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PubMed2004

Aerobic biological treatment of leachates from municipal solid waste landfill.

The main objective of the study was to improve chemical oxygen demand (COD) elimination by secondary biological treatment from leachate of municipal solid waste landfill. This effluent was a supernatant liquid obtained after physicochemical processes and coagulating with Al3+ followed by ammoniacal stripping. First, respirometric assays were carried out to determine the substrate biodegradability. Specific sludge respiration rate (R(s)) vs. concentration of substrate (S), showed an increasing specific rate of assimilation of substrate (Rs), which reached the highest value, when the substrate concentration (COD) was between 75 and 200 mg O2 L(-1). Second, continuous experiments were made in an aerobic digester to test the previous respirometric data and the results showed removal efficiency of COD between 83 and 69%, and a substrate assimilation rate between 1.3 and 3.1 g COD g(-1) volatile suspended solids d(-1).

Bacteria, Aerobic↗
PubMed2004

Anaerobic fluidized bed reactor for the treatment of landfill leachates.

Treatability of the sanitary young landfill leachate in a pilot-scale anaerobic fluidized bed reactor during reactor startup and steady-state phases was investigated. All runs were carried out at 35 degrees C due to environmental conditions in the mesophilic anaerobic fluidized bed reactor (AFBR) while organic loading rate (OLR) was increased from 2.5 to 37gCOD/L-day during the 220 days of operation. The AFBR process attained steady-state conditions about on day 80 and a good and stable COD removal were achieved at about 90%. Biogas production in the bed continuously increased during the process. The mean specific biogas production was found 0.52 L biogas/gCODrem while the methane content was about 75%. The attached biomass concentration, measured as volatile solids rapidly increased as containing about 90% of the total biomass concentration. Furthermore, an increase in the suspended solid concentration was found as an evidence of biomass detachment from the media.

Bacteria, Anaerobic↗
PubMed2002

Movement of leachate from beneath turkey litter sited over chalk in southern England.

Farm waste stores are widespread in the UK, with many overlying the principal aquifer, the Chalk. The stores pose a threat to groundwater quality through the infiltration of high concentrations of nitrogen species and organic carbon together with pathogenic microbes. Two cored boreholes have been drilled into the unsaturated chalk to depths of 15 and 20 metres, respectively, through a site which has been used to store turkey litter for in excess of 20 years. Porewaters were extracted from the cores and analysed for a range of chemical elements. In addition, chalk core material was also taken for microbial examination. Both boreholes showed very high concentrations of nitrate-N (3000 mg/L), ammonia (5000 mg/L), organic carbon (3000 mg/L), and potassium (10,000 mg/L) in the top 5 metres of the profile. Below this depth concentrations declined dramatically. Highest concentrations were found in the borehole constructed in the middle of the site. The borehole constructed at the edge of the store showed much lower concentrations but did show a peak of nitrate around 10 metres below ground level. The apparent lack of movement beneath the centre of the store suggests the turkey litter is relatively impermeable and most leaching occurs where the covering of litter is thin or when the litter is annually cleared. If the leachate continues to migrate at this apparent rate, it will take more than 100 years to reach the water table.

Animals↗
PubMed1999

Thauera mechernichensis sp. nov., an aerobic denitrifier from a leachate treatment plant.

A heterotrophic bacterial strain TL1T capable of aerobic denitrification was previously enriched in continuous culture from a landfill leachate treatment plant and isolated as a pure culture. The taxonomic position of this isolate within the beta-subclass of the Proteobacteria was determined by 16S rDNA sequence analysis and by conventional taxonomy including substrate spectrum, quinone type (ubiquinone Q-8) and cellular fatty acid composition. Detection of the specific polyamine 2-hydroxyputrescine supports the membership of strain TL1T in the beta-subclass of the Proteobacteria. The results of 16S rDNA sequencing showed that the strain clustered with, but was separate from, Thauera aromatica and Thauera selenatis. DNA-DNA hybridization experiments indicated that the new isolate represents a new species of the genus, for which the name Thauera mechernichensis is proposed; the type strain is DSM 12266T.

Aerobiosis↗
PubMed2001

Comamonas nitrativorans sp. nov., a novel denitrifier isolated from a denitrifying reactor treating landfill leachate.

