Refuse Landfill Research Articles

Leachate treatment using a demonstration aged refuse biofilter

Approximately 7000 m 3 of aged refuse (AR) with a placement of over eight years was excavated from Shanghai Refuse Landfill, the largest landfill in China, and used for the construction of a two-stage bioreactor (AR biofilter) media for the biological treatment of 100 m 3 of refuse landfill leachate. It was found that over 64% of COD, 96.9%–99.8% of NH 4 +-N, and 95.8%–99.8% of BOD 5 could be removed by the AR biofilter, when the leachate with initial COD, BOD 5, and NH 4 +-N concentrations were 986–4128 mg/L, 264–959 mg/L, and 538–1583 mg/L, respectively. The corresponding concentrations in the effluent were reduced to below 300–400 mg/L, 2–12 mg/L, and 10–20 mg/L, respectively. The effluent was clear and pale yellow with suspended solid below 150 mg/L and color below 150 Pt/Co degree. Meanwhile, the total nitrogen removal was only 49%–63%, indicating a relative poor denitrification capacity of AR biofilter. The effluent pH was neutral and the population of Escherichia coli was less than 10 −1 CFU/mL. Hence, it was considered that the demonstration project can work well for the effective treatment of leachate.

Effect of bio-column composed of aged refuse on methane abatement – A novel configuration of biological oxidation in refuse landfill

An experimental bio-column composed of aged refuse was installed around the exhaust pipe as a new way to mitigate methane in refuse landfill. One of the objectives of this work was to assess the effect of aged refuse thickness in bio-column on reducing CH 4 emissions. Over the study period, methane oxidation was observed at various thicknesses, 5 cm (small size), 10 cm (middle size) and 15 cm (large size), representing one to three times of pipeline diameters. The middle and large size both showed over 90% methane conversion, and the highest methane conversion rate of above 95% occurred in the middle-size column cell. Michaelis-Menten equation addressed the methanotrophs diffusion in different layers of the bio-columns. Maximum methanotrophic activity ( V max) measured at the three thicknesses ranged from 6.4 × 10 −3 to 15.6 × 10 3 units, and the half-saturation value ( K M) ranged from 0.85% to 1.67%. Both the highest V max and K M were observed at the middle-size of the bio-column, as well as the largest methanotrophs population, suggesting a significant efficiency of methane mitigation happened in the optimum zone with greatest affinity and methanotrophic bacteria activities. Therefore, bio-column is a potential style for methane abatement in landfill, and the aged refuse both naturally formed and artificially placed in the column plays a critical role in CH 4 emission.

Landfill Refuse Stabilization Process Characterized by Nutrient Change

Abstract Landfill stabilization was investigated with nutrient change in aged refuse excavated from 3- to 15-year-old capped cell compartments at Shanghai Laogang Refuse Landfill, China. Field samples were characterized by total nitrogen (TN), available nitrogen (AN), total phosphate (TP), available phosphate (AP), total potassium (TK), available potassium (AK), total organic matter (TOC), and heavy metals (HM). Concentrations of TN, TP, TK, and organic matter contents in aged refuse ranged between 2.30 and 5.50, 2.13 and 7.43, 23.07 and 38.75 mg·g−1, and 6.32 and 11.57%, respectively, and these values apparently declined with disposal time. Physical properties of the composition in aged refuse indicated that the percentage of larger fractions, that is, stone/tile, fiber/fabric/paper, and wood/bamboo/bone, decreased slightly over time, whereas the proportions of finer fractions (Y) (≤40 mm) increased as refuse age increased, following a logarithmic equation: Y = 33.345*Ln (t, years) − 20.406 (R2 = 0.9738)...

