Hazardous Waste Landfill Research Articles

Arsenic and lead mobility: From tailing materials to the aqueous compartment

This study concerns the mineralogy of the tailings of a former Ag–Pb mine (Auzelles district, France) and the contribution of the waste materials to the heavy metal dissemination in the environment. Accumulation of metals in fish flesh was reported and this pollution is attributed to past mining activities. Tailings were studied to establish the major transfer schemes of As and Pb in order to understand their mobility that leads to contamination of a whole ecosystem. Mineralogical investigation, solubility and compliance tests were performed to assess the stability of the metal-bearing phases. Among the various metallic elements measured, As and Pb show the highest bulk concentrations (up to 0.7% and 6.3% respectively) especially for samples presenting near neutral pH values. According to X-ray diffraction (XRD), Scanning Electron Microscopy (SEM-EDX), Electron Probe Micro-Analysis (EPMA) and micro-Raman spectrometry (μRS), tailings mineralogy still contain primary minerals such as sulfides (e.g., galena, pyrite), phosphates (monazite, apatite) and/or carbonates (e.g., (hydro-)cerussite, dolomite, siderite). Sulfates (e.g., anglesite, lanarkite, plumbojarosite and beudantite) are the main secondary metal-bearing phases with other interesting phases accounting for metals mobility such as Fe and/or Pb and/or Mn oxides (e.g., lepidocrocite, goethite -up to 15 wt% of Pb was measured-, plumboferrite-type phase, mimetite). The lowest Pb solubilities were obtained at pH 8–9 and at a larger range than for As for which the lowest solubilities are reached around pH 6–7. At this minimum solubility pH value, Pb concentrations released still over exceed the National Environmental Quality Standards (NEQS), whatever the samples. The highest solubility is reached at pH 2 for both elements whatever the considered sample. This represents up to 51% of total Pb and up to 46% of total As remobilized and concentrations exceeding the NEQS. As and Pb released mainly depends on the Fe/Mn oxides (e.g., goethite, lepidocrocite) and carbonates (cerussite) which are the less stable phases. Compliance tests also show that Pb concentrations released are higher than the upper limit for hazardous waste landfills. Determination of the mineralogy allows understanding both the solubility and leaching test experiments results, as well as to forecast the impact of the residues on the water quality at a mid-term scale.

Classification of unregulated landfills by waste stream analysis method, a case of Chief Albert Luthuli Municipality, South Africa

The characterisation of unregulated landfills as general landfills is misleading particularly because these landfills are used to dispose of a mixed stream of general and hazardous waste. Unregulated landfills are unlicensed on-land waste disposal facilities that are not designed, constructed or operated according to any regulatory framework. These landfills are common among non-metropolitan municipalities in South Africa. This paper tests how waste stream analysis can be useful in the pre-characterisation of unregulated landfills. Thus, it is proposed that a waste source trace method be used to pre-classify the waste streams disposed of in the landfills and ultimately for the characterisation of the landfills. Structured interviews and observations were used to trace the origin and types of waste materials disposed of in three unregulated landfills in the Chief Albert Luthuli Municipality. The results show that the landfills resorting under the Chief Albert Luthuli Municipality were used to dispose of a mixed stream of general and hazardous waste. These landfills should therefore be pre-characterised as hazardous waste landfills, and stringent management measures are recommended in this regard. This proposed method for waste stream analysis and pre-characterisation of unregulated landfills has proven to be effective.

Concentrations of metals and PCDD/Fs and human health risks in the vicinity of a hazardous waste landfill: A follow-up study

ABSTRACTIn 2007, an environmental surveillance program to evaluate the impact of a hazardous waste landfill (HWL) located in Castellolí (Catalonia, Spain) was initiated. Between 2011 and 2014, samples of soil and air were collected inside the HWL as well as in nearby villages, and the concentrations of arsenic (As), some metals (cadmium (Cd), chromium (Cr), mercury (Hg), nickel (Ni), and lead (Pb)), and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed. As expected, pollutant levels were higher inside the HWL than in the remaining points. In contrast, air concentrations were similar inside and outside the HWL. Furthermore, an increasing trend of the pollutant levels was not observed in any of the environmental monitors, either soil or air, when comparing with the results from the baseline (2007) and precedent surveys. The human exposure to those pollutants was estimated to contribute to 1–26% of the total exposure, after including the dietary intake. In any case, conclusions are partially limited by the scope of the investigation, which was conducted with a relatively low number of samples. Despite this limitation, it must be highlighted that health risks for the population living in the neighborhood of HWL were considered acceptable, according to international standards.

