Semi-aerobic Landfill Research Articles

Preparation of tamarind fruit seed activated carbon by microwave heating for the adsorptive treatment of landfill leachate: A laboratory column evaluation

The preparation of tamarind fruit seed granular activated carbon (TSAC) by microwave induced chemical activation for the adsorptive treatment of semi-aerobic landfill leachate has been attempted. The chemical and physical properties of TSAC were examined. A series of column tests were performed to determine the breakthrough characteristics, by varying the operational parameters, hydraulic loading rate (5–20mL/min) and adsorbent bed height (15–21cm). Ammonical nitrogen and chemical oxygen demand (COD), which provide a prerequisite insight into the prediction of leachate quality was quantified. Results illustrated an encouraging performance for the adsorptive removal of ammonical nitrogen and COD, with the highest bed capacity of 84.69 and 55.09mg/g respectively, at the hydraulic loading rate of 5mL/min and adsorbent bed height of 21cm. The dynamic adsorption behavior was satisfactory described by the Thomas and Yoon–Nelson models. The findings demonstrated the applicability of TSAC for the adsorptive treatment of landfill leachate.

Preparation of activated carbon from sugarcane bagasse by microwave assisted activation for the remediation of semi-aerobic landfill leachate

This study evaluates the sugarcane bagasse derived activated carbon (SBAC) prepared by microwave heating for the adsorptive removal of ammonical nitrogen and orthophosphate from the semi-aerobic landfill leachate. The physical and chemical properties of SBAC were examined by pore structural analysis, scanning electron microscopy, Fourier transform infrared spectroscopy and elemental analysis. The effects of adsorbent dosage, contact time and solution pH on the adsorption performance were investigated in a batch mode study at 30°C. Equilibrium data were favorably described by the Langmuir isotherm model, with a maximum monolayer adsorption capacity for ammonical nitrogen and orthophosphate of 138.46 and 12.81mg/g, respectively, while the adsorption kinetic was best fitted to the pseudo-second-order kinetic model. The results illustrated the potential of sugarcane bagasse derived activated carbon for the adsorptive treatment of semi-aerobic landfill leachate.

Odour Nuisance near Semi-Aerobic Landfill: A Distance-Based Study in Malaysia

Odour Nuisance near Semi-Aerobic Landfill: A Distance-Based Study in Malaysia

生ごみ主体の準好気性埋立構造からの浸出水発生メカニズム

生ごみの直接埋立が主体である開発途上国では，準好気性埋立構造における生ごみ由来の浸出水量は，埋立条件によっては，降水由来の浸出水量と比較して無視できないと考えられる。そこで本研究では，生ごみを充填して行った準好気性埋立構造の大型埋立実験槽の物質収支を考慮して，埋立廃棄物層内部の主要な物質変換である有機物生物分解過程に関する既往の知見に基づき，化学量論的に関連する物質量 (H2O等) の推定法を考案し，この推定法に基づいて実験データを再解析した。その結果，生ごみとともに運び込まれた水分に生ごみの生物分解に伴う生成水が加わった保有水が，埋立廃棄物層の沈下に伴って浸出水となる浸出水発生メカニズムを明らかにすることができた。また，降水由来の浸出水量と生ごみ由来の浸出水量は，一定の条件下においては，それぞれ独立して算出することが可能であることを明らかにすることができた。

Assessment of internal condition of waste in a roofed landfill

Recently, roofed landfills have been gaining popularity in Japan. Roofed landfills have several advantages over non-roofed landfills such as eliminating the visibility of waste and reducing the spread of offensive odours. This study examined the moisture balance and aeration conditions, which promote waste stabilisation, in a roofed landfill that included organic waste such as food waste. Moisture balance was estimated using waste characterization and the total amount of landfilled waste. Internal conditions were estimated based on the composition, flux, and temperature of the landfill gas. Finally, in situ aeration was performed to determine the integrity of the semi-aerobic structure of the landfill.With the effects of rainfall excluded, only 15% of the moisture held by the waste was discharged as leachate. The majority of the moisture remained in the waste layer, but was less than the optimal moisture level for biodegradation, indicating that an appropriate water spray should be administered. To assess waste degradation in this semi-aerobic landfill, the concentration and flow rate of landfill gas were measured and an in situ aeration test was performed. The results revealed that aerobic biodegradation had not occurred because of the unsatisfactory design and operation of the landfill.