Natural attenuation and characterization of contaminants composition in landfill leachate under different disposing ages

Chemical Oxygen Demand (COD) composition in landfill leachate would vary as the disposal time extended. Leachates with different ages were collected from Laogang Refuse Landfill of Shanghai, the largest landfill in China with a placement scale of 7600 t refuse per day. To characterize COD composition in leachate, samples were size-fractioned into suspended fractions (> 0.45 μm), colloid fraction (0.45 μm < fraction < 1 K Da MW) and dissolved fractions (< 1 KDa MW) based on the molecular weight distribution. The fractions < 0.45 μm (including colloid fraction and dissolved fractions) in leachate were further divided into 6 fractions, i.e. hydrophobic bases (Ho-base), hydrophobic acids (Ho-acid), hydrophobic neutral (Ho-neutral), hydrophilic bases (Hi-base), hydrophilic acids (Hi-acid) and hydrophilic neutral (Hi-neutral). It was found that the ratio of TOC/TC in leachate decreased over time, indicating that the percentage of organic matters in leachate decreased as the disposal time extended. It was also observed that the hydrophobic fraction accounted to about 50% of the total matters presented in the fraction < 0.45 μm of all leachate samples. The main components in < 0.45 μm fraction were the Ho-acid, Hi-acid and Hi-base fractions. The percentage of Ho-acid in leachate decreased from 60.8% (2 a) to 43.2% (12 a). In addition, leachate with different ages was categorized into 3 phases according to the results of Principle component analysis (PCA). TOC/COD ranges of leachate in periods I, II and III were 40–54.6%, 16.9–41.3% and 10–38.9%, respectively, indicating that the COD contribution of non-carbon reduction substances increased over time in leachate. Hence, the corresponding landfill leachate treatment process should be modified according to the leachate characterization. The results obtained in this study might provide the important information for modeling, design, and operation of landfill leachate treatment systems.

Characterization of refuse landfill leachates of three different stages in landfill stabilization process

Landfill leachates with different ages (mature leachate, 11 years; semi-mature leachate, 5 years; fresh leachate, under operation) were collected from Laogang Refuse Landfill, Shanghai to characterize the colloid size distribution and variations of leachate. These leachates were separated using micro-filtration and ultra-filtration into specific size fractions, i.e., suspended particles (SP) (> 1.2 microm), coarse colloids (CC) (1.2-0.45 microm), fine colloids (FC) (0.45 microm, 5 kDa/1 kDa molecular weight (MW)), and dissolved organic matters (DM, < 5 kDa/1 kDa MW). The specific colloids in each size fraction were quantified and characterized through chemical oxygen demands (COD), total solid (TS), pH, NH4+-N, total organic carbon (TOC) and fixed solid (FS). It was found that COD, NH4+-N and TS in leachate decreased significantly over ages, while pH increased. The dissolved fractions (< 5 kDa/1 kDa) dominated (over 50%) in three leachates in terms of COD, and the organic matter content in dissolved fraction of leachates decreased and the inorganic matter increased as the disposal time extended, with the TOC/COD ratio 30%-7%. Dissolved fractions decreased from 82% to 40% in terms of TOC as the disposal time extended, suggested that the organic matter remained in leachate would form into middle molecular weight substances during the degradation process.

Three-stage aged refuse biofilter for the treatment of landfill leachate

A field-scale aged refuse (AR) biofilter constructed in Shanghai Refuse Landfill, containing about 7000 m3 aged refuse inside, was evaluated for its performance in the treatment of landfill leachate. This AR biofilter can be divided into three stages and can manage 50 m3 landfill leachate per day. The physical, chemical, and biological characteristics of AR were analyzed for evaluating the AR biofilter as leachate treatment host. The results revealed that over 87.8%-96.2% of COD and 96.9%-99.4% of ammonia nitrogen were removed by the three-stage AR biofilter when the influent leachate COD and ammonia nitrogen concentration were in the range 5478-10842 mg/L and 811-1582 mg/L, respectively. The final effluent was inodorous and pale yellow with COD and ammonia nitrogen below 267-1020 mg/L and 6-45 mg/L, respectively. The three-stage AR biofilter had efficient nitrification but relative poor denitrification capacity with a total nitrogen (TN) removal of 58%-73%. The external temperature of AR biofilter did not influence the total ammonia nitrogen removal significantly. It was concluded that the scale-up AR biofilter can work very well and can be a promising technology for the treatment of landfill leachate.

