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PubMed2006

Treatment of landfill leachate by irrigation and interaction with landfill gas.

The treatment efficiency of landfill leachate irrigation and the effect of landfill gas addition were investigated in a vegetated compost/gravel substrate by monitoring soil moisture content, drainage water volume and quality in a two years lysimeter experiment. Landfill leachate irrigation exceeding 350 mm increased soil moisture and drainage volumes owing to the deterioration of the vegetation resulting from high sodium chloride inputs. Even so sodium chloride was lost in between the irrigation periods, the total reduction of the landfill leachate volume by irrigation decreased from 71% in the first year to 38% in the second year. Landfill gas addition also increased drainage volumes, but was less pronounced. Twenty-two percent of magnesium was retained under landfill leachate irrigation, while decreasing pH values, redox potential and high initial concentrations in the substrate released calcium, iron and potassium. Ninety-eight percent of ammonium was removed by irrigation, but 44% of the applied ammonium was leached as nitrate after oxidation took place due to a decreased uptake after the vegetation deteriorated. Landfill gas fumigation influenced landfill leachate treatment by decreasing the redox potential and the pH and increasing the drainage water content, which improved the retention of total nitrogen and sulfate, but increased the release of iron, calcium and magnesium. To conclude, landfill leachate irrigation is a valuable treatment option to minimize leachate quantities and remove ammonium independent from the presence of landfill gas if salt accumulation is avoided.

Drainage, Sanitary↗
PubMed2005

Nitrogen removal from landfill leachate using a compact constructed wetland and the effect of chemical pretreatment.

Onsite treatment of leachate was implemented at the Tveta Landfill, adjacent to the city of Södertälje, Sweden. The system consists of leachate collection in a pond, precipitation of metals with chemicals, a constructed wetland, and forest irrigation. This article describes the constructed wetland and its effectiveness at removing ammonia in the system. Pulsed-discharge hydrology and wetland ecology formed the basis for the development of a compact constructed wetland (CCW). The system presented here has most design similarities with vertical sub-surface flow wetlands, though this system is run in batch mode. Chemically purified leachate and untreated leachate were applied to separate sections of the CCW using a filling and emptying schedule. A leachate treatment cycle of about 14 days duration was used, involving a 7 day submerged phase followed by a 7 day drained period. The removal efficiency varied between 40 and 75% on a mass basis. A maximum mass removal rate of up to 5.1 g m(-2) d(-1) was achieved in wetlands receiving leachate after chemical pretreatment. In wetlands receiving non-treated leachate a net release of up to 18 g m(-2) N occurred in the form of nitrate. This indicated a considerable nitrification but limited denitrification in those systems. It was unclear whether the chemical treatment enhanced the nitrogen removal efficiency because of lower toxicity and/or content of fewer competing cations, or other mechanisms. Mechanisms responsible for the NH4-N removal in the CCW system have to be further investigated.

Ammonia↗
PubMed2002

Linking landfill hydrology and leachate chemical composition at a controlled municipal landfill (Kåstrup, Denmark) using state-space analysis.

Leachate production and composition data for a municipal landfill measured over a 25-year period was used to investigate important processes and parameters. Long-term leachate production could be satisfactorily predicted from a simple top-layer landfill hydrology model while short-term predictions were less accurate, likely due to water storage in the waste. State-space and multiple regression modelling were used to identify relations between different parameters. State-space models proved most accurate in fitting measured data, likely because temporal correlation between measurements is accounted for unlike multiple regression. State-space modelling showed that temporal correlation in leachate production must be taken into account and confirmed that water storage inside the landfill is important. Temporal correlation is also important when predicting pH and chloride concentrations but less so for BOD5 and NH3/NH4+concentrations. Leachate flow did in general not have a strong impact upon leachate composition, small effects were observed for Cl-, and NH3/NH4+ concentrations. It was also observed that the mass load of nitrogen from the landfill was strongly dependent upon leachate nitrogen (ammonia/ammonium) concentrations and to a lesser degree upon leachate flow rates. This study introduces state-space modelling in solid waste management as a powerful tool to identify governing parameters for hydrological and bio-chemical processes.

Facility Design and Construction↗
PubMed2003

Toxicity and chemistry of aspen wood leachate to aquatic life: field study.

