Landfill Leachate Treatment System Research Articles

Characteristics and key driving factors of nitrous oxide emissions from a full-scale landfill leachate treatment system

The characteristics of N2O emission from a full-scale landfill leachate treatment system were investigated by in-situ monitoring over 1.4 years and driving factors responsible for these emissions were identified by statistical analysis of multidimensional environmental variables. The results showed that the maximum N2O emission flux of 2.21 × 107 mg N·h−1 occurred in the nitrification tanks, where 98.5 % of the total N2O was released, with only 1.5 % of the total N2O emitted from the denitrification tanks. Limited oxygen in nitrification tank was responsible for N2O hotspot. The N2O emissions from the parallel lines A and B (both comprising the primary biochemical system) accounted for 52.6 % and 46.6 %, respectively, while the secondary biochemical system contributed only 0.8 % to the total emissions. Higher nitrite concentration in line A and lower nitrogen loading in the secondary biochemical system caused these discrepancies. We found that during the steady state of leachate treatment, intensive N2O emissions of 253.4–1270.5 kg N·d−1 were measured. The corresponding N2O emission factor (EF) ranged from 8.86 to 49.6 %, much higher than those of municipal wastewater treatment. But N2O EF was inconceivably as low as 0.42 % averagely after system maintenance. Influent with low salinity was the key reason, followed by the high MLSS and varying microbial community after maintenance. The dominant genus shifted from Lentimicrobium and Thauera to Norank-F-Anaerolineaceae and Unclassified-F-Rhodocyclaceae. This study underscores the significance of landfill leachate treatment in urban nitrogen management and provides valuable insights into the characteristics and driving factors of N2O emissions from such systems. The findings offer important references for greenhouse gas emission inventories and strategies for N2O control in full-scale wastewater treatment plants.

Simulation of landfill leachate treatment systems involving self-designed disk tube reverse osmosis (DTRO) model integrated with mechanical vapor recompression (MVR)

Four landfill leachate treatment systems involving self-designed disk tube reverse osmosis (DTRO) module integrated with mechanical vapor recompression (MVR) were established in Aspen Plus. To assess the treatment efficiency and the economic feasibility of landfill leachate treatment techniques, simulation of leachate treatment by four systems were conducted, and the corresponding recovery rate Y, removal rate Rt, energy consumption and operating cost were obtained. Results indicate that for the two-stage DTRO system, the optimal operational pressures in compliance with emission standards are 5.6 MPa in the first stage and 3.5 MPa in the second stage. Adding an MVR system to further treat the membrane concentrate (MC) can greatly reduce the pollutant recharge and the energy consumption of the DTRO system. When Y in MVR is not strictly required, the single-stage MVR system is the most energy-saving one. When a high Y (≥80 %) is required, the series double-stage MVR system affords the highest energy-efficiency, offering a 3.14 % lower operating cost, a 3.27 % lower unit COD removal cost, and a 7.29 % lower unit water production cost as compared to the single-stage MVR system.

Comparison of the PFAS and physical-chemical parameter fluctuations between an ash landfill and a MSW landfill

Studies of per- and polyfluoroalkyl substances (PFAS) fluctuations at landfills have focused on municipal solid waste (MSW) leachate. Few studies exist that evaluate fluctuations (defined by the coefficient of variation, CV) in MSW incinerator ash (MSWA) landfill leachate and that evaluate PFAS fluctuations in stormwater, groundwater, and treated liquids on-site. In this study, aqueous landfill samples (leachate, treated leachate, stormwater, gas condensate, ambient groundwater, and effluent from a groundwater remediation system) were collected from a MSW and an MSWA landfill geographically located within close proximity (less than 40 km). The objective of this study was to compare the leachate compositions between these two landfill types and to evaluate temporal variations. Results indicated that the CV of total detected PFAS concentrations in leachate was higher for the MSW landfill (CV = 43 %) compared to the MSWA landfill (CV = 16 %). The total detected PFAS concentration in MSW leachate samples (mean: 9641 ng/L) was higher than in MSWA leachate samples (mean: 2621 ng/L) (p < 0.05). Within a landfill, PFAS concentrations were correlated (rs > 0.6, p < 0.05) with alkalinity, total organic carbon (TOC), and ammonia. Results from the on-site leachate treatment system at the MSW landfill indicated reductions in COD, TOC, and ammonia; however, the ∑26PFAS concentration increased 3 % after the treatment. Overall, results demonstrated that differences between landfill types and fluctuations in PFAS within landfills should be considered when designing landfill leachate collection and treatment systems to remove PFAS. The comparative analysis in this study can provide insights into optimizing leachate management for MSW and MSWA landfills.

