scholarly journals Modelling the fate of a larviciding chemical, methoprene, at drainage systems

2021 ◽  
Author(s):  
Kevin Sze
Keyword(s):  
Main Concern ◽  
Storm Events ◽  
Quality Model ◽  
Surface Hydrology ◽  
Residual Concentration ◽  
Catch Basin ◽  
Greater Toronto Area ◽  
Catch Basins ◽  
Sewer Outfalls ◽  
Storm Sewer

With the recent occurance of mosquito-borne WEst Nile Virus (WNV) in Canada, the City of Toronto and the surrounding municipalities have undertaken the larviciding program to control mosquitoes during the summer months. The larviciding chemical, methoprene, can be incorporated in clay pellets or chalks which sink to the bottom of a catch basin sump. The main concern is whether or not the methorprene pellets or chalks will still be in a catch basin sump or to be flushed out during storm events. The objective of this thesis is to develop a water quality model, which is based on surface hydrology, mass balance and hydraulic characteristics of flushing at catch basin, in order to predict residual concentration of methoprene at catch basins and storm sewer outfalls. The findings of the research and all information from other contributing parties are expected to contribute to our understanding of the fate of methoprene at catch basins and storm sewer outfalls and improve the mosquito larviciding program in the Greater Toronto Area.

scholarly journals Modelling the fate of a larviciding chemical, methoprene, at drainage systems

2021 ◽  
Author(s):  
Kevin Sze
Keyword(s):  
Main Concern ◽  
Storm Events ◽  
Quality Model ◽  
Surface Hydrology ◽  
Residual Concentration ◽  
Catch Basin ◽  
Greater Toronto Area ◽  
Catch Basins ◽  
Sewer Outfalls ◽  
Storm Sewer

With the recent occurance of mosquito-borne WEst Nile Virus (WNV) in Canada, the City of Toronto and the surrounding municipalities have undertaken the larviciding program to control mosquitoes during the summer months. The larviciding chemical, methoprene, can be incorporated in clay pellets or chalks which sink to the bottom of a catch basin sump. The main concern is whether or not the methorprene pellets or chalks will still be in a catch basin sump or to be flushed out during storm events. The objective of this thesis is to develop a water quality model, which is based on surface hydrology, mass balance and hydraulic characteristics of flushing at catch basin, in order to predict residual concentration of methoprene at catch basins and storm sewer outfalls. The findings of the research and all information from other contributing parties are expected to contribute to our understanding of the fate of methoprene at catch basins and storm sewer outfalls and improve the mosquito larviciding program in the Greater Toronto Area.

scholarly journals The Fate and Transport Of Methoprene in an Urban West Nile Virus Mosquito Control Program

2021 ◽  
Author(s):  
Angelune Des Lauriers
Keyword(s):  
Water Quality ◽  
West Nile Virus ◽  
Mosquito Control ◽  
Water Quality Monitoring ◽  
Quality Monitoring ◽  
West Nile ◽  
Catch Basin ◽  
Catch Basins ◽  
The City ◽  
Storm Sewer

The recent occurrence of vector-borne West Nile virus in Canada has resulted in the use of larvicides for widespread urban mosquito control. The City of Toronto has focused its larviciding program on storm water catch basins as they are concentrated breeding grounds of the mosquito (Culex pipiens) most likely to carry West Nile virus. The City of Toronto undertook a larviciding program to control mosquitoes during the summer months of 2003. The larvicide approved for mosquito control in Canada is methoprene, commercially known as Altosid, in pellet formulation. In order to determine the fate of the larvidice methoprene, the researcher, in conjunction with current studies at Ryerson University, the City of Toronto and the Ontario Ministry of the Environment, have undertaken a water quality monitoring study within the Toronto area. Three study catch basins in the Newtonbrook sewershed in Toronto, Ontario, were dosed with methoprene (Altosid) pellets three times over the summer of 2003, at the recommended mosquito control does of 0.7g. Water from each catch basin was sampled daily and analyzed for methoprene concentration, and mosquito larvae presence was observed. Precipitation, as well as the chemical composition of each of the catch basins was also monitored. A catch basin model in the laboratory was also dosed with methoprene pellets and sampled daily to observe methoprene concentration over time. The fate of methoprene in the urban environment is of interest, to ensure that the larviciding program is not conpromising human and environmental safety. It was found that rainfall flushes methoprene from the catch basins into the storm sewer outfall. The storm sewer outfall did not release methoprene at detrimental concentrations during the sampling period. Many factors such as physical dissolution, chemical degradation and catch basin water volume, affect the concentration of methoprene in a catch basin. In order to monitor the impacts of larviciding programs, comprehensive water quality monitoring and mosquito control efficacy should continue.

