Raw Leachate Research Articles

Pumice as Biological Carriers Improve Impact Load Resistance of UASB Reactors During the Treatment of Raw Incineration Leachates

Pumice as Biological Carriers Improve Impact Load Resistance of UASB Reactors During the Treatment of Raw Incineration Leachates

Analysis of the Bacterial Biocenosis of Activated Sludge Treated with Leachate from Municipal Landfills.

The influx of toxic pollutants into wastewater treatment plants can negatively affect the quality of the activated sludge (AS). One source is landfill leachate. The identification of microorganisms present in AS is very important, e.g., while improving wastewater treatment technology. Therefore, the aim of the study was to investigate the effect of raw leachate and after purification of Phragmites australis and Ceratophyllum demersum on the composition of the AS bacterial biocenosis. In addition, AS status was assessed by LIVE/DEAD BacLight ™ fluorescent staining. The obtained results showed that the leachate did not significantly affect the cell membranes of AS bacteria, and even a slight improvement was noted. The research carried out using the next-generation sequencing method shows that the origin of the samples (active and closed storage) and the method of processing do not significantly affect the composition of the AS bacterial biocenosis at higher taxonomic levels. However, at the species level, the appearance of bacteria not previously present in AS was observed, namely: Flavobacterium luticocti, Candidimonas nitroreducens and Nitrobacter hamburgensis. The obtained results suggest that the leachate may be a source of microorganisms positively influencing the condition of AS bacteria.

Nitrogen resource recovery from mature leachate via heat extraction technology: An engineering project application.

A large pool of ammonia in mature leachate is challenging to treat with a membrane bioreactor system to meet the discharge Standard for Pollution Control on the Landfill Site of Municipal Solid Waste in China (GB 16889-2008) without external carbon source addition. In this study, an engineering leachate treatment project with a scale of 2,000 m3/d was operated to evaluate the ammonia heat extraction system (AHES), which contains preheat, decomposition, steam-stripping, ammonia recovery, and centrifuge dewatering. The operation results showed that NH3-N concentrations of raw leachate and treated effluent from an ammonia heat extraction system (AHES) were 1,305-2,485 mg/L and 207-541 mg/L, respectively. The ratio of COD/NH3-N increased from 1.40-1.84 to 7.69-28.00. Nitrogen was recovered in the form of NH4HCO3 by the ammonia recovery tower with the introduction of CO2, wherein the mature leachate can offer 37% CO2 consumption. The unit consumptions of steam and power were 8.0% and 2.66 kWh/m3 respectively, and the total operation cost of AHES was 2.06 USD per cubic metre of leachate. These results confirm that heat extraction is an efficient and cost-effective technology for the recovery of nitrogen resource from mature leachate.

Evaluation of an adsorption process for the treatment of leachates using biopolymers extracted from organic waste obtained from the poultry industry

The adsorption capacity of three eggshell bioadsorbents was evaluated to remove contaminants from raw leachate. Optimal conditions for the removal of suspended solids, color, and organic compounds, as COD, were achieved by batch experiments with three levels of pH and absorbent concentrations. Kinetic studies and isotherms were developed to understand the behavior of COD removal by the bioadsorbents. The chemical and physical characterizations indicate the leachate used in the present study had characteristics between mature and intermediate leachates. The optimal adsorption conditions were pH 2.0 and 1.0 gram (0.5 g/L) of adsorbent. Adsorbent M showed the best adsorption capacities, removing 99.06% (1446 NTU) of turbidity, 86.25% (4140 UPt-Co) of color and 54.56% of COD (1530mg/L). The data obtained through the kinetic and isothermal tests were better fitted to the pseudo first order and Langmuir models, with an equilibrium adsorption capacity (Qe) of 139 mg of COD/g of adsorbent and a specific speed of 1.51 min-1.

