Management Of Acid Mine Drainage Research Articles

Treating waste with waste: Lignin acting as both an effective bactericide and passivator to prevent acid mine drainage formation at the source

Acid mine drainage (AMD) induced by pyrite oxidation is a notorious and serious environmental problem, but the management of AMD in an economical and environmentally friendly way remains challenging. Here, lignin, a natural polymer and abundant waste, was employed as both a bactericide and passivator to prevent AMD formation. The addition of lignin to a mimic AMD formation system inoculated with Acidithiobacillus ferrooxidans at a lignin-to-pyrite weight ratio of 2.5: 10 reduced the combined abiotic and biotic oxidation of pyrite by 68.4 % (based on released SO42−). Morphological characterization of Acidithiobacillus ferrooxidans revealed that lignin could act on the cell surface and impair the cell integrity, disrupting its normal growth and preventing biotic oxidation of pyrite accordingly. Moreover, lignin can be used alone as a passivator to form a coating on the pyrite surface, reducing abiotic oxidation by 71.7 % (based on released SO42−). Through multiple technique analysis, it was proposed that the functional groups on lignin may coordinate with iron ions on pyrite, promoting its deposition on the surface. In addition, the inherent antioxidant activity of lignin may also be actively involved in the abatement of pyrite oxidation via the reduction of iron. Overall, this study offered a “treating waste with waste” strategy for preventing AMD formation at the source and opened a new avenue for the management of AMD.

PENGELOLAAN KUALITAS AIR ASAM TAMBANG SETTLING POND PADA KEGIATAN PERTAMBANGAN BATUBARA DI KABUPATEN TANAH LAUT

Management of acid mine drainage is necessary to ensure that the seetlingpond outlet meets the required environmental quality standards. This research was conducted at the seetlingpond location of PT. Jorong Barutama Greston. The aim of this research is to analyze the relationship between the seetlingpond inlet discharge and the use of lime using manual and automatic methods with the outlet parameter sizes being pH Fe, Mn and Cd. Data collection was carried out for approximately 1 year. Observations were taken on a monthly average, both discharge, amount of lime and results of chemical analysis of water quality. The results showed that the method of using lime automatically produces a significant linear relationship between the amount of discharge and the use of lime, while the use of lime manually does not occur consistently between the amount of discharge and the amount of lime so that the use, for the results of water quality analysis either manually or using a lime mixing machine, both produce water quality output that meets environmental quality standards based on the standards of South Kalimantan Governor Regulation No. 36 of 2008.

Literature Study on Coal Acid Mine Drainage Management Using Phytoremediation Method

Literature study on the management of Acid Mine Drainage through phytoremediation has become crucial to gain a better understanding of its potential, challenges, and recent developments. The research method employed in this study is Literature Review. Literature Review involves a series of activities related to collecting literature data, reading and note-taking, as well as processing research materials. The findings reveal that using a greater variety of plants provides a more comprehensive overview. The use of diverse plants or more complex phytoremediation systems offers a broader understanding. The evaluation of plant abilities in absorbing iron (Fe) and manganese (Mn) is emphasized. Adding evaluations for other metals or potential pollutants would enhance the research completeness. A decline in plant absorption abilities after ten days is observed, but external factors such as temperature, pH, or environmental conditions affecting this decline are not extensively discussed

Peningkatan pH dengan Pemberian Bahan Organik pada Pengelolaan Air Asam Tambang Menggunakan Metode Passive Treatment

Mining is the process of extracting beneficial minerals from the surface of the earth that have an impact on the formation of acid mine drainage (AMD). One method of passive AMD management is passive treatment. This study used the Nested Factorial Experiment Design method. The types of organic matter used were empty fruit bunch oil palm (EFB) and cow dung, with doses of 0 Mg ha-1 (control), 50 Mg ha-1, 100 Mg ha-1, 150 Mg ha-1 and 200 Mg ha-1. Each treatment was three repeats so that 30 units of experimental units were obtained. The pH value of AMD in the untreated (control) reactor was 3.67. The initial reaction (pH) of AMD (0 days) with EFB application at a dose of 50 – 200 Mg ha-1 ranged from 3.63 – 4.28 and the initial pH of cow dung was 3.84 – 4.13. The reaction (pH) of the 1st to 4th weeks of AMD after adding EFB organic matter at a dose of 50 – 200 Mg ha-1 show a pH range (6.38 – 7.59) and cow manure at a dose of 150 – 200 Mg ha-1 show a pH (6.09 – 7.01). The conclusion are that the application of EFB organic matter on constructed wetland media for 4 weeks had a very real effect on increasing the pH of the AMD dose of 100 – 200 Mg ha-1 while cow dung 150 – 200 Mg ha-1 are the most effective against increasing pH.

