Landfill Section Research Articles

Hazards Assessment of Medical Waste Unit of the Waste Management Organization Using Failure Mode and Effects Analysis Technique

Introduction: Hospital waste is one of the most important pollutants caused by hospital processes. The purpose of this study was to evaluate Health, Safety and Environmental (HSE) risks of medical waste unit.
 Method: This cross-sectional study was conducted in 2020. The study tool included the Failure Mode and Effects Analysis (FMEA) technique. This research was conducted in three sections of medical Waste Unit of the Waste Management Organization including collection, processing and landfill sections.
 Results: The FMEA results showed that the highest levels of environmental Risk Priority Number (RPN) in the collection, processing and landfill sections were estimated 245, 392, and 294 respectively. Furthermore, the lowest levels of environmental risk in these three sections were calculated as 144, 80, and 60 respectively. The FMEA results indicated that the highest levels of safety and health risk in the collection, processing and landfill sections were calculated to be 252, 420 and 420, respectively. Also, the lowest level of safety and health risk in all three sections was estimated to be RPN=90.
 Conclusion: Findings of this study indicated that the level of hospital waste risk is high. Therefore, reducing the incidence of catastrophic consequences associated with these wastes should be considered a priority of the waste management system.

Mitigation of methane emissions from three Danish landfills using different biocover systems

The establishment of biocover systems is an emerging methodology in reducing methane (CH4) emissions from landfills. This study investigated the performance of three biocover systems with different designs (biowindow and passively and actively loaded biofilters) in mitigating CH4 emissions from three landfills in Denmark. A series of field tests were carried out to evaluate the functionality of each system, and total CH4 emissions from relevant landfill sections or the entire landfill were measured before and after biocover implementation. Surface CH4 concentration screening and local CH4 fluxes showed generally low emissions from the biowindow/biofilters (mostly < 5 g CH4 m−2 d−1), although some hotspots were identified on two actively loaded biofilters. One passively loaded biofilter exhibited high CH4 emissions, mainly due to gas overloading into the system. Gas concentration profiles measured at different locations suggested uneven gas distribution in the biofilters, and significant CH4 oxidation occurred in both the gas distribution layer (when oxygen was fed into the system) and the CH4 oxidation layer. High CH4 oxidation efficiencies of above 95% were found in all systems except for one biofilter (55%). Whole-site emission measurements showed CH4 reduction efficiencies between 29 and 72% after implementing biocover systems at the three landfills, suggesting that they were efficient in reducing CH4 emissions. The most challenging task for the passively loaded biocover systems was to control gas flow and secure homogenous gas distribution, while for actively loaded biocovers, it might be more important to eliminate emission hotspots for better functionality.

Mapping biogeochemically active zones in landfills with induced polarization imaging: The Heferlbach landfill

In this study, we investigate the applicability of the Induced Polarization (IP) imaging method to discriminate between biogeochemically active and inactive areas of a landfill. The elevated amount of degradable organic carbon in landfills results in the development of biogeochemical hot-spots associated with high rates of microbial activity and the generation of landfill gas and leachate as metabolic products. Our results demonstrate that the electrical conductivity is mainly sensitive to the increase in the fluid conductivity associated to leachate production and migration. Whereas images of the polarization effect, expressed in terms of the imaginary component (σ″) or the phase of the complex conductivity (ϕ), reveal the potential to characterize variations in the architecture and biogeochemical activity of the landfill. Correspondingly, biogeochemically active zones (leachable TOC contents above 1500 mg/kg dry waste) are related to high polarization values (σ″ > 10 mS/m, ϕ > 40 mrads), whereas low leachable TOC contents (<300 mg/kg dry waste) in the inactive areas are characterized by low polarization values (σ″ < 1 mS/m, 10 < ϕ < 25). Additionally, landfill sections corresponding to construction and demolition waste (CDW), associated to negligible TOC content, exhibit the lowest polarization response (σ″ < 0.1 mS/m, ϕ < 15). We prove that IP imaging is a well-suited method for landfill investigations that permits an improved characterization of landfill geometry, variation in waste composition, and the discrimination between biogeochemically active and inactive zones.

