In this study, graphene oxide (GO) was coated in geotextiles (GO-GT) to evaluate its potential for bio-clogging mitigation in the leachate collection system (LCS) of a landfill. Results showed that ...GO coating enhanced the surface hydrophilicity of geotextile. Bacterial experiments revealed that dead cells in the bio-clogging increased to 68.7% with GO-GT, compared to that in the GT (44.0%). After 136 days of operation, the GO-GT reduced the bio-clogging by decreasing the total amount of bacteria and the percentage of living bacteria. The total amount of extracellular polymeric substances in the GO-GT and GT was 22.8 ± 4.4 and 52.8 ± 4.8 mg/g of volatile suspended solids, respectively. Microbial analysis showed that Limnochordia and Symbiobacteriia were the most sensitive groups, with a decreased percentage in the GO-GT. Electrostatic repulsion and surface wrinkling were attributed to the attenuation effect on the GO-GT. These results imply the potential application of GO-coated geotextile for reducing bio-clogging in landfill LCS.
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•The graphene oxide-coated geotextiles could mitigate bio-clogging in landfills.•The bacteria were killed in graphene oxide coated geotextile.•Proteins and polysaccharides contents were reduced in graphene oxide coated geotextile.•The microbial diversity changed accordingly to the presence of graphene oxide.
Hydrogen sulfide (H
2
S) in landfill gas, formed with the biodegradation of municipal solid waste, is a major odorous component in a landfill. It poses a potential risk to humans and causes odor ...problems and complaints by the residents near landfills. Many studies have been conducted on landfill gas qualities. Also, various H
2
S control technologies have been used in different industrial sectors. However, comprehensive reviews on H
2
S issues in landfill gas are rare. An understanding of the formation of H
2
S encountered in landfill gas and the emission at which it occurs helps assess risk and problems. The authors review recent publications from different perspectives on H
2
S odor in landfills, including H
2
S generation the impact on the environment and human health, H
2
S levels in the landfill environment, and H
2
S control technologies at landfills.
•Methane production rate increased when compaction was applied.•Compaction reduced pore space and increased the contact surface area among MSW.•Waste compaction can promote methane generation in ...decelerated methanogenic phase.
This study investigated the impact of compaction on anaerobic degradation of municipal solid waste (MSW) during the phase of decelerated methane formation. Two stainless steel lysimeters were constructed by equipping a hydraulic cylinder to apply pressure load on the MSW. When methane production rates decreased from the peak rate of each column, pressure load was applied at different degrees of decomposition (DOD). Methane production rate increased when compaction was applied. However, the impact of compaction on the methane production rate varied according to DOD. The MSW compaction reduced MSW pore space, increasing the contact surface area among MSW lumps. It was hypothesized that the mass transfer of substrate and substrate accessibility could be enhanced due to the decrease of void space and the increase of the contact area among waste mass as a consequence of the compaction.
Research has been conducted to investigate the effects of daily aeration frequency on leachate quality and waste settlement in simulated hybrid landfill bioreactors. Four laboratory-scale reactors ...were constructed and operated for about 10 months to simulate different bioreactor operations, including one anaerobic bioreactor and three hybrid bioreactors with different aeration frequencies (one, two, and four times per day). Chemical oxygen demand (COD) and biochemical oxygen demand (BOD
5
) reduced more than 96% of the initial concentrations in all aerated bioreactors. The differences of COD and BOD
5
reductions among tested aeration frequencies were relatively small. For ammonia nitrogen, the higher aeration frequency (two or four times per day) resulted in the quicker reduction. Overall, the concentrations of heavy metals (Cr, Co, Cu, Mn, Ni, and Zn) decreased over time except Cd and Pb. The reduction of redox-sensitive metal concentrations (Mn, Co, Ni, and Cu) was greater in aerated bioreactors than in anaerobic bioreactor. Settlement of municipal solid waste (MSW) was enhanced with higher frequency of aeration events (four times per day).