Evaluating the Operation of a Full-Scale Sequencing Batch Reactor–Reverse Osmosis–Evaporation System Used to Treat Landfill Leachates: Removal of Pollutants, Energy Consumption and Greenhouse Gas Emissions

Limited information is available in the literature regarding the energy consumption and the greenhouse gases emitted during landfill leachates treatment. A full-scale landfill leachates treatment system that included primary sedimentation, biological treatment in sequencing batch reactors, reverse osmosis and mechanical vapor recompression evaporation was monitored and evaluated for the removal of major pollutants, energy consumption and greenhouse gas emissions. Samples were taken during a period of two years from different points of the system, while the actual power consumption was calculated considering the available mechanical equipment and the hours of operation. The quantities of greenhouse gases emitted were estimated using appropriate equations and based on the operational characteristics of the system. According to chemical analyses, biological treatment resulted in partial removal of COD and total nitrogen, while the removal of BOD5 and NH4-N was significant, reaching 90 and 98%, respectively. Use of reverse osmosis increased the removal of all pollutants, satisfying the requirements of the legislation on wastewater discharge into the environment. Power consumption was calculated to be 35.3 KWhr per m3 of treated leachate, while mechanical vapor recompression evaporation was responsible for 60.5% of the total energy required. The contribution of other processes to energy consumption was as follows, in decreasing order: sequencing batch reactors &gt; reverse osmosis &gt; primary treatment. The roots blower vacuum pump used for mechanical vapor recompression evaporation, and the blowers providing air to the sequencing batch reactors, were the most energy-intensive pieces of apparatus, contributing 44.2% and 11.3% of the required energy, respectively. The quantity of greenhouse gases emitted was estimated to be 27.7 Kg CO2eq per m3 of treated leachates. Among the different processes used, biological treatment and mechanical vapor recompression evaporation contributed to 45.7% and 44.1% of the total emissions, respectively. The findings of this study reveal that an integrated landfill leachate treatment system that combines biological treatment and reverse osmosis can assure the protection of the aquatic environment by producing high-quality effluent; however, further research should be conducted regarding the sustainable management of reverse osmosis concentrate. Mechanical vapor recompression evaporation contributes significantly to the environmental footprint of the landfill leachates treatment system due to both high energy consumption and elevated emissions of greenhouse gases.

Response of partial nitritation and denitrification processes to high levels of free ammonia in a pilot mature landfill leachate treatment system: Stability and microbial community dynamics

The high levels of free ammonia (FA) challenge the application of partial nitritation (PN) and denitrification (DN) in the treatment of ammonia-rich wastewater. This study explored the impact of high levels of FA on the PN and DN stability and microbial community dynamics. By reducing reflux and increasing influent load, the concentrations of FA in PN and DN reactors increased from 28.9 mg/L and 140.0 mg/L to 1099.8 mg/L and 868.4 mg/L, respectively. During this process, the performance of PN and DN remained stable. The microbial analysis revealed that the Nitrosomonas exhibited strong tolerance to high levels of FA, and its relative abundance was positively correlated with amoABC (R2 0.984) and hao (R2 0.999) genes. The increase in microbial diversity could enhance the resistance ability of PN against the FA impact. In contrast, high levels of FA had scant influence on the microbial community and performance of DN.

Efficient nitrogen removal and robustness enhancement of a two-stage partial nitrification-anammox (PN/A) process with low sludge concentration for mature landfill leachate

The biological treatment system for high-strength wastewater, particularly landfill leachate, typically requires high sludge concentration to maintain nitrogen removal performance. However, it frequently causes an excessive accumulation of toxins in microbial metabolism, resulting in unstable performance during long-term operation. An efficient two-stage partial nitrification/anammox (PN/A) mature landfill leachate process with low sludge concentration was constructed by settling time reduction and Ca2+ addition. The ammonia removal rate reached 46.7 mg N/(L·h) in PN-SBR. Nitrosomonas (2.0%) was the sole genus responsible for partial nitrification. The influent NO2−-N/NH4+-N of A-SBR was kept at 1.39, leading to a dynamic equilibrium of anammox and denitrification. Ca. Brocadia recovered fastest (0.32% → 1.8%) among the detected AnAOB genera. The process achieved NRE of 95.0% with effluent TIN of 37.6 mg/L (<40 mg/L). This research offered recommendations for the favorable operation of the two-stage PN/A mature landfill leachate treatment system with low sludge concentration.