A group of Gram-negative denitrifying bacteria has been isolated from a denitrifying reactor treating landfill leachate. The new isolates produced both oxidase and catalase and showed growth on acetate, butyrate, n-caproate, i-butyrate, i-valerate, propionate, n-valerate, lactate, alanine, benzoate, phenylalanine and ethanol. No growth was observed on sugars. The bacteria could perform anoxic reduction of nitrate, nitrite and nitrous oxide to nitrogen, coupled to the oxidation of the same substrates as those used under aerobic conditions, except for aromatic compounds. They were very efficient denitrifiers, as estimated from the specific rate of N2 gas production. All the strains showed the same 16S rDNA restriction profile and one of them, designated 23310T, was selected for phylogenetic analysis. The organism clustered within the family Comamonadaceae, being related to Comamonas terrigena (95.8% sequence similarity). On the basis of the phylogenetic analysis, physiological characterization and the ability to efficiently reduce nitrate to N2, it is proposed that the bacterium be assigned to a new species, Comamonas nitrativorans. The type strain is 23310T (= DSM 13191T = NCCB 100007T = CCT 7062T).

Anaerobiosis↗
PubMed1994

Evidence for microbial iron reduction in a landfill leachate-polluted aquifer (Vejen, Denmark).

Aquifer sediment samples obtained from the anaerobic part of a landfill leachate plume in Vejen, Denmark, were suspended in groundwater or in an artificial medium and incubated. The strictly anaerobic suspensions were tested for reduction of ferric iron [Fe(III)] oxides, which was measured as an increase in the concentration of dissolved Fe(II). Iron reduction did not occur when the medium was inoculated with inactive sediment and when the organisms in the inoculated medium were killed by formaldehyde, by chloroform, or by pasteurization, whereas the level of iron reduction was significant when living bacteria were present. Mixed cultures were obtained from the sediment samples, and differences in apparent iron reduction rates among the different cultures were maintained during several transfers. In addition, iron reduction was observed in unamended incubation mixtures containing whole sediment and groundwater. Synthetic amorphous Fe(III) oxides, as well as naturally occurring sediment-bound Fe(III) oxides, could be reduced by the cultures. Together, our results provide evidence that iron-reducing bacteria are present and microbial iron reduction occurs in the polluted aquifer sediments which we studied.

Bacteria, Anaerobic↗
PubMed2002

A study on the appearance of persistent organic pollutants (POPs) in leachate treatment processes.

The presence of PCDDs/DFs, PCBs and PAHs in the adsorbed or dissolved phases (depending on the leachate treatment process) was investigated in two landfills in Japan (Landfill M and Landfill N). The results of the investigations showed that, in general, persistent organic pollutants (POPs) having high Kow such as PCDDs/DFs and PCBs tended to exist in the adsorbed phase in both Landfill M and Landfill N. Furthermore, it was confirmed that their presence depended on log Kow by the appearance of PAHs.

Adsorption↗
PubMed2002

Methane and leachate pollutant emission potential from various fractions of municipal solid waste (MSW): effects of source separation and aerobic treatment.

The effects of source-separation of putrescibles as well as aerobic pre-treatment and landfill aeration on the pollutant emission potential of methane and leachate pollutants were studied in the fresh (PFMSW) and composted (CPFMSW) source-separated putrescible fraction of municipal solid waste, and in the grey waste, and in lysimeter landfilled grey waste and ten-year-old unsorted MSW from our landfill lysimeter study. After 0, 23 and 51 days, an aerobic lysimeter experiment, an elution test and biochemical methane potential (BMP) test was done on samples. PFMSW had high methane (CH4) potential (410 m(3) CH4 t(-1)TS) as well as a high amount of ammonium-nitrogen (3.6 kg NH4-N) was eluted, whereas CPFMSW produced 41 m(3) CH4 t(-1)TS and 2.0 kg NH4-N t(-1)TS. A high nitrogen elution potential was found in the grey waste (2.1 kg NH4-N t(-1)TS). Aeration for 51 days in lysimeters reduced CH4 potential by more than 68% for the PFMSW and CPFMSW samples, whereas for the lysimeter landfilled grey waste the reduction was 50% indicating the potential of aeration for CH4 emission reduction. The effective separation and biological treatment of the PFMSW are important in reducing the environmental impacts of waste management, especially for minimising the methane potential of MSW fractions.