ACCUMULATION OF HEAVY METAL IN CHINESE WATERCHEST-NUT (Eleocharis dulcis Burm.f.) Trin. Ex Hensch.) IN PHYTOREMEDIA-TION OF COAL ACID MINE WATER ON CONSTRUCTED WETLANDS.

The coal open mining is an activity that has an impact on the environment, including acid mine drainage (AMD). The management of AMD can be done by phytoremediation using Chinese Waterchestnut (Eleocharis dulcis Burm.f.) Trin. ex Hensch.) on system of constructed wetlands (CWs). So the research was carried out with the aim of evaluation the accumulation of heavy metals iron (Fe) and Manganese (Mn) which were absorbed in E. dulcis in constructed wetlands system at WTP Air Laya PT. Bukit Asam. The accumulation of Fe in the roots of E. dulcis was 986.42 ppm (w/w) while the accumulation of Fe in the leaves was 392.22 ppm (w/w). The accumulation of Mn in the roots of E. dulcis was 24.49 ppm (w/w), while the accumulation of Mn in the shoots was 96.83 ppm (w/w). E. dulcis is known to have the potential to increase AMD pH and reduce levels of Fe, Mn and SO42- so that it can meet the quality standards of coal mining activity wastewater. The accumulation of Fe and Mn in the roots and shoots of E. dulcis and on AMD can be used as an effort to monitor the success of AMD phytoremediation on Constructed Wetlands system at WTP Air Laya.

Application of Active and Passive Treatment of Acid Mine Drainage to Comply with the Threshold Parameter of Coal Mining Wastewater

Most of the coal mining in Indonesia that uses the open pit mining method faces serious problems, namely the treatment of acid mine drainage. This constitutes a relatively large volume of wastewater, especially in areas that have rainfall in the range of 2000–4000 mm yearly. Acid mine drainage as acidic wastewater formed during excavation cannot be avoided due to the oxidation process during overburden removal. The acidic wastewater that has formed must be managed strictly and appropriately prior to being released into public waters. There are two methods of treating acid mine wastewater, namely active and passive treatments. Active treatment is generally used more frequently during operations, considering the time, effort, and costs; however, when entering the mine closure period, natural processes must be used at lower costs. Undertaking passive treatment in this area has shown a reduction in the chemical materials used and has enabled a greater amount of wastewater to be managed. The purpose of this research is to describe the active and passive treatment processes in the management of acid mine drainage and to analyze the results of passive treatment in preparation for the mine closure stage. Development of passive treatment by swampy forest system can reduce cost of treatment, naturally process and more environment friendlier by reducing the quicklime materials.

A review: The formation, prevention, and remediation of acid mine drainage.

In abandoned open-pit coal mines, surface water and groundwater form acidic waters with high concentrations of metal ions due to chemical interactions with ores such as pyrite, and the formation of acid mine drainage (AMD) is one of the major sources of pollution of world concern. For this reason, this paper reviews the formation mechanisms and influencing factors of AMD. It also describes the prediction, prevention, and remediation techniques for AMD, identifying key research gaps. It also discusses the current challenges and shortcomings faced globally in the management of AMD. The formation of AMD is mainly caused by the oxidation of pyrite in mines, but it is mainly influenced by history, climate, topography, and hydrogeology, making the formation mechanism of AMD extremely complex. Currently, the remediation technologies for AMD mainly include active treatment and passive treatment, which can effectively neutralize acidic wastewater. However, the prediction technology for AMD is blank, and the source treatment technology such as passivation and microencapsulation only stays in the experimental stage. This leads to the high cost of treatment technologies at this stage and the inability to identify potential risks in mines. Overall, this review provides remediation tools for AMD from predicting root causes to treatment. Geophysical technology is an effective method for predicting the motion path and pollution surface of AMD in the future, and resource recovery for AMD is a key point that must be paid attention to in the future. Finally, integrated treatment technologies that deserve further exploration need to be emphasized.