A dark, toxic leachate has been observed around woodpiles of trembling aspen (Populus tremuloides Michx.) cut in winter for pulp or structural lumber. We measured production of leachate from 18 m3 of harvestable aspen logs stacked in an open field near Dawson Creek, British Columbia, Canada. The logpile began producing leachate during the first winter thaw and continued to do so for the duration of the two-year study (mean, 250 L/collection). Aspen leachate was characterized by dark color, acidic pH (5.0-6.5), elevated conductivity (200-500 microS/cm), high to very high biochemical oxygen demand (500-5,000 mg/L) and total organic carbon concentrations (500-2,000 mg/L), variable levels of phenolic compounds (2-27 mg/L), and low dissolved oxygen tensions (<2 mg/L). In tests with rainbow trout (Oncorhynchus mykiss), Daphnia magna, and luminescent bacteria, the leachate varied from weakly toxic (median lethal concentration, >10%) to very toxic (median lethal concentration, <1%). The volume of leachate generated by the logpile was correlated with total precipitation (rain or snow) since the last collection. Loads of chemical constituents or toxicity (lethal concentration x volume) in the leachate did not decline over the duration of the study. Less than 10% of the total mass of leachable material in the aspen logs was removed during two years of exposure.

Animals↗
PubMed1978

Field survey of enteric viruses in solid waste landfill leachates.

Because municipal solid waste may contain fecal material from a variety of sources, there is concern that the leachate discharged from some solid waste landfills may contain enteric pathogens, including enteric viruses. In this study, 22 leachate samples from 21 different landfills in the United States and Canada were examined for enteric viruses. The sites represented a broad range of conditions for solid waste landfills and the leachate samples ranged from 10.3 to 18 liters in volume. Enteric viruses were found in only one of the 22 leachate samples examined. Two viruses, identified as poliovirus types 1 and 3, were found in an 11.8 liter sample obtained from a site where solid waste landfill practice was deficient. The low levels of enteric viruses detected in field samples of raw leachate and the opportunities for further reductions in the virus concentration of leachates by such processes as thermal inactivation, removal by soil and dilution in ground and surface waters, suggest that leachates from properly operated solid waste landfills do not constitute an environmental or public health hazard due to enteric viruses.

Bacteria↗
PubMedDate not supplied

Leachate chemistry of field-weathered spent mushroom substrate.

Passive leaching by rainfall and snowmelt is a popular method to treat piles of spent mushroom substrate (SMS) before its reuse. During this field weathering process, leachate percolates into the underlying soils. A field study was conducted to examine the chemistry of SMS leachate and effects of infiltration. Two SMS piles were deposited (90 and 150 cm in height) over a Typic Hapludult and weathered for 24 mo. Leachate was collected biweekly using passive capillary samplers. The SMS leachate contained high concentrations of dissolved organic carbon (DOC; 0.8-11.0 g L(-1)), dissolved organic nitrogen (DON; 0.1-2 g L(-1)), and inorganic salts. The pH, electrical conductivity, and acid neutralizing capacity were 6.6 to 9.0, 21 to 66 ds m(-1), and 10 to 75 mmolc L(-1), respectively. Inorganic chemistry of the leachate was dominated by K+, Cl-, and SO24-. Leachate DOC was predominantly low molecular weight (<1000 Da) organic acids. During 2 yr of weathering, the 90-cm SMS pile released (per cubic meter of SMS) 3.0 kg of DOC, 1.6 kg of dissolved N, and 26.6 kg of inorganic salts. The 150-cm pile released (per cubic meter of SMS) 2.8 kg of DOC, 0.7 kg of dissolved N, and 13.6 kg of inorganic salts. The 150 cm pile retained more water and exhibited lower net nitrification compared with the 90-cm pile. The top 90 cm of soil retained 20 to 89% of the leachate solutes. Weathering of SMS in piles of 90 cm depth or greater may adversely affect ground water quality.

Agaricales↗
PubMedDate not supplied

The effect of five forage species on transport and transformation of atrazine and isoxaflutole (balance) in lysimeter leachate.