Evaluation of solid residues quality after enhanced Cu leaching of polluted soils

Excavation followed by landfilling is one of the most common methods for treating soils contaminated with metals. Removing the metals through soil washing not only allows valuable substances to be recovered, but also results in cleaner soil residues. In this project a method for leaching and recovering Cu from polluted soils using acidic wastewater is further developed and evaluated, with special attention to the leaching process. In addition, the qualities of the soil residues are assessed in order to investigate how the proposed remediation method affects the soil properties. Soil samples highly polluted with copper (Cu) were collected from two sites in Sweden. After acidic leaching and water washing, the Cu content of the soil samples was reduced five times or more. The original soils could not even be deposited in landfills for hazardous waste; however after treatment of the soils according to the proposed method, the Cu leaching decreased six-fold and the solid residue was safe enough to be deposited in landfills for non-hazardous waste. The soil function “soil as filter and buffer for heavy metals” was evaluated using the TUSEC (technique for soil evaluation and categorization for natural and anthropogenic soils) manual. Originally the soils were of “low” i.e. class 4 or “very low capacity of binding and buffering heavy metals” i.e. class 5, while after the remediation process, both soils were categorized as Class 5. To summarize, the proposed method clearly shows potential not only for remediation of Cu polluted soils but also indicate a potential for recovery and reuse of Cu from the leachates generated. Even though the previously highly polluted soils could not be directly put back at the original sites, the solid residues could be deposited in landfills for non-hazardous waste, which is an improvement, considering the original soils could not even be deposited in a landfill for hazardous waste.

Immobilization and volume reduction of heavy metals in municipal solid waste fly ash using nano-size calcium and iron-dispersed reagent

This study was conducted to examine the synthesis and application of novel nano-size calcium/iron-based composite material as an immobilizing and separation treatment of the heavy metals in fly ash from municipal solid waste incineration. After grinding with nano-Fe/Ca/CaO and with nano-Fe/Ca/CaO/[PO4], approximately 30 wt% and 25 wt% of magnetic fraction fly ash were separated. The highest amount of entrapped heavy metals was found in the lowest weight of the magnetically separated fly ash fraction (i.e., 91% in 25% of treated fly ash). Heavy metals in the magnetic or nonmagnetic fly ash fractions were about 98% and 100% immobilized, respectively. Additionally, scanning electron microscopy combined with energy-dispersive X-ray spectrometry (SEM-EDS) observations indicate that the main fraction of enclosed/bound materials on treated fly ash includes Ca/PO4-associated crystalline complexes. After nano-Fe/Ca/CaO/[PO4] treatment, the heavy metal concentrations in the fly ash leachate were much lower than the Japan standard regulatory limit for hazardous waste landfills. These results appear to be extremely promising. The addition of a nano-Fe/Ca/CaO/PO4 mixture with simple grinding technique is potentially applicable for the remediation and volume reduction of fly ash contaminated by heavy metals.Implications: After grinding with nano-Fe/Ca/CaO and nano-Fe/Ca/CaO/[PO4], approximately 30 wt% and 25 wt% of magnetic fraction fly ash were separated. The highest amount of entrapped heavy metals was found in the lowest weight of the magnetically separated fly ash fraction (i.e., 91% in 25% of treated fly ash), whereas heavy metals either in the magnetic or nonmagnetic fly ash fractions were about 98% and 100% immobilized. These results appear to be very promising, and the addition of nano-Fe/Ca/CaO/PO4 mixture with simple grinding technique may be considered potentially applicable for the remediation and volume reduction of contaminated fly ash by heavy metals.

