Integrated river basin management: incorporating the use of abandoned mining pool and implication on water quality status

Exploring alternative water resource has been an option in an Integrated River Basin Management approach for Selangor River Basin, Malaysia. This includes the use of abandoned mining pool water as additional raw water resource to downstream water treatment plants. Monitoring of water quality along Selangor River was performed at selected locations within the river basin including active (sand mining) and abandoned mining pools to evaluate on current water quality status of the river for raw water supply. Measured variables were compared with the recommended acceptable value by the Ministry of Health (MOH) for guideline compliance. Generally, the abandoned mining pools were classified as Class II according to Water Quality Index sufficient to be used as alternative water resource in terms of water quality and have metal contents below the recommended acceptable values. The water intake point of the water treatment plant downstream the river basin indicated satisfactory water quality level and in compliance with the MOH guidelines despite partly sourced from the abandoned mining pool

Manganese removal from aqueous solution by steel slag: kinetic and equilibrium studies

Batch experiments were conducted to evaluate the ability of steel slag in removing manganese from aqueous solution. Several variables had been setup to evaluate the performance of steel slag to remove manganese from aqueous solution in different experimental condition. The variables include contact time, size, dosage, pH and initial concentration of manganese. The equilibrium contact time was achieved at 10 hours. The small size of adsorbent has the higher removal of manganese from aqueous solution compared to the large size. 1 g of adsorbent of dosage is considered enough to remove heavy metal from aqueous solution. The optimum pH for manganese adsorption onto steel slag was 6. Higher initial concentration leads to the decrease in percentage removal of Mn from solution, but increase in adsorption capacity. The Langmuir isotherm models fit well with data of Mn adsorption on steel slag compared to Freundlich isotherm model. Kinetic test using several models indicate that data obtained fit well with the pseudo second order model. Steel slag are capable to remove to remove high percentage of Mn from aquoues solution (>95%) thus suggesting that steel slag has the potential to be used in real application

Assessing the potential use of abandoned mining pool as an alternative resource of raw water supply

The water crisis in the state of Selangor has prompted the state water authority to use water from abandoned mining pools as an alternative resource of raw water supply. In this study, the potential use of the mining pool water has been assessed to evaluate its safe use for potable water consumption, which is the source of raw water to be supplied to water treatment plants. Assessments were made between sampling sites that include abandoned mining pools, active sand mining pools, and the receiving streams (two tributaries and the main river, Selangor River) within Bestari Jaya catchment, Selangor River Basin. As anticipated, some concentrations of metals were found in the active mining pool and in its discharge, such as iron, manganese, lead, copper and zinc. However, the trace elements were found at very low concentrations or below detection limits in the abandoned mining pools and in the rivers. It was found that generally the quality of the water in the rivers (upstream of water intake of the water treatment plants) was well below the recommended guideline limits set out by the Malaysia Ministry of Health for untreated raw water, and therefore is safe for potable water use

The occurrence and potential ecological risk assessment of bauxite mine-impacted water and sediments in Kuantan, Pahang, Malaysia

Recent bauxite mining activities in the vicinity of Kuantan, Pahang, have been associated with apparent environmental quality degradation and have raised environmental concerns among the public. This study was carried out to evaluate the overall ecological impacts on water and sediment quality from the bauxite mining activities. Water and sediment samples were collected at seven sampling locations within the bauxite mining areas between June and December 2015. The water samples were analyzed for water quality index (WQI) and distribution of major and trace element geochemistry. Sediment samples were evaluated based on geochemical indices, i.e., the enrichment factor (EF) and geoaccumulation index (Igeo). Potential ecological risk index was estimated to assess the degree to which sediments of the mine-impacted areas have been contaminated with heavy metals. The results showed that WQIs of some locations were classified as slightly polluted and contained metal contents exceeding the recommended guideline values. The EFs indicated minimal to moderate enrichment of metals (Pb, Cu, Zn, Mn, As, Cd, Cr, Ni, Co, and Sr) in the sediments. Igeo showed slightly to partially polluted sediments with respect to As at some locations. The potential ecological risk index (RI) showed that As posed the highest potential ecological risk with RI of 52.35–60.92 at two locations, while other locations indicated low risk. The findings from this study have demonstrated the impact of recent bauxite mining activities, which might be of importance to the local communities and relevant authorities to initiate immediate rehabilitation phase of the impacted area

Hybrid off-river augmentation system as an alternative raw water resource: the hydrogeochemistry of abandoned mining ponds

The use of water from abandoned mining ponds under a hybrid off-river augmentation system (HORAS) has been initiated as an alternative water resource for raw water. However, it raises the questions over the safety of the use of such waters. In this study, the hydrogeochemical analysis of the waters is presented to assess the degree to which the water has been contaminated. Comparisons were made between sampling sites, i.e. abandoned mining ponds, active sand mining ponds and the receiving streams within Bestari Jaya, Selangor River basin. The aqueous geochemistry analysis showed different hydrochemical signatures of major elements between sites, indicating different sources of minerals in the water. Discharges from the sand mining ponds were found to contain elevated availability of dissolved concentrations of iron, manganese, lead, copper and zinc, among others. However, the quality of the water (from the main river) that is supplied for potable water consumption is at a satisfactory level despite being partly sourced from the abandoned mining ponds. In fact, all the metal concentrations detected were well below the Malaysia Ministry of Health guideline limits for untreated raw water. In addition, the results of the geochemical index analysis (i.e. geoaccumulation index, enrichment factor and modified contamination factor) showed that the rivers and abandoned mining ponds were generally unpolluted with respect to the metals found in sediments

