Underground Waste Research Articles

LoRaWAN and Urban Waste Management-A Trial.

The city of Lisbon, as any other capital of a European country, has a large number of issues regarding managing waste and recycling containers spread throughout the city. This document presents the results of a study promoted by the Lisbon City Council for trialing LPWAN (Low-Power Wide-Area Network) technology for the waste management vertical under the Lisbon Smart City initiative. Current waste management is done using GSM (Global System for Mobile communications) sensors, and the municipality aims to use LPWAN in order to improve range and reduce costs and provisioning times when changing the communications provider. After an initial study, LoRa (Long Range) and LoRAWAN (LoRa Wide Area Network) as its network counterpart, were selected as the LPWAN technology for trials considering several use cases, exploring multiple distances, types of recycling waste containers, placements (underground or surface) and kinds of commercially available waste level measurement LoRa sensors. The results showed that the underground waste containers proved to be, as expected, the most difficult to operate correctly, where the container itself imposed attenuation levels of 26 dB on the LoRa link budget. The successful results were used to promote the deployment of a city-wide LoRa network, available to all the departments inside the Lisbon City Council. Considering the network capacity, the municipality also decided to make the network freely available to citizens.

Introduction of an underground waste container system–model and solution approaches

In Germany, household waste is collected via a door-to-door collection system. This form of waste collection is already reaching its limits due to the increasing volume of household waste and lack of space for even more dustbins, especially in densely populated cities. In this paper we investigate an alternative collection system: an underground waste collection system in which waste would be collected at central locations in so-called underground containers with a much larger capacity. If an underground container system is to be introduced to replace the present door-to-door waste collection system, a number of decisions of varying scope have to be made: Where should the underground containers be placed? How much capacity should be provided at which collection site? Which household should dispose of its waste where? How often, when and in what order should the waste collection vehicles empty the containers? In this paper we develop a model to illustrate the combination of the underlying problems by extending a problem known from literature. We present both hierarchical and integrated approaches to solve it. The proposed solution approaches combine in different ways two variable neighborhood search heuristics and a mixed integer programming-based exact method. We show that great benefits can be achieved through the use of integrated solution approaches. But we show too that integrated solution approaches do not necessarily dominate hierarchical ones.

Speciation by XANES of copper migrated into compacted bentonite using electromigration techniques

Copper is a promising overpack material for deep underground nuclear waste disposal, although it is susceptible to corrosion following closure of the repository, and subsequent migration of the corrosion products through the buffer material may affect the migration of redox-sensitive radionuclides. Electromigration experiments were performed in which a copper coupon in contact with compacted bentonite served as the working electrode and was held at a constant potential of + 300 mV vs. Ag/AgCl for up to 48 h. The chemical state of the copper that migrated into the bentonite specimens was investigated by copper K-edge X-ray absorption near-edge structure measurements at the Saga Light Source, Japan. The results confirmed that the oxidation state of copper in the bentonite was copper(II), as indicated by the correlation between the amount of copper migrated into bentonite specimens and the corrosion current. Copper(I) was also observed on the copper coupon, but not in the bentonite samples. The obtained results indicate that the copper initially dissolves as copper(II), which then reacts with the copper metal and precipitates as Cu2O.

Can CO2 sequestration in basalt efficiently reduce greenhouse gas emission?

ABSTRACT The research on the Columbia River Basalt is a unique combination of projects that minimise CO2 emissions to the atmosphere. Both are underground waste disposal projects: CO2 waste versus nuclear waste. The recent Wallula CO2 project and the previous nuclear-waste project in the Columbia River Basalt (CRB), USA, provide the database for a high-capacity CO2 sequestration model. Due to geomechanical constraints, the injection rate of CO2 sequestration must be limited in order not to jeopardise the integrity of the reservoir and cap rock. The interbed in the continental flood basalt tested in the Wallula project only allows injection at a rate in the range of 9–19 kg CO2/s, depending on permeability (4 × 10−14–10−13 m2) and porosity (0.1–0.15). At the end of a 50-year injection period, the fraction of CO2 converted to carbonate minerals is 37.1–67.1%. Underground space for waste disposal is a rare asset. The Columbia River Basalt occupies an area of 200,000 km2. Fifty years of CO2 sequestration from a single well would require about the same fraction of the area as that of a nuclear waste repository (0.025%). The repository design is for a capacity of 70,000 MTHM (metric tons heavy metal). If all the waste is spent nuclear fuel, it originates from 1.2 × 104–8.4 × 104 TWh electric power production, depending on reactor type. The CO2 injection well operating at maximum capacity (19 kg CO2/s) represents 50 TWh generated in a gas power station minus the energy consumed for CO2 separation, i.e. less than 0.4% of the nuclear option.

