Waste Deposits Research Articles

Diagnosis and proposal of erosion control downstream of the Park Alfredo Werner Nyffeler, in Maringá - Paraná

The surface runoff role in the urban erosion in Northwest Paraná cities was strengthened by many factors, such as the establishment of the cities often in disaggregated soil areas, vegetation cover removal, soil surface impermeabilization caused by construction and poorly executed embankment areas. In Maringá, Paraná, in a bottom valley located near the park Alfredo Werner Nyffeler, there is an accelerated erosive process, damaging half of the urban drainage pipes, which are located around one meter far from the sidewalk. In that way, it poses a risk to the local population and may lead to a collapse of the drainage structure. Within this context, this work aims to diagnose and identify the possible aspects that caused these issues and to design a gabion wall to stem the significative erosive process occurring in the area. Thus, on-site data survey and laboratory analysis were carried out in order to characterize the soil and, by means of the software GawacWin, a gabion retaining wall in order to use it as a prompt, needed retaining measure was designed. The obtained results showed a lack of awareness by the local population in regard to the solid waste deposition, which accumulates downstream of the park. In addition, the drainage pipes could not cope with the peak flows, causing structural damage, leaks and uncovering the junction box. A silty clay embankment was found in the area, which is an expansive soil, contaminated with rubble and the soil compaction was not properly executed. It was used to level the area for the pipeline passage, contributing to the erosion. A gabion wall, with 6m high and 3m base, showed to be an efficient solution with regard to terrain loads. Furthermore, the price, simple construction and the easy merging with the environment are advantages for the gabion wall, when compared to other structural measures.

Remobilization of dissolved metals from a coastal mine tailing deposit driven by groundwater discharge and porewater exchange

Mining impacts on coastal environments have been extensively studied around the world. However, the role of Submarine Groundwater Discharge (SGD) and Porewater Exchange (PEX) as pathways for pollutants from mining waste deposits into seawater has been largely overlooked. Portmán Bay is located in the Cartagena-La Unión Pb-Zn sulphur mining district in Murcia, SE of Spain. The disposal of about 60 million tons of metal-rich mine tailings from 1957 to 1990 led to the infill of most of the bay. Although the effects of metals on indicator organisms have been shown previously, there is a major lack of knowledge on the release of dissolved metals from the emerged tailing deposit into the sea, more than 25 years after the closure of the mining activities. Samples for Ra isotopes (223Ra, 224Ra, 226Ra and 228Ra) and dissolved metals (Ag, Cd, Co, Pb, Zn) were analyzed in porewaters and seawater in order to separately estimate SGD and PEX driven dissolved metal fluxes. Our results show a continuous release of dissolved metals into the sea driven by both PEX and SGD. Most of dissolved metals are remobilized and released into the water column by PEX, which is a ubiquitous mechanism acting along the shoreline. Although SGD only represents 13% of the water flow, it drives large fluxes of dissolved Fe into the sea, mainly restricted to the west side of the bay. Large inputs of dissolved Fe2+ from the anoxic tailings deposit trigger a massive precipitation of iron hydroxides that enables the removal of most dissolved metals from the water column. This study highlights the role of PEX and SGD as significant mechanisms for the land to ocean transfer of dissolved metals from coastal mine tailings deposits.

A High-Throughput Fluorescence-Based Assay for Rapid Identification of Petroleum-Degrading Bacteria.

Over the past 100 years, oil spills and long-term waste deposition from oil refineries have significantly polluted the environment. These contaminants have widespread negative effects on human health and ecosystem functioning. Natural attenuation of long chain and polyaromatic hydrocarbons is slow and often incomplete. Bioaugmentation of polluted soils with indigenous bacteria that naturally consume petroleum hydrocarbons could speed up this process. However, the characterization of bacterial crude oil degradation efficiency – which often relies upon expensive, highly specialized gas-chromatography mass spectrometry analyses – can present a substantial bottleneck in developing and implementing these bioremediation strategies. Here, we develop a low-cost, rapid, high-throughput fluorescence-based assay for identifying wild-type bacteria that degrade crude oil using the dye Nile Red. We show that Nile Red fluoresces when in contact with crude oil and developed a robust linear model to calculate crude oil content in liquid cell cultures based on fluorescence intensity (FI). To test whether this assay could identify bacteria with enhanced metabolic capacities to break down crude oil, we screened bacteria isolated from a former Shell Oil refinery in Bay Point, CA, and identified one strain (Cupriavidus sp. OPK) with superior crude oil depletion efficiencies (up to 83%) in only 3 days. We further illustrate that this assay can be combined with fluorescence microscopy to study how bacteria interact with crude oil and the strategies they use to degrade this complex substance. We show for the first time that bacteria use three key strategies for degrading crude oil: biofilm formation, direct adherence to oil droplets, and vesicle encapsulation of oil. We propose that the quantitative and qualitative data from this assay can be used to develop new bioremediation strategies based on bioaugmentation and/or biomimetic materials that imitate the natural ability of bacteria to degrade crude oil.