Bacteria, Aerobic↗
PubMed2002

Molecular characterisation of bacteria in a wetland used to remove ammoniacal-N from landfill leachate.

Bacteria associated with leachate from a constructed, surface-flow wetland effective at removing ammonium-N, were characterised using molecular methods which bypass the need for cultivation. DNA was extracted from the sample and bacterial 16S rDNA sequences amplified and cloned. Ninety-six individual clones were re-amplified and analysed by restriction digestion and targeted sequencing. A collector's curve was used to estimate the total number of bacterial groups (operational taxonomic units, OTUs) in the sample at 47. Thirty-six clones representing 28 OTUs were sequenced and characterised by aligning them against published sequences. Of these, 10 were confidently identified, whilst for the remaining 18, the closest match was obtained. The sequences in 64% of the OTUs were similar to those of the Proteobacteria but no classical nitrifying bacteria were identified. However, alkaliphilic Methylomicrobium sp. that oxidise ammonium and bacteria from the genus Alcaligenes, at least one species of which is capable of heterotrophic nitrification, were detected.

DNA, Bacterial↗
PubMed2005

Molecular analysis of microbial community in a groundwater sample polluted by landfill leachate and seawater.

Seashore landfill aquifers are environments of special physicochemical conditions (high organic load and high salinity), and microbes in leachate-polluted aquifers play a significant role for intrinsic bioremediation. In order to characterize microbial diversity and look for clues on the relationship between microbial community structure and hydrochemistry, a culture-independent examination of a typical groundwater sample obtained from a seashore landfill was conducted by sequence analysis of 16S rDNA clone library. Two sets of universal 16S rDNA primers were used to amplify DNA extracted from the groundwater so that problems arising from primer efficiency and specificity could be reduced. Of 74 clones randomly selected from the libraries, 30 contained unique sequences whose analysis showed that the majority of them belonged to bacteria (95.9%), with Proteobacteria (63.5%) being the dominant division. One archaeal sequence and one eukaryotic sequence were found as well. Bacterial sequences belonging to the following phylogenic groups were identified: Bacteroidetes (20.3%), beta, gamma, delta and epsilon-subdivisions of Proteobacteria (47.3%, 9.5%, 5.4% and 1.3%, respectively), Firmicutes (1.4%), Actinobacteria (2.7%), Cyanobacteria (2.7%). The percentages of Proteobacteria and Bacteroides in seawater were greater than those in the groundwater from a non-seashore landfill, indicating a possible influence of seawater. Quite a few sequences had close relatives in marine or hypersaline environments. Many sequences showed affiliations with microbes involved in anaerobic fermentation. The remarkable abundance of sequences related to (per)chlorate-reducing bacteria (ClRB) in the groundwater was significant and worthy of further study.

Bacteria↗
PubMed2006

Combined treatment of landfill leachate with fecal supernatant in sequencing batch reactor.

A laboratory-scale sequencing batch reactor (SBR) is used to treat landfill leachate containing high concentration of ammonium nitrogen with municipal fecal supernatant. The SBR system is operated in the following sequential phases: fill period, anoxic period, aeration period, settling period, decant and idle period. The results indicated that the average removal efficiencies of COD, BOD(5), TN,NH(4)(+)-N were 93.76%, 98.28%, 84.74% and 99.21%, respectively. The average sludge removal loading rates of COD, BOD(5), TN and NH(4)(+)-N were 0.24 kg/(kg SS.d), 0.08 kg/(kg SS.d), 0.04 kg/(kg SS.d) and 0.036 kg/(kg SS.d), respectively. Highly effective simultaneous nitrification and denitrification was achieved in the SBR system. The ratio of nitrification and denitrification was 99% and 84%, respectively. There was partial NO(2)(-) denitrification in the system.

Alkalies↗
PubMedDate not supplied

Evaluation of leachates from coal refuse blended with fly ash at different rates.