Comparison of electro-oxidation (BDD anode and Ti/Pt cathode) and electro-coagulation (aluminum electrodes) for the treatment of raw landfill leachate

Comparison of electro-oxidation (BDD anode and Ti/Pt cathode) and electro-coagulation (aluminum electrodes) for the treatment of raw landfill leachate

Performance Evaluation of Pressurized Anaerobic Digestion (PDA) of Raw Compost Leachate

Anaerobic digestion (AD) represents an advantageous solution for the treatment and valorization of organic waste and wastewater. To be suitable for energy purposes, biogas generated in AD must be subjected to proper upgrading treatments aimed at the removal of carbon dioxide and other undesirable gases. Pressurized anaerobic digestion (PDA) has gained increasing interest in recent years, as it allows the generation of a high-quality biogas with a low CO2 content. However, high pressures can cause some negative impacts on the AD process, which could be accentuated by feedstock characteristics. Until now, few studies have focused on the application of PAD to the treatment of real waste. The present work investigated, for the first time, the performance of the pressurized anaerobic digestion of raw compost leachate. The study was conducted in a lab-scale pressurized CSTR reactor, working in semi-continuous mode. Operating pressures from the atmospheric value to 4 bar were tested at organic loading rate (OLR) values of 20 and 30 kgCOD/m3d. In response to the rise in operating pressure, for both OLR values tested, a decrease of CO2 content in biogas was observed, whereas the CH4 fraction increased to values around 75% at 4 bar. Despite this positive effect, the pressure growth caused a decline in COD removal from 88 to 62% in tests with OLR = 20 kgCOD/m3d. At OLR = 30 kgCOD/m3d, an overload condition was observed, which induced abatements of about 56%, regardless of the applied pressure. With both OLR values, biogas productions and specific methane yields decreased largely when the pressure was brought from atmospheric value to just 1 bar. The values went from 0.33 to 0.27 LCH4/gCODremoved at 20 kgCOD/m3d, and from 0.27 to 0.18 LCH4/gCODremoved at 30 kgCOD/m3d. Therefore, as the pressure increased, although there was an enhanced biogas quality, the overall amount of methane was lowered. The pressured conditions did not cause substantial modification in the characteristics of digestates.

Evaluation of Pig Manure for Environmental or Agricultural Applications through Gasification and Soil Leaching Experiments

The current study aimed at evaluating an untreated pig manure, firstly for its suitability for soil amendment in combination with an agricultural/bio-solid biochar, and secondly for its potential to be used for adsorption of hazardous species, replacing expensive activated carbons. Column soil leaching experiments were designed to simulate field conditions, and physical, chemical and mineralogical analyses were performed for raw materials and/or leachates. For activated carbon production, the manure was gasified by steam or carbon dioxide at high temperatures. Biochars were analyzed for organic and mineral matter, structural characteristics and organic functional groups. Activation by steam or carbon dioxide greatly enhanced specific surface area, reaching values of 231.4 and 233.3 m2/g, respectively. Application of manure to the soil promoted leaching of nitrates and phosphates and raised COD values of water extracts. Biochar addition retained these ions and reduced COD values up to 10 times at the end of the three-month period. The concentrations of heavy metals in the leachates were low and, in the presence of biochar in soil blends, they were significantly reduced by 50–70%. The manure presents a significant potential for adsorption of various pollutants or improvement of soil amendment if carefully managed.

Influence of Leachate Matrix on Oxidation Performance of Ozonation and AOPs

Landfill leachate is a critical environmental issue that should be adequately treated to prevent it from spreading to the environment. This study explored the influence of raw leachate matrix and treated leachate matrix on O3, O3/H2O2, and O3/PS performance. O3 and AOPs were conducted in a laboratory-scale batch reactor. The findings showed the degradation of p-cresol, COD, and humic substances was much slower in treated leachate matrix than in raw leachate matrix. However, color was found easier to remove in treated leachate. The results revealed a synergic effect between molecular O3 and dissolved organic matter in the raw leachate as the O3 performance was enhanced in the presence of raw leachate matrix, except for color removal. The highest degradation of more than 90% was achieved in O3/H2O2 to remove COD, p-cresol, and humic substances, although it is the most affected by the leachate matrix. This study provides vital insight into the notable performance of O3/PS in color removal regardless of the influence of leachate matrix, suggesting that the sulfate radical-induced oxidation outperformed O3 and O3/H2O2 in reducing nitrogen-containing compounds.