Performance assessment of landfill in-situ aeration – A case study

The assessment of landfill in-situ aeration eludes standardization as its application highly depends on varying local conditions. The prevailing work tries to assess the procedure performance by using typically available data.In the here presented case study the aeration pipes were applied horizontally. To evaluate the air-distribution and its effect on the landfill solid body, two monitoring fields with 10 × 10 m were created. From there in total 60 solid and 336 gaseous samples were taken over five years. As the material from the landfill was rather old and characterized by comparatively low reactivity, “new” material from a mechanical biological treatment (MBT) plant was introduced in the landfill. Additionally online gas data from eight technically separated landfill sections were analyzed during in-situ aeration.In total, about 46 Mm3 (0.27 m3/kg waste) air was introduced into the landfill body. The eight sections showed differences in reactivity (overall C-discharge was 8 g C kg−1 dry weight, ranging from 4.5 to 11). With solid sampling we could not show a significant decrease in landfill TOC but for the introduced MBT-material. Ammonium in solid samples was significantly reduced (to 14.7% initial) and NO3 significantly increased (2.1% initial). The reduction of the initial TOC (4.58%) was on average 11%.The application of horizontal landfill aeration led to a widespread air-distribution in a rather shallow landfill. Monitoring fields allowed for a screening of the impact of the measures on the solid body with reduced sampling costs.

A practical approach for calculating the settlement and storage capacity of landfills based on the space and time discretization of the landfilling process

The settlement of any position of the municipal solid waste (MSW) body during the landfilling process and after its closure has effects on the integrity of the internal structure and storage capacity of the landfill. This paper proposes a practical approach for calculating the settlement and storage capacity of landfills based on the space and time discretization of the landfilling process. The MSW body in the landfill was divided into independent column units, and the filling process of each column unit was determined by a simplified complete landfilling process. The settlement of a position in the landfill was calculated with the compression of each MSW layer in every column unit. Then, the simultaneous settlement of all the column units was integrated to obtain the settlement of the landfill and storage capacity of all the column units; this allowed to obtain the storage capacity of the landfill based on the layer-wise summation method. When the compression of each MSW layer was calculated, the effects of the fluctuation of the main leachate level and variation in the unit weight of the MSW on the overburdened effective stress were taken into consideration by introducing the main leachate level’s proportion and the unit weight and buried depth curve. This approach is especially significant for MSW with a high kitchen waste content and landfills in developing countries. The stress-biodegradation compression model was used to calculate the compression of each MSW layer. A software program, Settlement and Storage Capacity Calculation System for Landfills, was developed by integrating the space and time discretization of the landfilling process and the settlement and storage capacity algorithms. The landfilling process of the phase IV of Shanghai Laogang Landfill was simulated using this software. The maximum geometric volume of the landfill error between the calculated and measured values is only 2.02%, and the accumulated filling weight error between the calculated value and measured value is less than 5%. These results show that this approach is practical for satisfactorily and reliably calculating the settlement and storage capacity. In addition, the development of the elevation lines in the landfill sections created with the software demonstrates that the optimization of the design of the structures should be based on the settlement of the landfill. Since this practical approach can reasonably calculate the storage capacity of landfills and efficiently provide the development of the settlement of each landfilling stage, it can be used for the optimizations of landfilling schemes and structural designs.

