Kinetic Modeling and Mechanisms of Manganese Removal from Alkaline Mine Water Using a Pilot Scale Column Reactor

Startup performance and microbial composition of a pilot-scale rapid sand filter for the treatment of manganese-containing mine water

The inexpensive removal of soluble manganese [Mn(II)] from mine water that contains large quantities of Mn(II) should be prioritized given that large quantities of alkaline reagents are typically used in the chemical treatment of Mn-rich water from abandoned mines. Rapid sand filter (RSF) systems are widely used as a cost-effective technology in drinking water treatment processes to remove iron and Mn from groundwater. Here, we applied a pilot-scale RSF to treat mine water with a neutral pH and containing approximately 22 mg/L of Mn(II). Following a lag phase from its startup (day 1-day 26), Mn removal rates increased to approximately 40% for around 1 month (day 27-day 55) without the use of alkaline reagents but did not increase during further operation. Quantitative elemental analysis revealed Mn oxides on the sand filters during the Mn removal period. The bacterial communities on the RSFs, recorded on day 42 and day 85, were characterized and compared using 16S rRNA gene amplicon sequencing. Although the well-known Mn-oxidizing bacteria (MOB) were not listed among the ten most dominant operational taxonomic units (OTUs) on the sand filters (relative abundances: >0.68%), a significant increase in the OTUs related to well-known alphaproteobacterial MOB, such as Pedomicrobium spp., were observed during the period.

Excellent Cooperation between Carboxyl-Substituted Porphyrins, k-Carrageenan and AuNPs for Extended Application in CO2 Capture and Manganese Ion Detection

Significant tasks of the presented research are the development of multifunctional materials capable both to detect/capture carbon dioxide and to monitor toxic metal ions from waters, thus contributing to maintaining a sustainable and clean environment. The purpose of this work was to synthesize, characterize (NMR, FT-IR, UV-Vis, Fluorescence, AFM) and exploit the optical and emission properties of a carboxyl-substituted A3B porphyrin, 5-(4-carboxy-phenyl)-10,15,20-tris-(4-methyl-phenyl)–porphyrin, and based on it, to develop novel composite material able to adsorb carbon dioxide. This porphyrin-k-carrageenan composite material can capture CO2 in ambient conditions with a performance of 6.97 mmol/1 g adsorbent. Another aim of our research was to extend this porphyrin- k-carrageenan material’s functionality toward Mn2+ detection from polluted waters and from medical samples, relying on its synergistic partnership with gold nanoparticles (AuNPs). The plasmonic porphyrin-k-carrageenan-AuNPs material detected Mn2+ in the range of concentration of 4.56 × 10−5 M to 9.39 × 10−5 M (5–11 mg/L), which can be useful for monitoring health of humans exposed to polluted water sources or those who ingested high dietary manganese.

Geo-Accumulation Index of Manganese in Soils Due to Flooding in Boac and Mogpog Rivers, Marinduque, Philippines with Mining Disaster Exposure

This paper presents the effects of flooding on the accumulation of manganese (Mn) in soils within proximity of the Boac and Mogpog rivers in Marinduque of The Philippines. Marinduque, an island province in the Philippines, experienced two catastrophic tailings storage facility (TSF) failures in the 1990s that released sulfide-rich tailings into the two major rivers. The Philippines experiences 21–23 typhoons every year, 11 of which pass thru Marinduque that causing inundation of floodplain areas in the province. A flood hazard map developed using LiDAR DEM was utilized for the Boac and Mogpog rivers for an accurate representation of flooding events. A portable X-ray fluorescence spectrometer (pXRF) and a Hannah multi-parameter device were used for the on-site analyses of Mn concentration and water physico-chemical properties, respectively. Spatial grid mapping with zonal statistics was employed for a comprehensive analysis of all the data collected and processed. Correlation analysis was carried out on Mn concentrations in soil and surface water, electrical conductivity (EC), total dissolved solids (TDS), pH, temperature, curve number (CN), and flood heights. The curve number indicates the runoff response characteristic of the Mogpog-Boac River basin. The results show that 40% of the total floodplain area of Boac and Mogpog were subjected to high hazards with flood heights above 1.5 m. The Mn content of soils had a statistically significant moderate positive correlation with flood height (r = 0.458) and a moderate negative correlation with pH (r = −0.438). This condition suggested that more extensive flooding promotes Mn contamination of floodplain soils in the two rivers, the source of which includes the mobilization of Mn-bearing silt, sediments, and mine drainage from the abandoned mine pits and TSFs. There is also a strong negative correlation between pH and Mn concentrations in surface water, a relationship attributed to the solubilization of Mn-bearing precipitates based on geochemical modeling results. Using Muller’s geo-accumulation index, 77.5% of the total floodplain of the two rivers was identified as “moderately contaminated” with an average Mn soil content of 3.4% by weight (34,000 mg/kg). The Mn contamination map of floodplain soils in the Mogpog and Boac rivers described in this study could guide relevant regional, national, and local government agencies in planning appropriate intervention, mitigation, remediation, and rehabilitation strategies to limit human exposure to highly contaminated areas.

A Review on Coagulation/Flocculation in Dewatering of Coal Slurry

Coal slurry is an essential component of mining operations, accounting for more than half of operating costs. Dewatering technology is simultaneously confronted with obstacles and possibilities, and it may yet be improved as the crucial step for reducing the ultimate processing cost. Coagulation/flocculation is used as a dewatering process that is reasonably cost-effective and user-friendly. This paper reviews application of different coagulants/flocculants and their combinations in dewatering mechanisms. In this context, various polymeric flocculants are discussed in the coal slurry in depth. Many operational parameters that influence the performance of coal slurry flocculation are also presented. Furthermore, a discussion is provided on the mechanism of flocculants’ interaction, the strategy of combining flocculants, and efficient selection methods of flocculants. Finally, coagulation/flocculation remaining challenges and technological improvements for the better development of highly efficient treatment methods were highlighted, focusing on the intricate composition of slurry and its treatment difficulties.