A review of bacterial indicator disinfection mechanisms in waste stabilisation ponds

Dias, D. F. C.; Passos, Ricardo Gomes; Sperling, Marcos von

doi:10.1007/s11157-017-9433-2

Cited by 41 publications

(31 citation statements)

References 96 publications

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“…Although eARGs could be damaged by disinfectants in System 3, the transformation ability of eARGs was not completely eliminated. In the current disinfection processes, the levels of bacteria such as E. coli are used as indicators to assess the water quality and safety [ 56 , 57 ]. Our results suggest that the single standard based on pathogen detection might not comprehensively evaluate microbial risks of water safety.…”

Section: Discussionmentioning

confidence: 99%

Chlorine disinfection facilitates natural transformation through ROS-mediated oxidative stress

et al. 2021

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The bacterial infection that involves antimicrobial resistance is a rising global threat to public health. Chlorine-based water disinfection processes can inactivate antibiotic resistant bacteria. However, at the same time, these processes may cause the release of antibiotic resistance genes into the water as free DNA, and consequently increase the risk to disseminate antibiotic resistance via natural transformation. Presently, little is known about the contribution of residual chlorine affecting the transformation of extracellular antibiotic resistance genes (ARGs). This study investigates whether chloramine and free chlorine promote the transformation of ARGs and how this may occur. We reveal that both chloramine and free chlorine, at practically relevant concentrations, significantly stimulated the transformation of plasmid-encoded ARGs by the recipient Acinetobacter baylyi ADP1, by up to a 10-fold increase. The underlying mechanisms underpinning the increased transformations were revealed. Disinfectant exposure induced a series of cell responses, including increased levels of reactive oxygen species (ROS), bacterial membrane damage, ROS-mediated DNA damage, and increased stress response. These effects thus culminated in the enhanced transformation of ARGs. This promoted transformation was observed when exposing disinfectant-pretreated A. baylyi to free plasmid. In contrast, after pretreating free plasmid with disinfectants, the transformation of ARGs decreased due to the damage of plasmid integrity. These findings provide important insight on the roles of disinfectants affecting the horizontal transfer of ARGs, which could be crucial in the management of antibiotic resistance in our water systems.

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Section: Discussionmentioning

confidence: 99%

Chlorine disinfection facilitates natural transformation through ROS-mediated oxidative stress

et al. 2021

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“…Microorganisms were eliminated in the shallower ponds, probably through sunlight penetration (Dias et al ., 2017). Increases of E. coli were observed in the anaerobic and first maturation ponds.…”

Section: Resultsmentioning

confidence: 99%

“…(2009) as high pH values were observed to be effective in bacteria reduction. Other removal mechanisms are through ligands which attach themselves to structures in the primary stage of any pond and contributing 50% of bacteria removal (Dias et al ., 2017). This is in agreement with the findings since E. coli and FC reductions were 44% and 42% in facultative pond and might have been attached to suspended solids during settling.…”

Section: Resultsmentioning

confidence: 99%

Evaluation of waste stabilisation pond units for treating domestic wastewater

Letshwenyo

Thumule

Elias

2020

Water & Environment J

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The purpose of this study was to evaluate the performance of individual units of waste stabilisation ponds (WSPs) system treating domestic wastewater. The study was conducted by measuring the concentrations of physiochemical parameters and bacteriological indictors in the influent and effluent samples of each pond. The thickness of sludge was determined by measuring depths of sludge layer in each pond. Knowing the performance of each pond will speed up targeted intervention to improve performance. The influent was mainly characterised by 224, 500, 270 mg L−1, 258 Nephelometric Turbidity Unit (NTU) respectively, of biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), turbidity and 35600 coliform forming units/100 ml of faecal coliforms. Bacteriological counts were fluctuating and effluent faecal coliforms counts were 1.22 × 104 ± 2.0 × 102 coliform forming units/100 ml. The hydraulic retention times (HRTs) decreased by 2.0, 13.6 and 7.2 days in the first three ponds and by 3.3 days in the last three ponds. Biochemical oxygen demand in the final effluent was 40 mg L−1 more than the design value of f 25 mg L−1. Chemical oxygen demand in the final effluent was 190 mg L−1, higher than the prescribed limit of 150 mg L−1 of discharge into rivers. Total suspended solids in the final effluent was 150 ± 127 mg L−1 more than the national limit of 25 mg L−1. Total suspended solids and turbidity correlated positively with bacteriological indicators, but there was no correlation with temperature except with faecal coliforms. There was also no correlation observed between suspended solids and pH. The treatment system did not meet the design treatment criteria because of overloading as a result of increased population which exceeded the design value. The final effluent from the system did not meet the discharge limits, therefore, it is unsuitable for discharge into the environment as it can pollute ground and surface waters as well as the open environment. Knowledge on the performance of each pond will help in proper interventions to be undertaken at the targeted pond or unit. It is therefore eminent to desludge each pond as a short‐term solution and expand the system for a long‐term solution.

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“…According to Dias et al (2017), the importance of baffles is to reduce preferential paths, therefore forcing wastewater to follow a predetermined path in the reactor in which they were installed. Thus, better hydrodynamic conditions are expected with increasing ratio of the units.…”

Section: Orthophosphate Removalmentioning

confidence: 99%

Sewage Phosphorus Removal Using Hen Eggshells Through Different Contact Systems

Siqueira¹,

Matos

Ribeiro

et al. 2020

Reveng

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Hen eggshell is a waste with high phosphorus (P) removal capacity from synthetic solutions. However, there is a lack of knowledge about how to use this material on P removal from real wastewater. The present study proposed to evaluate two types of system for P removal from wastewater using eggshells. On the first system, eggshells grinded, sieved in 0.425 mm, and contained in coffee filters, were fixed to baffles using calico cloth bags. On the second, the eggshells in the same conditions were attached to vertical wooden rods and distributed at different heights. For both systems, P concentration was daily monitored for four weeks, with and without medium acidification and hydraulic retention time of one day. The baffles system was more efficient, reaching a maximum removal of 15.93% in wastewater with pH 4.73. P removals did not differ significantly over the weeks; however, there is a tendency to vary the efficiencies according to the change in pH. The baffled tank, for presenting higher performance in P removal, is the most suitable for use in a domestic wastewater treatment system.

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A review of bacterial indicator disinfection mechanisms in waste stabilisation ponds

Cited by 41 publications

References 96 publications

Chlorine disinfection facilitates natural transformation through ROS-mediated oxidative stress

Chlorine disinfection facilitates natural transformation through ROS-mediated oxidative stress

Evaluation of waste stabilisation pond units for treating domestic wastewater

Sewage Phosphorus Removal Using Hen Eggshells Through Different Contact Systems

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