Manganese removal efficiencies and bacterial community profiles in non-bioaugmented and in bioaugmented sand filters exposed to different temperatures

C-di-GMP signalling links biofilm formation and Mn(II) oxidation in Pseudomonas resinovorans

“…Biological sand filter technology is widely used for groundwater potabilization as an eco-friendly strategy that does not require chemical addition, increases groundwater treatment capacity, and reduces operative costs (2). Biofilters harbour microbial communities recruited by the groundwater to be treated or by bioaugmentation approaches (4–8). Bioaugmentation using bacteria with high biofilm-forming and Mn(II)-oxidising capabilities provides an inexpensive, simple and efficient strategy for immobilizing these bacteria in the sand filters and optimising Mn removal (4, 5, 8).…”

“…Biological sand filter technology, based on bacterial oxidation of metals to form insoluble oxides that can be filtered out of the water, is widely used for groundwater potabilization. Bioaugmentation of this process through the inoculation of sand filters with appropriate Mn(II)-oxidizing bacteria (MOB) optimizes Mn removal (4–8).…”

“…Biofilms are sessile and densely populated communities of bacterial cells, surrounded by an extracellular matrix (ECM) that typically contains exopolysaccharides, proteins or extracellular DNA and serves as a shield that protects the cells from external aggressions and stresses (9). The biofilm-forming capability of bacteria is important to achieve the optimal filtration of groundwater for metals, as they have to be oxidized and retained into the biofilter matrix surface, and to decrease the loss of the MOBs, which can otherwise be washed out of the system (4, 5, 8). It has been recently shown that powdered MOB inoculates prepared by vacuum lyophilisation are useful to inoculate sand filters and remove Mn with high efficiencies (10).…”

Start-up strategies for nitrification and manganese oxidation on a single stage RSF for drinking water production

“…In all cases, biological activities and biofilm development for nitrification and manganese oxidation are dependent on environmental and/or operating conditions (such as temperature, inlet concentrations, pH and oxygen) (Bruins et al 2014). In real conditions, low temperature and low concentrations of ammonium and manganese lead to slow start-up of industrial biofilters (Ciancio Casalini et al 2020). Durations between 25 and 40 days for complete nitrification were reported by (Vandenabeele et al 1995;Cheng 2015;Albers et al 2018) and between 15 and 75 days for complete manganese oxidation (Bruins et al 2015a;Cheng et al 2018;Breda et al 2019).…”

“…Thus, for initial biofilm settlement enhancement, two different strategies can be considered: (1) start with inoculated sand from another location to enhance the initial biomass quantity (X) (Cai et al 2015;Albers et al 2018;Ciancio Casalini et al 2020); (2) modify the initial environmental conditions (T, [S]) to improve biological rates (Queinnec et al 2006). For natural mineral waters, biomass addition is impossible due to regulations that forbid any modification of the natural microbial ecosystem (Directive 2009/54/EC of the European Parliament).…”