Development of a DEM-Based Method for Modeling the Water-Induced Failure Process of Rock from Laboratory- to Engineering-Scale

Abstract The time-dependent hydromechanical behavior of rocks is crucial to assessing the long-term stability of rock engineering, such as reservoir rock slopes and underground waste storage facili...

Deep Underground Injection of Waste from Drilling Activities—An Overview

Oil and gas exploration and production activities generate large amounts of waste material, especially during well drilling and completion activities. Waste material from drilling activities to the greatest extent consists of drilled cuttings and used drilling mud with a smaller portion of other materials (wastewater, produced hydrocarbons during well testing, spent stimulation fluid, etc.). Nowadays, growing concerns for environmental protections and new strict regulations encourage companies to improve methods for the reduction of waste material, as well as improve existing and develop new waste disposal methods that are more environmentally friendly and safer from the aspect of human health. The main advantages of the waste injection method into suitable deep geological formations over other waste disposal methods (biodegradation, thermal treatment, etc.) are minimizing potentially harmful impacts on groundwater, reducing the required surface area for waste disposal, reducing the negative impact on the air and long-term risks for the entire environment. This paper gives a comprehensive overview of the underground waste injection technology, criteria for the selection of the injection zone and methods required for process monitoring, as well as a comprehensive literature overview of significant past or ongoing projects from all over the world.

Gis-based Analysis of Water Quality Parameters of Groundwater with Proximity to Onsite Wastes Pits in Vom Community of Jos South, Nigeria

Water quality assessment is an important part of environmental quality management especially in groundwater resources located close to sources of contamination. This study involved the assessment of groundwater quality for hand dug wells at locations with proximity to pit latrines in Vom community, Plateau State, Nigeria and the use of GIS for data analysis. Water samples were collected from six (6) locations in a small area to assume possible interaction between the water in the sampling wells, the maximum distance between any two points being 100 m and the minimum distance being 22 m. Eleven (11) physical, bacteriological and chemical parameters were analyzed for the water samples. The results were compared with World Health Organization and Nigerian Standard for Drinking Water Quality standards. The chemical parameters in the samples tested met the WHO and NSDWQ limits with the exception of pH which was slightly acidic for four samples. The results also showed that E. coli was found in all the samples tested. This may be attributed to the proximity of the wells to pit latrines. The results obtained from laboratory analyses were inputted into a GIS database in ILWIS 3.8 where the variation maps were developed and also classified maps for each of the parameters based on whether they meet WHO standards or not. The classified maps were all overlaid in GIS to develop the groundwater quality information map where any point highlighted gives information on the parameters for that point. This makes the retrieval of water quality parameters easy and also the comparison of the parameters with respect to location. Treatment of the groundwater with chemicals like soda ash and chlorine are recommended before consumption. It is generally recommended that wells should not be located in close proximity to onsite underground wastes disposal pits. Government should provide sufficient potable water for the Vom Community.

Laboratory testing of seepage in concrete

Due to the construction of underground structures and hazardous waste storages, understanding and modelling of water flow through concrete has become a major topic for life-span analyses. The water retention curve (WRC) is an essential unsaturated soil function, which can be determined not only for soil samples, but also for other porous media. This paper deals with the determination of drying water retention curve for six different concrete mixtures that provide a substantial characteristic for the investigation and modelling of seepage through the pores of concrete. According to the complex pore system of the concrete, the bimodal function of van Genuchten (1980) and Fredlund and Xing (1994) models were used for curve fitting. The fitted curves were used to estimate the permeability function using Fredlund et. al (1994) model.