There is great interest in returning coal combustion products to mining sites for beneficial reuse as liming agents. A column study examined the effects of blending two coal fly ashes with an acid-forming coal refuse (4% pyritic S). Both fly ashes were net alkaline, but had relatively low neutralizing capacities. One ash with moderate alkalinity (CRF) was bulk blended with coal refuse at 0, 20, and 33% (w/w), while another lower alkalinity ash (WVF) was blended at 0, 5, 10, 20, and 33% (w/w). The columns were leached (unsaturated) weekly with 2.5 cm of simulated precipitation for >150 wk. Where high amounts of ash alkalinity (>20% w/w) were mixed with the coal refuse, pyrite oxidation was controlled and leachate pH was >7.0 with low metal levels throughout the study. At lower rates of alkalinity loading, trace metals were sequentially released from the WVF ash as the 5, 10, and 20% treatments acidified due to pyrite oxidation. Lechate metals increased in proportion to the total amounts applied in the ash. In this strongly acidic environment, metals such as Mn, Fe, and Cu were dissolved and leached from the ash matrix in large quantities. If ash is to be beneficially reused in the reclamation of acid-producing coal refuse, the alkalinity and potential acidity of the materials must be balanced through the appropriate addition of lime or other alkaline materials to the blend. Highly potentially acidic refuse material, such as that used here, may not be suitable for ash/refuse codisposal scenarios.

Coal↗
PubMedDate not supplied

Removal and distribution of iron, manganese, cobalt, and nickel within a Pennsylvania constructed wetland treating coal combustion by-product leachate.

A flow-through wetland treatment system was constructed to treat coal combustion by-product leachate from an electrical power station at Springdale, Pennsylvania. In a nine-compartment treatment system, four cattail (Typha latifolia L.) wetland cells (designated Cells 1 through 4) successfully removed iron (Fe) and manganese (Mn) from the inlet water; Fe and Mn concentrations were decreased by an average of 91% in the first year (May 1996-May 1997), and by 94 and 98% in the second year (July 1997-June 1998), respectively. Cobalt (Co) and nickel (Ni) were decreased by an average of 39 and 47% in the first year, and 98 and 63% in the second year, respectively. Most of the metal removed by the wetland cells was accumulated in sediments, which constituted the largest sink. Except for Fe, metal concentrations in the sediments tended to be greater in the top 5 cm of sediment than in the 5- to 10- or 10- to 15-cm layers, and in Cell 1 than in Cells 2, 3, and 4. Plants constituted a much smaller sink for metals; only 0.91, 4.18, 0.19, and 0.38% of the Fe, Mn, Co, and Ni were accumulated annually in the aboveground tissues of cattail, respectively. A greater proportion of each metal (except Mn) was accumulated in cattail fallen litter and submerged Chara (a macroalga) tissues, that is, 2.81, 2.75, and 1.05% for Fe, Co, and Ni, respectively. Considerably higher concentrations of metals were associated with cattail roots than shoots, although Mn was a notable exception.

Biological Availability↗
PubMedDate not supplied

Screening for organotin compounds in European landfill leachates.

As industrial chemicals, organotin compounds are predominantly applied as polyvinyl chloride (PVC) stabilizers and biocides. They are widely encountered in environmental samples and may be introduced into landfills by disposal of municipal solid waste or sewage sludge. In the present study, leachate samples were obtained from several sanitary landfill sites in Sweden, Italy, and Germany. These samples were analyzed by means of a highly sensitive and species-selective method for methyltin, butyltin, and octyltin species. In total, twelve samples from eight different landfill sites at various ages were investigated. The findings of all target compounds range between less than the limit of detection at 0.1 microg/L and, at maximum, 4 microg/L. Only octyltin compounds can be attributed to PVC products with any certainty, whereas for methyltin and butyltin compounds alternative and less distinct sources exist. Organotin compounds are subject to microbial transformation, such as dealkylation and methylation processes. Consequently, caution should be exercised when attributing findings to potential sources and deriving any predicted environmental concentrations.

Biotransformation↗
PubMedDate not supplied

Trace element removal from coal ash leachate by a 10-year-old constructed wetland.