Growth kinetics of microalgae cultivated in different dilutions of fresh leachate for sustainable nutrient recovery and carbon fixation

Fresh leachate (FL) is toxic liquid generated from a solid waste transfer station. It is complex due to the presence of concentrated inorganics, nutrients, and degradable organic matter. Microalgae are an option for nutrient removal, however, only a few studies have reported raw leachate treatment using microalgae. Most of them emphasize on the need for its dilution to lighten the colour and minimize the toxicity and turbidity. In the present study, the effect of different dilutions of fresh leachate on the growth and nutrient recovery potential of Scenedesmus sp. was investigated. Fresh leachate dilutions viz. 5%, 10%, 15%, 20% and 25% fresh leachate were prepared using wetland treated municipal wastewater (MW) and growth kinetics of Scenedesmus sp. was studied. The highest biomass production of 2.75 gdw L−1 and carbon dioxide fixation rate of 243 mg L−1 d−1 was observed in 15% fresh leachate which was 172% and 157% higher than wetland treated municipal wastewater, respectively. Similarly, the highest removal rate of 3.27 and 0.036 mg L−1 d−1 for NH4+- N and NO2- - N was also observed in 15% fresh leachate. All dilutions and wetland treated municipal wastewater showed more growth and nutrient removal compared to 100% fresh leachate. Specific growth rate (µ) and doubling time of microalgae in 15% fresh leachate were 0.17 per day and 4.03 days, respectively.

Influence of humic substances on the landfill leachate biodegradability with a focus on temporal seasonality.

The high resilience to biological treatments from the landfill leachate is generally associated with the presence of humic substances (HS). The brown color characteristic of this effluent is also related to these substances. Landfill leachate with low biodegradability can make biological treatments unfeasible, which can drive up the cost for the treatment of large leachate volumes. In this context, this research aimed to characterize the leachate in different seasonal periods, and verify the influence of HS species on the biodegradability of the effluent to assist in the selection of adequate treatment techniques. The HS quantification was performed using the modified Lowry method and speciation through fractionation according to the molar masses of the HS species. The tropical regions can be the precursor for the rapid stabilization of biodegradable organic matter. The warmer climate contributed to a reduced BOD/COD ratio (0.03) and the predominance of compounds of lower mass (e.g.: fulvic acids). The tests showed an HS concentration of 26.9% of the total COD in the raw leachate in the rainy season, which increased to 37.3% in the dry season. Approximately 70% of HS species refer to fulvic acids, a fraction identified as having the highest biologic treatment resilience.

Enhanced removal of refractory humic- and fulvic-like organics from biotreated landfill leachate by ozonation in packed bubble columns

Biotreated landfill leachate contains much refractory organics such as humic and fulvic acids, which can be degraded by O3. However, the low O3 mass transfer and high energy cost limit its wide application in landfill leachate treatment. Previous studies proved that packed bubble columns could enhance the O3 mass transfer and increase the synthetic humic acids wastewater degradation, but the performance of packed bubble columns in real wastewater treatment has not been investigated. Therefore, this study aims to evaluate the feasibility of application of packed bubble column in the real biotreated landfill leachates treatment and provide insights into the transformation of organic matters in leachates during ozonation. Packed bubble columns with lava rocks or metal pall rings (LBC or MBC) were applied and compared with a non-packed bubble column (BC). At an applied O3 dose of 8.35 mg/(Lwater sample min), the initial COD (400 mg/L) was only removed for 26% in BC and 32% in MBC while this was 46% in LBC, indicating LBC has the best performance. GC–MS analysis shows that raw biotreated leachate contains potential endocrine disruptors such as di(2-ethylhexyl) phthalate (DEHP). 61% of DEHP was removed in LBC and the least intermediate oxidation products from humic- and fulvic-like organics was detected in LBC. The highest O3 utilization efficiency (89%) and hydroxyl radical (OH) exposure rate (3.0 × 10-10 M s) were observed in LBC with lowest energy consumption (EEO) for COD removal of 18 kWh/m3. The enhanced ozonation efficiency in LBC and MBC was attributed to the improved O3 mass transfer. Besides, LBC had additional adsorptive and catalytic activity that promoted the decomposition of O3 to generate OH. This study demonstrates that a packed bubble column increases removal and decreases energy use when treating landfill leachate, thus promoting the application of ozonation.