Migration Behavior of Copper in Compacted Bentonite Using Electromigration Techniques

ABSTRACTCopper is a candidate for use as an overpack material in deep underground nuclear waste disposal. Copper, however, is susceptible to corrosion following closure of the repository and migration of the corrosion products through the buffer material may affect the migration of redox-sensitive radionuclides. Electromigration experiments were performed whereby a copper coupon, which was in contact with compacted bentonite, served as the working electrode and was held at a constant potential of between +100 to +400 mV vs. Ag/AgCl electrode for up to 48 h. The amounts of copper that migrated into the bentonite specimens were found to be in good agreement with the calculated values based on the corrosion current flow for the assumption that copper underwent anodic dissolution as Cu(II). A model based on dispersion and electromigration was able to explain the measured copper profiles in the bentonite specimens. The fitted values of the dispersion coefficient did not depend on the applied potential and were about 10-12 m2/s.

MC-HFLTS&MAIRCA Yöntemi Kullanılarak Yeraltı Çöp Konteynerleri için Yer Seçimi

Underground Waste Container systems are systems that provide to collect all wastes and wastes under the ground working in confined spaces and in vertical position and that prevent spread of scent and water around. Underground waste containers have many advantages compared to conventional waste containers. These are; to prevent the formation of viruses and bacteria based illnesses that may be exposed due to the inner coating of the tank under the ground, to save space, to save time in the collection of waste, to collect the waste hygienically and untouchedly. Moreover, it contributes to recycling due to on-site waste separation with more than one container taking small place. The use of underground waste containers with many advantages is increasing. In this respect, the aim of this paper is to define the criteria that are effective in placing underground waste containers, to calculate the criteria weights and to evaluate alternative locations where waste containers will be placed for a particular region. As a result of the literature review, there was no study about the location selection for underground waste containers. In this study, the integrated MC-HFLTS&MAIRCA method is used for assessing and choosing the best location for underground waste containers. This method can increase the flexibility of representing linguistic information and it can reflect in defining the gap between the ideal and empirical ponders. According to the results obtained, the most important criterion was determined as Suitability of infrastructure (C 5 ), followed by Amount of waste (C 3 ), and respectively Population density (C 2 ), Number of institution of public/private utility (C 4 ) and Distance to waste disposal point (C 1 ). The alternative order is as A 3 >A 1 >A 2 . According to the results obtained in the calculation, the first location for under ground waste containers is district of Yakutiye (A 3 ) and neighborhood of Lalapasa (B 3 ). The comparison analysis is done using MABAC method to check the validity of the results. In the MC-HFLTS&MAIRCA and MC-HFLTS&MABAC methods, A 3 and B 3 alternatives are the best one and the ranking of location for underground waste containers is the same.

Automated Waste Transfer System using Dedicated Corridor in Cities

The Waste disposal techniques have become quite old for the modern period lately. The transfer of waste from the waste bins in the localities through the use of compactor trucks needs to be changed. It stands low on the efficiency scale. This can be improved by Channelizing waste through a separate corridor. The idea is to channelize the waste underground by using belt conveyor systems. The waste collector bins in the localities will be joined to the main conveyor heavy duty belts by small conveyor belts to move the waste. This waste will be taken to the waste processing plants by the belts fixed underground. The waste collector bins will be equipped with the pressure plates and will be connected to the network. As soon as the bin is full, it will send the information to the control centre. The operator at the centre can empty the bin by clicking a button. This will help to live monitor the waste and move it as soon as possible. The waste which is channelized can be easily segregated at the end where it enters the waste processing plant. Segregation of the waste will allow us to reuse the recyclable materials which most of the time are dumped in the landfills. The idea is to eliminate the Compactor Trucks as they cause pollution and congestion. Also many a times, waste materials are dropped out from the truck while carrying them to the processing plants which affects the riders behind it. The smoke from the trucks is dark and sooty which are the main causes for the lung diseases. Whereas the belt driven system will work on electricity. This energy can be harnessed by renewable energy resources or by power plants where the efficiency is the highest.