A field lysimeter study with bare ground and five different ground covers was established to evaluate the effect of forage grasses on the fate and transport of two herbicides in leachate. The herbicides were atrazine (ATR; 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) and isoxaflutole [IXF; 5-cyclopropyl-4-(2-methylsulfonyl-4-trifluormethyl-benzoyl)isoxazole], which has the commercial name Balance (Aventis Crop Science, Strasbourg, France). The ground covers included orchardgrass (Dactylis glomerata L.), smooth bromegrass (Bromus inermis Leyss.), tall fescue (Festuca arundinacea Schreb.), timothy (Phleum pratense L.), and switchgrass (Panicum virgatum L.). The results suggested that the total IXF (parent + metabolites) showed higher mobility than ATR and its metabolites. Differences in the timing of transport reflected the rapid degradation of IXF to the more soluble, stable, and biologically active diketonitrile (DKN) metabolite in the system. Although grass treatments did not promote the hydrolysis of DKN, they significantly reduced its transport in the leachate through enhanced evapotranspiration. Grass treatments significantly enhanced ATR degradation in the leachates and soils, especially through N dealkylation, but they did not reduce total ATR transported in the leachate. Leachate from the orchardgrass lysimeters contained the highest proportion of ATR metabolites (64.2%). Timothy and smooth bromegrass treatments also displayed a significant increase in ATR metabolites in leachate. Grass-treated lysimeters showed higher microbial biomass carbon than bare ground. For ATR treatments, the proportion of metabolites in the leachate strongly correlated with the elevated soil microbial biomass carbon in forage treatments. In contrast, DKN degradation was poorly correlated with soil microbial biomass carbon, suggesting that DKN degradation is an abiotic process.

Atrazine↗
PubMed2002

Effect of leachate recycling and inoculation on the biochemical characteristics of municipal refuse in landfill bioreactors.

Activity development of key groups of enzymes involved in municipal refuse decomposition was measured in laboratory landfill bioreactors with and without leachate recycling and inoculation for about 210 days. The results showed that the enzymes (amylase, protease, cellulase, lipase and pectinase) were present in fresh refuse but at low values and positively affected by leachate recycling and refuse inoculation. The total average of cellulase activity in digesters D3 operated with leachate recycling but no inoculation, D4 and D5 operated with leachate recycling and inoculation was much higher than that in digesters D1 and D2 without leachate recycling and inoculation by 88%-127%, 117%-162% and 64%-98%. The total average of protease activity was higher in digester D4 than that in digesters D1, D2, D3 and D5 by 63%, 39%, 24% and 24%, respectively, and the positive effect of leachate recycling and inoculation on protease activity of landfilled refuse mainly was at the first two months. The total average of amylase activity was higher in digesters D3, D4 and D5 than that in digesters D1 and D2 by 83%-132%, 96%-148% and 81%-129%. During the early phase of incubation, the stimulatory effect of inoculation on lipase activity was measured, but refuse moisture was the main factor affecting lipase activity of landfilled refuse. The inoculation, initial and continuous inoculation of microorganisms existing in leachate, was the mainly stimulatory factor affecting pectinase activity of landfilled refuse.

Bioreactors↗
PubMed2002

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.

Bacteria, Anaerobic↗
PubMed2005

[Phosphorus characteristics in leachate from soils irrigated with livestock wastewater].

Phosphorus fractions could enter water body from surface runoff and leachate due to excessive irrigation of centralized farm wastewater. Organic P is more mobile than inorganic P in the soil profile and represents a significant proportion of P present in leachate from irrigated farm soils. A set of parallel experiments were conducted to compare the characteristics of organic phosphorus in leachate. The experiment was established in a complete randomized block design with nine replicates. The plots received different combinations of P fertilizer and different rates of pig slurry, i. e. 100, 200,300, 400 t x (hm2 x a)(-1), accordingly, the phosphorus was added to the plots was 6.2, 12.4, 19.2, 24.8 kg x (hm2 x a)(-1), respectively. Leachate was collected over a year period and analyzed for different P fractions. Physico-chemical fractionation of P in leachate indicated that the majority of the P loss from the irrigated soil occurred in unreactive particulate (77% - 90%) P forms. 31P nuclear magnetic resonance analysis of eight leachate samples indicated that unreactive P was mainly comprised of monoester and diester forms of organic P. The presence of phosphomonoesterase and phosphodiesterase activity in leachate resulted in hydrolysis of 9% - 29% of total unreactive P (TUP), indicating that some of the monoesters and diesters can be eventually hydrolyzed into inorganic P forms during P transport. To the treatment P45 + F200, enzyme hydrolysis showed that 33% of the TUP was present as labile monoester P (LMP), followed by 17% as inositol hexakisphosphate (IHP) and 9% as diesters (phospholipids and nucleic acids). The results suggest that LMP, IHP and diesters are an important component of organic P leaching from the irrigated soil. The identification of these organic P forms will improve our understanding of the mechanisms responsible for their release from soils, so that specific mitigation strategies can be implemented at the P source.