Simultaneous removal of multiple metal(loid)s and neutralization of acid mine drainage using 3D-printed bauxite-containing geopolymers

The mining industry is one of the largest sources of environmental concern globally. Herein we report for the first time the application of highly porous 3D-printed sorbents containing high amounts (50 wt%) of red mud, a hazardous waste derived from the alumina industry, for the remediation of acid mine drainage (AMD). The sorption capacity of the inorganic polymers was initially evaluated for the simultaneous removal of five metal(loid) elements, namely Cu(II), Ni(II), Zn(II), Cd(II) and As(V) in synthetic wastewater. The effect of the initial concentration, pH and contact time were assessed, reaching removal efficiencies between 64% and 98%, at pH 4 and initial concentration of 50 mg L−1 of each cation, after 24 h of contact time. The 3D-printed lattices were then used for the remediation of the real AMD water samples, and the role of adsorption and acidic neutralization was investigated. Lattices were also successfully regenerated and reused up to five cycles without compromising their performance. This work paves the way for the use of an industrial waste derived from the production of alumina as raw material for the management of the hazardous AMD.

Selection of organic matter as a wetland substrate for acid mine drainage treatment

Acid mine drainage (AMD) is one of the problems arising from mining activities. Acid mine drainage is formed due to the oxidation of sulfide minerals such as pyrite (FeS2) by water and oxygen. Alternative management of AMD in a sustainable and eco-friendly way is constructed wetland. Therefore, this study was conducted to determine the type and composition of potential organic matter that can improve AMD quality. The study consisted of three stages: a screening of organic matter, a combination of two organic matters, and a combination of cow manure and empty fruit bunches (EFB) in various compositions. Types of organic matters used are cow, goat, and chicken manure, three types of compost, EFB, sawdust, wood chips, chopped water hyacinth, cocopeat, fresh waste and compost waste cajuputi leaf, waste of citronella distillation, baglog waste, and bagasse. The results showed that several types of organic matter could increase the pH of AMD. The combination of EFB and cow manure with a ratio of 2:1 is the best result because it can increase pH, reduce dissolved heavy metals and sulfates, and availability of raw materials that are abundant in nature, especially in Indonesia.

Reduction in acidity and heavy metal concentrations of acid mine drainage with organic matter and coal fly ash treatments in two different reclaimed-mining soils

Organic matter (OM) has a very crucial role in the management of acid mine drainage (AMD) using a passive treatment system, although information on the use of this system in different reclaimed-mining soils (RMS) is very limited. Therefore, this study aimed to determine the effect of adding OM to RMS with different characteristics. It was carried out by adding only OM or in combination with coal fly ash (CFA) to two RMS with different characteristics (Palam and Cempaka Soils) and quartz sand (control) in a batch reactor experiment. This was followed by the incubation of the mixture of soil/quartz-OM or soil/quartz-OM-CFA at 60% water holding capacity for 15 days. After incubation, AMD slowly flowed into the reactor, and its pH in the reactor was monitored every day for 30 days, while the concentrations of Fe (iron), Al (aluminum), and Mn (manganese) were measured on the 30th day. The results showed that the application of OM on Palam Soil only increased AMD pH by 0.38 units, while Cempaka Soil and quartz sand increased by 4.83 and 5.36 units, respectively. The addition of OM to Cempaka Soil and quartz sand also showed a higher reduction in heavy metals concentration in AMD than those in Palam Soil. It was also discovered that the application of OM combined with CFA led to a higher improvement in AMD quality than only using OM. This study demonstrated that the effect of OM addition on increasing pH and decreasing metal concentration on AAT management with the passive treatment system is controlled by soil characteristics.

Modelling of Acid Mine Drainage in Open Pit Lakes Using Sentinel-2 Time-Series: A Case Study from Lusatia, Germany