Passive remediation for metal-rich mine water using steel slag

Acid mine drainage (AMD) is one of the major environmental pollution that needs to be treated for sustainable environment in the future. AMD formation in the environment has become a great public concern globally due to their effects to human health, flora and fauna. Various efforts have been taken to reduce the metal contamination in AMD through controlling or remediation process. However, the usual conventional method based to treat the AMD problem are costly and required extra procedure to further remove the metal ion from water bodies. This study highlights the potential of steel slag which is industrial by product to remove metal ions from metal-rich acid mine drainage (AMD) based on batch and column system. The removal efficiency, adsorption capacity and behaviors of adsorbents were examined during the metal removal process and incorporated with isotherm and kinetic models. In the batch studies, the removal of metal ions was evaluated by varying the contact time, solution pH, initial metal concentration, adsorbent dosage, size and the effect of competing ions. While for the column study, the factors of adsorbent bed height, flow rate and competing ions were evaluated to obtain the removal performance of steel slag in continuous flow system. Results of batch experiment have indicated >90% metal removal efficiencies when pH of the AMD has reached near-neutral state (6.8- 7.5) at 14 hours contact time. Optimum equilibrium time was found at 24 hours whereby all the metals were 99-100% removed. An increased adsorption capacity with a decreased removal efficiency was observed as initial metal concentration increased. In contrast, increasing adsorbent dosage leads to increased removal efficiency but removal tends to be constant after reaching equilibrium amount of 2.0 g. Comparing the effect of competing ions, Fe was not affected despite the presence of other metal ions (100% removal) compared to Mn (59.3% removal) in mixed AMD solution. The adsorption behavior of Fe, Cu, Zn and Mn fits appropriately with the Langmuir isotherm model compared to Freundlich isotherm model indicated that the adsorption process occurred in monolayer surface rather than heterogeneous surface. The adsorption kinetics followed the pseudo-second-order kinetics trend which is consistent with chemisorption and is supported by the intra particle diffusion process. In the column study, the metal ions uptake mechanism is particularly bed depth and flow rate dependent, favoring higher bed depth at 3 cm and lower flow rate at 10 mL/min. The breakthrough curve simulation for metal ions removal were described using BDST and Thomas model. Both models were applied onto fixed bed column experimental data at different bed depths of 1.5, 2 and 3 cm with a constant flow rate of 10 mL/min and influent metal concentration of 27 mg/L. The linear plots at different bed depths indicate that adsorption of all metal fits well with BDST model. The performance of adsorption capacity for Mn is highly affected in mixed solution, by which 81.1% reduction from value in single solution, while Cu was only slightly affected, i.e. 10.1% reduction from value in single solution. Therefore, this study has highlighted the potential of steel slag as an adsorbent for metal-rich AMD with regard to metal removal efficiency, affecting variables, kinetics and models that explain the metal removal behavior

Limestone-based closed reactor for passive treatment of highly acidic raw water

Limestone has been widely used in the treatment of acidic water due to its potential of neutralising acid and removing metals in water. In this study, the efficiency of a laboratory-scale limestone-based closed reactor was evaluated for treatment of highly acidic raw water. The treatment reactor was basically designed to enhance limestone dissolution and alkalinity generation under anoxic condition thus minimising the potential of armouring which may decrease the rate of acid neutralisation. Actual raw water from two different sources that is highly acidic with very low pH was used in the experiment, treated with 30mm diameter of 112kg of limestone. The conditions under which the pH increases, acidity decreases, alkalinity produced and metals were removed in the closed limestone reactor have been determined in comparison to open limestone channel performance. pH was significantly increased from 3.27-4.09 to 6.49-6.67 after flowing through the reactor in 10minutes of contact with the limestone. Acidity was reduced from 73-99 mg/L as CaCO3 to 17-19 mg/L as CaCO3 as pH were raised to reach near neutral levels. Iron and aluminium were also found removed in the closed limestone reactor

Adsorption of manganese in aqueous solution by steel slag

Batch experiments had been conducted to evaluate the ability of steel slag in removing manganese from aqueous solution. Several variables had been setup to evaluate the performance of steel slag in different experimental conditions. The variables include contact time, dosage, pH and initial concentration of manganese. The equilibrium contact time was achieved at 10 hours. 1 g of adsorbent dosage is considered enough to remove heavy metal from aqueous solution. The optimum pH for manganese adsorption onto steel slag was 6. Higher initial concentration leads to the decrease in percentage removal of Mn from solution, but increase in adsorption capacity. The Langmuir isotherm model fits well with data of Mn adsorption onto steel slag compared to Freundlich isotherm model. Steel slag is capable of removing high percentage of Mn from aqueous solution (>95%) in batch experiments, showing potential for real application on-sit