Search results for "Leachate"
showing 10 items of 67 documents
Effect of single-species and mixed-species leaf leachate on bacterial communities in biofilms
2009
Dissolved organic matter in the form of leaf leachate represents an important carbon and energy source in many lotic ecosystems. In this study, we investigated utilization of mono-specific and mixed-species leaf leachate and impacts on biofilm bacterial community structure. Ceramic tiles were incubated in a Northeast Ohio stream to allow for biofilm development and then exposed in the laboratory to glucose or leachate from: sugar maple (Acer saccharum), pin oak (Quercus palustris), maple oak, American beech (Fagus grandifolia), witch hazel (Hamamelis virginiana), or beech witch hazel. Bacterial responses to these amendments were compared to un-amended controls based on fluorescent in situ h…
Biological nitrogen removal from landfill leachate: a pilot-scale study
1999
A pilot-scale two-stage process including an anaerobic pretreatment (up-flow anaerobic sludge blanket, UASB) unit and a pre-denitrification activated sludge process was studied for treating leachates from a municipal landfill (waste aged 4 to 5 years, area 2.5 ha) and from a windrow composting area (1ha). A single-stage pilot process was used for nitrification studies. The leachate characteristics were as follows: COD 740 to 2400 mg 1-1 (chemical oxygen demand), BOD7 (biochemical oxygen demand) approximately 1000 mg 1 -1, Ntot 40 to 120 mg 1-1 and the temperature was between 2 and 21°C. The results show that 45 to 50% COD removal could be achieved in the UASB reactor even at temperatures b…
Anaerobic and sequential anaerobic-aerobic treatments of municipal landfill leachate at low temperatures
1996
Abstract Anaerobic treatment of municipal landfill leachate (COD 1–4 g l −1 , NH 4 -N c. 0.16 g l −1 ) was studied at 11 and 24°C by using laboratory-scale UASB and hybrid reactors. Aerobic post-treatment of the anaerobically treated leachate was also studied at 24°C using an activated-sludge process. In the 11°C reactors, a COD removal of up to 60–65% was obtained with 1.5-2 day HRT and 0.7-1.5 kg COD m −3 day −1 organic loading rates. At 24°C, a COD removal of up to 75% was achieved with a 10 h HRT. The highest organic loading rate applied was 10 kg COD m −3 day −1 at 24°C. Inorganic material accumulated in the reactor sludges at both temperatures. However, the specific methanogenic activ…
Leachate formation and characteristics from gasification and grate incineration bottom ash under landfill conditions
2011
Characteristics and formation of leachates from waste gasification and grate firing bottom ash were studied using continuous field measurements from 112 m(3) lysimeters embedded into landfill body for three years. In addition, the total element concentrations of the fresh ash were analysed and laboratory batch tests were performed to study leachate composition. The three-year continuous flow measurement showed that about one fifth of the leachates were formed, when the flow rate was200 l/d, covering3.5% of the study time. After three years, the liquid/solid-ratio for the quenched grate ash was 1 (l/kg (d.m.)) and for the initially dry gasification ash 0.4 (l/kg (d.m.)). The low initial wate…
Microbial acidification and pH effects on trace element release from sewage sludge.
2003
Leaching of sludge-borne trace elements has been observed in experimental and field studies. The role of microbial processes in the mobilization of trace elements from wastewater sludge is poorly defined. Our objectives were to determine trace element mobilization from sludge subjected to treatments representing microbial acidification, direct chemical acidification and no acidification, and to determine the readsorption potential of mobilized elements using calcareous sand. Triplicate columns (10-cm diameter) for incubation and leaching of sludge had a top layer of digested dewatered sludge (either untreated, acidified with H2SO4, or limed with CaCO3; all mixed with glass beads to prevent …
Toxicity of waste gasification bottom ash leachate
2011
Abstract Toxicity of waste gasification bottom ash leachate from landfill lysimeters (112 m3) was studied over three years. The leachate of grate incineration bottom ash from a parallel setup was used as reference material. Three aquatic organisms (bioluminescent bacteria, green algae and water flea) were used to study acute toxicity. In addition, an ethoxyresorufin-O-deethylase (EROD) assay was performed with mouse hepatoma cells to indicate the presence of organic contaminants. Concentrations of 14 elements and 15 PAH compounds were determined to characterise leachate. Gasification ash leachate had a high pH (9.2–12.4) and assays with and without pH adjustment to neutral were used. Gasifi…
Speciation of Cr in Leachates of a MSWI Bottom Ash Landfill
1998
Cr concentrations and speciation were determined in leachate from a municipal solid waste incinerator bottom ash landfill both experimentally and by thermodynamic model calculations. Total dissolved Cr concentrations of 0.2 mmol L-1 were determined by GFAAS. Two orders of magnitude lower values were determined upon preconcentration by an in-situ solid-phase extraction technique based on the 8-HQ cation exchanger that is specific for Cr(III) but unspecific for Cr(VI). This suggests that chromate dominates the dissolved Cr concentrations in the leachates but was up to 5 orders of magnitude undersaturated with respect to the solubility of CaCrO4 or BaCrO4. Chromate adsorption by oxyhydroxides …
Assessment of the ecotoxicity of phytotreatment substrate soil as landfill cover material for in-situ leachate management
2019
Phytotreatment capping in closed landfills is a promising, cost-effective, in situ option for sustainable leachate treatment and might be synergistically coupled with energy crops to produce renewable energy (e.g.: biodiesel or bioethanol). This study proposes to use 0.30 m of soil as growing substrate for plants cultivated on the temporary cover of closed landfills. Once the leachate phytotreatment process is no longer required, 0.70 m of the same soil would be added to attain the final top cover configuration. This solution would entail saving the costs of excavation and backfilling. However, worsening of the initial soil quality due to potential contaminant transfer from the liquid to th…
Two-Stage Anaerobic Digestion of Energy Crops: Methane Production, Nitrogen Mineralisation and Heavy Metal Mobilisation
2006
Energy crops (willow, sugar beet and grass silage) were digested in pilot scale two-stage anaerobic digesters. The specific methane yields obtained were 0.16, 0.38 and 0.39 m3 kg(-1) added volatile solids (VSadded) for willow, sugar beet and grass, respectively, corresponding to yearly gross energy yields of 15, 53 and 26 megawatt-hours (MWh) per hectare. With grass and sugar beets as substrate, 84-85% of the harvestable methane was obtained within 30 days. In pilot scale two-stage digestion of willow and sugar beet, 56 and 85% of the laboratory scale methane yields were obtained, but digestion of grass in two-stage reactors yielded 5% more methane than digestion in laboratory scale complet…
Influence of the Height of Municipal Solid Waste Landfill on the Formation of Perched Leachate Zones
2015
Waste settlement as well as consolidation phenomena, which occur inside a landfill for municipal solid waste (MSW), can cause a decrease in waste permeability. This can lead to a reduction in conveyance of the leachate drainage system. It is therefore possible that a so-called perched leachate zone will form. Such a zone is constituted by an area in the body of the landfill where the leachate is temporarily trapped and is unable to infiltrate downward. This phenomenon is influenced by many factors, which include rain infiltration rate, waste moisture and composition, landfill height, and so on. The main aim of the paper is to elucidate the role played by landfill height in the formation of …