Issues of operational integrity in membrane drinking water plants

2003 ◽  
Vol 3 (5-6) ◽  
pp. 73-80 ◽  
Author(s):  
W. Johnson ◽  
T. MacCormick
Keyword(s):  
Drinking Water ◽  
Laboratory Data ◽  
Full Scale ◽  
Human Pathogens ◽  
Membrane Systems ◽  
Case Scenario ◽  
Fiber Failure ◽  
Worst Case ◽  
Virus Removal ◽  
Water Plants

In the last five years over 100 microfiltration (MF) and ultrafiltration (UF) drinking water plants have been installed in Europe with a combined output of some 1,500 ML/day. The impetus behind this growth is concern over drinking water quality, regulatory pressure, the rapidly declining costs of membrane systems, and consumer pressures for non-chemical treatment. Although the principal justification for membrane plants is their capacity to remove human pathogens more effectively than conventional treatment, the ability of large plants to retain an integral barrier is not well understood. Currently available technology can monitor a full-scale membrane plant for integrity against passage of bacteria and parasites but not viruses. In essence the plant operator has to rely on the membrane manufacturer – on an assumption that if the membrane is not compromised at a level of 1 to 2 μm (the current practical level of measurement) it is also not compromised for virus removal. This paper quantifies the loss of integrity that can occur from membrane fiber failure. It explains the mathematical models used to describe bypass flow through compromised fibers and correlates the results with laboratory tests. Both are compared with artificially compromised fibers in a large full-scale operating plant. Under the worst case scenario where a fiber breaks close to the pot (collection end of the filtration module or element) the relative loss of integrity between alternative process designs from a single broken fiber can differ by as much as 2 log reduction values. The analysis demonstrates the need for monitoring methodology that that can track incremental changes in integrity to allow scheduled rather than emergency maintenance. It highlights the need for regulatory authorities to approve membrane systems based on actual operating performance in preference to laboratory data.

Removal of cyanotoxins in drinking water using ozone and ozone-hydrogen peroxide (peroxone)

2019 ◽  
Vol 68 (8) ◽  
pp. 655-665 ◽  
Author(s):  
Guhankumar Ponnusamy ◽  
Lijo Francis ◽  
Kavithaa Loganathan ◽  
Oluwaseun O. Ogunbiyi ◽  
Saad Jasim ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Drinking Water ◽  
Organic Carbon ◽  
Water Temperature ◽  
Removal Efficiency ◽  
Water Samples ◽  
Case Scenario ◽  
Worst Case ◽  
Toxin Removal ◽  
Drinking Water Samples

Abstract Presence of cyanotoxins in drinking water poses a great risk to public health. Elevated levels of cyanotoxins in drinking water can lead to acute gastroenteritis, liver diseases, and neurotoxicity. In this study, drinking water samples were collected across the eastern part of Qatar and screened using a rapid assay to detect the presence of microcystins and nodularins. The results showed that the toxin concentrations in all the water samples were below the WHO prescribed limit of 1 μg/L. Considering a worst-case scenario, toxin removal efficiencies were evaluated using ozone and ozone-hydrogen peroxide by spiking drinking water samples with microcystin-LR (MC-LR) at different oxidant dosages, toxin concentrations, water temperatures, and total organic carbon. It was found that peroxone-treated water samples have better MC-LR removal efficiency than molecular ozone at lower oxidant dosages. Nevertheless, at higher oxidant dosages, both ozonation and peroxone oxidation methods showed a similar removal efficiency. The experimental results also clearly indicated that variation in water temperature between 22 °C and 35 °C has minimal effect on the removal efficiency in both the treatment methods. It was also confirmed that the presence of organic carbon has a more profound detrimental impact than water temperature for toxin removal.

