Microbial activity in drinking water-associated biofilms

Abstract

Microbial activity in drinking water-associated biofilmsAbbreviations DWTP -drinking water treatment plant; SRB -sulphate reducing bacteria; MPN -most probable number; TOC -total organic carbon. IntroductionDrinking water quality is dependent on the specific composition and activity of microbial populations present during water treatment, storage and distribution [1]. As in most aquatic environments, biofilms are the predominant mode of microbial growth in drinking water networks [2].Flemming et al. [3] estimated that approximately 95% of bacterial cells are attached to pipe walls, as biofilm communities, while less than 5% are found in the water phase. Bacterial adhesion and biofilm formation at the inner surfaces of water systems, from source abstraction to the consumers tap, represent a complex challenge to water professionals. Biofilms may play a beneficial role in drinking water treatment, as biological filters [4][5][6]. On the other hand, detrimental effects known as biofouling may occur, including microbially induced corrosion, disinfectant depletion, aesthetic problems i.e. colour, odour and taste degradation and microbiological deterioration of drinking water [7]. The complex structure of biofilms associated with drinking water processing and distribution is generally However, detrimental effects such as biofouling (i.e., biocorrosion and water quality deterioration) may also occur. In this study microbiological processes and factors influencing the activity of bacteria in biofilms were investigated by conventional cultivation methods. The presence of bacteria belonging to different ecophysiological groups was assessed during drinking water treatment, in biofilms developed on concrete, steel and sand surfaces. Influences of the treatment process, type of immersed material and physico-chemical characteristics of raw/bulk water and biofilms upon the dynamics of bacterial communities were evaluated. Results revealed intense microbial activity in biofilms occurring in the drinking water treatment plant of Cluj. Ammonification, iron reduction and manganese oxidation were found to be the predominant processes. Multiple significant correlations were established between the evolution of biofilm bacteria and the physico-chemical parameters of raw/ bulk water. The type of immersed material proved to have no significant influence upon the evolution of microbial communities, butthetreatmentstage,suggestingthattheprocessesappliedrestrictmicrobialgrowthnotonlyinbulkfluidbutinbiofilms,too.©VersitaSp.zo.o.Brought to you by | MIT Libraries Authenticated Download Date | 5/11/18 1:28 PM

Autochthonous tropical groundwater bacteria involved in manganese(ii) oxidation and removal

“…61 The actinobacterium of the genus Microbacterium, identified in HAC-3A, was also reported by Marcus et al 62 in drinking water systems. The Aeromonas genus, found in HAC-12, RUE-1 and RUE-2, has mainly been reported for its ammonium removal activity associated with drinking water 63 and in pilot scale biofilters for ammonium and Mn removal. 14 Finally, Zhang et al 64 ) removal in broth culture.…”

Diverse manganese(II)‐oxidizing bacteria are prevalent in drinking water systems

“…The presence and role of Mn(II)‐oxidizing bacteria in DW systems has been investigated only to a limited extent. In some cases, well characterized Mn(II)‐oxidizing groups such as Pseudomonas , Bacillu s and Leptothrix have been identified in DW systems (Katsoyiannis and Zouboulis, ; Burger et al ., ; Cerrato et al ., ; Farkas et al ., ), but it remains unclear if they are abundant and to what extent they contribute to Mn cycling. Despite recent advances in DNA sequencing technologies and in understanding the molecular mechanisms of bacterial Mn(II) oxidation, identifying Mn(II)‐oxidizing bacteria with culture‐independent methods remains challenging since there are no known universal molecular markers for Mn(II) oxidation.…”

Biocenoses in the loads of iron and manganese removal filters and the methods of settling them in zeolite

“…Ряд дослідників [5][6][7] відмічають певну роль мікроорганізмів у процесах, що відбуваються на біофільтрах при видаленні заліза та марганцю. Так у роботі [8] зазначено, що ефективність видалення заліза та марганцю із води не залежить від типу матеріалу, на якому закріплюють мікроорганізми та у деяких випадках формується біоплівка (пісок, сталь, бетон). Роль біологічних процесів під час видалення заліза та марганцю з води фізико-хімічними методами показана у роботах [9][10][11].…”