Animals↗
PubMed2006

[Ecological effect of recirculated landfill leachate with different hydraulic loading on plant-soil system].

The ecological effect of irrigating recirculated leachate with different hydraulic loading on bermudagrass (Cynodon dactylon) and soil system was evaluated. The results show that leachate irrigation with hydraulic loading of 2.77-12.00 mm d(-1) leads to high chlorophyll content, low proline (Pro) content, as well as low malondialdehyde (MDA) and H2O2 content. Soil enzyme activities, respirations, microbial biomass and ratio of biomass carbon to organic carbon (Cmic/Corg) are rather higher. Among leachte irrigation group, leachate irrigation with hydraulic loading of 6.46-10.15 mm x d(-1) leads to declined proline, increased chlorophyll content, low POD activity and low content of MDA and H2O2. Soil bio-activity related parameters, such as soil enzyme activities, respirations, microbial biomass and Cmic/Corg are all enhanced at 6.46-10.15 mm x d(-1) of hydraulic loading. However, when hydraulic loading increases to 12.00 mm x d(-1) or declines to 2.77-4.16 mm x d(-1), the stress of irrigation on bermudagrass is aggravated, and soil bioactivity declines. The results reveal that leachate irrigation could alleviate the stress of environment on bermudagrass and improve the bio-activity of soil. The positive effect of leachate irrigation on the plant-soil system might be contributed to changes of soil water and physico-chemical property after leachate irrigated to the soil. The experimental results suggest that leachate irrigation could benefit plant-soil system, especially when controlled at suitable hydraulic loading.

Cynodon↗
PubMed2000

Bacterial Growth on Photochemically Transformed Leachates from Aquatic and Terrestrial Primary Producers.

We measured bacterial growth on phototransformed dissolved organic matter (DOM) leached from eight different primary producers. Leachates (10 mg C liter(-1)) were exposed to artificial UVA + UVB radiation, or kept in darkness, for 20 h. DOM solutions were subsequently inoculated with lake water bacteria. Photoproduction of dissolved inorganic carbon (DIC), ranging from 3 to 16 µg C liter(-1) h(-1), and changes in the absorptive characteristics of the DOM were observed for all leachates upon UV irradiation. The effects of irradiation exposure on DOM bioavailability varied greatly, depending on leachate and type of bacterial growth criterion. Bacterial carbon utilization (biomass production plus respiration) over the entire incubation period (120 h) was enhanced by UV radiation of leachate from the terrestrial leaves, relative to carbon utilization in non-irradiated leachates. Conversely, carbon utilization was reduced by radiation of the leachates from aquatic macrophytes. In a separate experiment, the stable C and N isotope composition of bacteria grown on irradiated and non-irradiated DOM was estimated. Bacterial growth on UV-irradiated DOM was enriched in (13)C relative to the bacteria in the non-irradiated treatments; this result may be explained by selective assimilation of photochemically produced, isotopically enriched labile compounds.

Journal Article↗
PubMed2006

Characterization of the leachate in an urban landfill by physicochemical analysis and solid phase microextraction-GC/MS.