Effect of the association of coagulation/flocculation, hydrodynamic cavitation, ozonation and activated carbon in landfill leachate treatment system

Mature landfill wastewater is a complex effluent due to its low biodegradability and high organic matter content. Currently, mature leachate is treated on-site or transported to wastewater treatment plants (WWTPs). Many WWTPs do not have the capacity to receive mature leachate due to its high organic load leading to an increase in the cost of transportation to treatment plants more adapted to this type of wastewater and the possibility of environmental impacts. Many techniques are used in the treatment of mature leachates, such as coagulation/flocculation, biological reactors, membranes, and advanced oxidative processes. However, the isolated application of these techniques does not achieve efficiency to meet environmental standards. In this regard, this work developed a compact system that combines coagulation and flocculation (1st Stage), hydrodynamic cavitation and ozonation (2nd Stage), and activated carbon polishing (3rd Stage) for the treatment of mature landfill leachate. The synergetic combination of physicochemical and advanced oxidative processes showed a chemical oxygen demand (COD) removal efficiency of over 90% in less than three hours of treatment using the bioflocculant PGα21Ca. Also, the almost absolute removal of apparent color and turbidity was achieved. The remaining CODs of the treated mature leachate were lower when compared to typical domestic sewage of large capitals (COD ~ 600 mg L−1), which allows the interconnection of the sanitary landfill to the urban sewage collection network after treatment in this proposed system. The results obtained with the compact system can help in the design of landfill leachate treatment plants, as well as in the treatment of urban and industrial effluents which contains different compounds of emerging concern and persistence in the environment.

Up-flow dual-loop anammox system treating mature landfill leachate: ultra-efficient nitrogen removal, anammox granules formation, and functional divergence

Achieving the effective retention and rapid enrichment of anammox bacteria (AnAOB) remains a challenge in landfill leachate treatment systems. The application of the anammox process is also restricted by an inadequate supply of nitrite and poor resistance to adverse environments. To overcome these obstacles, an up-flow dual-loop anammox (UDLA) system treating mature landfill leachate was established, based on partial nitrification, anammox, and partial denitrification (PNAPD) technology. The nitrogen removal efficiency and nitrogen loading rate reached 92.9 ± 1.5% and 0.4 kg N/m3/d, and isotope tracing tests demonstrated that 88.2 ± 6.5%-93.9 ± 3.9% of the nitrogen loss contributed by anammox pathway. Under the up-flow dual-loop strategy, anammox granules were successfully cultivated when flux ratios of effluent/influent and produced gas/influent were maintained at 1640.0%, and 250.0%, respectively. The proportion of medium granules (500–1000 μm) with the highest PNAPD activity increased from 0 to 24.9%, whereas the percentage of floc (0–200 μm) reduced from 98.4% to 23.3%. The mechanism of anammox granules formation in the UDLA system was revealed by multidimensional analysis. Candidatus_Brocadia_sapporoensis (13.3%-13.5%), Candidatus_Kuenenia_stuttgartiensis (2.0%-4.8%), and Candidatus_Brocadia_sp. (0.9%-1.1%) were the predominant anammox species, enriched in medium and macro granules. Metagenomic sequencing confirmed the functional divergence of nitrogen and carbon metabolism among the size-fractioned granules, possible functions of specific species, and gene distribution in the nitrogen metabolism pathway. The abundant GlnA, GltB(D), GdhA, GudB (GDH2), and GLUD1_2 genes might promote the synthesis of adhesive proteins and further facilitate microbial aggregation. This study enhanced the comprehension of anammox granules formation and showed important implications for leachate treatment in engineering.

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.

Assessing the Fate of Dissolved Organic Compounds in Landfill Leachate and Wastewater Treatment Systems.