Influence of Cowl on the Spatial Distribution of Oxygen in Semi-Aerobic Landfill

To elevate the air flow rate in vent pipes of semi-aerobic landfill, promote oxygen transmit into waste and methane mitigation, a wind-driven cowl was fixed on one of the two semi-aerobic landfills’ vent pipe. With the aim of figuring out the influence of cowl on the spatial distribution of oxygen under different climates, wind speeds were set at 3 m/s, 5 m/s, 7 m/s and 0 m/s sequentially. Oxygen concentrations and temperatures were recorded once a week. Data from experimental results indicated that oxygen concentrations went up along with the height above the bottom of landfill after deducting the oxygen transported by leachate collection pipes. Average oxygen concentrations except the surface layer were 3.5%, 4.2%, 3.8%, 3.0% for S-A with cowl and 2.9%, 3.4%, 3.7%, 3.0% for S-A under the wind speeds of 3 m/s, 5 m/s, 7 m/s, 0 m/s, respectively. Meantime, the aerobic radius in S-A with cowl were 0.84 m, 1.01 m, 0.87 m, 0.62 m and 0.76 m, 0.84 m, 0.87 m, 0.65 m in S-A. The effect of the cowl on oxygen transmission maximized at the wind speed of 5 m/s. It is clearly that wind energy can be better used on enhancing the ventilation in vent pipe and expanding aerobic radius after application of cowl.

Color and Chemical Oxygen Demand Removal from Mature Semi-Aerobic Landfill Leachate Using Anion-Exchange Resin: An Equilibrium and Kinetic Study

Abstract Stabilized leachate generated from an aged sanitary landfill is typically classified as nonbiodegradable. The ion exchange technique has been rarely used for the treatment of stabilized landfill leachate, particularly for the removal of color and nonbiodegradable substances (measured as chemical oxygen demand [COD]). Thus, this study was undertaken to examine the effectiveness of anion-exchange resin (i.e., INDION FFIP MB) in removing color and COD from stabilized semi-aerobic landfill leachate in Malaysia. To predict the performance of the process, the effects of anion exchanger dosage, shaking speed, contact time, and pH on pollutant removal efficiency were investigated. Adsorption of color and COD was realistically explained through Langmuir and Freundlich isotherms. Adsorption kinetics mechanism was studied using reaction-based models. The anionic resin efficiently removed 91.2% color and 69.4% COD at pH 3 and removed only 69.4% color and 60.3% COD at pH 9. The color and COD adsorption data w...

Assessment of Gases Emission from the Operation of the Semi-Aerobic Landfill Site by Solid Waste of Kathmandu Valley, Nepal

Many landfill sites around the world have been poorly engineered and operated and hence face vociferous public opposition and criticism for their adverse environmental impacts. Because of the concerns arising from poor operation and management, siting and operation of landfill sites are very sensitive public issues in Nepal. The aim of this study was to assess the environmental impacts due to the foul odour during the operation of the the Sisdol landfill in Okharpauwa VDC, Nuwakot, Nepal. The study focused on identifying the composition of gases from the Kathmandu Valley's solid waste and impacts on local areas air flow moments from the land fill site. LandGEM Ver.3.02 Model was used for the emission calculation of the landfill gases. Furthermore, the gastec and specified ditector tubes were used for the measurement of H2S gas at the study area. Among nine sites, the H2S gas concentration at site (Vent pipe of landfill site) was 1.4 ppm (recorded maximum). The gas was found to be diluted at 208m downwind location and reached the value near to clean air, i.e., 0.2 ppb. The observed gas concentration was lower than the toxic range though the concentration level was found to have characteristic odour. The significant level of adverse impact was found nearby the landfill site. People working surrounding area of the landfill site were more vulnerable to different impacts.