The aim of this study is to evaluate extensively the characterization and identification of major pollutant parameters by paying attention to the organic chemical pollution for unregulated dumping site leachate in Eskişehir/Turkey. The study that is first and only one research has been very important data related with before new sanitary landfill site in Eskişehir city. For this purpose, in this study leachate samples were collected in-situ at monthly interval for a period of 8 months. Firstly, thirty three physicochemical parameters were monitored. Secondly, SPME technique was used for identification of organic pollutants. Meteorological data were also recorded for the same sampling period to correlate meteorological data and physicochemical parameters. Mean values are used in the correlation analysis. Correlation is shown only for the relationship between air temperature and NO(3) (-). No correlation has been found between rain and leachate quality parameters since the amount of rain was very low during the sampling period. However, analysis results were generally decreased in winter season when each parameter and each sampling point are examined separately. According to correlation between every parameter, especially solid content and dissolved oxygen concentration of leachate is affecting to other parameters. Also, sodium and potassium are changing proportionally with same parameters (suspended solids, fixed solids, dissolved oxygen) and high correlation between chloride and heavy metal concentration is showing. The results were statistically evaluated by use of SPSS 10.0 program. Second part of the study, the leachate was extracted by Solid Phase Microextraction (SPME) technique and then analyzed. Of the methodologies tested in this study, the best one selected was based on 100 micro m polydimethylsiloxane coated fiber (PDMS), headspace with heating (Delta HS) sampling mode and an extraction time of 15 min. at a temperature of 50 degrees C. Thirty three organic compounds in leachate were identified by GC/MS.

Dimethylpolysiloxanes↗
PubMed2005

Toxicological effects and reproductive impairments in female perch (Perca fluviatilis) exposed to leachate from Swedish refuse dumps.

We have previously found that leachate from a Swedish refuse dump caused toxicological effects, including endocrine disruption and reproductive failures, in feral female perch (Perca fluviatilis) from Molnbyggen and in brook trout (Salvelinus fontinalis) from Vadbäcken. This raised concerns that leachate-induced toxicity might affect fish in other leachate-contaminated lakes. This study looks at female perch from three different regions in Sweden, focusing on toxicological biomarkers (skin lesions, liver-somatic index (LSI), ethoxyresorufin O-deethylase (EROD) activity and DNA adducts) and reproductive biomarkers (number of mature females, gonadosomatic index (GSI), aromatase (P450arom), progesterone, 17alpha-hydroxyprogesterone (17alpha-OHP), testosterone (T) and 17beta-estradiol (E2)). Five out of seven contaminated locations had lower numbers of mature females and most of them exhibited higher frequencies of fin erosion relative to their comparable reference sites. Females from Lake Nedre Vättern exhibited these effects, as well as body sores, high EROD activity, high levels of DNA adducts in the liver and the intestinal mucosa, low GSI and low plasma levels of T and E2, similar to the anti-estrogenic effects earlier found in SM perch from Molnbyggen in 1997 and in brook trout from Vadbäcken. No effects on LSI, GSI, aromatase, or circulating steroids were found in mature females from Molnbyggen in this study. This indicated less leachate-contamination, but low numbers of mature females in Lake Siljan, at the sewage treatment plant which now processes the leachate that earlier contaminated Molnbyggen and Vadbäcken, suggested insufficient sewage treatment at this site. All females in Lake Simshyttsjön were mature, and their high GSI and LSI, low EROD activity, high level of 17alpha-OHP and low level of T, suggest an estrogenic rather than an anti-estrogenic effect. The results show that our earlier findings in Molnbyggen and Vadbäcken are not common, but neither are they unique. This study also shows that refuse dumps should be considered as potential point-sources for environmental pollutants, and that uncontrolled leachate-contamination of lakes and freshwater reservoirs could be a serious environmental hazard for both wildlife and humans.

Animals↗
PubMed2004

An economic analysis of leachate purification through willow-coppice vegetation filters.

In this study an economic analysis of the purification of integrated solid waste treatment facility leachates through a willow-coppice (Salix) vegetation filter in southern Sweden was carried out. Calculations were based on the use of two computer models that were initially used in estimating a pump-and-pipe irrigation system for a 36-ha willow-coppice plantation to purify an average annual quantity of 195,000 m(3) of leachate with an average nitrogen content of 24 g/m(3). Results showed that facility leachates could be purified at US dollars 0.34/m(3) compared with US dollars 0.62/m(3) for that of conventional leachate treatment at a wastewater treatment plant. Furthermore, results revealed that the increased income from willow growing and sale of the biomass chips represented only a small factor in the overall cost of the purification technique--decreasing purification costs to US dollars 0.326/m(3). Sensitivity analyses also demonstrated that, because of the large leachate holding pond expense, only a fraction of facility leachate should be treated through a vegetation filter.