Introduction of an Underground Waste Container System–Model and Solution Approaches

In Germany, household waste is collected via a door-to-door collection system. This form of waste collection is already reaching its limits due to the increasing volume of household waste and lack of space for even more dustbins, especially in densely populated cities. In this paper we investigate an alternative collection system: an underground waste collection system in which waste would be collected at central locations in so-called underground containers with a much larger capacity. If an underground container system is to be introduced to replace the present door-to-door waste collection system, a number of decisions of varying scope have to be made: Where should the underground containers be placed? How much capacity should be provided at which collection site? Which household should dispose of its waste where? How often, when and in what order should the waste collection vehicles empty the containers? In this paper we develop a model to illustrate the combination of the underlying problems by extending a problem known from literature. We present both hierarchical and integrated approaches to solving it. The proposed solution approaches combine in different ways two variable neighborhood search heuristics and a mixed integer programming-based exact method. We show that great benefits can be achieved through the use of integrated solution approaches. But we show too that integrated solution approaches do not necessarily dominate hierarchical ones.

Estimation of Unsaturated Hydraulic Conductivity of Granular Soils from Particle Size Parameters

Estimation of unsaturated hydraulic conductivity could benefit many engineering or research problems such as water flow in the vadose zone, unsaturated seepage and capillary barriers for underground waste isolation. The unsaturated hydraulic conductivity of a soil is related to its saturated hydraulic conductivity value as well as its water retention behaviour. By following the first author’s previous work, the saturated hydraulic conductivity and water retention curve (WRC) of sandy soils can be estimated from their basic gradation parameters. In this paper, we further suggest the applicable range of the estimation method is for soils with d10 > 0.02mm and Cu < 20, in which d10 is the grain diameter corresponding to 10% passing and Cu is the coefficient of uniformity (Cu=d60d10). The estimation method is also modified to consider the porosity variation effect. Then the proposed method is applied to predict unsaturated hydraulic conductivity properties of different sandy soils and also compared with laboratory and field test results. The comparison shows that the newly developed estimation method, which predicts the relative permeability of unsaturated sands from basic grain size parameters and porosity, generally has a fair agreement with measured data. It also indicates that the air-entry value is mainly relative to the mean grain size and porosity value change from the intrinsic value. The rate of permeability decline with suction is mainly associated with grain size polydispersity.

Coseismic Groundwater Drawdown Along Crustal Ruptures During the 2016 Mw 7.0 Kumamoto Earthquake

AbstractGroundwater‐level changes after earthquakes provide insight into changes in hydrogeological properties such as permeability and pore pressure. Quantifying such changes, both their location and magnitude, is usually hindered by limited data. Using extensive high‐resolution water‐level monitoring records, we provide direct evidence of significant groundwater drawdown (4.74‐m maximum) over a 160‐km2 area along crustal ruptures after the Mw 7.0, 2016, Kumamoto earthquake. Approximately 106 m3 of water disappeared within 35 min after the main shock. The loss of water was not caused by static‐strain driven pore‐pressure decrease nor by releasing of water through structural pathways, but most likely by water transfer downwards through open cracks. Such changes may impact the security of water resources, the safety of underground waste repositories, and contaminant transport in seismically active areas.

Behavior of rare earth elements in an aquifer perturbed by CO2 injection: Environmental implications

Three cubic-meters of CO2-saturated water was injected into a subsurface fractured aquifer in a post-mined area, using a push-pull test protocol. Groundwater samples were collected before and after CO2-injection to quantify geochemical changes. CO2-injection initially reduced the pH of water from 7.3 to 5.7, led to the enrichment of major ions (Ca2+, Mg2+, and alkalinity), and dissolved trace metals (including Fe, Mn, As, and Zn) in the groundwater. Rare earth elements (REE) and yttrium concentrations were also measured in these samples before and after CO2 perturbation, to evaluate their behavior. An enrichment of total Y plus REE (REY) occurred. REY fractionation was observed with higher heavy REE (HREE) enrichment compared to light REE (LREE), and significant variations in La/Yb and Y/Ho ratios were observed following CO2 perturbation. Enrichment by a factor of three was observed for Y, Lu, and Tm, and by nearly one order of magnitude for Dy and Yb. A geochemical model was used to evaluate the amount of REE aqueous ions complexed throughout the experiment. Modeling of the results showed that speciation of dissolved REE with carbonate, along with desorption from iron oxyhydroxide surface were the main factors controlling REE behavior. This study increases an understanding of dissolved REE behavior in the environment, and the potential use for applying iron oxides for REE recovery from mine drainages. Furthermore, the description of REE fractionation patterns may assist in surveying CO2 geological storage sites, surveying underground waste disposal sites, and for understanding the formation of ore deposits and fluid inclusions in geological formations.

