Manganese removal processes at 10 groundwater fed full-scale drinking water treatment plants

Abstract

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 metals showed limited effect on Mn removal capacity, indicating that the enhancement of Mn removal in matured filters is possible but challenging. There was limited effect of the filter material type (quartz, calcium carbonate and anthracite) on Mn removal in matured filters, which can be relevant information for the industry when assessing filter designs and determining returns of investments. This article has been made Open Access thanks to the kind support of CAWQ/ACQE (https://www.cawq.ca).

Predicting manganese and iron precipitation in drinking water biofilters

“…Water samples were collected from 1 pressurized and 9 unpressurized biofilters in Denmark in 10 -cm depth intervals (N = 121) by Breda, Ramsay, Søborg, Dimitrova, and Roslev (2019). The only pretreatment for these biofilters was aeration.…”

Understanding the impact of different source water types on the biofilm characteristics and microbial communities of manganese removing biofilters

“…16 Biologically produced Mn oxides, which continue to accumulate on the surface of biofilter media, may regenerate the sites necessary for auto-catalytic oxidation within these treatment plants. 14…”

“…Groundwater biofilters have been used extensively to treat Mn in Canada, China, Argentina, and Europe and have been well studied. [9][10][11][12][13][14] Particulate Mn can be removed by filtration in which solid Mn particles attach to filter media or biofilm and are then removed by backwashing. 15 Dissolved Mn can be oxidized to particulate Mn by biological or physicochemical mechanisms.…”

“…18,46 Although biological oxidation has been shown to play a significant role in the start-up of new Mn biofilters, Mn oxidation in mature biofilters can be a combination of both biological and physico-chemical mechanisms. 14,23 Physico-chemical mechanisms can include auto-catalytic oxidation of dissolved Mn(II) by existing manganese oxides however, in the absence of a strong oxidant these sites become exhausted which prevents further auto-catalytic oxidation. 16 Biologically produced Mn oxides, which continue to accumulate on the surface of biofilter media, may regenerate the sites necessary for auto-catalytic oxidation within these treatment plants.…”

Meta-omics profiling of full-scale groundwater rapid sand filters explains stratification of iron, ammonium and manganese removals

“…While the latter have been the subject of decades of research, our understanding of the involved microbiology is limited. Our current understanding is that Fe 2+ is removed both chemically and biologically (Van Beek et al, 2012), Mn 2+ via chemical autocatalytic oxidation and to some extent biologically (Breda, Søborg, et al, 2019), and NH 4 + exclusively biologically (Tekerlekopoulou et al, 2013). However, not only the impact of microbial activity on the removal processes and their stratification along the height of RSFs is largely unknown, but also the individual physiologies of the involved microorganisms remain elusive (Gülay et al, 2016).…”