases, a similar chemical oxygen demand (COD) removal is obtained, higher than 65%, which is high enough for a subsequent photo-Fenton treatment. However, the removal of absorbance at 254 nm (UV-254) was significantly higher with ferric chloride (83% vs. 55%), due to the important removal of humic acids at acid pH. The best results for coagulation are 2 g/L ferric chloride at initial pH = 5 and 5 g/L alum at initial pH = 7. After coagulation with ferric chloride, the final pH (2.8) is adequate for a homogeneous photo-Fenton using the remaining dissolved iron (250 mg/L). At these conditions, using a ratio H2O2/COD = 2.125 and 30 min contact time, the biodegradability increased from 0.03 to 0.51. On the other hand, the neutral pH after alum coagulation (6.7) allows the use of zero valent iron (ZVI) heterogeneous photo-Fenton. In this case, a final biodegradability of 0.32 was obtained, after 150 min, using the same H2O2/COD ratio. Both treatments achieved similar results, with a final COD, UV-254 and color removal greater than 90%. However, the economic assessment shows that the approach of ferric chloride + homogeneous photo-Fenton is much cheaper (6.4 €/m3 vs. 28.4 €/m3). Although the discharge limits are not achieved with the proposed combination of treatments, the significant increase of the pre-treated leachate biodegradability allows achieving the discharge limits after a conventional biological treatment such as sequencing batch reactor, which would slightly increase the total treatment cost.

Treatment of Low Biodegradability Leachates in a Serial System of Aged Refuse-Filled Bioreactors

This paper presents a technology based on the use of aged refuse that has proven to be highly effective in the treatment of low biodegradability leachates. The tests were developed using two filled bioreactors arranged in series and operated at steady state. The aged refuse used as filling material was extracted from a city located in the southeast of Mexico and characterized by particle size, humidity, volatile solids, and volumetric weight. On the other hand, bacterial characterization made it possible to identify the presence of species related to the degradation and mineralization of organic compounds, as well as to processes of nitrification or reduction of phosphates and Cr (VI). The bioreactor system was operated under four hydraulic loads (10, 20, 35, and 50 L/m3·d). Maximum removal efficiencies of 85, 86.1, 87.9, 98.6, 97.8, and 97.4% were achieved in COD, BOD5, Color, TP, TN, and N-NH3, respectively, complying with Mexican regulations (NOM-001-SEMARNAT-1996). The system also proved to be stable against shock loads, such as organic load fluctuations in the influent or pH variations. The results of this study show that, in countries such as Mexico, aged refuse extracted from landfills represents a promising option as a sustainable alternative for leachate treatment.

Application of electro-Fenton process for treatment of composting plant leachate: kinetics, operational parameters and modeling

BACKGROUND

Composting plant leachate is considered as one of the highly polluted wastewaters which is necessary to be treated by simple, economic, fast and environmentally compatible methods. In this study, treatment of fresh composting plant leachate by electro-Fenton (EF) process was investigated.

METHODS

The effect of various input variables like pH (2-7), DC currents (1.5-3 A), H₂O₂ concentrations (theoretical ratio H₂O₂/COD: 0.1-0.6), TDS changes (4-6%), feeding mode, and BOD/COD ratio at the optimal point were studied. The settling characteristics of the waste sludge produced by the treatment (sludge volumes after 30-min sedimentation: V₃₀) were also determined. Artificial neural network (ANN) approach was used for modeling the experimental data.

RESULTS

Based on the results, the best removal rate of COD was obtained at pH: 3, 3 A constant DC current value, 0.6 theoretical ratio H₂O₂/COD and the feeding mode at four step injection. BOD/COD ratio at the optimal point was 0.535 and the maximum COD removal was achieved at TDS = 4%. In the optimal conditions, 85% of COD was removed and BOD/COD ratio was increased from 0.270 to 0.535. The data follow the second-order kinetic (R² > 0.9) and neural network modeling also provided the accurate prediction for testing data.

CONCLUSION

Results showed that EF process can be used efficiently for treatment of composting plant leachate using the proper operating conditions.

