Hazardous Landfill Leachate Research Articles

Silver nanoparticles incorporated with superior silica nanoparticles-based rice straw to maximize biogas production from anaerobic digestion of landfill leachate

Treating hazardous landfill leachate poses significant environmental challenges due to its complex nature. In this study, we propose a novel approach for enhancing the anaerobic digestion of landfill leachate using silver nanoparticles (Ag NPs) conjugated with eco-friendly green silica nanoparticles (Si NPs). The synthesized Si NPs and Ag@Si NPs were characterized using various analytical techniques, including transmission electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. The anaerobic digestion performance of Si NPs and Ag@Si NPs was tested by treating landfill leachate samples with 50 mg/L of each NP. The results demonstrated an enhancement in the biogas production rate compared to the control phase without the nanocomposite, as the biogas production increased by 14% and 37% using Si NPs and Ag@Si NPs. Ag@Si NPs effectively promoted the degradation of organic pollutants in the leachate, regarding chemical oxygen demand (COD) and volatile solids (VS) by 58% and 65%. Furthermore, microbial analysis revealed that Ag@Si NPs enhanced the activity of microbial species responsible for the methanogenic process. Overall, incorporating AgNPs conjugated with eco-friendly green Si NPs represents a sustainable and efficient approach for enhancing the anaerobic digestion of landfill leachate.

Geotechnical properties of hazardous landfill leachate-contaminated sand

Many industrial activities dispose of their waste in the sand soil of the El-Khatatba region of Egypt. There is a need to reuse the site in building markets and shopping stores. Because it is difficult to obtain leachate from an open dumping site, we use hazardous landfill leachate (HLL) from an industrial waste landfill to identify changes in the geotechnical properties of soil. The HLL was obtained from Al-Nasreya Center, Alexandria, Egypt. This study, therefore, was directed to assess the effects of HLL on the geotechnical properties of the poor-graded sand (SP) soil. The natural sand was artificially mixed with HLL at different concentrations of 0%, 25%, 50%, 75%, and 100%. The results revealed that the permeability coefficient (k) of the natural sand decreased significantly from 1.28 × 10−2 to 0.8 × 10−2 cm/s when HLL concentration increased to 100%. Similarly, HLL contamination obviously reduced the angle of internal friction (φ) of sand. The optimum moisture content (OMC) of the natural sand decreased from 12 to 10%. In contrast, the maximum dry unit weight (MDD) of the natural sand increased slightly from 18.33 to 18.9 kN/m3 due to the increase of HLL concentrations from 0 to 100%. The change in the sand structure was interpreted by detailed analyses using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Based on these findings, HLL was found to modify the geotechnical properties of the studied sand.

Treatment of hazardous landfill leachate containing 1,4 dioxane by biochar-based photocatalysts in a solar photo-oxidation reactor

This study investigates a combined photocatalytic and adsorption system to maximize the removal of 1,4 dioxane from hazardous landfill leachate (HLL). The production of transformation products was also investigated to obtain a comprehensive evaluation of the treatment system. Copper/iron doped zinc oxide (Cu–Fe–ZnO) was introduced to biochar to form a hybrid materials and used to treat HLL contaminated with 1,4 dioxane of 355.0 ± 11.7 mg/L. The Cu–Fe–ZnO/biochar removed 93.1 ± 8.7% of 1,4 dioxane at a dose of 0.6 g/L within 90 min, as compared with only 42.7 ± 3.3% by 1.2 g/L of bare biochar within 210 min. The Cu–Fe–ZnO/biochar degraded 1,4 dioxane into ethylene glycol, glycolic acid, and formic acid. The 1,4 dioxane removal mechanisms were investigated using the density functional theory, demonstrating that doping of ZnO with metal atoms (Cu–Fe) narrowed the bandgap from 3.307 eV to 2.736 eV. The enhanced photocatalytic activity of ZnO was also supported by the role of biochar in increasing the reactive species and adsorbing the pollutant molecules. The high degradation efficiency of 1,4 dioxane using small catalyst doses with short reaction times would reduce the treatment cost and improve the system's applicability for treating HLL and industrial effluents.