Aeration of the teuftal landfill: Field scale concept and lab scale simulation

Long lasting post-closure care (PCC) is often the major financial burden for operators of municipal solid waste (MSW) landfills. Beside costs for the installation and maintenance of technical equipment and barriers, in particular long term treatment of leachate and landfill gas has to be paid from capital surplus. Estimations based on laboratory experiments project time periods of many decades until leachate quality allows for direct discharge (i.e. no need for further purification). Projections based on leachate samples derived from the last 37years for 35 German landfills confirm these assumption. Moreover, the data illustrate that in particular ammonium nitrogen concentrations are likely to fall below limit values only after a period of 300years.In order to avoid long lasting PCC the operator of Teuftal landfill, located in the Swiss canton Bern, decided to biologically stabilize the landfill by means of a combined in situ aeration and moisturization approach. In December 2014 the aeration started at a landfill section containing approximately 30% of the total landfill volume. From summer 2016 onwards the remaining part of the landfill will be aerated. Landfill aeration through horizontal gas and leachate drains is carried out for the first time in field scale in Europe. The technical concept is described in the paper.Parallel to field scale aeration, investigations for the carbon and nitrogen turnover are carried out by means of both simulated aerated landfills and simulated anaerobic landfills. The results presented in this paper demonstrate that aeration is capable to enhance, both carbon mobilization and discharge via the gas phase. This effect comes along with a significant increase in bio-stabilization of the waste organic fraction, which positively affects the landfill emission behavior in the long run. In terms of leachate pollution reduction it could be demonstrated that the organic load decrease fast and widely independent of the adjusted aeration rates whereby ammonium nitrogen load efficiently decrease later and only under higher aeration rates.

A three-index estimator based on active thermometry and a novel monitoring system of scour under submarine pipelines

A submarine pipeline system is a major asset. Scour monitoring under submarine pipelines is a tough problem and lacks research, especially for nearshore and landfill sections. While these sections are critical for the viability of the pipeline system, they are also the most vulnerable to scour. In this study, a three-index estimator (TIE11Three-index estimator.) based on active thermometry was developed for solving this problem and thereby a novel scour monitoring system was designed for nearshore and landfill sections. Heat dissipates in different ways between in-water and in-sediment scenarios. TIE, consisting of three indices obtained through time history analysis of temperature change during heating and cooling, can well characterize the distinction of heat transfer behaviors between in liquids and solids. By calculating TIE, it is possible to identify whether a location along a pipe is surrounded by water or soil. Considering this, the system utilizes a thermal cable to generate heat with a heating belt and concurrently measure temperature with DS18B20s. The thermal cable was deployed parallel to the pipeline. Analyzing the acquired data by TIE, identification of free spans is achieved. Several experimental tests were conducted using the system. Results confirm the methodology and substantiate the scour monitoring system.

Long term monitoring of leachate flux into drainage pipes of MSW landfills

The measurement of leachate quality and quantity is an essential part of the monitoring of landfills in the different phases during their lifespan. These measurements allow the evaluation of the decomposition processes in the landfill and the efficiency of technical installations for the reduction of the leachate generation. Normally the measurements are made at the outlet of larger sections of the landfill or at the overall landfill. An identification of smaller parts with different biological or hydraulic behaviour within the landfill section is not possible in that case. In the framework of a long-term research project concerning the monitoring of landfills, different devices for small-scale identification of the leachate discharge were developed at the Technical University of Braunschweig. The device allows a measurement of the leachate discharge inside a single drainage pipe having a length up to 375 m. The measurements showed the influence of changes in operation. It was found that the discharge in the pipes and the efficiency of the drainage system was strongly influenced by deformations and torsion of the high-density polyethylene pipes and unequal settlements of the subsoil. The discharge of leachate in the drainage system was, as expected, very non-uniform and in parts the leachate was not flowing inside the pipes, but rather in the surrounding gravel layer. Furthermore, large differences in leachate quality may occur, whereas the differences in discharge volume are small. With the developed system it is possible to control the efficiency and the functioning of top cover systems for landfills.