Mature landfill leachate utilization using a cost-effective hybrid method

The main goal of this study was to investigate the co-digestion of sewage sludge and mature landfill leachate pretreated through hydrodynamic cavitation. The process efficiency was analyzed from the aspects of organics removal, biogas production, kinetics and digestate quality. Energy efficiency of the overall treatment was evaluated as well. A dose of hydrodynamically cavitated leachate of 5% v/v was used as a substrate for co-digestion with sewage sludge at a hydraulic retention time of 20 days. This improved the kinetics, biogas production and corresponding yields, as well as digestate quality. Fourier transform infrared photoacoustic spectroscopy analysis seemed to indicate that no new toxic compounds were formed with co-digestion. The investigated two-stage treatment is recommended as a safe and cost-effective method of utilizing mature leachate.

Membrane bioreactor performance in treating Algiers' landfill leachate from using indigenous bacteria and inoculating with activated sludge

This study focuses on the treatment of both organic and metallic pollution in the Staoueli landfill leachate. This leachate contains a large amount of organic and inorganic matter and it must imperatively be treated before being released into the environment. Our work presents a comparative study between two membrane sequenced batch bioreactors (B2 contains indigenous leachate bacteria and B1 contains activated sludge). The purpose is to assess the best treatment to use, one that allows the reduction of the polluting load of the leachate and a reduction of membrane fouling. Performances were evaluated by measuring the chemical oxygen demand (COD) and the metal content of the leachate (zinc, iron). The results showed a similar COD removal efficiency in B2 (95%) and B1 (93%). Coupling the bioreactors with an ultrafiltration process allowed a notable reduction in zinc and iron concentrations: Fe of 35% and Zn of 78% for B1UF, and Fe of 71% and Zn of 74% for B2UF.

Fenton treatment of bio-treated fermentation-based pharmaceutical wastewater: removal and conversion of organic pollutants as well as estimation of operational costs

The Fenton process is used as a tertiary treatment to remove organic pollutants from the effluent of bio-treated pharmaceutical wastewater (EBPW). The optimal and most appropriate Fenton conditions were determined by an orthogonal array test and single-factor experiments. The removal of chemical oxygen demand (COD) was influenced by the following factors in a descending order: H₂O₂/Fe(II) molar ratio > H₂O₂ dosage > reaction time. Under the most appropriate Fenton conditions (H₂O₂/Fe(II) molar ratio of 1:1, H₂O₂ dosage of 120 mg L^-1 and reaction time of 10 min), the COD and dissolved organic carbon (DOC) were removed with efficiencies of 62 and 53%, respectively, which met the national discharge standard (GB 21903-2008) for the Lake Tai Basin, China. However, the Fenton treatment was inadequate for removal of N compounds, and the removal of organic nitrogen led to an increment in N-NH₃ from 3.28 to 19.71 mg L^-1. Proteins and polysaccharides were completely removed, and humic acids (HAs) were partly removed with an efficiency of 55%. Three-dimensional excitation/emission matrix spectra (3DEEMs) indicated complete removal of fulvic acid-like substances and 90% reduction in the florescence intensity of humic acid-like substances. Organic pollutants with molecular weights (MW) > 10 kDa were completely removed, MW 5-10 kDa were degraded into smaller MW ones, and some low molecular weight acids (MW 0.1-1 kDa) were mineralized during the Fenton process. Some species, including pharmaceutical intermediates and solvents were detected by gas chromatography-mass spectrometry (GC-MS). The operational costs of the Fenton's treatment were estimated to be 0.58 yuan RMB/m³ EBPW based on reagent usage and iron sludge treatment and disposal.

Impact of SRT on the performance of MBRs for the treatment of high strength landfill leachate