Implications: In recent years, hybird bioreactor landfill technology has gained a lot of attention. Appropriate aeration rate is crucial for hybrid bioreactor operation, but few studies have been done and different results were obtained. Research was conducted to investigate the effects of daily aeration frequency on leachate quality and waste settlement. Results indicated that aeration can effectively accelerate waste stabilization and remove organic carbon concentration and total nitrogen in the leachate.
This study examines the correlation between livestock odor civil petitions and the establishment of malodor control areas in Jeju Special Self-Governing Province, focusing on swine farms where ...numerous civil petitions regarding malodors have been received. After the designation of the malodor control areas, high odor concentrations occurred in Aewoleup and Jocheon-eup, and the odor concentration decreased in other areas. The number of civil petitions shows a consistent annual trend, with increased petitions from March, peaking during summer (July and August), and decreasing from September into winter. In Jeju-si, there were many civil petitions in Hallim-eup and Aewol-eup where there were many malodor control areas. However, in Seogwipo-si, there were also many civil petitions in Pyoseonmyeon, where there is no malodor control area. Additionally, we compared the average multiple of compound malodors and the rate of exceeding the maximum allowable emission level for compound malodors with the number of livestock malodor civil petitions to assess the actual state of malodors. The results reveal a stronger correlation between the number of civil petitions and the rate of exceeding the compound malodors allowable emission level than the average multiple for compound malodors. These findings provide valuable insights into addressing livestock odor concerns and enhancing malodor control measures in Jeju Island.
As a byproduct of municipal solid waste incineration (MSWI) plant, fly ash is becoming a challenge for waste management in recent years. In this study, MSWI fly ash (FA) was evaluated for the ...potential capacity of odorous gas H
S removal. Results showed that fly ash demonstrated longer breakthrough time and higher H
S capacities than coal fly ash and sandy soil, due to its high content of alkali oxides of metals including heavy metals. H
S adsorption capacities of FA1 and FA2 were 15.89 and 12.59 mg H
S/g, respectively for 750 ppm H
S. The adsorption of H
S on fly ash led to formation of elemental sulfur and metal sulfide. More importantly, the formation of metal sulfide significantly reduced the leachability of heavy metals, such as Cr, Cu, Cd and Pb as shown by TCLP tests. The adsorption isotherms fit well with Langmuir model with the correlation coefficient over 0.99. The adsorption of H
S on fly ash features simultaneous H
S removal and stabilization and heavy metals found in most MSWI fly ash, making fly ash the potential low cost recycled sorbent material.
To increase the moisture content of waste disposed in a bioreactor landfill, it is critical to secure the moisture source. In this study, industrial wastewater was evaluated as a potential moisture ...source for a bioreactor landfill with respect to the impact on methane generation. Industrial wastewater samples were collected from fishery, brewery and dairy industries. These samples were tested for basic water chemistry parameters, heavy metals, and methane generation using the regular and modified biochemical methane potential (BMP) assays. Despite high sodium and total phosphate concentrations in the fishery wastewater, a significant methane yield was observed (0.313 m
3
CH
4
/kg COD). However, a relatively large amount of fishery wastewater added at the phase of methane generation acceleration adversely affected microbial activity. Samples from the brewery and dairy wastewater did not indicate significant inhibitory effects on methane generation in either the regular or the modified BMP assay. This study demonstrates the utility of wastewater as an alternative to traditional moisture sources when used to enhance methane production in a bioreactor landfill.