Strong acid mine drainage (AMD) processes in the flooded, formerly open pits in the Lusatia area present an enormous environmental challenge for the rehabilitation of the post-mining landscape. Extensive and costly monitoring is required for optimal AMD management and remediation planning and control. Because of the large size of the area and the dimension of the problem, the regular sampling can only provide limited point data, which needs to be extrapolated to the entire area. Consequently, the search for effective approaches for extrapolating the point data to the area of all water bodies is essential for rehabilitation success monitoring and for understanding the dependencies between AMD and environmental factors such as land use, weather conditions, geology, and hydrogeology. The main aim of this study was to investigate the suitability of Sentinel-2 multispectral imagery and artificial neural networks (ANNs) for the quantitative mapping of acid mine drainage (AMD) constituents, such as dissolved iron, pH value, and sulfate in large water bodies, for an area of approximately 7220 km2 (the area of the pit lakes is about 185 km2). Correlations between different chemical water parameters were also investigated. An extensive water monitoring dataset was used to train artificial neural networks for the identification of dependencies between the multispectral remote sensing data and the water quality ground measurements. Respective relationships have been identified, especially for dissolved iron and pH. These trained ANNs have been used to produce water quality maps with high spatial (10 × 10 m) and temporal (any cloud-free period) resolution, which show the wide variability of water quality in the different parts of the mining region. Concrete sources of AMD can be identified using the water quality maps of single lakes, and the success of sanitation measures such as liming was visualized. The approach opens many doors for the optimization of both the monitoring program and sanitation technology.

Effects of organic substrates on sulfate-reducing microcosms treating acid mine drainage: Performance dynamics and microbial community comparison

Bioremediation techniques utilizing sulfate-reducing bacteria (SRB) for acid mine drainage (AMD) treatment have attracted growing attention in recent years, yet substrate bioavailability for SRB is a key factor influencing treatment effectiveness and long-term stability. This study investigated the effects of external organic substrates, including four complex organic wastes (i.e., sugarcane bagasse, straw compost, shrimp shell (SS), and crab shell (CS)) and a small-molecule organic acid (i.e., propionate), on AMD removal performance and associated microbial communities during the 30-day operation of sulfate-reducing microcosms. The results showed that the pH values increased in all five microcosms, while CS exhibited the highest neutralization ability and a maximum alkalinity generation of 1507 mg/L (as CaCO3). Sulfate reduction was more effective in SS and CS microcosms, with sulfate removal efficiencies of 95.6% and 86.0%, respectively. All sulfate-reducing microcosms could remove heavy metals to different degrees, with the highest removal rate of >99.0% observed for aluminum. The removal efficiency of manganese, the most recalcitrant metal, was the highest (96%) in the CS microcosm. Correspondingly, SRB was more abundant in the CS and SS microcosms as revealed by sequencing analysis, while Desulfotomaculum was the dominant SRB in the CS microcosm, accounting for 10.8% of total effective bacterial sequences. Higher abundances of functional genes involved in fermentation and sulfur cycle were identified in CS and SS microcosms. This study suggests that complex organic wastes such as CS and SS could create and maintain preferable micro-environments for active growth and metabolism of functional microorganisms, thus offering a cost-efficient, stable, and environmental-friendly solution for AMD treatment and management.

Pengaruh Tandan Kosong Kelapa Sawit pada Media Buatan terhadap pH, Fe, dan Mn untuk Pengelolaan Air Asam Tambang

Indonesia is a coal producing country and coal mining activities are carried out using the open pit method. The activity resulted in the acid mine drainage (AMD). AMD has low pH and contains high concentrations of heavy metals ions such as aluminum (Al), iron (Fe) dan manganese (Mn). One of the interesting technologies in the AMD treatment is passive treatment using constructed wetland. The system can increase pH and reduce level of dissolved metals. Oil palm empty fruit bunches (OPEFB) are potential to improve soil pH, because they have a high nutrient content such as N, P, and K. This study aims to determine the effect of OPEFB as amendment material on artificial wetland media on pH, Fe, Mn in AMD management. The method used was a single Randomized Complete Design with the treatment of OPEFB of 0, 100, 200, 300, and 500 g 5.5 kg-1 soil then replicated four times. The results showed that oil palm empty fruit bunches high significant increase in pH, Fe, Mn and 100 g 5.5 kg-1 soil doses effectively used for the AAT management by passive treatment as fulfilled the mining liquid waste quality standards according to the Ministerial Decree State of the Environment Number 113 of 2003 and South Kalimantan Province Governor Regulation Number 04 of 2007.