Effect of biocover equipped with a novel passive air diffusion system on microbial methane oxidation and community of methanotrophs

A novel biocover with passive air diffusion system (PADS) was designed in this study. Its effect on landfill gas components in the macrocosms of simulated biocover systems was also investigated. The results show that O2 concentration increased in the whole profile of the macrocosms equipped with PADS. When simulated landfill gas (SLFG) flow rate was no more than 40 mL min−1, the methane oxidation rate was 100%. The highest CH4 oxidation capacity reached to 31.34 mol m−3 day−1. Molecular microbiology analysis of the soil samples taken from the above macrocosm showed that the growth of type I methanotrophs was enhanced, attributable to enhanced air diffusion and distribution, whereas the microbial diversity and population density of type II methanotrophs were not so affected, as evidenced by the absence of any difference between the biocover equipped with PADS and that of the control. According to a phylogenic analysis, Methylobacter, Methylosarcina for type I, and Methylocystis, Methylosinus for type II, were the most prevalent species in the macrocosm with PADS. Implications Semiaerobic landfill technology was reported to be an effective in situ CH4 emission reduction method. A semiaerobic status is achieved through a continuous supply of fresh air sucked passively through the open end of a leachate collection pipe, with a temperature gradient created by organic matter degradation. In this research, a novel passive air diffusion system (PADS) was designed, and O2 concentration increased in the whole profile of the microcosms equipped with PADS. The constant supply of fresh air reduced CH4 production and enhanced biodegradation. Through molecular microbiology analysis, it was found that growth of methanotrophs was enhanced, and species of prevalent methanotrophs were found. Supplemental Materials Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of the Air & Waste Management Association for a list of abbreviations and PCR protocol.

Sustainable Approach for Landfill Management at Final Processing Site Cikundul in Sukabumi City, Indonesia

The main problem of landfill management in Indonesia is the difficulty in getting a location for Final Processing Sites (FPS) due to limited land and high land prices. Besides, about 95% of existing landfills are uncontrolled dumping sites, which could potentially lead to water, soil and air pollution. Based on data from the Ministry of Environment (2010), The Act of the Republic of Indonesia Number 18 Year 2008 Concerning Solid Waste Management, prohibits open dumping at final processing sites and in ratification, the Local Governments have to convert the open dump sites into controlled or sanitary landfill. The Research Institute for Human Settlements has been conducting multi-year researches related to the rehabilitation of dumpsites toward sustainable landfill. The research methods are literature reviews, experiments, laboratory analysis and field observations. A pilot model of dumpsite rehabilitation was carried out in 2010 at the Final Processing Site at Cikundul in Sukabumi City, consisting of (1) mining landfill (2) construction of landfill cells in a former mining area with a semi aerobic landfill and an anaerobic landfill and (3) landfill operations using decomposed material from landfill mining as a soil cover. The purpose of the study is to develop a sustainable approach for landfill management and rehabilitation through landfill mining and implementation of semi aerobic landfill. Findings in the construction of landfill mining indicate that (1) the construction of landfill mining is constrained by leachate that is trapped in a pile of waste, therefore, the leachate needs to be pumped to leachate treatment installations, (2) the volume of waste excavation is expanding due to the high plastic content of about 26% in landfills (3) the potency of decomposed materials from landfill mining is 40– 83% for landfill operations or greening.. The performance of landfill systems shows that leachate quality of semi aerobic landfill tends to be lower than that of anaerobic landfill. Gas composition at semi aerobic landfill in FPS Sukabumi shows about 6–10% CH4 and about 15–16% O2; for an aerobic landfill, the gas composition is about 47– 57% CH4 and about 2–3% O2. In conclusion the concept mining landfill could be developed especially for big cities where it is difficult to find a new site for landfill or to get soil cover for landfill operation. In a sustainable approach, the excavated area can be turned into a new area for landfill cell so that the capacity of existing Final Processing Site can be expanded using the block landfill concept. The landfill should be divided into three blocks: compost block, composting block and active block. Usage of the three blocks are rotated with the intention of using solid waste on the compost block as soil material for the active block through landfill mining.