Waste generation from the production of ready-mixed concrete

In Brazil, ready-mixed concrete (RMC) suppliers are adopting management strategies to reduce waste generation. This is because of the increasing scarcity of adequate places for the deposition of waste, which raises the associated costs. Therefore, it is necessary to know the actual volume production of residues in order to optimize the implementation of the recycling. The waste produced in RMC plants are mainly in the form of leftover concrete and adhered to the internal part of the drum of the mixer truck. The present study analyzed the data and produced an inventory of the amount of waste generated by of one of the largest Brazilian concrete companies. In parallel, an experimental study was performed in the real conditions of an RMC plant in order to measure the influence of concrete characteristics on the volume of concrete adhered to the drum. The results showed that about 3% of all the produced volume returns to the plant, comprising approximately 1.6% adhered concrete and 1.4% leftover concrete. The study proved that the volume of concrete adhered concrete depends on the cement consumption and the slump. The volume of concrete loaded and the region where the RMC plant is located do not influence those results. The inventory showed that the main cause of concrete leftovers is associated to over order and corresponds to 58% of this volume.

Mapping and modelling human exposure to uraniferous mine waste using a GIS-supported virtual geographic environment

Abstract The exposure of residents to large volumes of uraniferous mine waste deposits scattered across densely populated areas in the South African goldfields has long been identified as a potential health threat. To quantify this threat for selected locations numerous studies determined concentration levels of uranium and other radionuclides in different environmental media of the Witwatersrand basin including streams, soils, tailings deposits, mine water effluents, fluvial sediments, aquatic organisms as well as in the food chain (fish, cattle, crops, vegetables etc.). This paper describes how the secondary data were extracted from various sources in order to map the spatial extent and intensity of uranium pollution in selected goldfields and to quantify associated exposure of residents. Steps included geo-referencing, normalisation against selected benchmark values, and superimposition of complementary data sets in GIS. For easing access to the data base for non-GIS experts a virtual geographic environment (VGE) was used, offering updated satellite imagery and additional functionality that aided in modelling exposure of target populations. Exposure pathways considered here include ingestion of polluted water, food and soil (geophagia) as well as the inhalation of wind-blown tailings dust. In addition, anecdotal evidence and media-based reports on mining-related pollution and impacts were captured. Maps derived from the VGE were used to identify hot spots of radioactive pollution aiding the selection of suitable sampling sites for a screening survey on U-uptake by exposed residents using hair as a bio-indicator.

Health and Environmental Risks of Residents Living Close to a Landfill: A Case Study of Thohoyandou Landfill, Limpopo Province, South Africa.

The by-products of solid waste deposited in a landfill has adverse effects on the surrounding environment and humans living closer to landfill sites. This study sought to test the hypothesis that the deposition of waste on landfill has an impact on the surrounding environment and residents living closer to it. This was achieved by evaluating the perception of the respondents drawn from people living close (100–500 m) and far (1–2 km) from the landfill site, concerning environmental issues, health problems, and life satisfaction. Results from the study showed that 78% of participants living closer to the landfill site indicated serious contamination of air quality evident from bad odours linked to the landfill site. Illnesses such as flu, eye irritation and weakness of the body were frequently reported by participants living closer to the landfill than those living far from the landfill. More than half of the participants (56%) living closer to the landfill indicated fear of their health in the future. Thus, the participants living closer to the landfill site were less satisfied with the location of their community with respect to the landfill, than those living far from the landfill site. Therefore, the need for a landfill gas (LFG) utilisation system, proper daily covering of waste and odour diluting agents are necessary to reduce the problems of the residents living closer to the landfill site.