Improved imaging efficiency of large mine waste rock piles with integrated electrical and electromagnetic geophysical techniques

Acid mine drainage (AMD) can emanate from mine waste rock piles (WRPs) for extended periods, resulting in severe environmental contamination. Since the generation and release of AMD is dependent on the volume and composition of acid-generating waste rock, effective characterization of WRPs is necessary for successful long-term AMD management. Conventional methods such as coring and test pits are invasive and only provide sparsely distributed point information in WRPs which are typically large and highly heterogeneous. Geoelectrical methods such as direct current (DC) resistivity, time-domain induced polarization (TDIP) and electromagnetics (EM) can provide non-invasive and continuous information of WRPs. However, due to the enormous scale of typical WRPs, improved strategies are needed for more efficient imaging. The objective of this study was to demonstrate the improved efficiency of integrated imaging techniques with rapid but low-resolution EM, and laborious but high-resolution DC and TDIP, to characterize the acid-generating regions of a coal mine WRP in Nova Scotia, Canada. EM was first employed to rapidly image the entire pile footprint and locate zones with high conductivity. Focused 3D DC and TDIP surveys were then performed over these zones, which were <10% of entire WRP, to better characterize the associated waste rock composition. DC and TDIP images indicate coincident and continuous areas of low resistivity (<15 Ohm·m) and high chargeability (>15 mV/V), which are indicative of generated AMD (leachate) and stored AMD (sulfides), respectively. This interpretation is validated by corresponding geological and geochemical measurements within the WRP. This study demonstrates the value of integrating complementary electrical and electromagnetic methods for more efficient characterization of large mine WRPs, with EM rapidly locating zones of interest, and simultaneous DC and TDIP imaging then discriminating between areas that generate AMD and areas that are affected by AMD flow paths.

Insights into mechanisms governing the passive removal of inorganic contaminants from acid mine drainage using permeable reactive barrier

The permeable reactive barrier has been deemed as the most prudent and pragmatic way to passively manage and remediate acid mine drainage (AMD). Herein, insights into mechanisms governing the removal of inorganic contaminants from AMD using a permeable reactive barrier (PRB), i.e. pervious concrete, were reported. In particular, the effects of varying dosages, i.e., 6, 10, 30, and 60 g, of cementitious materials comprising CEM I 52.5R with or without fly ash, hydrated lime, and gypsum were evaluated whilst the fate of chemical species was underpinned using the state-of-the-art analytical techniques, along with PHREEQC geochemical modelling. The role of gypsum, a product formed from the interaction of PRB with AMD in heavy metals attenuation was also elucidated. Findings revealed cementitious materials to play an indispensable role in the removal of inorganic contaminants from AMD. Furthermore, alkalinity from used materials increases the pH (i.e. pH ≥ 12.5) of AMD leading to the precipitation of chemical species. Specifically, the efficacy registered the following sequence: Lime ≥ CEM I ≥ 30%FA ≥ Gypsum with ≥99 for Al and Fe except for Gypsum which attained ≥98 while the performance for Zn removal registered the following sequence, 97 ≥ 98 ≥ 88.8 ≥ 45% for CEM I ≥ Lime ≥30%FA ≥ Gypsum, respectively. Chemical species exist as divalent, trivalent, oxyanions, and other complexes in solution as predicted by PHREEQC. Moreover, they were removed as metal hydroxides, oxyhydrosulphates, and gypsum hence corroborating findings from XRD, SEM-EDS, and FTIR results. Mechanisms which were responsible for the removal of chemical species were precipitation, adsorption, co-adsorption, co-precipitation, ion exchange, and complexation. Henceforth, this study explicitly demonstrated mechanisms that underpin the removal of inorganic contaminants from AMD using PRB and findings from this study will be used to develop effective PRB for the management of acid mine drainage and the receiving environment.

Study of effects of some metals and hydraulic retention time on performance of AMD treatment by SAPS

Acid mine drainage (AMD) is presently observed as one of the major water pollution problems in mining area throughout the world. Proper scientific management of AMD is essential for achieving the national goals for environmental norms. In this studyperformance of AMD treatment by laboratory successive alkalinity producing system (SAPS) by observing the effects of some metals and hydraulic retention time. In this study the experiments were conducted in laboratory successive alkalinity producing system (SAPS) with different synthetic AMDs for five Hydraulic retention times(HRTs). The successive alkalinity producing system shown the promising results during the AMD treatment. The effects of iron, aluminium and manganese were jointly investigated, whichshowed that Net alkalinity generation (NAG) increases with increase in influent metal contents. It was also observed thatNAG also showed increasing tendency with HRT during AMD treatment by SAPS. The obtained findings from this study can be applied for efficient design and operation of successive alkalinity producing system for AMD treatment process in mining industry.