Making concrete blocks by raw leachate and construction and demolition waste

AbstractResearch was performed to determine if a viable concrete product can be produced using waste streams accumulating in landfills. The lack of recycling and reuse of construction and demolition (C&D), despite technical, economic, and environmental justifications, has led to the accumulation of C&D waste in landfills throughout Iran. Another issue with landfills in Iran is the existence of pools of municipal solid waste leachate, which has caused problems due to lack of treatment. In this study, by simultaneously utilizing raw municipal leachate and C&D waste in the concrete production process, an attempt was made to produce concrete that is environmentally sustainable and can be used in civil works. After crushing, the C&D waste was granulated into different sizes, its coarse aggregate was completely replaced, and 70% of its fine aggregate was replaced with natural aggregate to form concrete samples that were then made using different percentages of leachate. The utilization of the leachate and C&D waste for concrete production doubled the concrete slump and reduced the unconfined compressive strength of 7‐ and 28‐day curing time by 9 and 15.7 MPa, respectively, when compared to concrete produced with natural aggregates. A leaching procedure test showed that samples made using leachate and recycled C&D waste did not result in high concentrations of leachable heavy metals. Therefore, the study showed that low leachate percentages and recycled C&D wastes can be used in projects where high‐strength concrete is not necessary.

Combination of ozonation and microfiltration to condition landfill leachate for reverse osmosis treatment

Combinations between ozonation process (O3) and submerged microfiltration (MF) were evaluated as fouling-reducing pretreatments for reverse osmosis (RO) in the treatment of landfill leachate. The modified fouling index (MFI) was used to estimate the fouling potential of raw and pretreated leachates. The results demonstrate that a first ozonation step followed by the microfiltration step represents the best layout, being able to reduce the leachate's MFI over 170,000 times. The whole treatment (O3 + MF + RO) is capable of fitting the landfill leachate to the local standards in force for discharge in fresh water bodies. Additionally, it was possible to notice the benefits of using ozonation prior to the microfiltration step when compared to the opposite order, both because of the smaller MFI value obtained (19.53 s/L2 instead of 5095 s/L2) and also for the improvement in permeate flux during microfiltration step. Finally, the RO permeate characterization suggest that the established treatment route represents an effective treatment for a wastewater as complex as landfill leachate.

The Removal of Heavy Metals from the Leachate of Aged Landfill: The Application of the Fenton Process and Nanosilica Absorbent

Since leachate is typically composed of numerous constituents, its management requires special attention. After the raw leachate of Saravan in Rasht (Guilan Province, Iran) was transferred to a laboratory and its specifications were determined, it was subjected to experiments by the bench-scale method. The analyses of pH and heavy metals were performed in the main and control anaerobic reactors at time zero, before precipitation, and two hours after precipitation. After the anaerobic process was over and the optimal retention time was identified in the anaerobic reactor, the removal of heavy metals was analyzed by the Fenton process and nanosilica absorbent in leachate treatment. In the primary anaerobic reactor, the highest and lowest removal rates were 59 and 39% for Ni and Cu, respectively. In the Fenton process with optimal H2O2/Fe+2 ratio, Cu and Hg showed the lowest and highest removal rates of 22.4 and 54.54%, respectively. At the optimal rate of nanosilica absorbent and the retention time of 15 min, As was removed maximally with an efficiency of 38% and Cu was removed minimally. The results revealed that the integration of the anaerobic process with the Fenton process and nanosilica absorbent was very effective in removing heavy metals from the aged landfill leachate.