Quantification of multiple methane emission sources at landfills using a double tracer technique

A double tracer technique was used successfully to quantify whole-site methane (CH 4) emissions from Fakse Landfill. Emissions from different sections of the landfill were quantified by using two different tracers. A scaled-down version of the tracer technique measuring close-by to localized sources having limited areal extent was also used to quantify emissions from on-site sources at the landfill facility, including a composting area and a sewage sludge storage pit. Three field campaigns were performed. At all three field campaigns an overall leak search showed that the CH 4 emissions from the old landfill section were localized to the leachate collection wells and slope areas. The average CH 4 emissions from the old landfill section were quantified to be 32.6 ± 7.4 kg CH 4 h −1, whereas the source at the new section was quantified to be 10.3 ± 5.3 kg CH 4 h −1. The CH 4 emission from the compost area was 0.5 ± 0.25 kg CH 4 h −1, whereas the carbon dioxide (CO 2) and nitrous oxide (N 2O) flux was quantified to be in the order of 332 ± 166 kg CO 2 h −1 and 0.06 ± 0.03 kg N 2O h −1, respectively. The sludge pit located west of the compost material was quantified to have an emission of 2.4 ± 0.63 kg h −1 CH 4, and 0.03 ± 0.01 kg h −1 N 2O.

Effects of a temporary HDPE cover on landfill gas emissions: Multiyear evaluation with the static chamber approach at an Italian landfill

According to the European Landfill Directive 1999/31/EC and the related Italian Legislation (“D. Lgs. No. 36/2003”), monitoring and control procedures of landfill gas emissions, migration and external dispersions are clearly requested. These procedures could be particularly interesting in the operational circumstance of implementing a temporary cover, as for instance permitted by the Italian legislation over worked-out landfill sections, awaiting the evaluation of expected waste settlements. A possible quantitative approach for field measurement and consequential evaluation of landfill CO 2, CH 4 emission rates in pairs consists of the static, non-stationary accumulation chamber technique. At the Italian level, a significant and recent situation of periodical landfill gas emission monitoring is represented by the sanitary landfill for non-hazardous waste of the “Fano” town district, where monitoring campaigns with the static chamber have been annually conducted during the last 5 years (2005–2009). For the entire multiyear monitoring period, the resulting CO 2, CH 4 emission rates varied on the whole up to about 13,100 g CO 2 m −2 d −1 and 3800 g CH 4 m −2 d −1, respectively. The elaboration of these landfill gas emission data collected at the “Fano” case-study site during the monitoring campaigns, presented and discussed in the paper, gives rise to a certain scientific evidence of the possible negative effects derivable from the implementation of a temporary HDPE cover over a worked-out landfill section, notably: the lateral migration and concentration of landfill gas emissions through adjacent, active landfill sections when hydraulically connected; and consequently, the increase of landfill gas flux velocities throughout the reduced overall soil cover surface, giving rise to a flowing through of CH 4 emissions without a significant oxidation. Thus, these circumstances are expected to cause a certain increase of the overall GHG emissions from the given landfill site.

Identification of prevalent microbial communities in a municipal solid waste landfill

To identify the microbial communities in Istanbul, Odayeri Municipal Solid Waste Landfill, leachate samples were collected from different sections at different stabilization phases. In identification of microbial communities in leachate samples, molecular techniques such as FISH, DGGE and cloning based on 16S rRNA and mcrA genes were used. As the chemical and microbiological compositions of the samples were compared, obvious correlations were found between the stability of the landfill section and abundance of active methanogens. On the other hand, there were considerable differences between acidogenic and mature leachate samples in DGGE profiles of archaeal and bacterial 16S rRNA genes. Moreover, in acidogenic leachate samples having BOD5/COD ratio of about 0.5 acetate utilizing Methanosarcina and Methanosaeta species were intensively detected in FISH. Although only very few H2-utilizing methanogens were identified with FISH analysis, most of the clones isolated from mature leachate samples clustered within H2-utilizing Methanobacteriales and Methanomicrobiales according to phylogenetic analysis of 16S rRNA and mcrA clones, respectively.