Hazardous waste landfill leachate treatment by combined chemical and biological techniques

The efficacies of coagulation, ozonation, Fenton treatment, activated sludge process, Fenton treatment–activated sludge process (CHEM-BIO) and activated sludge process–Fenton treatment (BIO-CHEM) to treat hazardous waste landfill leachate were investigated and compared. The results of the biodegradability test revealed a high content of readily biodegradable organic matter in semicoke landfill leachate, and thus, aerobic biological oxidation was found to be a more reasonable and cost-effective technique for leachate treatment than direct chemical processes (ozonation, Fenton treatment). However, in terms of treatment efficacy, both chemical and biological processes resulted in a high residual organic load, indicating an insufficient leachate quality improvement. The treatment performance of the combined schemes (BIO-CHEM and CHEM-BIO) proved more effective and ensured the removal efficacy percentage met that required by EU legislation as well as the specific target discharge limits of the measured parameters. Accounting for the treatment cost-effectiveness, BIO-CHEM proved to be a more feasible option and could be suggested as the most efficient and practicable technological scheme for hazardous waste landfill leachate treatment.

Evaluation of heavy metals in hazardous automobile shredder residue thermal residue and immobilization with novel nano-size calcium dispersed reagent

This study was conducted to synthesize and apply a nano-size calcium dispersed reagent as an immobilization material for heavy metal-contaminated automobile shredder residues (ASR) dust/thermal residues in dry condition. Simple mixing with a nanometallic Ca/CaO/PO4 dispersion mixture immobilized 95–100% of heavy metals in ASR dust/thermal residues (including bottom ash, cavity ash, boiler and bag filter ash). The quantity of heavy metals leached from thermal residues after treatment by nanometallic Ca/CaO/PO4 was lower than the Korean standard regulatory limit for hazardous waste landfills. The morphology and elemental composition of the nanometallic Ca/CaO-treated ASR residue were characterized by field emission scanning election microscopy combined with electron dispersive spectroscopy (FE-SEM/EDS). The results indicated that the amounts of heavy metals detectable on the ASR thermal residue surface decreased and the Ca/PO4 mass percent increased. X-ray diffraction (XRD) pattern analysis indicated that the main fraction of enclosed/bound materials on ASR residue included Ca/PO4− associated crystalline complexes, and that immobile Ca/PO4 salts remarkably inhibited the desorption of heavy metals from ASR residues. These results support the potential use of nanometallic Ca/CaO/PO4 as a simple, suitable and highly efficient material for the gentle immobilization of heavy metals in hazardous ASR thermal residue in dry condition.

Removal of chromium from tanning wastewater and its reuse

The chromium (Cr) used in the manufacture of leather from hides has well-known adverse effects when inappropriately disposed in the environment. The tanneries use large quantities of water for processing hides. The recovery of Cr from the wastewater produced in the tanning step is an environmentally friendly and economically viable alternative avoiding the disposal of large amount of Cr-containing sludge in industrial hazardous waste landfills. This work aims at studying the removal of the Cr from the tanning wastewater through chemical precipitation (CP) and electrocoagulation (EC) techniques and its reuse in tanning process. In the CP experiments, efficient Cr removal from wastewater samples was achieved, with up to 99.74% removal efficiencies. In the EC experiments, three different electrode materials, Al, Cu, and Fe were tested. The highest removal efficiency of 97.76% was obtained with Al electrodes by conducting electrolysis at 3.0V for 110min. This was followed by Fe electrodes and Cu electrodes, which showed removal efficiencies of 90.27% (at 2.5V) and 69.91% (at 2.0V), respectively, for an electrolysis of 100min. The recovered Cr was reused as a tanning agent in leather processing, where good crossing of Cr was reached in leathers tanned with the liquors prepared from the sludge, and the pH and ash content values were measured. While the hides tanned with the Cr-containing liquor recovered by CP and by EC with Cu electrodes showed good hydrothermal stability and Cr content above 2.5% Cr2O3, the hides tanned with Cr-containing liquors recovered by chemical precipitation and by EC conducted with Fe and Cu electrodes showed contents of Cr according to technical specifications. However, the Cr samples obtained with the iron electrode showed a dark coloration due to oxidation of the iron. It can be concluded that the tanning process with Cr recovered by CP and by EC with Cu electrodes showed the best results.

Assessing the leaching of hazardous metals from pharmaceutical wastes and their ashes.