Response Surface Methodology (RSM)-Based Prediction and Optimization of the Fenton Process in Landfill Leachate Decolorization

As an advanced oxidative processes, the Fenton process is receiving popularity as a wastewater treatment technique that can be used for hazardous landfill leachate. The treatment is simple, yet involves complex interactions between the affecting parameters including reaction time, H2O2/Fe2+ ratio, pH, and iron (II) ion concentration. Hence, the purpose of this present study was to analyze the factors affecting landfill leachate treatment as well as their interaction by means of response surface methodology (RSM) with central composite design. The independent variables were reaction time, H2O2/Fe2+ ratio, iron (II) ion concentration, and pH, and the dependent variable (response) was color-removal percentage. The optimum treatment conditions for pH, H2O2/Fe2+ ratio, Fe2+ concentration, and reaction time were 8.36, 3.32, 964.95 mg/L, and 50.15 min, respectively. The model predicted 100% color removal in optimum conditions, which was close to that obtained from the experiment (97.68%). In conclusion, the optimized Fenton process using the RSM approach promotes efficient landfill leachate treatment that is even higher than that already reported.

Production of modified biochar to treat landfill leachate using integrated microwave pyrolytic CO2 activation

Improper handling of leachate in landfills leads to leakage to the surrounding environment and pollute soil surface, runoff water and groundwater among other. A new approach that integrates self-purging microwave pyrolysis and pyrolytic activation was developed to transform empty fruit bunch (EFB), being a plentiful waste in oil palm plantation, into microwave modified biochar (MB). The performance of steam and CO2 as activating agent was contrasted, and the subsequently produced MB was then applied to treat actual landfill leachate via batch and continuous adsorption operation. Using a single-mode microwave system, the pyrolysis approach integrating steam or CO2 activation showed a high heating rate and process temperature of up to 170 °C/min and 600 °C, respectively. However, MB produced via CO2 activation (MB-CO2) showed significantly higher surface area (95.6 m2/g) and mass yield (92.0 wt%) compared to that produced via steam activation (MB-Steam) (29.3 m2/g of surface area, 84.0 wt% of mass yield). The volatile matter of both MB-CO2 and MB-Steam were low at 19.0–22.0 wt% leading to MB with high content of fixed carbon (69.3–72.0 wt%). Compare to MB-steam, the treatment with MB-CO2 in fixed bed column (10 g) achieved a better adsorption efficiency of NH3-N up to 5.0 mg/g and 43.0 mg/g of COD. Our findings demonstrate that microwave pyrolysis combined with CO2 activation is an auspicious technique preferable to steam activation for the generation of desirable MB from oil palm waste to treat hazardous landfill leachate.

Measuring the engineering properties of landfill leachate-contaminated soil in Egypt

Industrial activities produce millions of tons of hazardous waste annually, which are eventually disposed of in landfills. In this study, the effect of saline industrial hazardous landfill leachate (SIHLL) on the geotechnical properties of natural and contaminated silty clay soil was investigated via laboratory-based experiments in order to assess the potential application of this soil as a barrier lining in a saline hazardous industrial waste landfill. Contaminated soil specimens were prepared by mixing natural soil with SIHLL at different concentrations (0%, 25%, 50%, 75%, and 100%). The results revealed that the permeability coefficient (k) and the total pore volume (TPV) of the SIHLL-contaminated soil decreased from 8.6 × 10−8 to 5.91 × 10−8 cm/s and from 10.24 × 10−2 to 7.65 × 10−2 cm3/g, respectively, as the SIHLL concentration was increased from 0 to 50%. These effects were mainly due to the high concentration of salts in the SIHLL. The addition of SIHLL reduced the optimum moisture content (OMC) of the soil from 18% for natural soil to 14% for 100% SIHLL-contaminated soil, and the maximum dry density (MDD) recorded (for 100% SIHLL-contaminated soil) was 17.95 kN/m3. The angle of internal friction (φ) of the soil dropped from 27.8° for 0% SIHLL-contaminated soil to 23.7° for 100% SIHLL-contaminated soil. Also, the cohesion (c) decreased as the SIHLL concentration increased. In addition, considerable lowering of the consistency limits was observed for the SIHLL-contaminated soils. Based on these findings, the studied silty clay soil would be suitable for use in the construction of a new hazardous solid-waste landfill liner due to its low permeability and widespread availability in Egypt.

Techno-economic feasibility of energy-saving self-aerated sponge tower combined with up-flow anaerobic sludge blanket reactor for treatment of hazardous landfill leachate