Leaf‐cutting ants use relative humidity and temperature but not CO2 levels as cues for the selection of an underground dumpsite

1. Leaf‐cutting ants remove copious amounts of colony waste, a potential pathogen source for workers and reared symbiotic fungus, to above‐ground heaps or deep underground chambers. However, the dumpsite may also contain information about plants initially harvested and disposed of because of unsuitability for the fungus.2. The underground environment presents climatic gradients across the soil profile and it is an open question whether leaf‐cutting ants use microclimatic cues to choose suitable sites for waste disposal, as displayed for other in‐nest tasks.3. Climatic preferences in leaf‐cutting ants were investigated for the deposition of colony waste. In the laboratory, deposition of waste particles by workers of Atta laevigata was quantified by offering them, in different experiments, a binary choice of temperatures (range, 15–30 °C), levels of air humidity (range 10–98%), and CO2 concentrations (range, atmospheric values to 10%).4. Leaf‐cutting ants used temperature and air humidity, but not CO2 levels, as cues for the deposition of their waste. They consistently preferred a dry (≤ 33% air humidity) environment. Less consistent, temperature preferences varied depending on colony (15–25 °C for one colony and 25–30 °C for the other). Although workers showed clear preferences for high levels of CO2 for themselves, they were CO2‐indifferent for waste deposition.5. It is argued that the observed climatic preferences for underground waste disposal might aid nest hygiene by providing unsuitable dry conditions for pathogen growth, with thermal preferences that do not hinder worker activities for further waste management and inspection of discarded plants.

Importance of root uptake of 14CO2 on 14C transfer to plants impacted by below-ground 14CH4 release

14C-labelled methane (14CH4) released from deep underground radioactive waste disposal facilities can be a below-ground source of 14CO2 owing to microbial oxidation of 14CH4 to 14CO2 in soils. Environmental 14C models assume that the transfer of 14CO2 from soil to plant occurs via foliar uptake of 14CO2. Nevertheless, the importance of 14CO2 root uptake is not well understood. In the present study, below-ground transport and oxidation of 14CH4 were modeled and incorporated into an existing land-surface 14CO2 model (SOLVEG-II) to assess the relative importance of root uptake and foliar uptake on 14CO2 transfer from soil to plants. Performance of the model in calculating the below-ground dynamics of 14CH4 was validated by simulating a field experiment of 13CH4 (as a substitute for 14CH4) injection into subsoil in a wheat field in the UK. The proposed model simulation was then applied to 14C transfer in a hypothetical ecosystem impacted by continuous 14CH4 input from the water table (bottom of 1-m thick soil), which simulated continuous release of 14CH4 from a deep underground radioactive waste disposal facility. The contrast between the results obtained from the model calculation that assumed different distributions of roots (rooting depths of 11 cm, or 97 cm) and methane oxidation (characterized by e-folding depths of 5 cm, 20 cm, or 80 cm) in the soil provided insight into the relative importance of root uptake and foliar uptake pathways. In the shallowly rooted ecosystem with rooting depth of 11 cm, foliar uptake of 14CO2 was significant, accounting for 80% of the 14C accumulation (as organic 14C) in the plant (leaf compartment). By contrast, in a deeply rooted ecosystem (rooting depth of 97 cm), where the root penetrated to depths close to the water-table, more than half (63%) the 14C accumulated in the plant was transferred via the root uptake pathway. We found that 14CO2 root uptake (thus 14C accumulation in the plant) in this ecosystem depended on the distribution of methane oxidation in the soil; all 14C accumulated in the plant was transferred by the root uptake pathway when methane oxidation occurred at considerable depths (e-folding depths of 20 cm, or 80 cm) in the soil. The high level of 14CO2 root uptake was ascribed to the oxidation of added 14CH4 (i.e., production of 14CO2) in the deep part of the soil and the subsequent high level of root uptake of the deep soil-water containing 14CO2. These results indicate that 14CO2 root uptake contributes significantly to 14CO2 transfer to plants if 14CH4 oxidation occurs at great depths and roots penetrate deeply into the soil. It is recommended that current environmental 14C models must be refined to consider the importance of the root uptake pathway to ensure that dose estimates of 14CH4 release from deep underground waste disposal facilities are accurate.