Bio-hydrogen production from food waste and sewage sludge in the presence of aged refuse excavated from refuse landfill

In this work, the aged refuse (AR) excavated from a typical refuse landfill with over 10 years of placement was used for the enhancement of bio-hydrogen production from food wastes. Firstly, the food wastes taken from a university dining hall were inoculated with sewage sludge (SL) pre-treated by 15 min heating at 80 °C. It was found that below 0.4% of hydrogen concentration could be detected in the biogas produced due to its severe acidification properties. However, the addition of AR (50% in weight) can considerably increase the hydrogen concentration in the biogas to over 26.6% with pH ascending from 4.36 to 5.81, in comparison with 4–6% using activated carbon as additive with pH descending from 4.43 to 3.91. Meanwhile, it was also found that the hydrogen content in the biogas decreased drastically to 3.3% when the AR was sterilized by heating at 160 °C for 2 h and then used as additive for bio-hydrogen production from food wastes, indicating that the AR may chiefly function as a microbial inoculum instead of a porous material like activated carbon. Statistical analysis showed that the ultimate hydrogen production potential ( H p), hydrogen production rate ( R max) and lag-phase time ( λ) were found to be 193.85 mL/gVS, 94.35 mL/(h gVS), 15.28 h, respectively, in the presence of 50% AR, and the optimal mixing ratios were 100:50 (wet weight) for food wastes to AR and 100:30 (dry weight) for food wastes to sewage SL, respectively.

In situ simultaneous organics and nitrogen removal from recycled landfill leachate using an anaerobic–aerobic process

An anaerobic–aerobic process including a fresh refuse landfill reactor as denitrifying reactor, a well-decomposed refuse reactor as methanogenesis reactor and an aerobic activated sludge reactor as nitrifying reactor was operated by leachate recirculation to remove organic and nitrogen simultaneously. The results indicated that denitrification and methanogenesis were carried out successfully in the fresh refuse and well-decomposed landfill reactors, respectively, while the nitrification of NH 4 + – N was performed in the aerobic reactor. The maximum organic removal rate was 1.78 kg COD/m 3 d in the well-decomposed refuse landfill reactor while the NH 4 + – N removal rate was 0.18 kg NH 4 + – N /m 3 d in the aerobic reactor. The biogas from fresh refuse reactors and well-decomposed refuse landfill reactors were consisted of mainly carbon dioxide and methane, respectively. The volume fraction of N 2 increased with the increase of NO 3 - – N concentration and decreased with the drop of NO 3 - – N concentration. The denitrifying bacteria mustered mainly in middle layer and the denitrifying bacteria population had a good correlation with NO 3 - – N concentration.

Recycling of aged refuse from a closed landfill

In this study, refuse excavated from a typical refuse landfill in Shanghai after 8-10 years of placement was characterized in terms of particle size, total nitrogen, total phosphorus, and biodegradable matter. The refuse contained a large and diverse population of micro-organisms with a high capacity for decomposing refractory organic matter present in some wastewaters, including leachate. It was found that the aged refuse was quite stable after about a decade of decomposition in the warm, humid climate of southern China. The fine fractions resembled and had the properties of black soil, a medium that is suitable for green construction, organic fertilizer, or as bioreactor media for biological treatment of organic wastewaters. Excavation of the aged refuse would make about 50% of the space available for fresh refuse. The plastics, glass, textiles, and cans can be readily mechanically separated and recycled after cleaning. It is estimated that at least 200 millions tonnes of such aged refuse are available in China alone, and at least 10 times that much is buried worldwide. Hence, the evaluation of mined landfill waste and consideration of its potential uses is of great significance.

Analysis of Long-Term Settlement of Municipal Solid Waste Landfills as Determined by Various Settlement Estimation Methods

In this study, several existing municipal solid waste (MSW) settlement estimation methods are reviewed and applied to analyze the settlement data of nine MSW land-fills. Because a biodegradation-related settlement contributes differently to a long-term total settlement depending on the age of landfills, the actual MSW landfill sites are classified into three groups to specifically address the validity of each method in its prediction of a long-term settlement for each age category. Results demonstrate that there are considerable decreases in predicted settlement potentials as fill age increases. Comparisons indicate that the individual estimation methods display a considerable variation in predicting settlements in the fresh MSW landfills. On the other hand, for the old refuse landfills, all of the estimation methods, except the extended soil model, predict low settlement potentials.