The purpose of this research was the determination of the leaching potential of eight hazardous metals from expired pharmaceutical wastes and their ashes obtained after simulated incineration. A standardized leaching test (EN 14429) was used to assess leaching over a range of pH and comparison with the limits included in Decision 2003/33/EC was done at liquid/solid ratio 10. The goal was to assess the environmental impacts of pharmaceutical wastes after different disposal techniques (direct landfilling, incineration). A 3-year old composite sample of expired pharmaceutical wastes (drugs) was obtained and was separated into solid and liquid drugs. The packaging from each type of drug was also removed and tested separately, whilst the solid drugs and their packaging were incinerated at 900°C. Leaching tests on all solid substrates (solid drugs, packaging, ashed drugs, ashed packaging) were performed over a wide range of pH. The experiments showed that ashed drugs leached the highest amounts of all metals, except iron, and should be disposed of to a hazardous waste landfill, since Cd, Ni, and Pb exceeded the corresponding limits. Raw expired drugs, raw and ashed packaging did not exceed the pertinent limit values and could be, thus, disposed of directly to a non-hazardous waste landfill. In all experiments, the highest leaching potential (>90% of the total metal content) was measured at acidic pHs (<4). The leachable concentration of all metals increased as pH decreased, whilst Zn observed a small re-dissolution in the alkaline range.

Utilization of phosphogypsum in tannery sludge stabilization and evaluation of the radiological impact.

The current global trend towards increasingly stringent environmental standards and efforts for efficient utilization and re-use of available by-products and/or wastes, favors the use of low-cost sorbent materials for the treatment of heavy metal-contaminated solid wastes. In this study, the stabilization of tannery sludge, produced from the physicochemical and biological treatment of tannery wastewaters, was examined by the addition of phosphogypsum (PG) at a ratio of 1:1. Characterization of the tannery sludge leachates showed high amounts of chromium which exceeded the acceptable level for disposal in non-hazardous waste landfills, while the dissolved organic carbon (DOC) concentrations exceeded the limits for disposal in landfills for hazardous wastes, according to the EU Decision 2003/33/EC. Leachates of the waste stabilized with PG presented chromium and DOC concentrations below the regulation limits for disposal in landfills for non-hazardous wastes. Moreover, mixing PG with tannery sludge resulted in a stabilized waste with reduced radioactivity.

Stabilization of waste bottom ash generated from hazardous waste incinerators

Stabilization of bottom ash generated from hazardous waste incineration by the means of solidification was assessed by applying three different amounts of cement admixture (10%, 20% and 30%) and four distinct solidification periods (1 day, 4 days, 7 days and 28 days) in order to decrease the amount of harmful elements or compounds in the waste. Complex assessment of all the observed parameters was performed both according to the EU standard 2003/33/EC for waste acceptable at landfills for hazardous waste and by using ecotoxicological test on the freshwater algae Desmodesmus subspicatus. Whilst unmodified bottom ash exceeded the permit limit concentrations, after the solidification, most of the elements was immobilized in the admixture. The growth inhibition of D. subspicatus was, however, found out to be increasing during the process, possibly because the increase of molybdenum in the leachate with the increased cement addition and prolonged solidification period. From all the combinations tested, 30% cement addition and the standard 28 days solidification period appears to be the ideal one.

Application of geographical information system in disposal site selection for hazardous wastes.

BackgroundThe aim of this study was to provide a scientific method based on Geographical Information System (GIS) regarding all sustainable development measures to locate a proper landfill for disposal of hazardous wastes, especially industrial (radioactive) wastes.MethodsSeven effective factors for determining hazardous waste landfill were applied in Qom Province, central Iran. These criteria included water, slope, population centers, roads, fault, protected areas and geology. The Analysis Hierarchical Process (AHP) model based on pair comparison was used. First, the weight of each factor was determined by experts; afterwards each layer of maps entered to ARC GIS and with special weight multiplied together, finally the best suitable site was introduced.ResultsThe most suitable sites for burial were in northwest and west of Qom Province and eventually five zones were introduced as the sample sites.ConclusionGIs and AHP model is introduced as the technical, useful and accelerator tool for disposal site selection. Furthermore it is determined that geological factor is the most effective layer for site selection. It is suggested that geological conditions should be considered primarily then other factors are taken into consideration.

Landfill restoration and biodiversity: a case of study in Northern Italy.