Investigation of Acid-Base and Redox Regimes of Tin Ores Enrichment Wastes in Primorye and Priamurye

The elemental and mineral composition of enrichment and processing wastes of tin ore and possible chemical processes occurring in these wastes are analyzed. The article discusses the manifestations of acid-base and redox potentials of waste enrichment of tin ores of Primorye and Priamurye. As a result of these processes, the composition and chemical properties of the studied objects are constantly changing in time and space, so it is important to study their acid-base and redox potentials. Typically, the state of the waste deposits is estimated using indicators Eh and pH, characterizing the active manifestation of the acid-base and redox properties; the hidden possibilities of the studied objects are not taken into account and are not evaluated. To evaluate these possibilities, the authors determined such indicators as total acidity and alkalinity, the number of oxidation and reduction centers (mmole equivalent per kilogram of waste). Analysis of results showed that waste processing tin ore can at the expense of the latent acidity to constantly maintain an acid-base mode, but at the expense of reduction centers to support rH less 28, i.e. to create a shortage of oxygen. Thus, when developing a system of measures to prevent the negative impact of tin ore processing wastes, it is necessary to take into account the facts of “inexhaustibility” of reserves of constantly generating acidic and reducing centers of these wastes.

Загальна характеристика правового режиму земель під сміттєзвалищами

Загальна характеристика правового режиму земель під сміттєзвалищами

Reclamation of phosphogypsum deposition site in Wislinka near Gdansk with municipal sewage sludge

Utilization of sewage sludge is becoming one of the biggest environmental problems.One of the possible solutions is application of sludge to soil amendment. Sludge is a goodnatural fertilizer due to high concentration of organic carbon and nutrient elements (N, P).On the contrary, sewage sludge also contains heavy metals and may be contaminatedwith enteric parasites. Thus application of sludge to land could result in contamination ofsurface and ground waters and including trace metals in the food chains due tocontamination of plants grown on sludge amended soils. Hence land application of sludgeought to be carefully monitored and follow stringent regulations, which are often difficultto fulfil. However, if sludge is applied to reclamation of degraded post-industrial lands,waste deposition sites, landfills and formation of soil-like surface layer on soil-lessgrounds, the restrictions are not so stringent and easier to fulfil than in cases when cropsare grown on sludge amended soils.In the article reclamation of a phosphogypsum deposition site in Wislinka near Gdanskusing sewage sludge from a municipal wastewater treatment plant (WWTP) is discussed.Phosphogypsum deposit in Wislinka for many years has been one of the biggestenvironmental problems of the region, causing permanent complainants from localcommunities. Reclamation of the deposition site started in 1999 and has been continuedup till now. Covering of the slopes with a layer of sludge reduces dangerous wind erosionof dust and promotes plants succession.

Zmiany rzeźby terenu pod wpływem zwałowisk pogórniczych w powiecie mikołowskim


 Tradycje górnictwa węglowego na Górnym Śląsku datują się na XVI wiek, z którego pochodzą pierwsze wzmianki o wydobyciu węgla kamiennego w sąsiedztwie Rudy Śląskiej, Katowic i Mikołowa. Intensywny rozwój górnictwa w poprzednich wiekach był nie tylko źródłem zysków ekonomicznych, ale spowodował także wyraźne zmiany w środowisku przyrodniczym regionu. Te zmiany to głównie szkody górnicze w postaci osiadań, zasolenia wód powierzchniowych czy ruchów górotworu oraz przekształcenia wynikające z procesów technologicznych – np. deponowanie odpadów wydobywczych i przeróbczych na zwałowiskach. Celem artykułu jest ocena wpływu deponowania odpadów górniczych na powierzchnię terenu powiatu mikołowskiego, a także przedstawienie zmian w strukturze przemysłu wydobywczego w skali lokalnej. Treść artykułu zawiera opis budowy geologicznej obszaru badań, przedstawienie stopnia przekształcenia powierzchni terenu przez działalność górniczą, ocenę wpływu deponowanych odpadów na rzeźbę terenu i środowisko przyrodnicze, a także ocenę stanu rekultywacji opisywanych obiektów. Na podstawie badań wykonano przekroje obrazujące wpływ deponowania odpadów na powierzchnię terenu. Zmiany struktury przemysłu wydobywczego w skali lokalnej przedstawiono na przykładzie odzysku węgla z jednego ze zwałowisk, usytuowanego w północnej części powiatu mikołowskiego.

