Manganese removal processes at 10 groundwater fed full-scale drinking water treatment plants (original) (raw)
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Water Quality Research Journal
Manganese removal in drinking water biofilters is facilitated by biological and physico-chemical processes, but knowledge regarding the relative role of these mechanisms during start-up is very limited. The aim of this study was to identify the dominant process for manganese removal occurring during the start-up period of sand filters with and without inoculation by addition of matured sand collected from an operating groundwater-based waterworks. Inoculation with matured filter sand is frequently used to accelerate the start-up in virgin biofilters and to rapidly obtain compliant water quality. The non-inoculated filter took 41 days to comply with manganese quality criteria, whereas the inoculated filter with 20% matured sand showed removal from Day 1 and compliance from Day 25. By Day 48, the inoculated filter showed two times higher manganese removal rates and manganese oxides deposits. Using sodium azide as an inhibitor of microbial activity, it was found that manganese removal ...
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.
Biological manganese removal from potable water using trickling filters
Biochemical Engineering Journal, 2008
Two pilot-scale trickling filters were constructed and tested for manganese removal from potable water, using different fractions of silicic gravel as support media (mono-and multilayer filter). Manganese oxidation in drinking water was found to be cause by both biological oxidation and heterogeneous catalytic paths. Mixed culture populations were used to inoculate the trickling filters and the feed manganese concentrations and volumetric flow rates (VFRs) were between 0.6-2.0 mg/l and 500-2000 ml/min, respectively. The monolayer filter was flooded for high VFRs, and it was very effective for all conditions tested (100% removal efficiency, up to 2850 mg Mn/day). The multilayer filter was less effective for high manganese concentrations but it could remove up to 3250 mg Mn/day. A new mathematical model was developed assuming heterogeneous autocatalytic and biological as the main oxidation manganese paths. First order kinetics was used to describe the heterogeneous catalytic oxidation, while Monod-type kinetics was used to describe the net biological manganese oxidation. The simplicity of the pilot-scale design, the lack of need for an external mechanical aeration source and the ability to predict operation of the system offers a very attractive solution for manganese removal from potable water.
Manganese removal in groundwater treatment: practice, problems and probable solutions
Water Supply, 2009
Most drinking water production plants use rapid sand filters for the removal of manganese from groundwater. The start-up of manganese removal on newly installed sand media is slow, taking several weeks till months. Reducing this period in order to prevent the loss of water during this phase has become an issue of concern. In this study pilot and bench scale experiments were conducted to investigate the mechanism, influence of operational conditions (e.g. filtration rate, manganese loading) and measures that enhance manganese removal capacity of the sand media. Other filter media were investigated with the objective of finding suitable substitutes for the sand. The development of the adsorptive/catalytic coating the sand media in a pilot plant was very slow, notwithstanding the relatively high pH of 8. Low manganese concentration and more frequent backwashing resulted in a longer start up period of the manganese removal. It can not be excluded, that nitrite has a negative effect as w...
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.
Influence of Fe+2 ions on the process of biological removal of manganese in rock filter
trakia journal of sciences, 2010
An efficient removal of manganese from polluted waters was achieved by means of a laboratory-scale rock filter. The rock filter consisted of three cells connected in a series with a total volume of about 12 l. The cells were filled with mix of limestone and gravel with a particle size of about 20-50 mm. Experiments for treatment of synthetic Mn-containing waters have been carried out using laboratory installation, containing biofilms of Mn-oxidizing bacteria. The oxidation of manganese was connected with the bacterial production of hydrogen peroxide and enzyme catalase. The Mn 2+ was then precipitated as MnO2. The concentration of dissolved manganese in the filter effluents was less than 0.8 mg/l and this was achieved within residence times of about 72 hours. It was determined that the higher concentrations of Fe 2+ , lead to negative effects in the rock filter related to reduction of Mn 4+ to Mn 2+ and its reversible mobilization in the water.
Removal of manganese from water supplies intended for human consumption: a case study
Desalination, 2007
In the Volcano Etna area (Sicily) a substantial part of groundwater, used for potable purpose, has concentrations of metals (vanadium, iron and manganese) higher than the maximum contaminant levels (MCLs) set by European and National regulations (European Directive 98/83 and D.Lgs. 31/2001). Specifically, high levels of manganese, up to 1810 µg/l, significantly exceeding the maximum contaminant level (MCL = 50 µg/l), were detected in groundwaters currently used as drinking water supply upwelled from the Etna Volcano aquifer. The paper presents the results of the manganese removal process by potassium permanganate oxidation followed by flocculation, settling and filtration. Batch tests were carried out varying pH, oxidant doses and polyelectrolytes. Two different filters (35 µm and 0.45 µm mesh) were tested as a final step of the treatment. Significant removal (up to 95%) was achieved by addition of polyelectrolytes at pH 8.5, with a 0.5 stoichiometric dose of oxidant and final filtration through 35 µm mesh filter.
Water Research, 2017
The Mn oxide (MnO x(s)) surfaces of water treatment filtration media are known to aid in the capture of dissolved Mn species, but the discovery of significant deposits of Al within these coatings (Tobiason et al., 2008) raised certain questions about the possible role of Al in soluble Mn removal and the formation of the MnO x(s) surface on the media. This phenomenon was addressed by conducting a series of bench-scale column studies that involved the application of solutions containing varying amounts of soluble Al and Mn to MnO x (s)-coated media. The experimental results confirmed that soluble Al was removed in significant amounts by adsorption onto the MnO x(s) media surface. The deposition of soluble Al onto the media surface did not have any significant effect on its ability to remove soluble Mn. Likewise, the relative amounts of Al incorporated into the media coating suggested that uptake of soluble Al alone cannot fully explain the levels of Al often found in real-world, MnO x (s)-coated filter media; instead, the incorporation of particulate forms of Al (routinely found in water treatment plant situations) must contribute to the formation of the MnO x (s) coatings on these media.