Size-fractionation and characterization of refuse landfill leachate by sequential filtration using membranes with varied porosity

Fresh leachate and effluents samples were collected from the holding tank, anaerobic, anoxic, and aerobic lagoons at Shanghai Laogang Refuse Landfill, the largest landfill in China with a placement scale of 9000 t refuse per day. To characterize the difference in leachate along the treatment processes, especially the information about size distribution of colloids in those leachate, the organic matters were size-fractioned into suspended particles (SP, >1.2 μm), coarse colloids (CC, 1.2–0.45 μm), fine colloids (FC, 0.45 μm to 1 kDa MW, 1 Da = 1/16 O atomic mass unit), and dissolved organic matters (DM, <1 kDa MW) using micro-filtration and ultra-filtration membranes in order. The parameters, such as COD (chemical oxygen demand), TOC (total organic carbon), TS (total solid), pH, TP (total phosphate), TN (total nitrogen), FS (fixed solid), NH 4 +, IC (inorganic carbon), TC (total carbon), color, turbidity and conductivity in the filtrates resulting from sequential filtration of leachate, were then determined, and quantitative relationships between these parameters and the membrane molecular sizes used were established. Typically, the total removal of COD, NH 4 +, conductivity and P were found to be 75%, 75%, 42% and 85%, respectively, after the biological treatment processes used at Laogang Refuse Landfill. Dissolved fractions were predominant in fresh leachate and in effluents from treatment processes in terms of TOC with a content of over 47%. The molecular weight (MW) percentage distribution in leachate varied as the leachate was treated in the biological treatment stages. The percentages of TOC of fine colloid fractions increased from 6% to 38% while those of dissolved fractions decreased from 78% to 47%. TN in leachate also predominated in the dissolved fraction, occupying over 58%, while those TP in leachate were combined with the SS and CC fractions. The ratios of ortho-phosphate/TP and NH 4 +/TN in leachate and effluents were over 50% and 80%, respectively.

Treatment of sewage using an aged-refuse-based bioreactor

The refuse in landfills becomes stabilized or aged after years of placement, and the resultant partly or fully stabilized refuse thus obtained is referred to as “aged refuse” in this work. The aged refuse contains a wide spectrum and large quantity of microorganisms, which have been proved to have a strong decomposition capability for both biodegradable and refractory organic matter present in some wastewaters. In this study, the aged refuse excavated from a 10-year old closed landfill compartment at Shanghai Refuse Landfill was used as the substrate in a bioreactor for the biofiltration of sewage taken from the sewage pipeline systems in Shanghai downtown areas. Typically, 120 kg of screened aged refuse with a diameter less than 15 mm was used as biofiltration material in a round shaped bioreactor with an inner diameter of 80 cm and a height of 150 cm. Influent sewage with initial COD, BOD, and NH 3-N concentrations of 400–500, 240–300, and 45–50 mg/L, respectively, was introduced into the bioreactor. The corresponding concentrations in the effluent were reduced to below 80–100, 10–20, and 10–15 mg/L, respectively, at a hydraulic load of 1000–1200 L/m 3 refuse/day, and the treatment efficiencies decreased with increased hydraulic load. The treatment mechanismwas also studied. It was found that the pollutant removal efficiencies dramatically decreased when the aged refuse in the bioreactor was preliminarily disinfected using NaClO solutions, indicating that the pollutants in the sewage were biologically removed. The treatment process developed in this work is cost-effective.