Enhancement of metal creep lifetime by graphene coating

An advancement can be seen in ultra-thin coatings used for the enhancement of material durability and lifespan. Among candidate materials, copper is used in various applications, such as micro sensors, nuclear fuel waste deposition canisters, and International Thermonuclear Experimental Reactor first walls. However, it is easily susceptible to metal creep, due to its exposure to harsh environments. In this study, graphene, a promising ultra-thin material, is tested as a single-layer coating substance used to enhance the creep property of copper. For measuring creep life, the small punch creep test methodology is adopted. Results show that, remarkably, the creep lifetime of copper increases by up to 19% with the use of the graphene coating. In testing, the heat-treated copper specimen without graphene was fractured at 45 hours, while the graphene-coated copper specimen was fractured at 55.4 hours. The finite element method also supports the experimental results obtained.

Aspecto da sazonalidade nos parâmetros físico – químicos da água dos poços, Raposa - Maranhão, Brasil

A água potável é um dos principais meios para preservação da saúde humana, entretanto, a água que não possui o tratamento adequado pode servir como um potencial veículo para transmissão de doenças, pois é capaz de veicular inúmeras enfermidades a partir de falhas no controle de qualidade dos mananciais e reservatórios que fornecem água para população, seja por ingestão ou por contato da pele e mucosas com a água contaminada. O aumento da demanda por água potável e os riscos de contaminação dos poços subterrâneos por se encontrarem próximos a fossas e depósitos inadequados de lixo são alguns dos problemas enfrentados pelo Serviço Autônomo de Água e Esgoto (SAAE) do município de Raposa. Com o auxílio de Análises das Componentes Principais, foram geradas três Componentes Principais (CP) explicando mais de 75% da variância total entre os períodos estudados. Nas CP1, CP2 e CP3 foram enquadradas as variáveis pH, turbidez, condutividade, sólidos totais dissolvidos, teor de nitrato e nitrito relacionadas a variação em períodos sazonais.

Potentially toxic metal contamination and microbial community analysis in an abandoned Pb and Zn mining waste deposit

Bioindicators have been widely used to assess the contamination of lead/zinc (Pb/Zn) in smelter areas, mining waste disposal areas and in areas containing slags from Pb ore smelting. In this context, the analysis involving microorganisms has gained prominence as a complementary tool in studies aimed at assessing contaminated sites. Therefore, the objective of this study was to assess the contamination of Pb, Zn and cadmium (Cd) in an area where a PbZn smelter operated, using the integration of geochemical and microbial data. The experimental analysis was conducted to characterize the soil collected at three different sites (samples NS, EW and EP). The analysis conducted was physicochemical, metal concentration, metal speciation and analysis of the microbial community through high-throughput sequencing technique. Through the results it was observed that the high concentrations of metals altered the bacterial community present in the soil. Differences were noted between the microbial communities according to the sampling site, especially in sample EP, collected at the margin of the dirt road, which presented higher metal concentrations and microbial diversity. The main phyla detected in the samples were: Proteobacteria, Bacteroidetes and Acidobacteria. Bacteria tolerant to the presence of potentially toxic metals (PTM), such as Rhodoplanes, Kaistobacter, Sphingomonas and Flavisolibacter were identified in the analyzed samples. The phylogenetic groups identified in the study area are similar to those obtained in other studies in metal contaminated areas. The differences between the bacterial communities in each sample indicate that the concentration of PTM may have influenced the microbial community in the soil. Thus, it is noted the importance of the integration of geochemical and microbial data to evaluate the impact of the improper disposal of high PTM concentrated slags in natural soils.