The Advantages and Mechanism of Semi-aerobic Landfill

This paper reviews the differences in the two ways of anaerobic landfill and semi-aerobic landfill. The leachate came from semi-aerobic landfill being recycled leachate has such characteristics: A small quantity of acid and COD, high degradation rate of NH3-N. The acid accumulation phenomenon is not occurred when anaerobic landfill leachate was recycled to the landfill at the initial stage and also not occurred high NH3-N concentration in the middle and end stage. The improving way of landfill accelerated the degradation of COD and BOD, and speeded up the course of stabilization of the waste by the way of mix half of new waste with half of old waste.

Estimation of the Amount of Moisture Generated by Biodegradation Processes in Semi-aerobic Landfills

最終処分場を適切に計画する上で，浸出水の水量予測は浸出水処理施設計画にとって必須であるが，生ごみの直接埋立が主体である開発途上国では，準好気性埋立構造における生ごみ生物分解過程から生成する水分量は，降水量に比較して無視できないと考えられる。そこで本研究では，生ごみを充填して行った準好気性埋立構造の大型埋立実験槽の物質収支を考慮して，埋立廃棄物層内の主要な物質転換である有機物生物分解過程に関する既往の知見に基づき，化学量論的に関連する物質量の推定法を考案し，この推定法に基づいて実験データを解析した。その結果，生ごみ生物分解過程から生成する水分量は，埋立当初1年目は降水量に対して約6～8%であったが，年間降水量が1,000mm以下の地域においては年間降水量の10%を超えることなどから，生ごみ生物分解生成水量は，埋立条件によっては，埋立初期において降水量と比較して無視できないことを明らかにした。

準好気性埋立構造における生ごみ生物分解過程から生成する水分量の予測手法に関する研究

最終処分場を計画する上で，浸出水の水量予測は浸出水処理施設計画にとって必須であるが，生ごみの直接埋立が主体である開発途上国では，準好気性埋立構造における生ごみ生物分解過程から生成する水分量は，降水量に比較すると埋立条件によっては，埋立初期には無視できない寄与があることが明らかになっている。本研究では，生ごみ分解生成水量の予測手法を開発するため，2006 IPCC Guidelines for National Greenhouse Gas Inventoriesで示されているCH4発生量推定手法を応用することについて検討し，生ごみを充填して行った準好気性埋立構造の大型埋立実験槽で得られたデータに基づいて，その応用可能性と各パラメーターの設定方法等について考察を行った。その結果，IPCCガイドラインで提案されているCH4発生量推定手法は，生ごみ分解生成水量の予測手法として応用可能性があることが明らかとなった。

QUANTIFICATION OF LEACHATE GENERATION RATE FROM A SEMI-AEROBIC LANDFILL IN MALAYSIA

One of the most important problems associated with the design, operation and long-term care of landfills is managing the landfill leachate. Leachate generation rates are primarily dependent on the amount of liquid the waste originally contains, and the quantity of precipitation that enters the landfill through infiltration. The estimation of leachate generation rate is important in designing the leachate collection system, and the treatment process. There are very limited data on the amount of leachate generation from landfills in Malaysia. This study aims to quantify the actual amount of leachate generation in the field from a semi-aerobic landfill site immediately after closure and after 10 years of waste stabilization under both dry and wet conditions. Flow rates of leachate at Ampang Jajar Landfill Site (AJLS) were determined both in the field and by the Water Balance Method (WBM). Field measurements were carried out on site using random sampling with more than 50 data per site. A significant decrease in the quantity of leachate produced was observed after 10 years of landfill closure. It was found from the field study that the maximum amount of leachate generated from AJLS was 4.2 m3 lift-1 ha-1 day-1 in 2001, while it decreased to 1.39 m3 lift1ha-1day-1 after 10 years. The corresponding values obtained from WBM were 3.46 m3 lift-1 ha-1 day-1 and 1.37 m3 lift-1 ha-1 day-1, respectively. The results showed that the leachate generation from landfills decreases significantly over the years and the WBM can be helpful in designing the leachate management system by predicting long term leachate generation rates.