Treatment of intermediate landfill leachate using different anode materials in electrooxidation process

AbstractThis study aims to investigate the performances of widely used anode materials in the treatment of intermediate landfill leachate treatment by electrooxidation (EO) process. The raw leachate was collected from an 8‐year‐old landfill facility and had a chemical oxygen demand (COD) of 4660 mg/L, biological oxygen demand (BOD5) of 1370 mg/L, and total organic carbon (TOC) of 2260 mg/L. TOC and COD removal efficiencies of Boron‐Doped Diamond (BDD), Pt, and four different Ti‐based mixed metal oxide (MMO) anodes ((RuO2–TiO2, RuO2–IrO2, PtO2–IrO2, and IrO2–Ta2O5) were compared at the current densities of 25 mA/cm2, 75 mA/cm2, and 125 mA/cm2. At the highest current density, the BDD achieved 100% TOC and COD removal efficiencies in 240 min. BDD was followed by the Pt anode, which achieved 95.53% COD and 92.74% TOC removal efficiencies. The Pt electrode also had the lowest SEC values at all current densities. Although the performances of four MMO electrodes were very close, RuO2–TiO2 achieved a slightly higher performance than the others. It was concluded that Pt anode can be a promising alternative to BDD, which was 18 times more expensive, with its comparable pollutant removal performance and low specific energy consumption.

Removal of colour and suspended solids from landfill leachate using Tin tetrachloride (SnCl4): The effects of pH, zeta potential, and particle sizes

ABSTRACT Old landfill leachate is normally rich in colloidal particles, has low organic compound, poor biodegradability and hard to be biologically treated. The suspended particles are generally dispersed, negatively charged and do not settle by gravity due to their instability and repulsion. This paper aimed to evaluate the effectiveness of SnCl4 as a positively charged coagulant in treating concentrated colour and suspended solids (SS) from an old leachate sampled at one of the local landfills in Malaysia (Alor Pongsu Landfill Site, Keria Perak), which may also represent other landfills with similar property. The mechanism and the effect of pH, zeta potential (ZP) and particle size of colloids on the reduction of the pollutants were evaluated through standard coagulation and flocculation experiment with ZP measurement. The standard jar test was examined at a pre-determined SnCl4 dosage and varied from pH 3 to pH 12. The raw leachate was found negatively charged throughout pH 3 to pH 12. Adding a positively charged SnCl4 increased the leachate surface charge to close to the point of zero charges (IEP) at pH 8 with −0.4 mV. Generally, as the pH value increase from acidic to basic condition, the raw leachate becomes more negatively charged as at higher pH values It was also found that the pH of the solution correlated with the size of the particles, where 221.3 d.nm was recorded from pH 4 to pH 11 and improved to the largest size 660 d.nm at pH 3. The highest colour and SS performance were observed at optimum pH 8 with reductions of 98.9% and 100%, respectively The reduction of repulsive forces at this pH promoted the collision of particles and thus made the aggregation possible. ZP measurement in is important as it provides an early estimation of the effective pH for the optimum coagulation and flocculation process of landfill leachate contributed by the colloidal particles.

Physical–chemical pre-treatment of sanitary landfill raw leachate by direct ascending filtration

Several environmental problems in Brazil are caused by the accelerated urban and industrial growth and by the multiplicity of urban waste generated. Waste disposal in landfills is still common practice in Brazil. This work was conducted in sand filters and activated carbon column, proposing an alternative for the physical-chemical treatment of leachate as a pre-treatment to preserve the biological process. The results showed reductions of up to 74% for COD, 47% for BOD5, 93% for color, 90% for ammonia and an increase from 0.3 to 0.9 in the BOD5/COD ratio. Although the results obtained do not fall within the limits of the legislation, the results for ammonia concentration was reduced by 33.25% and 85.37% after filtration and activated carbon column treatment respectively. The use of activated carbon columns resulted in an excellent performance in the reduction of heavy metals in the leachate. The performance demonstrated a removal of 60–96%. Limitations were found in the length of the filtration races, as a limiting factor in the process. The results show the potential of using direct upward filtration with sand and activated carbon filters for the treatment of landfill leachate.