Geo-Chemical Exploration of Granite Mining Waste Using XRD, SEM/EDX and AAS Analysis

The purpose of the study was to investigate the mineralogical and Heavy Metals (HMs) present in the granite mining soils in Chimakurthy, India. The mineral exploration of mining soils were identified by X-Ray Diffractometer (XRD) pattern analysis. However, the morphological features and quantitative HMs were detected by Scanning Electron Microscopy/Energy Dispersed Spectroscopy (SEM/EDS). The relative concentrations of HMs measured by Atomic Absorption Spectrometry (AAS). In this study, the major minerals were identified as Quartz, Albite, Anorthite, K-Feldspars, Hornblende, Muscovite, Annite, Lepidolite, Illite, Clintonite, Enstatite, Ferrosilite, Kaolinite, Kyanite, Augite, and Phologopite. Moreover, the presence of six HMs such as Chromium (Cr), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn) and Manganese (Mn), and their relative concentrations were measured. The concentrations of HMs in three groups of mining soils were in the range of Cr: 149-177 mg/kg (>100), for Co: 128-175 mg/kg (>50), for Ni: 166-204 mg/kg (>50), for Cu: 288-363 mg/kg (>100), for Zn: 433-548 mg/kg (>200) and for Mn: 714-769 mg/kg (<2000) as compared with maximum permissible levels set by standard organizations (WHO/FAO) limits. The results demonstrated that the HMs concentrations in mining soils were exceeded WHO/FAO limits except for Mn. The study is useful for assessment of environmental impact due to excessive deposition of mineral waste and assessment of the quality of investigated granites based on their mineralogical aspect, particularly in the production of granite stones.

Concentration of Heavy Metals in Soil around Dumpsites in Jimeta and Ngurore, Adamawa State, Nigeria

Rapid urbanization and industrialization in developing countries have been associated with production and deposition of hazardous wastes in the soil environments. Heavy metals are major components of these wastes and have been implicated in several metal-related diseases and food poisoning in man. This study examined the concentration of Iron (Fe), Lead (Pb), Copper (Cu), Chromium (Cr), and Cadmium (Cd) heavy metals in soil near dumpsites of Jimeta and Ngurore, Yola North Local Government Areas (LGAs), Adamawa State. Soil samples from 0-20cm layer depth were collected in triplicates and analyzed using atomic absorption spectrophotometer (AAS). Results reveal that Fe, Pb, Cu and Chromium were detected, while Cadmium was found to be below the limit of detection. The mean concentration of the exchangeable cation in mg/kg in soil at Jimeta sites were: Fe (31.4 mg/kg) &gt;Pb (0.92 mg/kg) &gt; Cu (0.34 mg/kg) &gt; Cr (0.11 mg/kg) &gt;Cd (below limit of detection), while the mean concentration of the heavy metals in soil at Ngurore sites were: Fe (32 mg/kg) &gt;Pb (0.83 mg/kg) &gt; Cu (0.28 mg/kg) &gt; Cr (0.07 mg/kg) &gt;Cd (below limit of detection), respectively. Iron (Fe) was the most abundant element in both sites, followed by Pb. Heavy metal concentrations in soil followed the order of Fe&gt;Pb&gt;Cu&gt;Cr&gt;Cd, respectively. The paired T-test analyses for concentration of Cr, Fe, and Pb in soil nearthe two dumpsites show that there were statistically significant differences in the concentration levels of Cr, Fe, and Pb, while Cu showed no statistically significant difference between the two dumpsites. However, all the metals detected were below the permissible limit of WHO international standard with the exception of Pb whose concentration was above maximum permissible concentration (MPC). Persistent heavy metals accumulation in soils near these dumpsites may lead to increase uptake by vegetables grown near the dumpsites and this may pose a threat to its quality and safety and ultimately human health. The need to replace open dumpsites with well-designed landfills is advised.

Nucleolar alterations are reliable parameters to determine the cytogenotoxicity of environmental pollutants

Pollution generated by deposition of industrial activity waste in the environment without due care can lead to serious environmental consequences. Bioassays in higher plants are means of understanding the cytogenotoxic effects of these substances. In the present work, Allium cepa L. was used as a model species to assess nucleolar changes induced by environmental pollutants. The substances used were Methyl Methane Sulfonate (MMS), cadmium (Cd), Spent Potliner (SPL) and the herbicide Atrazine. Water was used as a negative control. The silver-stained nucleolar organizer region (AgNOR) assay was used making it possible to evaluate how nucleolar parameters (number of nucleoli per nucleus and nucleoli area) behave when facing stress caused by such pollutants. The results obtained showed a variation in the observed parameters: an increase in the number of nucleoli in the treated cells and tendency to a reduction in nucleolar area, indicating that the tested pollutants may have impaired nucleolar activity. In addition, it was possible to establish a relationship between the behavior of the nucleolus with other changes as plantlet growth, cell proliferation, and DNA damage.