Waste stabilization mechanism by a recirculatory semi-aerobic landfill with the aeration system

The main purpose of this research is to clarify and compare the mechanism of waste stabilization by a recirculatory semi-aerobic landfill with the aeration system. Our research is proposing the semi-aerobic landfill system for developing countries because of the simple and low-cost technology for the final disposal. Moreover, this system with leachate recirculation can be a more effective system for waste stabilization because of the improvement of leachate quality as an organic pollutant and, also, nitrogen removal. In this research, five different systems of landfill (Ae: aerobic, An: anaerobic, Se: semi-aerobic, SeR: recirculatory semi-aerobic landfill, and SeRA: recirculatory semi-aerobic landfill with aeration system) are compared with lysimeters which are 1 m high with a diameter of 0.3 m. The results of the leachate quality shows that the leachate treatment effect of the SeRA system can be observed to be as high as the Ae system. To determine the mechanism of this process, all lysimeters are dismantled after 1,100 days in the experimental period and the waste composition, the dissolution test, the mass balance of carbon and nitrogen, the determination of bacterial counts, etc., were analyzed. In this research, it was proven that the SeRA system has an optimal leachate treatment effect that is the same as the Ae system. And, from the results of the mass balance of carbon and nitrogen, the SeR and SeRA systems show higher waste stabilization effectiveness and nitrogen removal than the other systems. Moreover, the number of the aerobic bacteria can be observed to be higher in the SeR and SeRA systems. To determine these results, the waste stabilization mechanism is considered by the results of leachate quality, the mass balance of carbon and nitrogen, and, also, the bacterial numbers.

The Simulation Study on the Rules of Spatial and Temporal Changes of Total Nitrogen in Semi-Aerobic Landfill Leachate in the Laboratory

Two experimental equipments of semi-aerobic landfill and anaerobic landfill were constructed. The total nitrogen concentrations of leachate (Recorded as CTN) that located at the bottom of equipments were determined periodically (1 or 2 times per week), the variation laws of CTN that located at the bottom of two landfill equipments with time were researched, and the reasons for the differences were also analyzed; During the period that the degradation of the landfill waste came into a relatively stable stage, the leachate that located at each sampling points of upper, middle and lower horizontal sections of the landfill equipments was collected periodically, and the CTN was determined, the CTN data of each point of upper, middle and lower layers were processed by using Surfer software respectively, and the spacial variation characteristics and differences of two landfill equipments were also discussed. The results indicated that the CTN of each point of the semi-aerobic landfill treatment were significantly lower than the corresponding anaerobic landfill treatment, the semi-aerobic landfill treatment could achieve the effective removal of total nitrogen from the leachate, and could accelerate the process of degradation stabilization and balance of total nitrogen in leachate.

The Degradation Regulation and Numerical Simulation of Ammonia Nitrogen in Semi-Aerobic Landfilling Leachate

The semi-aerobic landfill and anaerobic landfill simulation experimental devices were constructed. The leachate that lay at the bottom and space horizon of two landfilling devices was sampled periodically, and the content of ammonia nitrogen (Recorded as C(NH3-N)) was determined. Based on the monitoring data of the leachate that were located at bottom of devices in the 69 th week, the rule of C(NH3-N) that came from the bottom of the two landfilling devices with time change was simulated, and its reasons for the differences were compared and analyzed; the monitoring data of the upper, middle and lower C(NH3-N) were processed during the stable operation phase of waste degradation by using Sufer and Excel software, then the spatial variability and differences of leachate C(NH3-N) of two landfilling devices were discussed. The experimental results indicated that the content of leachate C(NH3-N) that located at upper, middle and lower layers as well as the bottom of semi-aerobic landfill were lower than the corresponding layer of the anaerobic landfill. Compared with the structure of anaerobic landfill, the semi-aerobic landfill structure could accelerate the balance and stability process of leachate C(NH3-N), and the content of leachate C(NH3-N) was reduced effectively.