Variations of disinfection by-product levels in small drinking water utilities according to climate change scenarios: a first assessment

2015 ◽  
Vol 7 (1) ◽  
pp. 1-15 ◽  
Author(s):  
I. Delpla ◽  
A. Scheili ◽  
S. Guilherme ◽  
G. Cool ◽  
M. J. Rodriguez
Keyword(s):  
Climate Change ◽  
Drinking Water ◽  
Water Treatment ◽  
Drinking Water Treatment ◽  
Water Utilities ◽  
Climate Change Scenarios ◽  
Case Scenario ◽  
Worst Case ◽  
Small Water ◽  
Water Treatment Process

In Québec, Canada, shifts in climate patterns (i.e., rainfall increase) could have consequences on source water quality due to the intensification of surface/groundwater runoff contamination events, leading to a decline in drinking water treatment efficiency and ultimately disinfection by-products (DBPs) formation following treatment. To assess the impacts of climate change (CC) scenarios on DBP formation, a suite of models linking climate to DBPs was used. This study applies three emissions scenarios (B1, A1B and A2) for three 30-year horizons (2020, 2050 and 2080) in order to produce inputs to test several DBP models (total trihalomethanes (TTHMs), haloacetic acids and haloacetonitriles). An annual increase is estimated for all DBPs for each CC scenario and horizon. The highest seasonal increases were estimated for winter for all DBP groups or species. In the worst-case scenario (A2-2080), TTHMs could be affected more particularly during winter (+34.0%), followed by spring (+16.1%) and fall (+4.4%), whereas summer concentrations would remain stable (−0.3 to +0.4%). Potentially, small water utilities applying only a disinfection step could be more affected by rising TTHMs concentrations associated with CC than those having implemented a complete water treatment process (coagulation–flocculation, filtration and disinfection) with +13.6% and +8.2% increases respectively (A2-2080).

Behavior of NDMA precursors at 21 full-scale water treatment facilities

2018 ◽  
Vol 4 (12) ◽  
pp. 1966-1978 ◽  
Author(s):  
Stuart W. Krasner ◽  
Paul Westerhoff ◽  
William A. Mitch ◽  
David Hanigan ◽  
Daniel L. McCurry ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Full Scale ◽  
Treatment Facilities ◽  
Water Plants

A source-to-tap evaluation of the origin and fate of chloramination N-nitrosodimethylamine (NDMA) precursors at 21 full-scale drinking water plants was conducted.

Centralised versus decentralised sewage systems: a comparison of pathogen and nutrient loads released into Sydney's drinking water catchments

2004 ◽  
Vol 48 (11-12) ◽  
pp. 53-60 ◽  
Author(s):  
K. Charles ◽  
N. Ashbolt ◽  
C. Ferguson ◽  
D. Roser ◽  
R. McGuinness ◽  
...  
Keyword(s):  
Drinking Water ◽  
Sewage Treatment ◽  
Enteric Viruses ◽  
Nutrient Loads ◽  
Case Scenario ◽  
Nitrogen And Phosphorus ◽  
Worst Case ◽  
Catchment Population ◽  
Decentralised Systems ◽  
Water Catchments

Data collected from centralised and decentralised sewage treatment plants throughout Sydney's drinking water catchments was used to calculate the relative catchment loads of Cryptosporidium, enteric viruses, nitrogen and phosphorus for an initial screening assessment. Loads were assessed at median and 90 percentile values for expected and worst-cases scenarios. The expected scenario in the Sydney drinking water catchments is that decentralised systems (servicing 32,800 people) provide similar total loads to centralised systems (serving 70% of the catchment population) for total phosphorus (37,090 kg.y-1), Cryptosporidium (1011 oocysts.y-1) and enteric viruses (9.1 × 1013 y-1), but higher loads of total nitrogen (237,610 vs. 136,740 kg.y-1). Decentralised systems, however, were predicted to have higher loads in the worst-case scenario with 620,620 kg.y-1 TN, 82,040 kg.y-1 TP, 7.3 × 1013Cryptosporidium oocysts.y-1 and 9 × 1015 enteric viruses per year. Greater load variability was experienced with decentralised systems, which presumably reflects less reliability in their current operation and maintenance. Overall, catchment water quality is therefore not only affected by sewage disposal methods, but also failure issues. Decentralised system disposal to land may afford a degree of mitigation that can be enhanced, if the degree of failure is reduced.