This study examines the performance and fouling potential of flat sheet (FS) and hollow fiber (HF) membrane bioreactors (MBRs) during the treatment of high strength landfill leachate under varying solid retention times (SRT = 5-20 days). Mixed-liquor bacterial communities were examined over time using 16S rRNA gene sequence analysis in an attempt to define linkages between the system performance and the microbial community composition. Similarly, biofilm samples were collected at the end of each SRT to characterize the microbial communities that evolved on the surface of the FS and HF membranes. In general, both systems exhibited comparable removal efficiencies that dropped significantly as SRT was decreased down to 5 days. Noticeably, ammonia and nitrite oxidizing bacteria were not detected at the tested SRTs. This suggests that the nitrifiers were not enriched, possibly due to the high organic and ammonium content of the leachate that led to low TN and NH₃ removal efficiency. The steady-state fouling rate of both membranes increased linearly with the decrease in SRT at an estimated factor of 1.1 and 1.2 for the FS- and HF-MBR, respectively, when the SRT was reduced from 15 to 10 days and from 10 to 5 days. Similar dominant genera were detected in both MBRs, including Pseudomonas, Aequorivita, Ulvibacter, Taibaiella, and Thermus. Aequorivita, Taibaiella; Thermus were the dominant genera in the biofilms. Hierarchical clustering and non-metric multidimensional scaling revealed that while the mixed liquor communities in the FS-MBR and HF-MBRs were dynamic, they clustered separately. Similarly, biofilm communities on the FS and HF membranes differed in the dynamic bacterial community structure, especially for the FS-MBR; however this was less dynamic than the mixed liquor community.

Quantitative dynamics of ammonia-oxidizers during biological stabilization of municipal landfill leachate pretreated by Fenton's reagent at neutral pH

The application of multi-stage systems including biological step, for the treatment of leachate from municipal landfills, is economically and technologically justified. When microbial activity is utilized as 2nd stage of treatment, the task of 1st stage is to increase the bioavailability of organic matter. In this work, the effect of advanced oxidation process by Fenton's reagent for treatment efficiency of landfill leachate in the sequencing batch reactor was assessed. The quantitative dynamics of bacteria taking a part in ammonia removal process was evaluated by determination of number of DNA copies of 16S rRNA and amoA. Products of neutral pH chemical oxidation, had a definite positive impact on the quantity of β-proteobacteria 16S rRNA, whereas the same gene specified for Nitrospira sp. as well as amoA did not show a significant increase during the process of biological treatment, regardless of whether the reactor was fed with raw leachate or chemically pre-treated.

Effect of low aeration rate on simultaneous nitrification and denitrification in an intermittent aeration aged refuse bioreactor treating leachate

Three intermittent aeration aged refuse bioreactors (ARBs), A, B, and C, with aeration rates of 670, 1340, and 2010L/m³ aged refuse·d in stage 1, and 670, 503, and 335L/m³ aged refuse·d in stage 2 were constructed to evaluate the effect of low aeration rate on leachate treatment by simultaneous nitrification and denitrification (SND). Results show that SND can be achieved and improved by reasonably adjusting the aeration rate of the ARB. In stage 1, the average chemical oxygen demand (COD) removal rates of ARBs A, B, and C were 91%, 92%, and 93%, respectively. The ammonia nitrogen (NH₄⁺-N) removal rate of the three ARBs approached 100%. The total nitrogen (TN) average removal rates were 68%, 59%, and 57%. The average SND efficiency values were 73%, 66%, and 65%. In stage 2, the COD removal rates of ARBs A, B, and C decreased from the original values of 85%, 92%, and 93% to 84%, 81%, and 80%. The NH₄⁺-N removal rate decreased from above 99% to 90%-92% in ARB B and from above 99% to 87%-91% in ARB C. The TN removal rates of ARBs B and C increased to 59% and 53% on day 15 from the initial values of 49% and 43% and were maintained at 49%-61% and 50%-60%. The SND efficiency of ARBs B and C improved, and the average values were 68% and 70% after day 15. These values were higher than the 66% of ARB A during the same period. Comprehensively considering the COD, NH₄⁺-N, TN removal rate, and SND efficiency, the optimal aeration rate of 670L/m³ aged refuse·d is therefore suggested in this study.

Ferrous ion-activated persulphate process for landfill leachate treatment: removal of organic load, phenolic micropollutants and nitrogen

The innovative [Formula: see text] treatment technology based on sulphate radicals induced oxidation was applied for the treatment of landfill leachate. The performance of chemical oxygen demand (COD) and dissolved organic carbon (DOC) removal in the Fe²⁺-activated persulphate system was moderate; however, the results of dissolved nitrogen (DN) and total phenols removal showed significant efficacy (≤39% and ≥87%, respectively). [Formula: see text] addition to the [Formula: see text] system enhanced the treatment efficacy and resulted in supplementary 15% of COD and 5% of DN removal. Hydroxyl radical-based H₂O₂/Fe²⁺ treatment of the landfill leachate was performed as well; the results indicated higher removal efficacy of COD and DOC compared to the [Formula: see text] system. However, practical application of the H₂O₂/Fe²⁺ system is considerably influenced by temperature rise and excessive foam formation. Generally, the ferrous ion-activated persulphate treatment could be a promising technology for ex situ as well as in situ landfill leachate treatment applications.