Landfill leachate and municipal wastewater are major sources of chemical pollutants that contaminate our drinking water sources. Evaluating the dissolved organic chemical composition in wastewater treatment plants is therefore essential to understand how the discharge impacts the environment, wildlife, and human health. In this study, we utilized a nontargeted analysis method coupling liquid chromatography and tandem mass spectrometry (LC-MS/MS) to analyze chemical features at different points along two landfill leachate treatment plants (LLTPs) and two municipal wastewater treatment plants (WWTPs) in the Southeastern United States. Significant feature differences were observed for the WWTPs where activated sludge clarification was employed versus the LLTPs utilizing reverse osmosis. Specifically, even though both LLTPs had the largest number of features in their influent water, their effluent following reverse osmosis yielded a lower number of features than the WWTPs. Additionally, the clarification processes of each WWTP exhibited different efficiencies as chemical disinfection removed more features than UV disinfection. Feature identification was then made using the LC, MS, and MS/MS information. Analysis of the identified molecules showed that lipids were the most effectively removed from all plants, while alkaloid and organic nitrogen compounds were the most recalcitrant.

Distribution and removal of antibiotic resistance genes in a landfill leachate treatment process

ABSTRACT Domestic waste landfills have been regarded as the main source of antibiotic resistance genes (ARGs) which are considered to be emerging environmental contaminants. Fluorescent quantitative PCR detection was used to determine the occurrence and abundance of ARGs in a landfill leachate treatment system. Fourteen ARGs were detected initially in the leachate influents. The most abundant ARGs were IntI1, followed by sulI, sulII, sulIII, tetC and tetW. The abundance of ARGs increased in the biological treatment unit and then decreased in the effluent of ultrafiltration membrane treatment. The absolute abundance of ARGs in effluent was 1.05–1.94 orders of magnitude lower than that in influent. There was a very significant strong correlation between various ARGs and heavy metals, especially Zn, Pb, Cu, Cd and As, indicating that there may be obvious co-selection between heavy metals and ARGs. Although the leachate treatment process could effectively reduce the abundance of ARGs, its effect on reducing the number of species of ARGs was relatively limited, which may have potential environmental health risks to the urban sewage plant receiving leachate effluent and the final receiving water body.

Do PFAS changes in landfill leachate treatment systems correlate with changes in physical chemical parameters?

Per- and polyfluoroalkyl substances (PFAS) have been found at relatively elevated concentrations in landfill leachates. Some landfill facilities treat physical-chemical parameters of their leachates using on-site leachate treatment systems before discharge. The objective of this study was to evaluate whether changes in physical-chemical parameters of leachate at on-site treatment systems (including bulk measurements, oxygen demanding components, and metals) were associated with concentration changes in PFAS. Leachates were evaluated at 15 on-site treatment facilities which included pond systems, aeration tanks, powdered activated carbon (PAC), sand filtration, reverse osmosis (RO) and combination treatment processes. Results show that most physical-chemical parameters and PFAS were significantly reduced in RO systems (over 90 %). For pond systems, statistically significant correlations (rs > 0.6, p < 0.05) were observed between ∑26PFAS changes and the changes in pH, alkalinity, ammonia, and some metals. Significant correlations were also found between ∑8PFAAs precursors changes and specific conductivity (SPC), pH, alkalinity, ammonia, and metals changes. For aeration tank systems, significant correlations (rs > 0.6, p < 0.05) were observed between ∑26PFAS changes and changes in total dissolved solids and zinc, and between the changes of ∑8PFAAs precursors and field pH. These correlations are believed to be associated with rainfall dilution and precipitation of calcium carbonate and other metals as leachate is introduced to the atmosphere.

Reverse osmosis treatment system for landfill leachate: Operation conditions, advantages and challenges

Landfill leachate treatment by Reverse Osmosis (RO) system was evaluated in this study. Operational conditions of sand filters, sulfuric acid dosing and pH adjustment, cartridge filters and cat pumps, and membrane modules were discussed in detail. Advantages and challenges of RO for leachate treatment in developing countries handled with sustainability logic. The system has been successfully applied in leachate treatment with high removal rates as 98% of COD, 99% of total Nitrogen and suspended solids and substantial heavy metal removal. However, high costly operating expenses, dependency on the manufacturers for membranes, chemicals and other materials indicated the system unsustainable. Especially high-strength characteristic of leachate, high energy consumption of RO process, difficulty to struggle with scaling problems, limited lifetime of membranes and management/treatment of concentrate were expressed as the constraints of the system.