Factors affecting water balance and percolate production for a landfill in operation

Percolate production and precipitation data for a full-scale landfill in operation measured over a 13-year period were used to evaluate the impact and importance of the hydrological conditions of landfill sections on the percolate production rates. Both active (open) and closed landfill sections were included in the evaluation. A simple top cover model requiring a minimum of input data was used to simulate the percolate production as a function of precipitation and landfill section hydrology. The results showed that changes over time in the hydrology of individual landfill sections (such as section closure or plantation of trees on top of closed sections) can change total landfill percolate production by more than 100%; thus, percolate production at an active landfill can be very different from percolate production at the same landfill after closure. Furthermore, plantation of willow on top of closed sections can increase the evapotranspiration rate thereby reducing percolate production rates by up to 47% compared to a grass cover. This process, however, depends upon the availability of water in the top layer, and so the evaporation rate will be less than optimal during the summer where soil-water contents in the top cover are low.

On-site treatment and landfilling of MSWI air pollution control residues

Air pollution control (APC) residues from municipal solid waste incineration (MSWI) are difficult to landfill due to substantial leaching of trace metals. An on-site pretreatment prior to landfilling of APC-residues was investigated in terms of bench-scale experiments with a semidry APC-residue and a fly ash. The treatment involved mixing of the residues with a ferrous sulphate solution and subsequent oxidation of the suspension. Afterwards, the suspension was spread on a dedicated landfill section and allowed to drain by gravity through the drainage system of the landfill. The wastewater from the process, collected through the drainage system, contained large concentrations of salts (Cl: 14–30 g/l, Na: 4–9 g/l, K: 5–11 g/l, Ca: 2–12 g/l) but low concentrations of trace metals (e.g. Pb: 14–100 μg/l, Cd: <2–7 μg/l). The treated residues left in the landfills were later subject to leaching by simulated rainfall. The leachate contained low concentrations of trace metals (Pb: <120 μg/l, Cd: <2 μg/l, Cr: <485 μg/l). The leachate concentrations from the treated APC-residues were substantially reduced compared to concentrations in leachate from untreated APC-residues. Particularly in the early stages of the leaching, concentrations of trace metals were reduced by up to four orders of magnitude.

P-Toluenesulfonate in Landfill Leachates: Leachability from Foundry Sands and Aerobic Biodegradation

p-Toluenesulfonate (pTS) was found at concentrations between 9.6 and 48.8 mg/L in leachates from two Swiss landfill sections where foundry wastes are stored. pTS represented ≤33% of the nonpurgable organic carbon (NPOC) in the leachates. A standard test showed that pTS is easily leached from foundry sands that contained 1% (w/w) of a technical hardener consisting of tolu enesulfonates. Hence, the hardener is a likely source of pTS in the landfill leachates. Furthermore, analyses using liquid chromatography coupled to mass spectrometry and UV absorption detection indicated that the hardener also was the source for toluene-2,4-disulfonate, benzenesulfonate and o- and m-toluenesulfonate, all of which were detected in the landfill leachates. Modified OECD screening tests with pure pTS or hardener as carbon source and landfill leachate as inoculum indicated that aerobic bacteria using pTS for growth are present in the landfill leachates. The intermediates p-sulfobenzyl alcohol and p-sulfobenzoate gives strong evidence for a degradation pathway common to Comamonas testosteroni.

Two‐Dimensional Leachate Estimation through Landfills

A numerical model is developed to compute the time variation of leachate flow in landfills. The two‐dimensional moisture‐transport equation, along with the boundary conditions, is solved using an implicit finite difference scheme in a vertical plane. The time‐varying boundary conditions include computation for runoff, evapotranspiration, and infiltration in an unsteady state condition. The leachate accretion is obtained from the time history of moisture content. The downward leachate accretion helps develop the leachate mound at the bottom of the landfill. Solution of the saturated leachate flow equation with respect to the bottom of the landfill establishes lateral flows toward the perimeter or collection system at the landfill. Also, vertical flow through the bottom clay layer is computed using Darcy's law. The model is applied to a landfill section in New York to demonstrate the simulation of runoff, moisture content, recharge, as well as lateral and vertical flows for the field conditions in a landfill.