Hollow fiber vs. flat sheet MBR for the treatment of high strength stabilized landfill leachate

The Membrane Bioreactor (MBR) technology is increasingly becoming a prominent process in the treatment of high-strength wastewater such as leachate resulting from the decomposition of waste in landfills. This study presents a performance comparative assessment of flat sheet and hollow fiber membranes in bioreactors for the treatment of relatively stable landfill leachate with the objective of defining guidelines for pilot/full scale plants. For this purpose, a laboratory scale MBR system was constructed and operated to treat a leachate with Chemical Oxygen Demand (COD) (3900-7800mg/L), Biochemical Oxygen Demand (BOD5) (∼440-1537mg/L), Total Phosphorus (TP) (∼10-59mg/L), Phosphate (PO4(3)(-)) (5-58mg/L), Total Nitrogen (TN) (1500-5200mg/L), and ammonium (NH4(+)) (1770-4410mg/L). Both membranes achieved comparable BOD (92.2% vs. 93.2%) and TP (79.4% vs. 78.5%) removals. Higher PO4(3)(-) removal efficiency or percentage (87.3% vs. 81.3%) and slightly higher, but not statistically significant, COD removal efficiency were obtained with the hollow fiber membrane (71.4% vs. 68.5%). On the other hand, the flat sheet membrane achieved significantly higher TN and NH4(+) removal efficiencies (61.2% vs. 49.4% and 63.4% vs. 47.8%, respectively), which may be attributed to the less frequent addition of NaOCl compared to the hollow fiber system.

Application of hydrodynamic cavitation to improve the biodegradability of mature landfill leachate

In this study, the application of hydrodynamic cavitation to improve the biodegradability of mature landfill leachate was investigated. Three configurations of cavitation device were examined and operational parameters of the process were selected. The study indicated that the orifice plate with a 3/10mm diameter conical concentric hole, characterized by the cavitation number of 0.033, is a reasonable choice to ensure the enhanced biodegradability of mature leachate. Using such a configuration and maintaining 30 recirculation passes through the cavitation zone at inlet pressure of 7 bar, the highest increase of biodegradability index (BI) of approximately 22% occurred, i.e., from the value of 0.046 to 0.056. The FT-IR/PAS analysis confirmed a degradation of refractory compounds that typically prevail in mature leachate. An evaluation of energy efficiency was made in terms of the actual consumed energy measured by using the Kyoritsu KEW6310 Power Quality Tester. A cavitational yield of 9.8 mg COD kJ(-1) was obtained for the optimum configuration and 30 recirculation passes. Regarding energy efficiency, the application of 10 cavitation cycles appeared to be the most profitable. This was due to an almost threefold higher cavitational yield of 27.5 mg COD kJ(-1). However, the preferable option should be selected by considering a satisfactory effect in the biodegradability enhancement.

Investigation on pretreatment of centrifugal mother liquid produced in the production of polyvinyl chloride by air-Fenton technique

Centrifugal mother liquid (CML) is one of the main sources of wastewater produced during the production of polyvinyl chloride in chlor-alkali industry. CML is a typical poorly biodegradable organic wastewater, containing many kinds of refractory pollutants. Specifically, it contains dissolved refractory polymers, especially polyvinyl alcohol (PVA), which can pass though the biotreatment processes and clog the membranes used for further treatment. In this study, to ensure the CML applicable to biotreatment and membrane treatment, a novel efficient and mild technique, air-Fenton treatment, was employed as a pretreatment technique to improve biodegradability of the CML and to break down the polymers in the CML. Firstly, the technique was optimized for the CML treatment by optimizing the main parameters, including the dosage of ferrous sulfate, initial pH of the wastewater, [H2O2]/[Fe(2+)], aeration rate, reaction time, and temperature, based on removal efficiency of COD and PVA from the CML. Then, the optimized technique was tested and evaluated. The results indicated that under the optimized conditions, the air-Fenton treatment could remove 66, 98, and 55 % of the COD, PVA, and TOC, respectively, from the CML. After the treatment, biodegradability of the wastewater increased significantly (BOD/COD increased from 0.31 to 0.68), and almost all of the PVA polymers were removed or broken down. Meanwhile, concentration of the remaining iron ions, which were added during the treatment, was also quite low (only 2.9 mg/L). Furthermore, most of the suspended materials and ammonia nitrogen, and some of the phosphorus in the wastewater were removed simultaneously.

