scholarly journals Decreasing the Discoloration Risk of Drinking Water Distribution Systems through Optimized Topological Changes and Optimal Flow Velocity Control

2018 ◽  
Vol 144 (2) ◽  
pp. 04017093 ◽  
Author(s):  
Edo Abraham ◽  
Mirjam Blokker ◽  
Ivan Stoianov
2020 ◽  
Vol 20 (4) ◽  
pp. 1253-1263
Author(s):  
Yanyan Liu ◽  
Rongrong Shan ◽  
Guowei Chen ◽  
Li Liu

Abstract Hydrodynamics impacts interactions between microbes and their micro-habitats in aqueous systems, thus the study of hydrodynamics is key to understanding the formation and dynamics of biofilms. Yet mechanisms of how microbial responses to hydrodynamics regulate biofilm formation in drinking water distribution systems (DWDS) are underappreciated. Here, we investigated the linkage between early-stage biofilm formation and flow velocity fluctuations in a model DWDS. Results showed that an intermediate velocity (1.0 m/s) enhanced biofilm formation, with the highest biofilm/total cells ratio of 96.91% ± 2.26%. Moreover, the intermediate velocity promoted extracellular polymeric substances (EPS) release, accompanied with lowered zeta potential and elevated hydrophobicity of suspended cells, which could be responsible for surface aggregation. Shifts in biofilm community were observed along with hydrodynamics fluctuations. Intermediate velocity (1.0 m/s) stimulated the dominance of Proteobacteria (78.16%) along with the genus predominance of Pseudomonas, known to secrete large amounts of EPS favoring biofilm formation. Overall, this study provides new understanding of biofilm formation responding to hydrodynamic fluctuations in DWDS.


2020 ◽  
Vol 41 (S1) ◽  
pp. s255-s255
Author(s):  
Ayodele T. Adesoji ◽  
Adeniyi A. Ogunjobi

Background: Multidrug-resistant bacteria can lead to treatment failure, resulting in infectious diseases being transferred through nonpotable water. Aminoglycosides are an important class of antibiotics that are abused in Nigeria. Few studies have investigated aminoglycoside-modifying genes (AMGs) that are likely responsible for resistance in Nigeria bacteria isolates. Therefore, we aimed to characterize AMGs from isolates in drinking water distribution systems (DWDS) in southwestern Nigeria. Methods: Multidrug-resistant bacteria (n = 181) that had been previously characterized by 16S rDNA sequencing and that were positive for resistance to at least 1 aminoglycoside antibiotic were selected from 6 treated and untreated water distribution systems. Strains were PCR genotyped for 3 AMGs: aph(3)c, ant(3)b and aph(6)-1dd. Results: Of 181 MDR bacteria tested, 69 (38.12%) were positive for at least 1 of the AMGs. The most common was ant(3)c (27.6%), followed by aph(3")c (18.23%). Both aph(3)c and ant(3")b were found in 7.73% of tested isolates, ant(3)b was most commonly found in Alcaligenes spp (50%). Furthermore, aph(3")c was most commonly detected in Proteus spp (50%). Other genera positive for AMGs included Acinetobacter, Aeromonas, Bordetella, Brevundimonas, Chromobacterium, Klebsiella, Leucobacter, Morganella, Pantoae, Proteus, Providencia, Psychrobacter, and Serratia. Conclusions: High occurrence of ant(3)c and aph(3)c among these bacteria call for urgent attention among public health workers because these genes can be easily disseminated to consumers if present on mobile genetic elements like plasmids, integrons, and transposons.Funding: NoneDisclosures: None


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