Intensification of supercritical water oxidation (ScWO) by ion exchange with zeolite for the reuse of landfill leachates

The disposal of solid residues in sanitary landfills results in the formation of a complex, variable, and recalcitrant wastewater, known as leachates. Supercritical water oxidation (ScWO) can be applied to treat leachates although most studies are based on removing the most relevant contaminants, such as organic matter and ammonia. Therefore, comprehensive analysis of this process is essential for large-scale applications. In this study, we investigated a system composed of ScWO and ion exchange using zeolite (ScWO/zeolite) for the reuse possibilities of treated leachates based on different regulations for municipal wastewater reuse. This system was applied to both raw leachate (RL) and leachate treated via conventional processes at the studied landfill (PL). The continuous ScWO reactor operated under a pressure of 23 MPa at 600 °C without the addition of oxidants. A commercial zeolite (clinoptilolite) in a fixed-bed glass column was used for ion exchange. The intensified system significantly improved the characteristics of RL by removing 89% of COD and 99% of NH3-N. Moreover, the contaminant concentrations of PL were within the limits for discharge and reuse, except arsenic and molybdenum contents. The unexpected high concentrations of arsenic in RL and PL necessitated the requirement of further investigation of the complex and toxic characteristics of leachates. Nevertheless, the intensified process was conducted without the addition of oxidants or auxiliary substances and resulted in a less expensive and more environmentally -friendly process that can be applied for the treatment of leachates with similar characteristics.

Treatment of young and stabilized landfill leachate by integrated sequencing batch reactor (SBR) and reverse osmosis (RO) process

In this paper, the performance and effectiveness of combined sequencing batch reactor (SBR) and reverse osmosis (RO), as well as differences in treating young and matured landfill leachate, was investigated. Samples of young and stabilized leachate were collected from a municipal landfill in north-eastern Poland. The general pollution parameters, organic and inorganic indicators were determined in raw leachate and after each step of leachate treatment. The performance characteristics of the reverse osmosis system were made based on permeate flux, electroconductivity removal rate, concentration factor and removal rate. The use of biological pre-treatment had a good efficiency (>98% for both leachate) in ammonia nitrogen removal. The SBR treatment effectiveness for BOD (64%), Fe (29%), Cl− (0.2%) and Total Organic Carbon (-5.3%) was lower for young leachate compared to a stabilized. Pretreated leachate was directed to a RO system which was characterized by better operational parameters during the filtration of stabilized leachate: the average permeate flux was higher by 3.3 L/m2⋅s⋅10−6 and the filtration time was shorter by 110 min compared to the young leachate. The main reason of membrane clogging during young leachate filtration was a higher content of organic matter and its neutralization by Ca2+ and N-NH4+ presented in leachate, causing clogging of negatively charged RO membrane. Another reason could be complex formation between iron and natural organic matter that may precipitate on the membrane surface or inside the pores. This study has shown a high removal efficiency (over 80%) of the integrated SBR-RO method for all analyzed parameters.

Chemical safety assessment of transformation products of landfill leachate formed during the Fenton process

Organic chemicals identified in raw landfill leachate (LL) and their transformation products (TPs), formed during Fenton treatment, were analyzed for chemical safety following REACH guidelines. The raw LL was located in the metropolitan region of Campina Grande, in northeast Brazil. We elucidated 197 unique chemical structures, including 154 compounds that were present in raw LL and 82 compounds that were detected in the treated LL, totaling 39 persistent compounds and 43 TPs. In silico models were developed to identify and prioritize the potential level of hazard/risk these compounds pose to the environment and society. The models revealed that the Fenton process improved the biodegradability of TPs. Still, a slight increase in ecotoxicological effects was observed among the compounds in treated LL compared with those present in raw LL. No differences were observed for aryl hydrocarbon receptor (AhR) and antioxidant response element (ARE) mutagenicity. Similar behavior among both raw and treated LL samples was observed for biodegradability; Tetrahymena pyriformis, Daphnia magna, Pimephales promelas and ARE, AhR, and Ames mutagenicity. Overall, our results suggest that raw and treated LL samples have similar activity profiles for all endpoints other than biodegradability.