This study investigated the ability of a 10-yr-old constructed wetland to treat metal-contaminated leachate emanating from a coal ash pile at the Widows Creek electric utility, Alabama (USA). The two vegetated cells, which were dominated by cattail (Typha latifolia L.) and soft rush (Juncus effusus L.), were very effective at removing Fe and Cd from the wastewater, but less efficient for Zn, S, B, and Mn. The concentrations were decreased by up to 99% for Fe, 91% for Cd, 63% for Zn, 61% for S, 58% for Mn, and 50% for B. Higher pH levels (>6) in standing water substantially improved the removing efficiency of the wetland for Mn only. The belowground tissues of both cattail and soft rush had high concentrations of all elements; only for Mn, however, did the concentration in the shoots exceed those in the belowground tissues. The concentrations of trace elements in fallen litter were higher than in the living shoots, but lower than in the belowground tissues. The trace element accumulation in the plants accounted for less than 2.5% of the annual loading of each trace element into the wetland. The sediments were the primary sinks for the elements removed from the wastewater. Except for Mn, the concentrations of trace elements in the upper layer (0-5 cm) of the sediment profile tended to be higher than the lower layers (5-10 and 10-15 cm). We conclude that constructed wetlands are still able to efficiently remove metals in the long term (i.e.,>10 yr after construction).

Biological Availability↗
PubMed2006

Heterotrophic bacterial activities and treatment performance of surface flow constructed wetlands receiving woodwaste leachate.

Heterotrophic activities were investigated by measuring 3H-leucine incorporation to bacterial protein and 14C-glucose turnover in surface flow constructed wetlands receiving woodwaste leachate. No significant longitudinal variation was found in heterotrophic activities of bacterioplankton. An open wetland, a vegetated wetland, and a fertilized vegetated wetland were used to examine the effects of vegetation and ammonium nitrate amendment. There was not a significant difference in treatment performance among the three wetlands, except for a significant pH increase and more efficient volatile fatty acids removal in the fertilized wetland. The fertilized wetland had the highest leucine incorporation rate and shortest glucose turnover time accompanied by the lowest glucose mineralization percentage, followed by the open wetland, then the vegetated wetland. Planktonic and sedimentary bacteria contributed to the majority of the total heterotrophic activities; epiphytic bacteria played a minor role. Heterotrophic activities were influenced by the availability of nutrient, electron acceptor, and organic substrate.

Bacteria↗
PubMed1984

Irradiation conditions required in combined radiation-microbial process for landfill leachate.

A landfill leachate, which contains large amounts of microbially refractory humic substances, was irradiated with 60Co gamma-rays under several conditions and the modification of its biodegradability was examined. The effects of initial pH and dose rate on the modification were found to be insignificant. The apparent effect was observed for the initial concentration of the humic substances. High biochemical oxygen demand (BOD) value was obtained as the initial concentration was higher. As the initial concentration was lower, in contrast, the decreasing rates of total organic carbon (TOC) and chemical oxygen demand (COD) were high. Therefore two possible designs of the combined radiation-microbial processes with and without dilution are proposed. Both processes require only about 30% of the irradiation dose, compared with a simple radiation process.

Biodegradation, Environmental↗
PubMed2003

Nutrient removal using anaerobically fermented leachate of food waste in the BNR process.

Nutrients removal efficiencies highly depend on the presence of biodegradable organic carbon in the biological nutrient removal (BNR) process but most domestic wastewater in Korea has shown a low C/N ratio and has a small amount of biodegradable COD (chemical oxygen demand). On the other hand, about 11,577 tons of food waste that contains a lot of organic material has been produced in Korea per day. The feasibility and applicability of anaerobically fermented leachate of food waste (AFLFW) as an external carbon source was examined in the laboratory-scale BNR process at different operation conditions with synthetic wastewater and domestic sewage. As the addition of AFLFW increased, the average removal efficiencies of SCOD, T-N, T-P changed from 96%, 60%, and 2% to 90%, 77%, and 67%, respectively. From anoxic nitrate utilization tests, it was observed that once the readily biodegradable COD (especially VFAs) was depleted, the denitrification rate reduced from 8.2 mg NO3-N/g VSS/hr to 0.7 mg NO3-N/g VSS/hr. From the molecular size distribution test, it was concluded that about 60% of soluble COD in effluent, which was considered to originate from AFLFW, had a large molecular size (> 30 kDa) that was not used by microorganisms.

Bacteria, Anaerobic↗