Significance of bacteria associated with invertebrates in drinking water distribution networks

2005 ◽  
Vol 52 (8) ◽  
pp. 171-175 ◽  
Author(s):  
E. Wolmarans ◽  
H.H. du Preez ◽  
C.M.E. de Wet ◽  
S.N. Venter
Keyword(s):  
Drinking Water ◽  
Water Distribution ◽  
Drinking Water Treatment ◽  
Distribution Networks ◽  
Water Distribution Networks ◽  
Case Scenario ◽  
Worst Case ◽  
Potential Health ◽  
Water Users ◽  
Drinking Water Distribution

The implication of invertebrates found in drinking water distribution networks to public health is of concern to water utilities. Previous studies have shown that the bacteria associated with the invertebrates could be potentially pathogenic to humans. This study investigated the level and identity of bacteria commonly associated with invertebrates collected from the drinking water treatment systems as well as from the main pipelines leaving the treatment works. On all sampling occasions bacteria were isolated from the invertebrate samples collected. The highest bacterial counts were observed for the samples taken before filtration as was expected. There were, however, indications that optimal removal of invertebrates from water did not always occur. During the investigation, 116 colonies were sampled for further identification. The isolates represent several bacterial genera and species that are pathogenic or opportunistic pathogens of humans. Diarrhoea, meningitis, septicaemia and skin infections are among the diseases associated with these organisms. The estimated number of bacteria that could be associated with a single invertebrate (as based on average invertebrate numbers) could range from 10 to 4000 bacteria per organism. It can, therefore, be concluded that bacteria associated with invertebrates might under the worst case scenario pose a potential health risk to water users. In the light of the above findings it is clear that invertebrates in drinking water should be controlled at levels as low as technically and economically feasible.

Development of a Standardized Buttress for Approach Guardrail Transitions

2018 ◽  
Vol 2672 (39) ◽  
pp. 41-51
Author(s):  
Scott K. Rosenbaugh ◽  
Jennifer D. Schmidt ◽  
Ronald K. Faller
Keyword(s):  
Full Scale ◽  
Safety Performance ◽  
Span Length ◽  
Case Scenario ◽  
Worst Case ◽  
Worst Case Scenario ◽  
Crash Testing

Approach guardrail transitions (AGTs) incorporate increased post and rail sizes, reduced post spacings, and specialized buttress end geometries to smoothly transition from deformable W-beam guardrail to rigid barriers. This transition in barrier stiffness makes AGTs sensitive systems that require specific combinations of these components to function properly. Changing components, or even the removal of a curb below the rail, can negatively affect the safety performance of an otherwise crashworthy system. However, recent full-scale crash testing has indicated that a properly designed buttress at the downstream end of an AGT may be utilized with multiple AGT systems. Thus, the objective of this project was to develop a standardized buttress to reduce vehicle snag and be compatible with a wide variety of previously developed Thrie beam AGT systems, either with or without a curb. The standardized buttress was designed with a dual taper on its front upstream edge. A longer lower taper was designed to mitigate tire snag below the rail, while a shorter upper taper was designed to prevent vehicle snag and limit the unsupported span length of the rail. This buttress design was evaluated in combination with a critically weak AGT without a curb, which represented the worst-case scenario. The standardized buttress was successfully crash tested to MASH TL-3. Guidance was provided for both the attachment of the buttress to various Thrie beam AGTs as well as how to transition the shape of the buttress to adjacent bridge rails or rigid parapets downstream of the AGT.

Reducing Probabilistic Weather Forecasts to the Worst Case Scenario: Anchoring Effects

2008 ◽  
Author(s):  
Sonia Savelli ◽  
Susan Joslyn ◽  
Limor Nadav-Greenberg ◽  
Queena Chen
Keyword(s):  
Case Scenario ◽  
Worst Case ◽  
Weather Forecasts ◽  
Worst Case Scenario ◽  
Anchoring Effects

Deep-Amplicon Sequencing(DAS) to evidence the presesence of human pathogens in drinking water