scholarly journals The Fate and Transport Of Methoprene in an Urban West Nile Virus Mosquito Control Program

2021 ◽  
Author(s):  
Angelune Des Lauriers
Keyword(s):  
Water Quality ◽  
West Nile Virus ◽  
Mosquito Control ◽  
Water Quality Monitoring ◽  
Quality Monitoring ◽  
West Nile ◽  
Catch Basin ◽  
Catch Basins ◽  
The City ◽  
Storm Sewer

The recent occurrence of vector-borne West Nile virus in Canada has resulted in the use of larvicides for widespread urban mosquito control. The City of Toronto has focused its larviciding program on storm water catch basins as they are concentrated breeding grounds of the mosquito (Culex pipiens) most likely to carry West Nile virus. The City of Toronto undertook a larviciding program to control mosquitoes during the summer months of 2003. The larvicide approved for mosquito control in Canada is methoprene, commercially known as Altosid, in pellet formulation. In order to determine the fate of the larvidice methoprene, the researcher, in conjunction with current studies at Ryerson University, the City of Toronto and the Ontario Ministry of the Environment, have undertaken a water quality monitoring study within the Toronto area. Three study catch basins in the Newtonbrook sewershed in Toronto, Ontario, were dosed with methoprene (Altosid) pellets three times over the summer of 2003, at the recommended mosquito control does of 0.7g. Water from each catch basin was sampled daily and analyzed for methoprene concentration, and mosquito larvae presence was observed. Precipitation, as well as the chemical composition of each of the catch basins was also monitored. A catch basin model in the laboratory was also dosed with methoprene pellets and sampled daily to observe methoprene concentration over time. The fate of methoprene in the urban environment is of interest, to ensure that the larviciding program is not conpromising human and environmental safety. It was found that rainfall flushes methoprene from the catch basins into the storm sewer outfall. The storm sewer outfall did not release methoprene at detrimental concentrations during the sampling period. Many factors such as physical dissolution, chemical degradation and catch basin water volume, affect the concentration of methoprene in a catch basin. In order to monitor the impacts of larviciding programs, comprehensive water quality monitoring and mosquito control efficacy should continue.

Mixed Layer Models and Their Application to Water Quality Problems

1994 ◽  
Vol 29 (2-3) ◽  
pp. 221-232
Author(s):  
M.J. McCormick
Keyword(s):  
Water Quality ◽  
Mixed Layer ◽  
Thermal Structure ◽  
Mass Conservation ◽  
Eddy Diffusion ◽  
Rate Of Change ◽  
Surface Mixed Layer ◽  
Storm Events ◽  
Quality Model ◽  
Mixing Processes

Abstract Four one-dimensional models which have been used to characterize surface mixed layer (ML) processes and the thermal structure are described. Although most any model can be calibrated to mimic surface water temperatures, it does not imply that the corresponding mixing processes are well described. Eddy diffusion or "K" models can exhibit this problem. If a ML model is to be useful for water quality applications, then it must be able to resolve storm events and, therefore, be able to simulate the ML depth, h, and its time rate of change, dh/dt. A general water quality model is derived from mass conservation principles to demonstrate how ML models can be used in a physically meaningful way to address water quality issues.

scholarly journals Residual Activity of Pyriproxyfen Against Mosquitoes in Catch Basins in Northwestern Riverside County, Southern California

