Evaluating the role of soluble aluminum in manganese removal via MnOx(s)-coated filtration media in drinking water treatment (original) (raw)
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Low-temperature effects on the removal of soluble manganese in MnOx(s)-coated media systems
Aqua, 2016
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Mn(II) Dissolution from the Surface of Manganese Oxide-Coated Filter Media
Manganese oxides on the surface of filter media adsorb soluble manganese and organic matter in the water. Previous studies have suggested that surface coated manganese removes soluble manganese by adsorption and subsequent oxidation in the presence of oxidants at neutral pH's. However, the adsorbed Mn(II) and surface coated manganese oxide coatings can be dissolved from the surface of filter media under anoxic conditions and/or acidic conditions in the presence of adsorbed organics on the surface of the filter media. The first objective of this investigation was to determine what conditions might lead to dissolution of adsorbed Mn(II) and Mn02(s) from the surface of manganese-coated filter media. The second objective was to develop a better understanding of manganese dissolution by organics and solution pH in the absence and presence of free chlorine. The third objective was to recommend procedures to control the release of manganese from the filter media. Experiments were perfo...
Water Research X, 2018
Discontinuing application of pre-filter chlorine is a common water treatment plant practice to permit a bioactive filtration process for the removal of soluble Mn. However, soluble Mn desorption has sometimes been observed following cessation of chlorine addition, where filter effluent Mn concentration exceeds the influent Mn concentration. In this paper it is hypothesized that Mn-reducing bacteria present in a biofilm on the filter media may be a factor in this Mn-release phenomenon. The primary objective of this research was to assess the role of Mn-reducing microorganisms in the release of soluble Mn from MnO x(s)-coated filter media following interruption of pre-filtration chlorination. Bench-scale filter column studies were inoculated with Shewanella oneidensis MR-1 to investigate the impacts of a known Mn-reducing bacterium on release of soluble Mn from MnO x(s) coatings. In situ vial assays were developed to gain insight into the impacts of MnO x(s) age on bioavailability to Mn-reducing microorganisms and a quantitative polymerase chain reaction (qPCR) method was developed to quantify gene copies of the mtrB gene, which is involved in Mn-reduction. Results demonstrated that microbiallymediated Mn release was possible above a threshold equivalent of 2 Â 10 2 S. oneidensis MR-1 CFU per gram of MnO x(s) coated media and that those organisms contributed to Mn desorption and release. Further, detectable mtrB gene copies were associated with observed Mn desorption. Lastly, MnO x(s) age appeared to play a role in Mn reduction and subsequent release, where MnO x(s) solids of greater age indicated lower bioavailability. These findings can help inform means of preventing soluble Mn release from drinking water treatment plant filters.
X-ray photoelectron spectroscopy (XPS) was applied to investigate Mn(II) removal by MnO x (s)-coated media under experimental conditions similar to the engineered environment of drinking water treatment plants in the absence and presence of chlorine. Macroscopic and spectroscopic results suggest that Mn(II) removal at pH 6.3 and pH 7.2 in the absence of chlorine was mainly due to adsorption onto the MnO x (s) surface coating, while removal in the presence of chlorine was due to a combination of initial surface adsorption followed by subsequent surface-catalyzed oxidation. However, Mn(III) was identified by XPS analyses of the Mn 3p photoline for experiments performed in the absence of chlorine at pH 6.3 and pH 7.2, suggesting that surface-catalyzed Mn oxidation also occurred at these conditions. Results obtained at pH 8.2 at 8 and 0.5 mg 3 L À1 dissolved oxygen in the absence of chlorine suggest that Mn(II) removal was mainly due to initial adsorption followed by surface-catalyzed oxidation. XPS analyses suggest that Mn(IV) was the predominant species in experiments operated in the presence of chlorine. This study confirms that the use of chlorine combined with the catalytic action of MnO x (s) oxides is effective for Mn(II) removal from drinking water filtration systems.