Low-cost Treatment Method for Organic Matter and Nutrients in Landfill Leachate-Batch Sorption Experiments

In this study, the ability of a low-cost composite adsorbent prepared using Washed Sea Sand (WSS), Dewatered Alum Sludge (DAS), Zero Valent Iron (ZVI), and Granular Activated Carbon (GAC), to treat Organic Compounds in terms of COD, Total Nitrogen (TN) and Total Phosphorus (TP) was investigated. The percentages of the materials used for the composite are DAS 40%, WSS 40%, ZVI 10%, and GAC 10%. The results of the study indicated that the removal efficiency of COD in landfillleachate by the composite adsorbent was 79.93±1.95%, which was followed by DAS (10.1%), WSS (51.3%), ZVI (42.0%), and GAC (100.0%). The corresponding adsorption capacity was 8.5 mg/g by the composite adsorbent and adsorption capacities of GAC, ZVI, WSS, and DAS were 24.39 mg/g, 2.27 mg/g, 7.01 mg/g, and 1.70 mg/g, respectively. Further, the maximum removal efficiencies of the composite adsorbent for TN and TP were 84.9% and 97.4%, respectively, and the respective adsorption capacities were 1.85 mg/g and 0.55 mg/g. A study on the behaviour of the equilibrium data of COD and nutrient adsorption revealed that Elovich and Langmuir isotherm models provided the best fits. Further, batch studies on the composite adsorbent media indicated that the optimum COD removal took place at a temperature of 35° C, an initial concentration of 398 mg/L, and pH of 5.55. The importance of the composite lies in the fact that it can treat more than one contaminant simultaneously. In addition, the application of used materials is sustainable as proper disposal sites are highly limited. According to the results of the study, 200 times diluted leachate having a COD value of 380 mg/L can be treated up to a percentage efficiency of 80%, by the composite adsorbent. The data were statistically analyzed. The result showed the ability of the composite adsorbent to be used as packing media in any landfill-leachate treatment system or any treatment system targeting COD of any given wastewater of the same characteristics as landfill-leachate. Packing media can be either filtration media in pump-and-treat treatment systems or reactive media in permeable reactive barriers. This research was based on a mass range of 3-18 g within 180 minutes. However, further research on a widened mass range within a longer time period is needed. &#x0D; Keywords: Adsorption, Batch sorption experiments, Composite adsorbent, Landfill-leachate, Organic matter

Pyrite-activated persulfate oxidation and biological denitrification for effluent of biological landfill leachate treatment system

The feasibility of pyrite as catalysts in the persulfate oxidation and electron donor for subsequent bacterial denitrification was investigated. The results demonstrated that pyrite-activated persulfate oxidation could efficiently degrade the organic matter in the effluent of biological landfill leachate treatment system, and COD removal efficiency of about 45% was achieved at the optimum parameters: pH = 6, pyrite dosage = 9.28 mM, dimensionless oxidant dose = 0.25. Among the dissolved organic matter, hydrophobic dissolved organic carbon (HO DOC), humic acids and building blocks were the main components. After the pyrite-activated persulfate oxidation, humic acids and HO DOC were primarily degraded, followed by building blocks, while low molecular weight neutrals were probably the degradation products. In the subsequent biological process, nitrate reduction was satisfactorily accomplished with autotrophic denitrification as the main pathway. When the influent nitrate concentration was about 180 mg L−1, the effluent nitrate concentration was stable below 20 mg L−1 with the nitrogen removal rate of about 108 mg L−1 d−1. To sum up, the pyrite-activated persulfate oxidation and the following biological denitrification was a feasible application in the effluent of biological landfill leachate treatment system.

Analysis of the Landfill Leachate Treatment System Using Arima Models: A Case Study in a Megacity

Leachate has been reported as the most significant source of landfill pollution. Predicting the characteristics of untreated and treated leachate may be useful during optimal scheduling of leachate treatment systems. The objective of this paper is to show an analysis of the operation of a landfill leachate treatment system in a Latin American megacity (Bogota, Colombia) by means of auto-regressive integrated moving average (ARIMA) models. A comparative analysis of the leachate treated with respect to reference legislation is carried out. The influence of climate variables during the operation of the treatment system is also considered. The results suggest that the concentrations of heavy metals (HMs), BOD5, and COD in untreated leachate do not follow the same annual cycles observed for the quantity of solid waste disposed within the landfill. This difference is possibly associated with the hydraulic retention time (HRT) of the leachate inside the conduction and pre-treatment system (storage/homogenization ponds). The ARIMA analysis suggests an HRT of up to one month (AR = 1) for the HMs identified as indicators of untreated leachate (Cu, Pb, and Zn). It is noted that the removal efficiency of HM indicators of the operation of the leachate treatment plant (Fe and Ni) is probably conditioned by operations carried out over a period of one month (AR = 1). The high input concentration of these HM indicators may prevent changing their ARIMA temporal structure during leachate treatment. This is reflected in the low removal efficiencies for all HMs under study (average = 26.1%).