2020 ◽  
Vol 36 (3) ◽  
pp. 175-180
Author(s):  
Lal S. Mian ◽  
Angela Caranci ◽  
Jesus Ramos ◽  
J. C. Nelson ◽  
Nikia Smith ◽  
...  
Keyword(s):  
Southern California ◽  
Developmental Stages ◽  
Mosquito Species ◽  
Residual Activity ◽  
Insect Growth Regulator ◽  
Amusement Park ◽  
Complete Control ◽  
Catch Basin ◽  
Riverside County ◽  
Catch Basins

ABSTRACT A field study was carried out on the year-long residual activity of the insect growth regulator (IGR) pyriproxyfen (Nylar 0.5G) in comparison with methoprene (Altosid® XRP Pellets) against mosquito developmental stages in catch basins in northwestern Riverside County, southern California. Pyriproxyfen was applied at 75, 100, 125, 150, 175 g per catch basin and methoprene at 3.5 g per catch basin. A total of 80 catch basins (10 per each treatment and 20 for control) were used. Posttreatment observations of catch basins were carried out at weekly intervals, with all pupal collections reared to adults. Mosquito species composition in this study, consisting mostly of Culex species (693), was predominated by Cx. quinquefasciatus (92.8%), followed by Cx. erythrothorax (5.5%), Cx. tarsalis (1.2%), Cx. stigmatosoma (0.3%), and Cx. thriambus (0.2%). Activity of both IGRs was expressed as percent inhibition of adult emergence (% IAE). Data generated on % IAE showed that, like methoprene, pyriproxyfen provided complete control of mosquitoes at 75, 125, and 175 g per catch basin up to 50 wk posttreatment at the Riverside amusement park, whereas its activity against mosquitoes in catch basins treated with 100 g and 150 g at the Eastvale site was short-lived, up to 48 wk. Water samples, bioassayed against laboratory-reared, 4th-stage larvae of Cx. quinquefasciatus 1–2 wk after the 50-wk-long study, showed evidence of significant % IAE (∼50) by pyriproxyfen at the 2 higher rates (125 g, 175 g) used at the amusement park. In conclusion, pyriproxyfen can be used to effectively control mosquitoes in catch basins for 48–50 wk, depending on the rate of application.

Hydraulic Performance and Control of Pollutants Discharged from a Combined Sewer Storage Overflow

1989 ◽  
Vol 21 (8-9) ◽  
pp. 747-756 ◽  
Author(s):  
A. J. Saul ◽  
R. C. Thornton
Keyword(s):  
Temporal Variation ◽  
River Basin Management ◽  
Hydraulic Performance ◽  
Research Centre ◽  
Separation Performance ◽  
Storm Events ◽  
Retention Performance ◽  
Quality Model ◽  
North West ◽  
Combined Sewer

The development of the Wallingford Procedure WASSP (1981) and the MOSQITO (Moys 1987) models will provide the sewerage engineer with design tools to assess the quantitative and qualitative performance of sewer systems. As part of the development of such a quality model, the University of Manchester, financed by the Water Research centre and North West Water, have undertaken a fieldwork program of research to monitor the hydraulic performance and the temporal variation of pollutants in the inflow and the overflow at five combined sewage overflows in the North West of England. These projects are integrated into the program of research co-ordinated by the River Basin Management group at WRc Engineering. This paper describes the instrumentation used at a typical field site and illustrates the monitored temporal variation of pollutants for a number of storm events. These results show the complexity of the monitored pollutographs and highlight the large number of variables which influence combined sewer quality. Using data monitored in 1986, it is hypothesised that the long term impact of combined sewer discharges on receiving waters may be estimated from the flow retention performance and some estimate of annual average pollutant concentration. To predict the short term impact on river quality it is necessary to consider the complex processes associated with combined sewer flow and to include the separation performance of the overflow structure.