Use of an Aged-Refuse Biofilter for the Treatment of Feedlot Wastewaters

Refuse in the landfills and dumping sites becomes stabilized or aged over time. The aged refuse contains a wide spectrum and large quantity of micro-organisms, which can effectively decompose refractory organic matter present in some wastewaters, such as MSW landfill leachate. In this study, a biofiltration reactor consisted of the aged refuse excavated from a 10-year-old closed landfill compartment in the Shanghai Refuse Landfill (SRL) was used for biofiltration of livestock and poultry waste water sampled from a farm. Two hundred kilograms of screened aged refuse (diameter less than 15 mm) was used as biofiltration material in a cylindrical biofilter with a 40-cm inner diameter and a 150-cm height. Around 50 L/day (at a hydraulic load of 250 L/m3 refuse/day) of the preliminary-treated influent livestock wastewaters with initial CODCr, BOD5, NH3-N, total phosphorus concentrations of 197-2,419, 102-459, 260-1,140, and 24-102 mg/L, was intermittently sprayed over the refuse surface once a day with 3 h per interval. The pollutant concentrations were reduced to below 185 mg/L CODCr, 15 mg/L BOD5, 27 mg/L NH3-N, and 0.5 mg/L total phosphorus, with a removal of 64, 54, 75, 88, 94, and 99%, respectively. However, the removal of the total N is quite low, only around 20-30%. The NH3-N is mainly converted to nitrate N. The removal of the total P is high, possibly because of the strong chemical absorption capacity of the aged refuse in the biofiltration reactor used. The effluent looks clear, in contrast to the brownish color of the influent. The treatment process developed is cost-effective and easily operated.

A risk factor analysis of municipal domestic refuse landfills using a reactor with high water input.

Collapse, explosion and water pollution by leachate have been three major problems in confining the development of sanitary landfilling technology as an economical method for disposal of municipal refuse. Potential risk factors including settlement of landfilled refuse, the generation of methane, carbon dioxide and other gases from landfill, the dynamic changes in temperature within the landfill and its ambient environment, as well as COD(Cr), BOD5, nutrients (TKN, TP and organic matter), heavy metals (Cu, Pb and Zn) and pH in landfill leachate were simulated using a reactor with high water input. It was indicated that high content of organic components in landfilled refuse is a key risk factor to cause abrupt collapse and accidental explosion in the landfill because they have impact not only on the settlement, but also on the release of methane and other gases. Elevated temperatures coincided with maximum generation of methane and other gases, thus increasing the risk of accidental explosion. Leachate quality was closely related with the release of COD(Cr) and BOD5 and heavy metals such as Cu, Pb and Zn, as well as organic pollutants, there was less release of TKN and TP. The mass balance analysis for the reactor showed that 36% of organic carbon reduction in the refuse during the simulations was discharged into leachate as soluble organic carbon, and 3% was converted to methane and carbon dioxide as gas production. Mixing of refuse with soil and sand particles, the so-called drill-a-hole method and recycling leachate were measures suggested in order to mitigate and avoid potential accidents.

Treatment of Leachate by Aged-Refuse-based Biofilter

Refuse in landfills becomes stabilized or aged, as organic matter in the refuse gradually degrades and as the soluble inorganic substances dissolve during its long-term stabilization process. Within this paper, this process is referred to as mineralization and the resultant stabilized or essentially stabilized refuse is referred to as “aged refuse.” The aged refuse contains a wide spectrum and large quantity of microorganisms, which have a strong decomposition capability for refractory organic matter present in some wastewaters, such as leachate. In this study, aged refuse excavated from two to ten year old closed landfill compartments in Shanghai Refuse Landfill (SRL) was characterized in terms of particulate distribution by screening, and a biofilter consisting of ten year old aged refuse was then used for biofiltration of leachate sampled from the landfill. Typically, 400 kg of screened aged refuse with limiting diameter less than 15 mm was used as biofiltration materials in a round shaped biofilter wi...