A novel initiative to counteract illegal dumping in rural areas of Valladolid Province (Spain).

In the whole territory of Castilla y León (Spain), there are currently more than 2000 waste dumps that will be restored through a novel programme in the period 2017-2019 with an investment of more than 10 M€. Castilla y León regional government is currently implementing this programme in the province of Valladolid for the environmental recovery of areas heavily degraded by the deposit of inert waste, which entails the restoration of illegal dumps in the province bigger than 1000m2, a total of 133. The programme also includes the implementation of an alternative and legal system for the management of construction and demolition waste, amongst other waste streams. The sealing of landfills and tailings is encompassed within the actions that the regional government is developing in the field of integrated management of waste for their prevention, recovery, recycling and disposal in all the provinces of the community, framed within the line established in the 7th Environmental Action Programme of the European Union. The situation of illegal deposits must be corrected both through direct situations on the affected areas and through measures aimed at ensuring proper management of construction and demolition waste and pruning. This paper shows the first results obtained after the implementation of this regional initiative with the focus set on the description of the implemented waste management programme. The programme provided 2518 services in 2017 managing 6000t of waste which, without the implementation of this programme, would probably have ended up in illegal dumps. These waste streams included debris (33%), discarded appliances (45%) and pruning (22%). The costs associated with the management of these streams were 25.53 €/t debris, 183.16 €/t appliances and 162.40 €/t pruning.

Reprocessing of a mining waste deposit in the Harz mountains – How contaminated sites might become raw material deposits in the future

AbstractDerzeit steigt durch das weltweite Wachstum und Umweltbewusstsein das Interesse an der Rückgewinnung von knappen Rohstoffen aus anthropogenen Ablagerungen. Weitere Motive sind neben dem Rohstoffhunger der modernen Welt das Flächenrecycling und die Gefahrenabwehr. Der Bergeteich Bollrich ist eine feuchte Ablagerung von Aufbereitungsrückständen aus dem Bergbau mit hohen Wertstoffanteilen. In diesem Beitrag wird eine in dem Forschungsprojekt REWITA entwickelte Aufbereitungsroute zur Rückgewinnung verschiedener Rohstoffe bei gleichzeitiger Reduktion von Schadstoffen und des Rückstands vorgestellt. Die Hauptverfahren sind Flotation, Laugung und ionenselektive Anreicherung.

Socioeconomic Status and Temporal Urban Environmental Change in Accra: a Comparative Analysis of Area-based Socioeconomic and Urban Environmental Quality Conditions Between Two Time Points.

The influence of area-based socioeconomic (SE) conditions on environmental quality conditions has recently been reported showing the precise spatial relationship between area-based SE conditions and neighborhood environmental quality in an urban area in a low-income setting. Nonetheless, there is still a lack of understanding of the nature of the relationship on a temporal scale. This study aimed to investigate the dynamic temporal relationship between area-based SE conditions and urban environmental quality conditions over a decadal period in Accra, Ghana. The results showed that there were differences in environmental quality across the SE quintiles in space (with regard to per capita waste generation (p < 0.012), waste collection/clearing (p < 0.01), and waste deposition (p < 0.001) and that the urban environmental quality conditions had changed dramatically over the decade for most of the environmental variables (p < 0.001). Despite the enormous urban development initiatives, some of the environmental quality indicators (e.g., proportion of households without flush toilet/Water Closet, connection to central sewer p < 0.001) appeared to have worsened in the high class quintile, suggesting that a high proportion of households were without acceptable sanitation facilities. The study concludes that urban development in low-income countries will need to follow strictly international best practice by observing standardized building codes and guidelines, if progress should be made in meeting the Millennium Development Goals targets.

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.