Nitrogen removal through different pathways in an aged refuse bioreactor treating mature landfill leachate

In this study, an aged refuse bioreactor was constructed to remove nitrogen in a mature landfill leachate. The nitrogen removal efficiency and the microbial community composition in the bioreactor were investigated. The results showed that the aged refuse bioreactor removed more than 90 % of total nitrogen in the leachate under the nitrogen loading rate (NLR) of 0.74 g/kg (vs) day, and the total nitrogen removal rate decreased to 62.2 % when NLR increased up to 2.03 g/kg (vs) day. Quantitative polymerase chain reaction results showed that the average cell number of ammonia-oxidizing bacteria in the bioreactor was 1.58 × 10(8) cells/g, which accounted for 0.41 % of total bacteria. The number of anammox bacteria in the reactor was 1.09 × 10(8) cells/g, which accounted for 0.27 % of total bacteria. Isotopic (15)N tracing experiments showed that nearly 10 % of nitrogen was removed by anammox. High-throughout 454 pyrosequencing revealed that the predominant bacteria in the bioreactor were Proteobacteria, Chloroflexi, Actinobacteria, Bacteroidetes, and Gemmatimonadetes, including various nitrifiers and denitrifiers with diverse heterotrophic and autotrophic metabolic pathways, supporting that nitrogen was removed through different pathways in this aged refuse bioreactor.

Electro-Fenton treatment of concentrates generated in nanofiltration of biologically pretreated landfill leachate

The electro-Fenton (E-Fenton) treatment of landfill leachate concentrates was investigated in this study. The concentrates were generated from nanofiltration of biologically pretreated landfill leachate, and contained high concentrations of refractory organics and inorganic salts. During the E-Fenton treatment, H(2)O(2) was electrochemically produced at a carbon-polytetrafluorethylene (PTFE) cathode with oxygen feeding. The in situ generated H(2)O(2) then reacted with Fe(2+) that was added into the concentrates to bring about Fenton oxidation of the refractory organics in the concentrates. The effectiveness of the E-Fenton treatment of the concentrates was appraised in terms of its removal efficiency of total organic carbon (TOC) of the concentrates. The effects of FeSO(4) dosage, current density, initial pH of the solution, and cathode area on the process performance were also evaluated. Under optimal reaction conditions that included a current density of 30 mA cm(-2), FeSO(4) dosage of 10mM, initial pH of 3, and cathode area of 20 cm(2), the TOC and total nitrogen (TN) removal efficiencies were 82% and 51% after 6h of the E-Fenton treatment. The results indicated that the E-Fenton technology could produce sufficient amounts of advanced oxidants in situ to effectively degrade the refractory organic pollutants in high-strength leachate concentrates.

Performance and bacterial compositions of aged refuse reactors treating mature landfill leachate

Aged landfill leachates become more refractory over time and difficulty to treat. Recently, aged refuse bioreactors show great promise in treating leachates. In this study, aged refuse bioreactors were constructed to simulate landfill leachate degradation process. The characteristics of leachate were: CODcr, ∼2200 mg/L; BOD5, ∼280 mg/L; total nitrogen, ∼2030 mg/L; and ammonia, ∼1900 mg/L. Results showed that bioreactor could remove leachate pollutants effectively at hydraulic loading of 20 L/m3 d. The removal rate reduced when hydraulic loading doubled or temperature lowered. Effluent recirculation could alleviate the temperature effect. Combining aged refuse and slag biofilters could treat leachate more efficiently. Pyrosequencing analysis indicated that bacteria from Pseudomonas, Lysobacter, Bacillus and δ-proteobacter, Flexibacteraceae were more abundant in the samples. The Shannon index decreased at lower temperature, while evenness and equitability increased with recirculation. We suggest that filter medium and temperature may be the main factors for shaping bacterial community structure.