Acid Mine Drainage Treatment Using a Process Train with Laterite Mine Waste, Concrete Waste, and Limestone as Treatment Media

Without treatment, the harmful effects of acid mine drainage (AMD) lead to the destruction of surrounding ecosystems, including serious health impacts to affected communities. Active methods, like chemical neutralization, are the most widely used approach to AMD management. However, these techniques require constant inputs of energy, chemicals, and manpower, which become unsustainable in the long-term. One promising and sustainable alternative for AMD management is to use passive treatment systems with locally available and waste-derived alkalinity-generating materials. In this study, the treatment of synthetic AMD with laterite mine waste (LMW), concrete waste, and limestone in a successive process train was elucidated, and the optimal process train configuration was determined. Six full factorial analyses were performed following a constant ratio of 0.75 mL AMD/g media with a 15-min retention time. The evolution of the pH, redox potential (Eh), total dissolved solids (TDS), heavy metals concentration, and sulfates concentrations were monitored as the basis for evaluating the treatment performance of each run. LMW had the highest metal and sulfates removal, while concrete waste caused the largest pH increase. A ranking system was utilized in which each parameter was normalized based on the Philippine effluent standards (DENR Administrative Order (DAO) 2016–08 and 2021–19). Run 4 (Limestone-LMW-Concrete waste) showed the best performance, that is, the pH increased from 1.35 to 8.08 and removed 39% Fe, 94% Ni, 72% Al, and 52% sulfate. With this, the process train is more effective to treat AMD, and the order of the media in treatment is significant.

Novel approach for the management of acid mine drainage (AMD) for the recovery of heavy metals along with lipid production by Chlorella vulgaris

The treatment of acid mine drainage (AMD) is of paramount importance for environmental sustainability. A two-stage process involving AMD remediation and simultaneous lipid production represents a highly efficient approach with zero-waste generation. Alkaline (NaOH) treatment of AMD at pH 8.0, 10.0, and 12.0 had significantly reduced metal loads (copper (Cu), cobalt (Co), chromium (Cr), cadmium (Cd), nickel (Ni), and zinc (Zn)) compared to the acidic pH range (4.0 and 6.0). The concentration levels of sulfates (SO4 = 4520 mg/L), iron (Fe = 788 mg/L), aluminum (Al = 310 mg/L), and manganese (Mn = 19.4) were reduced to 2971 mg/L, 10.3 mg/L, 16.4 mg/L, and 1.3 mg/L, respectively at pH value 8.0. AMD with a pH value of 8.0 was later chosen as an ideal medium to favor the lipid accumulation by Chlorella vulgaris. Algal biomass was increasing to 5.5 g/L from 0.6 g/L of AMD-based medium within 15 days of cultivation. The FTIR and SEM-EDS studies revealed significant morphological changes in the microbial cell wall. The metals might positively impact lipid production in microalgae, where lipid yield achieved 0.18 g/g of glucose with lipid content of 0.35 g/g of biomass. The fatty acid profile presented 53.4% of saturated fatty acid content with a cetane value of 60.7. Thus, the efficiency of C. vulgaris was demonstrated with AMD treatment proving it to be a good candidate for bioenergy production.

Editorial for Special Issue “Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management”

Climate change is one of the most pressing problems facing humanity this century [...]

Influence of type and amount of organic matters on the iron sorption of acid mine drainage onto reclaimed-mining soils

Mining activity may potentially produce acid mine drainage (AMD), which has relatively high acidity and dissolved heavy metal concentrations. Constructed wetlands is one of the AMD management methods in which organic matter (OM) plays a very important function in reducing the concentration of heavy metals in AMD through absorption and precipitation processes. Three types of OM (empty fruit bunches of oil palm, chicken manure and water hyacinth) and five levels of OM (0, 10, 20, 30 and 40 Mg ha-1) were applied to reclaimed-mining soils (RMS) in an incubation study. A batch experiment was then performed to measure the effect of OM application on the maximum sorption capacity (Qmax) of iron (Fe) from the AMD onto the mixed soil-OM. The application of OM resulted in increases in soil pH, carboxylic groups, and total functional groups, in which these increases varied based on the types and amounts of OM application. This study also revealed that OM application resulted in increasing Fe sorption. The application of OM increased Qmax values from 2077 to 2348-3259 mg kg-1 (water hyacinth), to 2607-3635 mg kg-1 (chicken manure), and to 2219-2992 mg kg-1 (empty fruit bunches of oil palm). Increasing these Qmax values may ascribe to increasing functional groups of the RMS with OM application. The results prove the importance of OM in controlling the sorption of Fe from AMD onto soils.