Temporal changes of geochemistry and microbial community in low and intermediate level waste (LILW) repository, South Korea

Microbes play a major role in affecting the radioactive wastes disposed of in underground wastes repositories. In particular, low- and intermediate-level waste (LILW) contains biodegradable constituents that can affect stability and mobility of radionuclides by the changes of geochemical conditions due to microbial activity. Despite these potential impacts, the bacterial communities in underground repository remain largely unexplored and previous studies have focused on the traditional culture-dependent methods. We examined the bacterial community in a large-scale in situ container packed with simulated waste in LILW underground repository of South Korea using 454 pyrosequencing. Taxonomic analysis showed the presence of Curvibacter, Azonexus, Pseudomonas, Novosphingobium, Acidovorax, and Victivallis as the dominant bacterial genera. Based on the thermodynamic and geochemical results, the precipitation of calcite was estimated to occur in the presence of genus Curvibacter. Although the flow rate of groundwater input had an impact on the bacterial communities, the community structure was resilient to the change of groundwater’s velocity. In addition, total Fe concentration, [Fetotal] was positively correlated to [Cl−] in this system. The temporal changes of geochemical parameters and bacterial communities provide insight for understanding of the microbial activity inside the large scale container and additional biogeochemical information for long-term risk assessment of disposal facility.

Properties and Application of Backfill Materials in Coal Mines in China

Coal is the basic resource underpinning energy generation in China, however, constant, large-scale mining of coal results in many problems such as ecological destruction of mining areas. As a result, backfilling of solid waste underground is proposed to control strata and surface subsidence and to protect the environment. At present, these materials, such as granular material, cemented material and high-water-content materials are mainly used for backfilling. This study summarised the types of backfill materials that are used in coal mines in China along with the backfilling process. Moreover, distribution and characteristics of mines backfilled with these backfill materials were obtained and analysed. Considering the socio-environmental aspects that affect backfilling, this research proposed a guideline for the selection of backfill materials and then analysed specific engineering cases of three backfill materials. In addition, the future development of backfill materials was discussed. With extensive extraction of shallow coal resources in China and, therefore, rapid depletion of coal resources in eastern regions of China, coal mining depth is increasing significantly. As a result, it is required to investigate new backfill materials suited for the deep high-stress environment.

Waste deposition in leaf-cutting ants is guided by olfactory cues from waste.

Social insects often use olfactory cues from their environment to coordinate colony tasks. We investigated whether leaf-cutting ants use volatiles as cues to guide the deposition of their copious amounts of colony refuse. In the laboratory, we quantified the relocation of a small pile of colony waste by workers of Atta laevigata towards volatiles offered at each side of the pile as a binary choice, consisting of either waste volatiles, fungus volatiles, or no volatiles. Fungus volatiles alone did not evoke relocation of waste. Waste volatiles alone, by contrast, led to a strong relocation of waste particles towards them. When fungus and waste volatiles were tested against each other, waste particles were also relocated towards waste volatiles, and in a high percentage of assays completely moved away from the source of fungus volatiles as compared to the previous series. We suggest that deposition and accumulation of large amounts of refuse in single external heaps or a few huge underground waste chambers of Atta nests is due to both olfactory preferences and stigmergic responses towards waste volatiles by waste-carrying workers.