MOUSETRAP — A DETERMINISTIC SEWER FLOW QUALITY MODEL

1994 ◽  
Vol 30 (1) ◽  
pp. 107-115 ◽  
Author(s):  
R. Crabtree ◽  
H. Garsdal ◽  
R. Gent ◽  
O. Mark ◽  
J. Dórge
Keyword(s):  
Storm Event ◽  
Storm Events ◽  
Urban Wastewater ◽  
Quality Model ◽  
Short Term ◽  
Sewer System ◽  
Erosion And Deposition ◽  
Run Off ◽  
Flow Quality

Recent research into the behaviour of sediments and associated pollutants in sewers has formed the foundation for a dynamic pollutograph-based sewer flow quality simulation model called MOUSETRAP. This is a new component to the MOUSE sewer system hydraulic modelling package. MOUSETRAP has been developed by an international consortium of sewer model developers and users to predict short term variations in sewer flow quality and sediment transport in response to storm events. MOUSETRAP is composed of a series of modules to represent: the quality of surface run off; sediment and pollutant transport, erosion and deposition within pipes; and the biological and chemical processes within the sewer system. By representing the current understanding of real sewer sediments, this new tool gives the user the capability to simulate storm event pollutographs incorporating first foul flush phenomena. The paper describes the basis of the new MOUSETRAP modules. Results of initial theoretical testing and pilot study applications are presented to illustrate the model's capabilities and potential for use in the management of urban wastewater discharges.

Sampling, testing and modeling particle size distribution in urban catch basins

2014 ◽  
Vol 70 (11) ◽  
pp. 1873-1879 ◽  
Author(s):  
G. Garofalo ◽  
M. Carbone ◽  
P. Piro
Keyword(s):  
Particle Size ◽  
Numerical Model ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Particle Diameter ◽  
Experimental Treatment ◽  
Catch Basin ◽  
Traffic Intersection ◽  
Parking Lot ◽  
Catch Basins

The study analyzed the particle size distribution of particulate matter (PM) retained in two catch basins located, respectively, near a parking lot and a traffic intersection with common high levels of traffic activity. Also, the treatment performance of a filter medium was evaluated by laboratory testing. The experimental treatment results and the field data were then used as inputs to a numerical model which described on a qualitative basis the hydrological response of the two catchments draining into each catch basin, respectively, and the quality of treatment provided by the filter during the measured rainfall. The results show that PM concentrations were on average around 300 mg/L (parking lot site) and 400 mg/L (road site) for the 10 rainfall-runoff events observed. PM with a particle diameter of <45 μm represented 40–50% of the total PM mass. The numerical model showed that a catch basin with a filter unit can remove 30 to 40% of the PM load depending on the storm characteristics.

scholarly journals Comparison between constant and variable chlorine decay models applied to urban water supply network

2020 ◽  
Author(s):  
Ababu T. Tiruneh ◽  
Tesfamariam Y. Debessai ◽  
Gabriel C. Bwembya ◽  
Stanley J. Nkambule
Keyword(s):  
Water Quality ◽  
Water Supply ◽  
Decay Rate ◽  
Distribution System ◽  
Distribution Systems ◽  
Residual Chlorine ◽  
Quality Model ◽  
Residual Concentration ◽  
Chlorine Residual ◽  
Significant Difference

Abstract. Monitoring of chlorine residual in water distribution systems is necessary not only for ensuring potable water quality but also prevent emergence of disinfection by-products due to excess chlorination. Modelling work for chlorine residual was carried out for water supply distribution network of a town using both second order and first order reaction rate models. For the development of the model, the bulk reaction decay rate was determined in the laboratory using bottle testing while the wall decay rate was determined by calibration of the water quality model using field residual chlorine concentration measurements. The model results show that there is no significant difference in the residual chlorine between the two models or the cost saving that result in terms chlorine usage for the range of initial chlorine dosages anticipated. Constant rate chlorine model is more conservative and offers additional safety in terms of chlorine residual present. Significant differences only occur at excess chlorine residual concentration within the distribution system above the intended maximum residual to be attained. Further research that relates the chlorine dose with the water quality characteristics is necessary to make a more general evaluation.

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