Characterizing Seasonal Variation in Landfill Leachate Using Leachate Pollution Index (LPI) at Nam Son Solid Waste Landfill in Hanoi, Vietnam

The improper treatment of landfill leachates is one of the major problems associated with waste landfilling and causes serious environmental pollution at waste landfill sites and their surroundings. To develop a suitable landfill leachate treatment system and to minimize the risk of environmental pollution, it is important to characterize seasonal and temporal variations of landfill leachates. This study investigated the leachate quality of the Nam Son waste landfill in Hanoi, Vietnam in 2017–2019 and characterized the potential risks of landfill leachate using a leachate pollution index (LPI). The results of this study showed that the seasonal and temporal variation of the overall LPI during the monitoring period was small and in the range of 20–25 (values 2.5 times higher than the maximum permissible limits of Vietnam National Technical Regulation on Industrial Wastewater). The LPI sub-indices attributed to organic and inorganic pollutants were major components of the LPI. Especially, the annually averaged values of LPI of inorganic pollutants were 7.7 times higher than the maximum permissible limits, suggesting that the treatment of inorganic pollutants, such as ammonium-nitrogen (NH4+–N) and total nitrogen (TN), is highly required at Nam Son landfill to prevent environmental pollution surrounding the landfill site.

Evaluation of landfill leachate treatment system using multivariate analysis

Evaluation of landfill leachate treatment system using multivariate analysis

Engineering design of landfill leachate treatment system in a waste incineration plant in Chengdu

The engineering design and operation of landfill leachate treatment system in a waste incineration plant in Chengdu are systematically introduced. The engineering design experience of UBF+MBR+NF+RO process for leachate treatment of incineration plant and advanced oxidation process for treatment of nanofiltration concentrate are summarized, which provides reference for engineering design of leachate treatment in incineration plant. The operation results show that the effluent can meet the “make-up water for open circulating cooling water system” in The Reuse Of Urban Recycling Water—Water Quality Standard For Industrial Uses (GB/T19923-2005), and the effluent treated by nanofiltration concentrate can meet the corresponding standards in Table 2 of Standard For Pollution Control On the Landfill Site Of Municipal Solid Waste (GB16889-2008).

Landfill leachate treatment through the combination of genetically engineered bacteria Rhodococcus erythropolis expressing Nirs and AMO and membrane filtration processes

This study developed a process of genetically engineered bacteria Rhodococcus erythropolis expressing Nirs and AMO combined with membrane bioreactor (MBR), nanofiltration (NF) and reverse osmosis (RO) membrane (pRho-NA-MNR) for advanced treatment of landfill leachate. Results demonstrated that pRho-NA-MNR presented higher removal rate of chemical oxygen demand (COD), biological oxygen demand (BOD), ammonia nitrogen (N–NH4), total nitrogen (TN) and total organic carbon (TOC) than activated sludge (AS-MNR) system. Administration of pRho-NA increased nitrification by converting N–NH4 to nitrite (N–NO2) and Nitrate (N–NO3), and promoting denitrification by converting N–NO2 to nitrogen (N2) in the landfill leachate treatment, promoted the pH control, increased sludge activity and effluent yield, shortened phase length adaptation under alternating aerobic-anoxic conditions. pRho-NA increased the nitration and denitrifying rate in the aerobic and anaerobic stage in the system by increasing Cyt cd1 and Cyt c expression in the activated sludge. Nitrogen removal by nitrification and denitrification was positively correlated to the concentration of Nirs and AMO expression. Treatment with pRho-NA promoted pollutant removal efficiency of membrane bioreactor, nanofiltration and reverse osmosis membrane processes in landfill leachate. In conclusion, data suggest that pRho-NA-MNR facilitates the formation of granular sludge and enhances comparable removal of nitrogen and organic compounds, indicating the practice of this process should be considered in landfill leachate treatment system.