2020 ◽  
Author(s):  
Laura Moreno-Mesonero ◽  
Jorge García Hernández ◽  
Yolanda Moreno ◽  
PATRICIA SOLER
Keyword(s):  
Drinking Water ◽  
Amplicon Sequencing ◽  
Human Pathogens

EXPEDITION TO MALI, 2020

2020 ◽  
pp. 12-28
Author(s):  
D. V. Vaniukova ◽  
◽  
P. A. Kutsenkov ◽  
Keyword(s):  
Mass Murder ◽  
The State ◽  
Case Scenario ◽  
Worst Case ◽  
Traditional Art ◽  
Peter The Great ◽  
State Museum ◽  
Bobo Dioulasso ◽  
Oriental Studies ◽  
The Village

The research expedition of the Institute of Oriental studies of the Russian Academy of Sciences has been working in Mali since 2015. Since 2017, it has been attended by employees of the State Museum of the East. The task of the expedition is to study the transformation of traditional Dogon culture in the context of globalization, as well as to collect ethnographic information (life, customs, features of the traditional social and political structure); to collect oral historical legends; to study the history, existence, and transformation of artistic tradition in the villages of the Dogon Country in modern conditions; collecting items of Ethnography and art to add to the collection of the African collection of the. Peter the Great Museum (Kunstkamera, Saint Petersburg) and the State Museum of Oriental Arts (Moscow). The plan of the expedition in January 2020 included additional items, namely, the study of the functioning of the antique market in Mali (the “path” of things from villages to cities, which is important for attributing works of traditional art). The geography of our research was significantly expanded to the regions of Sikasso and Koulikoro in Mali, as well as to the city of Bobo-Dioulasso and its surroundings in Burkina Faso, which is related to the study of migrations to the Bandiagara Highlands. In addition, the plan of the expedition included organization of a photo exhibition in the Museum of the village of Endé and some educational projects. Unfortunately, after the mass murder in March 2019 in the village of Ogossogou-Pel, where more than one hundred and seventy people were killed, events in the Dogon Country began to develop in the worst-case scenario: The incessant provocations after that revived the old feud between the Pel (Fulbe) pastoralists and the Dogon farmers. So far, this hostility and mutual distrust has not yet developed into a full-scale ethnic conflict, but, unfortunately, such a development now seems quite likely.

Risk-Based Robust Bidding Strategies for EVs’ Aggregators in Day-ahead Markets with Uncertainty

2020 ◽  
Author(s):  
Ahmed Abdelmoaty ◽  
Wessam Mesbah ◽  
Mohammad A. M. Abdel-Aal ◽  
Ali T. Alawami
Keyword(s):  
Robust Optimization ◽  
Electricity Market ◽  
Real Life ◽  
Optimization Approach ◽  
Case Scenario ◽  
Worst Case ◽  
Bidding Strategies ◽  
Wind Generators ◽  
Proposed Model ◽  
Optimal Bidding

In the recent electricity market framework, the profit of the generation companies depends on the decision of the operator on the schedule of its units, the energy price, and the optimal bidding strategies. Due to the expanded integration of uncertain renewable generators which is highly intermittent such as wind plants, the coordination with other facilities to mitigate the risks of imbalances is mandatory. Accordingly, coordination of wind generators with the evolutionary Electric Vehicles (EVs) is expected to boost the performance of the grid. In this paper, we propose a robust optimization approach for the coordination between the wind-thermal generators and the EVs in a virtual<br>power plant (VPP) environment. The objective of maximizing the profit of the VPP Operator (VPPO) is studied. The optimal bidding strategy of the VPPO in the day-ahead market under uncertainties of wind power, energy<br>prices, imbalance prices, and demand is obtained for the worst case scenario. A case study is conducted to assess the e?effectiveness of the proposed model in terms of the VPPO's profit. A comparison between the proposed model and the scenario-based optimization was introduced. Our results confirmed that, although the conservative behavior of the worst-case robust optimization model, it helps the decision maker from the fluctuations of the uncertain parameters involved in the production and bidding processes. In addition, robust optimization is a more tractable problem and does not suffer from<br>the high computation burden associated with scenario-based stochastic programming. This makes it more practical for real-life scenarios.<br>

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