Landfilling is a worldwide common waste treatment method. Final recovery usually consists of capping the area with top soil on which vegetation can grow. Depending on the suitability of the recovery pattern, landfill sites can work as potential reserve of semi-natural habitats. A recovery pattern applied to land reclamation of two hazardous waste landfills sited in Northern Italy (Po floodplain) was studied to assess the results in terms of biodiversity. These landfills lie within a landscape dominated by intensive agriculture. After final sealing, both landfills were covered by soil on which a meadow was sown and a hedgerow was planted around the borders. One of the compared areas was not provided with a pond and the hedgerow was incomplete. Butterflies and birds were used as indicators, and their seasonal abundance was related to habitat structure and ecological factors. Meadows grown on both areas supported a rich butterfly population (30 species), including some species that are by now uncommon in the Po floodplain. In both areas butterfly abundance was affected by summer drought. The birds' community included 57 species; 16 Species of European Conservation Concern (SPECs) were observed. Each bird community was different in the compared study areas because of their different size and habitat structure. For example, landfill A, provided with a pond and a more complex structure of the hedgerow, supported a richer birds community (52 species versus 39). Both restored landfills worked well as a stepping stone for migratory birds, but they were a reproductive habitat of poor quality.

Using MCDA and GIS for hazardous waste landfill siting considering land scarcity for waste disposal

The main aim of this study was to develop a procedure that minimizes the wasting of space for the siting of hazardous waste landfills as part of a solid waste management system. We wanted to tackle the shortage of land for waste disposal that is a serious and growing problem in most large urban regions. The procedure combines a multi-criteria decision analysis (MCDA) approach with a geographical information system (GIS). The GIS was utilised to obtain an initial screening in order to eliminate unsuitable areas, whereas the MCDA was developed to select the most suitable sites. The novelty of the proposed siting procedure is the introduction of a new screening phase before the macro-siting step aimed at producing a “land use map of potentially suitable areas” for the siting of solid waste facilities which simultaneously takes into consideration all plant types. The issue of obtaining sites evaluations of a specific facility was coupled with the issue of not wasting land appropriate to facilitate other types of waste management options. In the developed case study, the use of an innovative criteria weighting tool (the “Priority Scale”) in combination with the Analytic Hierarchy Process was useful to easier define the priorities of the evaluation criteria in comparison with other classic methods such as the Paired Comparison Technique in combination with the Simple Additive Weighting method.

Mechanical behavior of typical hazardous waste and its influence on landfill stability during operation

The stability of hazardous waste (HW) landfill is a major security risk to the landfill environmental safety. The mechanical behavior of waste controls many aspects of landfill design and operation, including stability and settlement issues and the integrity of geosynthetic and liner components. This study presents the results of a laboratory experiment to learn the mechanical properties of HW collected from the Hangzhou HW landfill. Measured mechanical behavior was compared with results for municipal solid waste (MSW) to assess their discrepancies. The particle size of HW was analyzed by the sieving and hydrometer methods. Because HW comes primarily from industrial plants in the form of sludge or slag, their particle sizes are generally smaller than those of MSW. This study indicates that the shear strength parameters of HW are more sensitive to the methods of testing and calculation than those of MSW. Numerical simulations demonstrate that the safety factor of a landfill is affected by the mechanical properties of HW, especially cohesion and friction angle. Because of the lower particle size and wider compression ratio, compared to MSW, an HW landfill should be taken more care in its operational procedures so as to increase its stability.

Simulation on forecast and control for groundwater contamination of hazardous waste landfill

The groundwater flow and solute transport models were established by Visual Modflow, which was used to forecast the transport process of Cr6+ in groundwater and simulate the effects of three control measures of contaminants transport after percolation solution leakage happened in the impermeable layer of the landfill. The results showed that the contamination plume of Cr6+ would reach the pool’s boundary in 10 years, and the distance of contamination transport was 1,450 m. However, the contamination plume will not be obviously expanded between 10 and 20 years. While the ground was covered by hardened concrete, the contamination plume would not reach the pool’s boundary in 20 years. When the leakage-proof barrier was set in the bottom of an unconfined aquifer, the concentration of Cr6+ was higher than that of the leakage-proof barrier unset, but the result was opposite when setting the leakage-proof barrier in the bottom of confined aquifer. The range of the contamination plume was effectively controlled by setting drainage ditches in which water discharge was 2,298.05 m3 d−1, which produced monitoring wells which are not contaminated in 20 years. In sum, combining ground hardening with drainage ditches could produce the best effect in controlling contaminants diffusion, and meanwhile, the drainage ditches daily discharge was reduced to 1,710.19 m3 d−1.

