Deposition of manganese in a drinking water distribution system (original) (raw)
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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.
Identification of the bacterial population in manganese removal filters
Water Science and Technology: Water Supply
The aim of this study was to identify bacteria present in ripened manganese removal filters for drinking water production. The bacterial population was identified with 'next generation' DNA sequencing, and specific bacteria were quantified with quantitative polymerase chain reaction (qPCR) and characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. The 'next generation' DNA sequencing analysis showed a bacteria population shift from the iron oxidizing species Gallionella spp. in the Fe-filter to manganese and nitrite oxidizing species Pseudomonas spp. and Nitrospira spp., respectively, present in the manganese removal filter. qPCR analysis confirmed the presence of a low concentration of the wellknown Mn 2þ-oxidizing species Ps. putida in the manganese removal filter backwash water. Bacteria of the genus Pseudomonas, isolated from backwash water from a manganese removal filter were cultured and identified with MALDI-TOF MS analysis. Amongst others, P. gessardii, P. grimontii, and P. koreensis were identified. The presence of several manganese oxidizing bacteria species in ripened filter media supports the assumption that a microbial consortium is involved in the oxidation of manganese. Understanding the mechanisms by which manganese coating of filter media commences could endorse the creation of conditions favouring Birnessite formation, and possibly help in reducing typically long ripening periods of manganese removal filters with virgin filter media.
Manganese: Its Speciation, Pollution and Microbial Mitigation
International Journal of Applied Sciences and Biotechnology, 2013
Manganese is known to be one of the essential trace elements and has plenty of applications. Inspite of its essential nature, concerns are arising due to its toxic nature at higher concentration. Several methods of removing manganese from environment have been proposed during the last few decades. However, the most favourable option based on cost-effectiveness, performance, and simplicity is still under investigation. The current review summarizes updated information on various technical aspects on manganese, including chemical nature, speciation, toxicity and remediation strategies. The review starts with covering the major sources of manganese, its interaction with biological biomolecules causing toxicity. This is followed by its speciation in environment, describing both biotic and abiotic processes. The biotic processes describe the role of microorganisms in the oxidation/ reduction of various oxidation states of manganese. Whereas, abiotic processes mainly describes the role of...
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
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 ...
FEMS Microbiology Ecology, 2002
Biofilm formation on 316L stainless steel was investigated in a pilotscale flow-through system fed with brackish surface water using an alternating flow/stagnation/flow regime. Microbial community analysis by denaturing gradient gel electrophoresis and sequencing revealed the presence of complex microbial ecosystems consisting of, amongst others, Leptothrix-related manganese-oxidizing bacteria in the adjacent water, and sulfur-oxidizing, sulfate-reducing and slime-producing bacteria in the biofilm. Selective plating of the biofilm indicated the presence of high levels of manganese-oxidizing microorganisms, while microscopic and chemical analyses of the biofilm confirmed the presence of filamentous manganese-precipitating microorganisms, most probably Leptothrix species. Strong accumulation of iron and manganese occurred in the biofilm relative to the adjacent water. No evidence of selective colonization of the steel surface or biocorrosion was found over the experimental period. The overall results of this study highlight the potential formation of complex microbial biofilm communities in flow-through systems thriving on minor concentrations of manganese.
Frontiers in Water, 2020
Water from the Blyderiver dam in the Mpumalanga province, South Africa is used for gravity-fed irrigation. Biofilm development in the pipelines causes an increase in pipeline surface roughness, reduced hydraulic capacity, and water delivery below design capacity. The role of manganese (Mn) concentration on biofilm development is of interest, since the water is currently extracted at depth near the bottom of the reservoir (45-50 m when full) where high Mn levels were measured during four sampling events over 2 years. In the water body, dissolved oxygen (DO) and Mn concentrations showed a strong, inverse correlation, with rapid decrease in DO at increased depth, mirrored by an increase in total and soluble Mn. The depth of this inflection point correlated with the reservoir's water level. DO concentrations typically remained constant between 8 and 9 mg l −1 in the upper regions of the water column, followed by a rapid decline to lower than 2 mg l −1 at deeper zones. Similarly, Mn concentrations remained constant with increasing depth, ranging between 10 and 100 µg l −1 , followed by a rapid increase once the depth is reached where DO levels started to decline, to 8,631 µg l −1 near the bottom. In the main, 1.5 m diameter pipeline, Mn concentrations decreased with distance; from 8,631 µg l −1 at the extraction point to 134 µg l −1 at 23 km downstream in the bulk aqueous phase, while in the biofilm biomass, Mn concentrations decreased from 30105.4 mg kg −1 at 4.5 km to 23501.9 mg kg −1 at 12.5 km, and 13727.7 mg kg −1 at 28.4 km downstream. This decrease in Mn concentration with distance suggests that biofilm accumulation has not yet reached a steady state. The aesthetic and operational problems caused by manganese in drinking water systems is well-documented, with biological removal gaining increasing interest as alternative to physical and chemical removal strategies. This study showed that the microbial processes that are being harnessed in drinking water treatment, i.e., Mn accumulation through biofilm formation supported by Mn cycling in sand filters, may have undesirable consequences in bulk water distribution systems by causing notable reduction in flow.
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.