Bacterial community composition and abundance in leachate of semi-aerobic and anaerobic landfills

The abundance and phylogenetic composition of bacterial community in leachate of semi-aerobic and anaerobic landfill were compared through real-time polymerase chain reaction and denaturing gradient gel electrophoresis. In semi-aerobic landfill scenario, the bacterial 16S rRNA copy numbers in leachate had no significant reduction from initial stage to stable period. In the scenario of anaerobic landfill, the largest bacterial 16S rRNA gene copy number was found in leachate at initial stage, but it reduced significantly at stable period. Moreover, methane-oxidizing bacteria population in stable period was lower than that in initial period in both two landfill processes. However, semi-aerobic landfill leachate had more methanotrophic bacteria populations than that in the anaerobic one. Furthermore, according to the sequences and phylogenetic analysis, obvious difference could be detected in bacterial community composition in different scenarios. Proteobacteria and bacteroidetes took up a dominantly higher proportion in semi-aerobic landfill leachate. To summarize up, different landfill methods and its landfill ages had crucial impacts on bacterial abundance and composition in leachate of semi-aerobic and anaerobic landfills.

The Effect of Leachate Collection Layer Structure on Leachate Quality in Semi-Aerobic Landfill: A Pilot Study

Due to the leachate collection layer’s good ventilation and leachate leaching role, aerobic bio-filter bed for treating leachate can be formed in the bottom of the semi-aerobic landfill. Six groups of simulated semi-aerobic landfill columns were used, whose leachate collection layers were 60mm gravel (1#), 120mm gravel (2#), 180mm gravel (3#), 240mm gravel (4#), 180mm cobblestone (5#), and 180mm gravel with 60mm ceramsite on the surface (6#) respectively. This paper researched the influence of leachate collection layer structure on the oxygen volume fraction in semi-aerobic landfill as well as the leachate concentrations of COD, NH4+-N, organic nitrogen and sulfate. The results showed that the oxygen volume fraction declined according to the sequence of upper-layer, middle-layer and lower-layer. After 22 weeks, the leachate COD removal rate of 1#, 2#, 3#, 4#, 5# and 6# reached 92.64%, 95.18%, 94.48%, 96.44%, 92.06% and 96.39%, respectively. The concentrations of NH4+-N were reduced respectively from the initial 1670.3, 1704.1, 1866.2, 1873.0, 1920.3 and 2116.2 mg/L to 117.8, 119.2, 123.2, 101.6, 635.4 and 200.3 mg/L, and the phenomenon of ammonia nitrogen concentration gradually rising did not appear. Leachate concentration of sulfate could be increased through semi-aerobic landfill and less H2S gas was produced. Increasing the leachate collection layer’s height would help to improve the removal effect of leachate, and gravel collection layer was better than that of cobblestone. Adding ceramsite on the surface of gravel collection layer would help to increase the removal rate of leachate at the later stage.

Influence of semi-aerobic and anaerobic landfill operation with leachate recirculation on stabilization processes

To investigate the influence of semi-aerobic and anaerobic landfill operation on stabilization processes of landfill sites with leachate recirculation, in situ simulated semi-aerobic landfill sites with leachate recirculation (SLR) and anaerobic landfill sites with leachate recirculation (ALR) were constructed. Refuse properties and landfill settlement were determined. Leachate quality and landfill gas compositions were monitored regularly. Based on the data obtained, leachate quality, landfill gas and final refuse characteristics were adopted as assessment factors to quantitatively evaluate stabilization of landfill sites. The results showed that volatile solids (VS), total organic carbon (TOC) and biologically degradable matter (BDM) of aged refuse in SLR (15.8, 7.3 and 9.9%, respectively) were lower than those in ALR, which were 19.1, 9.2 and 11.3%, respectively. Settlement and reduction ratio of SLR were 1.71 m and 30.91%, respectively, and 1.40 m and 25.45% in the case of ALR. Concentrations of organic pollutants, especially ammonia, were reduced in SLR, and variation in leachate quality was also smoother than ALR. Throughout the experiment the average concentration of CH4 in ALR was higher than that in SLR (36.7 and 14.5%, respectively). At the end of the experiment, SLR was moderately stable, while ALR was moderately unstable. The comprehensive assessment index (I) for SLR and ALR was 200 and 355, respectively.