Forensic Evaluation of Metals (Cr, Cu, Pb, Zn), Isotopes (δ13C and δ15N), and C:N Ratios in Freshwater Sediment

A forensic approach was used to evaluate sediments from Portão Stream, including analysis of metals, carbon (C) and nitrogen (N) stable isotopes, and C:N ratios. Samples collected at various points located along the stream were tested in order to investigate a possible illegal leachate input. The studied stream is heavily impacted by sewage and industrial discharges from two cities along its course. Among the metals analyzed, chromium (Cr) was noticeably the main pollutant, showing the highest levels, above regulatory limits, downstream from some potential sources of effluents enriched with this metal. Isotope analyses revealed a general trend of depletion in the heavier isotope along the stream for C and N. The exception was one point near a hazardous waste landfill, where relatively more enriched δ13C and δ15N values were found. The isotope and metal analysis results indicated that this site was affected by a particular source, demonstrating the combination of these parameters could be used for the discrimination of sources in a heavily polluted stream. Nevertheless, further investigations are necessary to provide a comprehensive evaluation of the biogeochemical processes involved in the incorporation of leachate in sediments to use this analysis as evidence for the illegal leachate discharge.

A Holistic Model of Leakage Risk Assessment in a Hazardous Waste Landfill

Risk-based method has been increasingly frequently used by regulators and managers in modern landfill to scientifically manage solid waste and reduce its environmental hazards. As far as hazardous waste landfill is concerned, the main risk can be identified as the leakage of leachate. To quantify the uncertainties and its influences on risk assessment of leachate leakage, EPACMTP model with the involvement of Monte Carlo method is used to propagate the randomness of input parameters; Fault tree analysis method is employed to compute the uncertainties of liner damage; and the last, health risk assessment model was also integrated into to form a holistic model of leakage risk assessment.. A hazards waste landfill located in the southwest China is taken as a case study. The assessment result indicates that 1) the main exposure pathway is oral intake;2) The total non-carcinogenic risks for adult and for child are, accordingly, equal to 0.68 and 0.75, which under most circumstance is acceptable.

Detection of landfill cover damage using geophysical methods

ABSTRACTIn closed hazardous waste (i.e. industrial) landfills, impermeable covers are used to seal in the waste so as to minimise water infiltration and the accumulation of leachate inside the waste. In this paper, we present a geophysical study performed on a French landfill where the cover was designed using impermeable (clay) and drainage (sand) layers along with a Geosynthetic Clay Liner (GCL) in between. As observed, the quantity of leachate increases after rain events making the leachate treatment more expensive. This could be due to areas of weakness in the cover that have developed over time or which date back to its installation. Three different geophysical methods were employed and confronted to detect and assess such damage, and, if necessary, to help choose the most suitable remediation of the cover: Automatic Resistivity Profiling (ARP) which enables a rapid mapping of the entire landfill; the self‐potential method (SP) as one of its sources is water drainage; and electrical resistivity tomography (ERT) to obtain 2D resistivity models. Based on the ARP results revealing high lateral heterogeneities of the superficial cover materials, the SP and ERT measurements were conducted on a limited area. A negative SP anomaly was observed at the top of the landfill, where the cover is the thinnest and the GCL the most damaged, suggesting preferential infiltration under the GCL. The 2D ERT profile showed both vertical and horizontal variations. Comparison with manual auger holes showed that the alternating clayey and sandy layers did not conform to plans for the original cover when it was installed at this site about twenty years ago. Variations in electrical resistivity noticed at the depth of the GCL were attributed to possible damage to the GCL and a greater than expected permeability since the GCL is normally very resistive. The results obtained in this study were important to understand the damage to the cover due to the use of different types and thicknesses of cover materials compared to what was originally planned, and deterioration of the GCL.

Study of the Properties of Concrete Containing Waste Foundry Sand as Part of the Aggregate

The foundry industry has greatly increased in many parts of the world, and their generation of enormous amounts of waste foundry sand is a major environmental concern. Such waste may be classified as hazardous, requiring special precautions for its management, which may include disposal in landfills for hazardous waste. However, this waste can be used as a partial substitute for the sand in a concrete aggregate. Slump flow, water absorption, concrete compression strength, and index void tests were performed to study the properties of fresh and hardened concrete made by substituting 10% and 20% of the sand by weight with foundry sand as concrete aggregate. Image analysis by optical microscopy was also performed in the present study. The results showed that the replacement of the waste foundry sand is technically feasible under the conditions studied and that both the substitutions studied increase the compression strength of the concrete.