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Best Management Practices as an Alternative Approach for Urban Flood Control
Published in Saeid Eslamian, Faezeh Eslamian, Flood Handbook, 2022
The runoff pollutant load is a product of the runoff volume and the targeted pollutant concentration. Reducing one or both of these terms will cut pollutant loads. Runoff reduction capabilities, expressed in percent reduction of the 90th-percentile rain event, are known for common BMPs and can be used in selecting an appropriate series of techniques. Similarly, BMP pollutant removal capacities indicate the ability of BMPs to reduce the annual pollutant load (%) by reducing the event mean concentration of the particular pollutant. Published table values for these measures facilitate the selection of location-appropriate BMPs (Table 3.3). Performance for particular BMPs may often be enhanced by upgrading the “standard” level 1 design format to a level 2. Level 2 designs incorporate additional design features beyond those required, which enhance performance.
Representing Treatment Performance
Published in Robert H. Kadlec, Treatment Marshes for Runoff and Polishing, 2019
Next, the correlation between pollutant load reduction and inlet pollutant loading is examined. Pollutant loading is defined as hydraulic loading times concentration, for both the inlet and outlet. Pollutant load reduction is the difference between inlet and outlet pollutant loadings. An excellent correlation is obtained, with an R2 = 0.93, which makes the data look great, and makes us feel that we can use this for design (Figure 7.4). Unfortunately, there is no connection of performance to inlet loading, no matter how much this load graph appeals to us. The hydraulic loading appears in both the ordinate and the abcissa, thus causing a stretching of a random two-dimensional cloud along a diagonal axis. Many examples of this inappropriate representation and analysis are to be found in the treatment wetland literature (Knight et al., 1993; Hammer and Knight, 1994; Vymazal, 2001a), but they are of no value in design.
Inorganic Chemical Pollutants
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
CO inhibits the cytochrome oxidase system (e.g., cytochrome A3, cytochrome P-450) by binding to hemoproteins. It also inhibits most oxidation, degradation, and conjugation reactions which can be devastating for the chemically sensitive and chronic degenerative disease patients. Therefore, its intake into the body, even in low levels, may adversely affect detoxification systems and allow for the accumulation of toxic substances that are usually eliminated by these systems. The total body pollutant load increases. For the already vulnerable chemically sensitive, this physiological response of exposure to carbon monoxide results in exacerbation of signs and symptoms of their illness whatever they may be (Chapter 1).2 The current exposure threshold limit value (TLV) for healthy people is 9 ppm for 8 hours and 35 ppm for 1 hour. No safe exposure threshold has been established for 7 days/week, 24 hours/day for people who are already damaged by disease or other toxic exposures such as the chemically sensitive or chronic degenerative disease. No agreed thresholds are present for mixtures in the normal population or the chemically sensitive or chronic degenerated patient, the thresholds are individual.
Optimal size, type and location of low impact developments (LIDs) for urban stormwater control
Published in Urban Water Journal, 2021
Khashayar Saniei, Jafar Yazdi, Mohammad Reza MajdzadehTabatabei
The optimization model is applied to determine the best arrangement of LID methods by which the performance of the drainage system is improved and hence the pollutant load entering the rivers is reduced. After evaluating the condition of urban subcatchments in the study area and also based on the local studies, appropriate potential LID systems were determined. Then, the coupled model called SWMM-NSGA-II was prepared to find the best LID strategy by minimizing the construction and maintenance costs, flood volume and pollutant loads, simultaneously. This enabled the authors to work out optimal pond dimensions and locations accompanied by the size and type of other LIDs including the swale, bioretention, and permeable pavement. In this study, flood volume or flooding is referred to as all stormwater that exceeds the storm sewer network capacity and overflows throughout the urban surface. Stormwater pollutant load is defined as a weighting sum of the two pollutant masses: TSS and TN in the catchment outlet. Also, the costs of LIDs are of the factors contributing to the development of stormwater management. Therefore, the cost of construction and maintenance of LIDs were introduced as another objective function. The mathematical form of the optimization problem is presented as follows. This problem is solved by the Non-dominated Sorting Genetic Algorithm (NSGA-II) (Deb et al. 2002).