A comparison of refuse attenuation in laboratory and field scale lysimeters

For this study, small and middle scale laboratory lysimeters, and a large scale field lysimeter in situ in Shanghai Refuse Landfill, with refuse weights of 187, 600 and 10,800,000 kg, respectively, were created. These lysimeters are compared in terms of leachate quality (pH, concentrations of COD, BOD and NH 3–N), refuse composition (biodegradable matter and volatile solid) and surface settlement for a monitoring period of 0–300 days. The objectives of this study were to explore both the similarities and disparities between laboratory and field scale lysimeters, and to compare degradation behaviors of refuse at the intensive reaction phase in the different scale lysimeters. Quantitative relationships of leachate quality and refuse composition with placement time show that degradation behaviors of refuse seem to depend heavily on the scales of the lysimeters and the parameters of concern, especially in the starting period of 0–6 months. However, some similarities exist between laboratory and field lysimeters after 4–6 months of placement because COD and BOD concentrations in leachate in the field lysimeter decrease regularly in a parallel pattern with those in the laboratory lysimeters. NH 3–N, volatile solid (VS) and biodegradable matter (BDM) also gradually decrease in parallel in this intensive reaction phase for all scale lysimeters as refuse ages. Though the concrete data are different among the different scale lysimeters, it may be considered that laboratory lysimeters with sufficient scale are basically applicable for a rough simulation of a real landfill, especially for illustrating the degradation pattern and mechanism. Settlement of refuse surface is roughly proportional to the initial refuse height.

Monitoring and long-term prediction of refuse compositions and settlement in large-scale landfill.

Settlement and changes in refuse composition for total sugar, raw cellulose, biological degradable matter, volatile solid, organic carbon, were monitored in a large-scale experimental landfill unit and closed landfill units at Shanghai Refuse Landfill from April 1995 through to October 1998. Mathematical simulation formulae between these parameters and refuse age were developed based on the data obtained from the experimental landfill unit and validated by data from landfill units closed in April of 1991, 1992, 1993 and 1994. Long-term predictions for these parameters for the landfill were made using these formulae. It was predicted that the refuse might be fully mineralized and the cumulative settlement might be over 30% of the initial height after around 22 to 30 years. The stabilization process and reuse approaches for landfills based on the compositions and settlement are discussed.

Long-term Monitoring and Prediction for Leachate Concentrations in Shanghai Refuse Landfill

Parameters such as pH, concentrations of Cl-, turbidity,NH3-N, CODCr and BOD5 (simplified as COD and BODrespectively in the following text) in leachate generated inthe large-scale testing landfill unit and closed landfill unitsat Shanghai Refuse Landfill were monitored from April 1995 toOctober 1998. The mathematical simulation formula between theseparameters and refuse age were established based on the dataobtained from the testing landfill unit and justified by thedata obtained at the closed landfill units from 1989 to 1993.The long-term predictions for the leachate concentrations forthe Landfill were made using the mathematical simulation formulaestablished. It was predicted that the COD and BOD may bereached to the strictest standard for pollution control on municipal solid wastes landfill in China, i.e., COD < 100 mg L-1 and BOD < 30 mg L-1, after 15 yr natural attenuation. The time predicted for NH3-N concentrations to reach the discharging standard, 15 mg L-1, was found to be at least 23–26 yr or even longer. The predictions for concentrations of Cl-, turbidity, and pH values in leachate are also given. The natural attenuation of Cl- is the slowest and might be decreased to 200 mg Cl- L-1, the agricultural irritation standard, after at least 58 yr.

Sanitary Landfills, Stigma and Industrial Land Values

A significant literature exists that documents reductions in property value around toxic, chemical and in some cases solid waste landfills. There is also an emerging literature on stigma-related damage, which can be defined as a loss in value due to the increased risk associated with a contaminated property even after the problem has been eliminated. This research extends the empirical literature on landfills by examining the impact that solid waste landfills have on surrounding industrial property. The results indicate that the value of industrial land around an open, solid waste landfill is reduced by the presence of the landfill. Property around closed, solid waste landfills and open and closed refuse landfills is not adversely affected by the landfills. These results are not affected by the presence or absence of methane gas controls and ground water monitoring systems. Landfills sold with industrial zoning are discounted substantially by the market for various reasons, probably including limited alte...

Geotechnical survey of refuse landfill ground in the Port of Tokyo : Shimizu, K Proc International Conference on Geotechnical Engineering for Coastal Development, GEO-COAST'91, Yokahama, 3–6 September 1991P75–80. Publ Japan: Coastal Development Institute of Technology, 1991

Geotechnical survey of refuse landfill ground in the Port of Tokyo : Shimizu, K Proc International Conference on Geotechnical Engineering for Coastal Development, GEO-COAST'91, Yokahama, 3–6 September 1991P75–80. Publ Japan: Coastal Development Institute of Technology, 1991