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Microbial Breakthroughs in Changing Source, Treatment, or Supply Parameters
Published in Edwin E. Geldreich, Microbial Quality of Water Supply in Distribution Systems, 2020
Examination of process water for coliform bacteria was also done and provided evidence that total coliforms may persist in both BAC and GAC columns (Table 7.10).16 The raw source water contained 100 to 10,000 coliforms per 100 ml that were not completely inactivated in the pretreatment of influent waters going to the pilot plant, nor by preozonation in BAC treatment. Coliforms were also occasionally isolated from BAC treated in a similar pilot-plant study conducted in Philadelphia, PA.15 In the Philadelphia study, the river source water contained 48,000 total coliform organisms per 100 ml and pretreatment was not very effective in the inactivation of coliforms. It is important to note that the ozone concentration used was selected to obtain maximum removal of dissolved organic carbon and was not necessarily optimum for disinfection of the raw source water.
Introduction
Published in Robert H. Kadlec, Treatment Marshes for Runoff and Polishing, 2019
The amount of municipal effluent water that might be polished is usually small in comparison to agricultural runoff for the same watersheds. The runoff finds its way into rivers and lakes of the region, which may then be the target for marsh treatment. Table 1.3 contains two sample river source waters for wetlands, the Trinity River in Texas (Kadlec et al., 2011) and the New River in California (Kadlec et al., 2010a). There is also an example of lake source water for the Apopka, FL wetlands. Alternatively, agricultural runoff may be directly pumped into treatment marshes, such as those located in Imperial, CA, and in Norway (Table 1.3). Target contaminants from agricultural fields vary, depending upon the perceived threat to receiving ecosystems. The principal contaminants include suspended solids, nitrate, phosphorus and agricultural chemicals; but normally not all at the same time. Runoff from row crops and pasture areas may be low or high in mineral solids, depending on farming practices, rainfall intensity, soil types, and topography. Nutrient concentrations and loads from row crops and pastures depend on fertilization practices. As for urban runoff, there is usually no pretreatment prior to the wetland.
Natural aggregate sources and production
Published in Mark Alexander, Sidney Mindess, Aggregates in Concrete, 2005
Mark Alexander, Sidney Mindess
A feature of many rivers is erratic flow, and consequently different particle sizes tend to be transported and deposited during different regimes of flow. This can lead to marked stratification, making it necessary to blend or mix the materials to obtain consistency and uniformity and improve the grading. On the other hand, rivers with consistent flow will sort and deposit the material, with rapid velocities giving a deficiency of fine material and vice versa. Thus it may be necessary to blend the materials with other sources to extend the grading envelope. River aggregates will generally have lower water requirements in concrete due to their superior shape and surface texture, but the water requirement may be increased by poor grading and absorptive fines in some cases. Figure 2.4 shows a typical river source of
Assessment and analysis of morphometric characteristics of Lake Tana sub-basin, Upper Blue Nile Basin, Ethiopia
Published in International Journal of River Basin Management, 2023
Bitew G. Tassew, Mulugeta A. Belete, K. Miegel
Different scholars provide definitions of a source of a river that has the same meanings. Some of the definitions are: According to Kammerer (1990) a river’s ‘length may be considered to be the distance from the mouth to the most distant headwater source (irrespective of stream name), or from the mouth to the headwaters of the stream commonly known as the source stream’. Most rivers have numerous tributaries and change names often; it is customary to regard the longest tributary or stream as the source, regardless of what name that watercourse may carry on local maps and in local usage. The most commonly identified definition of a river source specifically uses the most distant point (along watercourses from the river mouth) in the drainage basin from which water runs year-around (perennially), or, alternatively, as the furthest point from which water could possibly flow ephemerally (http://education.nationalgeographic.org/encyclopedia).
Polycyclic aromatic hydrocarbons (PAHs) in an urban river at mid and high latitudes: A case study in Siping, a traditional industrial city in Northeast China
Published in Journal of Environmental Science and Health, Part A, 2018
Yidian Sun, Deming Dong, Liwen Zhang, Sinan He, Xiuyi Hua, Zhiyong Guo
The spatial distribution of the mean concentrations of PAHs in water and sediments from this river is shown in Figure 2. The ΣPAHs in water from the mainstream (M1-M6) ranged from 946.7 to 2674.3 ng/L with a mean value of 1521.1 ng/L and ranged from1182.0 to 2906.3 ng/g with a mean value of 1895.1 ng/g in sediments. The ΣPAHs in water from the tributaries (T1-T4) ranged from 473.5 to 1160.5 ng/L with a mean value of 899.9 ng/L and ranged from 601.5 to 1285.9 ng/g with a mean value of 993.5 ng/g in sediments. Both the mean concentrations of ΣPAHs in water and sediments from the mainstream were much higher than those in the tributaries. The maximum concentration of ΣPAHs in both water and sediments occurred in site M1, and the minimum value was found at site T1. The highest concentration was five times higher than the lowest one. In general, the average concentrations of PAHs gradually decreased from upstream to downstream. T1 was located near the river source and far away from human habitation. There was no obvious pollution source nearby, so the concentration was the lowest among all the sampling sites. M1 was located near the downtown of Siping and its municipal wastewater treatment plant. The highest concentration could be related to the contribution from the industrial sources and residential activities. In the downstream of site M1, it was far away from the downtown. The PAH concentrations from site M2 to M5 was gradually attenuated due to the water self-purification.[17]
Types of dry-season stream pools: environmental drivers and fish assemblages
Published in Inland Waters, 2020
Maria Ilhéu, Janine da Silva, Manuela Morais, Paula Matono, João Manuel Bernardo
The study was conducted in the Degebe River basin, located in the southern region of Portugal (38°12′–38°46′N; 7°29′–7°46′W; Fig. 1). Sampling covered a large longitudinal gradient, from headwaters (3 km from Degebe River source) to downstream reaches (4 km from the main river, Guadiana River). One of the main tributaries of the Guadiana River, Degebe River, is 79 km long and its drainage area is 1538 km2. The river basin is located in a lowland region with few low-altitude mountains; the mean annual temperature is 16 °C and the mean annual precipitation is 550 mm (APA 2019). The climate is Mediterranean, with high intra- and interannual variability of precipitation and flow, unpredictable floods between autumn and spring (Oct–Mar), and summer droughts (Jun–Sep; Miranda et al. 2002). During the dry season period, lasting 4–5 months, the flow ceases and large sections of the streambed dry or shrink to isolated pools of variable size that remain as the only aquatic habitats until flow resumption. The degree of stream intermittency (i.e., the duration and intensity of the dry period) displays high interannual variation. The river hydrological regime depends largely on the precipitation regime, showing high interannual variability, and the mean (standard deviation [SD]) annual flow is 269.8 (216.1) hm3 on the Degebe River basin (APA 2019). Over the last 50 years of records, the duration of dry events was longer, resulting in extended drought periods (Matono et al. 2012, ARHA 2015). The studied year was hydrologically irregular, with high flow events in the winter and exceptionally low discharge during the spring months (Bernardo et al. 2003).