Forestry↗
PubMed2005

Stress tolerance of five willow clones after irrigation with different amounts of landfill leachate.

Short-rotation willow (Salix sp.) coppice, a commercial crop grown for energy purposes, is used for phytoremediation of landfill leachate in Sweden. However, the leachate's chemical composition can cause plant damage mainly due to high NaCl and NH4 concentrations. A pot experiment was conducted in order to quantify the growth responses of five different willow clones ("78-183", "Jorr", "Loden", "Olof", "Tora") to irrigation with different leachate mixtures (corresponding to 240, 180, and 120 mg Cl l(-1)) and to assess the applicability of leaf length and leaf fluctuating asymmetry as stress indicators. A series of plant traits (shoot, root and leaf dry weight, leaf area, leaf length and leaf fluctuating asymmetry) were measured. The irrigation with leachate resulted in reduced relative growth rates but there were no clear differences between the different concentrations. The clones "Jorr" and "Loden" performed best in terms of differences in relative growth rate between control and leachate treatments. Leaf length appeared to be a useful stress diagnostic tool for use in situ showing a high correlation to growth, whereas fluctuating asymmetry showed no such correlation. Higher N, lower P and higher Na concentrations in plant stems treated with leachate than control plants were observed.

Genetic Variation↗
PubMed2004

Treatment of landfill leachate by ozone-based advanced oxidation processes.

In this study, laboratory experiments are conducted to compare the efficacy using several ozone-based advanced oxidation processes (AOPs), such as O3, O3/H2O2, and O3/UV, to treat landfill leachate. Raw leachate was initially coagulated by ferric chloride (FeCl3) at the experimental-determined optimal dosage of 900 mgl(-1), and the ozone-based AOPs were subsequently applied. Results indicate that all AOPs would result in a significant increase on the ratio of BOD5/COD from 0.06 to 0.5 at the applied ozone dosage of 1.2 gl(-1). The increase on biodegradability for ozonated leachate indicates that these AOPs would be beneficial to the subsequent biological treatment process. To better explain the alteration of high organic molecules after oxidation, ultrafiltration was used to separate the leachate by several molecular weight cutoffs (MWCO). The COD distribution for coagulated leachate is 34% for MWCO>10 kDa, 7% for MWCO between 5 and 10 kDa, 22% for MWCO between 1 and 5 kDa, and 37% for MWCO<1 kDa. Following ozonation or AOPs, the predominant distribution of COD would be obviously shifted to the MWCO less than 1000 gmol(-1) (72-85%) over the other MWCO ranges. In addition, Gel Permeation Chromatograph (GPC) analysis has showed a substantial agreement on the cleavage of larger organic compounds into smaller ones. O3/UV was found to be the most effective approach among these ozone-based AOPs to enhancing the biodegradability and eliminating the color of leachate.

Biodegradation, Environmental↗
PubMed2004

Landfill leachate management in Istanbul: applications and alternatives.

Treatment alternatives for Istanbul, Komurcuoda Landfill (KL) leachate that is currently transported to the nearest central wastewater treatment plant were comprehensively investigated with laboratory scale experiments. As flow rate of leachate increases parallel to increment in landfilled solid waste, an individual treatment will be needed to reduce the transportation cost and pollution load on central treatment. However, if the leachate is separately treated and discharged to a brook, in that case more stringent discharge standards will be valid and therefore advanced processes in addition to conventional ones should be included. In laboratory scale experiments, the young landfill leachate having BOD5/COD ratio above 0.6 was successfully treated with efficiencies above 90% in upflow anaerobic reactors if pH is kept below free ammonia inhibition level. Subsequently, nitrification of anaerobically treated leachate was performed with rates of about 8.5 mg NH4+-Ng-1 VSS h-1 and efficiencies above 99% were provided with automated pH regulation by using sodium bicarbonate. Furthermore, denitrification rates as high as 8.1 mg NOx-N g-1VSS h-1 was obtained when carbon source was externally supplied. In addition to nitrification and denitrification, air stripping and struvite precipitation were also applied to remove ammonia in leachate and in average 94% and 98% efficiencies were achieved, respectively. Finally, in average 85% of biologically inert COD was successfully removed by using either ozone or Fenton's oxidation.

Ammonia↗