This study investigated the application of an up-flow anaerobic sludge blanket (UASB) reactor followed by a self-aerated sponge (SAS) unit as a combined system for the treatment of hazardous landfill leachate (HLL) for 310 days. The removal efficiencies of the integrated UASB/SAS system were 34.5–59.2% for COD total, 19.6–50.8% for COD soluble, 72.3–92.8% for NH4-N, 41.3–58.6% for TSS, and 32.9–49.4% for VSS. The removal efficiencies of polychlorinated biphenyls (PCBs), i.e., PCB-44, PCB-118, PCB-149, PCB-180, and PCB-194 were 88.1 %, 94.2 %, 87.2 %, 95.7 %, and 91.2 %, respectively, resulting in ΣPCBs of 0.019 μg/L in the treated effluent. The highest heavy metals removal efficiencies were 85.6 ± 4.8 %, 73.6 ± 5.4 %, 87.6 ± 6.2 %, 76.5 ± 3.8 %, 77.8 ± 4.0 %, 42.9 ± 1.9 %, 59.3 ± 4.5 %, and 80.6 ± 4.5 % for Fe2+, Zn2+, Cu2+, Ni2+, Cd2+, Pb2+, Cr3+, and Mn2+, respectively. The performance of the treatment system was found to be hydraulic retention time (HRT), salinity, and C/N ratio dependent. The profile analysis along the SAS height revealed that the COD fractions (COD total, COD soluble, and COD particulate) were initially consumed, followed by the nitrification process. An initial investment of 212.7 US$/m3/d and an annual cost of 11.3 US$/m3/d were estimated for the combined UASB/SAS system treating HLL. This study provided an environmental-eco-friendly and feasible sustainable solution for handling the HLL issues, particularly in developing countries.

Engineering pyrolysis biochar via single-step microwave steam activation for hazardous landfill leachate treatment

Improving the sustainability and cost-effectiveness of biochar production is crucial to meet increased global market demand. Here, we developed a single-step microwave steam activation (STMSA) as a simplified yet efficient method to produce microwave activated biochar (MAB) from waste palm shell (WPS). The STMSA recorded a higher heating rate (70 °C/min) and higher conversion (45 wt%) of WPS into highly microporous MAB (micropore surface area of 679.22 m2/g) in contrast with the conventional heating approach (≤ 12−17 wt%). The MAB was then applied as biosorbent for hazardous landfill leachate (LL) treatment and the adsorption performance was compared with commercial activated carbon under different pH, adsorbent quantity, adsorbate concentrations, and contact times. The MAB demonstrated high adsorption capacity, achieving maximum adsorption efficiency at 595 mg/g and 65 % removal of chemical oxygen demand (COD) with 0.4 g/L of adsorbent amount under optimal acidic conditions (pH ≈ 2–3) after 24 h of contact time. The Freundlich isotherm and pseudo second-order kinetic models were well-fitted to explain the equilibrium adsorption and kinetics. The results indicate the viability of STMSA as a fast and efficient approach to produce activated biochar as a biosorbent for the treatment of hazardous landfill leachate.

Treatment of hypersaline hazardous landfill leachate using a baffled constructed wetland system: effect of granular packing media and vegetation

ABSTRACT Constructed wetland is an engineered system that attains more attention as a feasible technology for the treatment of municipal landfill leachate. However, its feasibility for treatment of toxic, hazardous, and hypersaline leachate remains unexplored. This study aimed to investigate the feasibility of using a baffled constructed wetland (BCW) system for the treatment of hypersaline hazardous landfill leachate. Furthermore, the effects of granular packing media, toxicity, and hyper salinity conditions on the removal efficiency of COD fractions (CODt, CODs, and CODp), nitrogen, heavy metals, and coarse solids were extensively investigated. Our findings indicated that BCWs were highly effective in removing heavy metals particularly Cu2+, Mn2+, Fe2+, and Zn2+ and exhibited moderate efficiency for other contaminants (e.g. COD fractions, solids, and nitrogen species). Furthermore, use of a sand and gravel mixture for bed materials demonstrated higher performance over sand alone. However, we found that Phragmites australis is not tolerant enough to extreme toxicity and salinity conditions, and this reed could not survive for more than 27 and 33 days in sand BCW and sand/gravel BCW, respectively. Consequently, survivorship of reed and efficiency of treatment using vegetation were limited in the long-term operation with high salinity and toxicity conditions.

Feasibility of using non-vegetated baffled submerged constructed wetland system for removal of heavy metals, COD and nutrients from hyper-saline hazardous landfill leachate

Feasibility of using non-vegetated baffled submerged constructed wetland system for removal of heavy metals, COD and nutrients from hyper-saline hazardous landfill leachate

Treatment of hazardous landfill leachate using Fenton process followed by a combined (UASB/DHS) system.