Water Research, 2014
Manganese-oxidizing bacteria a b s t r a c t Soluble manganese (Mn) presents a significant treatment challenge to many water utilities, causing aesthetic and operational concerns. While application of free chlorine to oxidize Mn prior to filtration can be effective, this is not feasible for surface water treatment plants using ozonation followed by biofiltration because it inhibits biological removal of organics.
Manganese removal processes at 10 groundwater fed full-scale drinking water treatment plants
Water Quality Research Journal, 2019
Manganese (Mn) removal in drinking water filters is facilitated by biological and physico-chemical processes. However, there is limited information about the dominant processes for Mn removal in full-scale matured filters with different filter materials over filter depth. Water and filter material samples were collected from 10 full-scale drinking water treatment plants (DWTPs) to characterise the Mn removal processes, to evaluate the potential use of enhancers and to gain further insight on operational conditions of matured filters for the efficient Mn removal. The first-order Mn removal constant at the DWTPs varied from 10−2 to 10−1 min−1. The amount of Mn coating on the filter material grains showed a strong correlation with the amount of iron, calcium and total coating, but no correlation with the concentration of ATP. Inhibition of biological activity showed that Mn removal in matured filters was dominated by physico-chemical processes (59–97%). Addition of phosphorus and trace...
Deposition of manganese in a drinking water distribution system
Applied and Environmental Microbiology, 1990
The deposition of manganese in a water distribution system with manganese-related "dirty water" problems was studied over a 1-year period. Four monitoring laboratories with Robbins biofilm sampling devices fitted to the water mains were used to correlate the relationship among manganese deposition, the level of manganese in the water, and the chlorination conditions. Manganese deposition occurred by both chemical and microbial processes. Chemical deposition occurred when Mn(II) not removed during water treatment penetrated the filters and entered the distribution system, where it was oxidized by chlorine and chlorine dioxide used for disinfection. Microbial deposition occurred in areas with insufficient chlorination to control the growth of manganese-depositing biofilm. At 0.05 mg of Mn(II) per liter, the chemical deposition rate was much greater than microbial deposition. Significant deposition occurred at 0.03 mg of manganese per liter, and dirty water complaints were no...
Drinking water characterization and removal of manganese. Removal of manganese from water
Journal of Environmental Chemical Engineering, 2018
Samples of drinking water were taken during a year from two wells; all samples were tested for pH, temperature, electric conductivity, dissolved solids, dissolved oxygen, acidity, alkalinity hardness, chloride, nitrites, nitrates, sulfates, phosphates, Ca, Mn, Mg, Na, K, and Si. The analysis showed that the concentration of manganese in one well was higher than the official regulations. Qualitative and quantitative models were applied to determine the stability of water and the corrosion indexes were determined; the results indicated that water was aggressive or corrosive. Manganese was removed from drinking water by using a sodium modified zeolitic tuff; the kinetic equilibrium was reached in 48 hours. 10 mL/20 mg ratio was enough to remove the excess of manganese from aqueous solutions and 10
Reduction of ripening time of full-scale manganese removal filters with manganese oxide-coated media
Journal of Water Supply: Research and Technology—AQUA, 2015
Effective manganese removal by conventional aeration-filtration with virgin filter media requires a long ripening time. The aim of this study was to assess the potential of manganese oxide-coated media to shorten the ripening time of filters with virgin media under practical conditions. A full-scale filter filled with virgin sand and a full-scale filter filled with anthracite/sand were operated at two groundwater treatment plants, in parallel with (full-scale) test filters, with an additional layer of manganese oxide-coated sand (MOCS) or manganese oxide-coated anthracite (MOCA). Significantly different ripening times were observed to achieve an effective manganese removal: 55 days for a filter with virgin sand and 16 days for a filter with virgin anthracite/sand. The observed differences could be attributed to different feed water quality, different iron loading, and backwashing intensity and frequency. In batch experiments fresh MOCA and MOCS showed good manganese adsorptive properties. Addition of a shallow layer of fresh MOCA in test filters eliminated the ripening time, while a layer of aged MOCS did not significantly shorten the ripening period. The poor performance of the aged MOCS was probably caused by changed properties of aged and dried MOCS, that had lost its adsorption capacity, auto-catalytic activity and biological activity.