Quicklime is frequently used to facilitate construction projects by amending the physical properties of soil, such as water content and plasticity. A reaction process known as slaking occurs when ...calcium oxide is hydrated and heat is produced. Quicklime also has been used for soil cleanup. This research was motivated by observations of contaminant removal from quicklime-applied soils, particularly chlorinated solvents. Three feasible mechanisms for treatment of chlorinated ethylenes by adding CaO were studied: (1) degradation of the chemicals, (2) volatilization of the chemicals, and (3) immobilization of the contaminants in the soil-Ca(OH)2 matrix. The fate of chlorinated ethylenes (tetrachloroethylene (PCE), trichloroethylene (TCE), and cis-dichloroethylene (cis-DCE)) was examined when CaO reacted with a chlorinated ethylene-water mixture in test vessels designed to minimize volatile loss. Results of the experiments indicated that chlorinated ethylenes did react to some degree with Ca(OH)2 produced during the hydration of CaO to form organic byproducts. Evidence of dechlorination of chlorinated ethylenes was provided by concentrations of chloride in methanol extracts. The primary organic byproducts of the decomposition of TCE and cis-DCE were dichloroacetylene (DCA) and chloroacetylene (CA). Various secondary products formed likely because DCA and CA were unstable in the presence of air. The formation of DCA and CA from CaO-treated TCE and cis-DCE was hindered by the presence of excess water when the CaO/H2O ratio of 1:2 was used. The maximum decomposition of chloroethylenes was observed when the CaO/H2O ratio was 1:1 and air was present. This experiment proves that destruction of chlorinated ethylenes can occur to some extent when CaO reacts with a chlorinated ethylene-water mixture. The maximum destruction under the tested experiment conditions was estimated to be 0.3% of PCE, 37.3% of TCE, and 63.2% of cis-DCE. The production of organic and inorganic byproducts when TCE was exposed to Ca(OH)2 was investigated at different temperatures and times. The formation of organic byproducts and chloride increased with increasing temperature. However, the formation of organic byproducts did not vary with extended time. Dechlorination of TCE also was hindered as Ca(OH)2 was converted to chlorine compound(s). These results showed that the destruction of TCE was enhanced by increasing temperature, but that the reaction might be hindered by a byproduct formed on Ca(OH)2. Minimizing volatilization, the dechlorination of chlorinated ethylenes in soil was determined with different mole ratios of CaO to H2O (0.5, 1.0, and 1.5) when CaO was added to the soils. Dechlorination of chlorinated ethylenes (cis-DCE, TCE, and PCE) was estimated by measuring extractable chloride concentrations. Dechlorination of the chlorinated ethylenes increased when the CaO/H2O ratio increased. The degree of dechlorination varied among the different chlorinated ethylenes (cis-DCE < TCE < PCE). The use of excess water when the CaO/H2O ratio was 1:2 reduced dechlorination of the chlorinated ethylenes, perhaps, because water prevented chloroethylene vapor from contacting Ca(OH)2. When the chloride concentration was compared with the maximum temperatures observed with different CaO/H2O ratios, increasing the temperature by increasing the CaO dose enhanced the dechlorination of chlorinated ethylenes. Volatilization and formation of byproducts were examined when TCE-contaminated soils were treated by 0%, 5%, 10%, and 20% CaO doses. The results revealed that generating more heat with higher CaO doses overcame the obstacles retarding the TCE volatilization such as high organic content and clay content. However, the treatment with 20% CaO dose led to the formation of an organic byproduct (DCA). To assess the immobilization of TCE in a post-CaO treatment condition, simulated post-CaO-treated soils were synthesized by mixing a soil with Ca(OH) 2 and adding TCE-dissolved water. Non-treated TCE-contaminated soils (without Ca(OH)2) were also prepared to compare with the simulated post-CaO-treated materials. The total TCE concentrations in the simulated materials and the TCE concentrations in the SPLP extracts of the simulated materials were compared with those of non-treated TCE-contaminated soils. TCE reduction in the simulated post-CaO-treated materials was greater than in the non-treated soil in three of four soils used. The levels of TCE in the simulated post-CaO treated soils ranged from 17% to 60% of those in the non-treated TCE contaminated soils (FB, N and AE), but the levels of TCE in non-treated TCE-contaminated B soil ranged from 3% to 67% of those in the simulated post-CaO-treated B soil. The concentrations of TCE in the SPLP extracts were proportional to the total TCE concentrations added to the tested materials, but no evidence of enhanced immobilization was observed. The impact of adding CaO on chlorinated ethylenes in soil was studied with regard to degradation, volatilization, and immobilization. (Abstract shortened by UMI.)
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