Fenton process for pre-treatment of hazardous landfill leachate (HLL) was investigated. Total, particulate and soluble chemical oxygen demand (CODt, CODp and CODs) removal efficiency amounted to 67%, 47% and 64%, respectively, at pH value of 3.5, molar ratio (H2O2/Fe(2+)) of 5, H2O2 dosage of 25 ml/L and contact time of 15 min. Various treatment scenarios were attempted and focused on studying the effect of pre-catalytic oxidation process on the performance of up-flow anaerobic sludge blanket (UASB), UASB/down-flow hanging sponge (DHS) and DHS system. The results obtained indicated that pre-catalytic oxidation process improved the CODt removal efficiency in the UASB reactor by a value of 51.4%. Overall removal efficiencies of CODt, CODs and CODp were 80 ± 6%, 80 ± 7% and 78 ± 16% for UASB/DHS treating pre-catalytic oxidation effluent, respectively. The removal efficiencies of CODt, CODs and CODp were, respectively, decreased to 54 ± 2%, 49 ± 2% and 71 ± 16% for UASB/DHS system without pre-treatment. However, the results for the combined process (UASB/DHS) system is almost similar to those obtained for UASB reactor treating pre-catalytic oxidation effluent. The DHS system achieved average removal efficiencies of 52 ± 4% for CODt, 51 ± 4% for CODs and 52 ± 15% for CODp. A higher COD fractions removal was obtained when HLL was pre-treated by Fenton reagent. The combined processes provided a removal efficiency of 85 ± 1% for CODt, 85 ± 1% for CODs and 83 ± 8% for CODp. The DHS system is not only effective for organics degradation but also for ammonia oxidation. Almost complete ammonia (NH4-N) removal (92 ± 3.6%) was occurred and the nitrate production amounted to 37 ± 6 mg/L in the treated effluent. This study strongly recommends applying Fenton process followed by DHS system for treatment of HLL.

Best Operative Practices for the Management of full Scale Biological Reactor for non Hazardous Landfill Leachate Treatment

Best Operative Practices for the Management of full Scale Biological Reactor for non Hazardous Landfill Leachate Treatment

The effect of humic acids on the reverse osmosis treatment of hazardous landfill leachate

This study deals with the treatment of hazardous waste landfill leachate with the help of reverse osmosis. The landfill is located in an abandoned brown coal pit in northern Bohemia. The leachate contained 7.2g/L of dissolved inorganic salts. Among other contaminants were heavy metals, arsenic, ammonia nitrogen and associated organic pollutants, especially chlorinated compounds. A mobile membrane unit (LAB M30) equipped with a spiral wound element (FILMTEC SW30-4040), with a membrane area equaling 7.4m2 was used for the pilot plant experiments. All experiments were carried out in batch mode. 94% conversion of the input stream into the permeate was achieved by use of a two-stage arrangement. Removal efficiencies of the monitored contaminants in the feed ranged from 94% for ammonia nitrogen to 99% for the two-valent ions. Removal efficiency for total dissolved solids was 99.3% on average.Due to varying levels of humic acids in the leachate throughout the year, fouling experiments were performed to investigate the separation process under different conditions than those used in the pilot plant. Leachates containing different concentrations of added humic acids were separated using a thin film composite on a propylene membrane. The added humic acids were obtained from samples of contaminated oxihumolite.

Toxicity and biodegradability of high strength/toxic organic liquid industrial effluents and hazardous landfill leachates

Industrial effluents and leachates from hazardous landfill sites were tested for toxicity using the anaerobic toxicity assay. This test was done on several industrial effluents (brewery spent grain effluent, a chemical industry effluent, size effluent), and several hazardous landfill leachates giving vastly different toxicity results. The brewery effluent, spent grain effluent and size effluent were found to be less toxic than the chemical effluent and hazardous landfill leachate samples. The chemical industry effluent was found to be most toxic. Leachate samples from the H:h classified hazardous landfill site were found to be less toxic at high concentrations (40% (v/v)) while the H:H hazardous landfill leachate samples were found to be more toxic even at low concentrations of 4% (v/v). The 30 d biochemical methane potential tests revealed that the brewery effluent, organic spent grain effluent and size effluent were 89%, 63%, and 68% biodegradable, respectively. The leachate from Holfontein hazardous landfill site was least biodegradable (19%) while the chemical effluent and Aloes leachate were 29% and 32% biodegradable under anaerobic conditions.

BIODEGRADATION PROCESS ANALYSIS BY ULTRAFILTRATION

Detailed analysis of biological processes for hazardous waste-water treatment presents extreme difficulty. Complexity of organic and inorganic solute mixtures in solution prohibits GC-MS analysis. Gross parameters must be used to monitor treatment process performance. Ultrafiltration, coupled with gross parameter estimation, provides enhanced definition of treatment. Results, employed to monitor in-situ biodegradation of a hazardous landfill leachate, are discussed.