![]() The same method was used in Mueva and Lockwitz (Germany) and results in 46% and 57% of infiltration inflow. In Berkhamsted (UK), chemical oxygen demand (COD) analysis results in 37.4% infiltration inflow (Brian and Bertrand-Krajewski 2010). It ranged from 15% (in summer) to 45% (in winter) of dry weather flow. A case study of the system in Brussels shows a considerable seasonal variation in infiltration inflow (de Ville et al. In German sewers, wastewater flow contains up to 40% of groundwater (Wittenberg and Brombach 2002). Its input is essentially related to the periodicity of the groundwater level (Wittenberg and Brombach 2002). Permeated groundwater in the sewerage system is non-polluted or a little polluted (Schultz et al. Regardless of its origin, extraneous water causes increasing hydraulic loads and consequently costs for pumping and treatment (Dimova et al. That is why in literature, rainwater input in the sanitary sewage system is calling accidental water. Rainwater-induced flows could penetrate the sewage system by the illicit connection of drains from private proprieties, misconnection of drains from gullies, misconnection of storm sewers, and entry of surface water through manhole covers (Machado et al. Basically, these are infiltration inflow, through leaky pipes and rainwater inflow (Karpf and Krebs 2005). External water in separated sewerage systems included two main fractions. This water input does not come directly from water users. Share of accidental water was in a range between 7 and 22%.īesides water used by inhabitants, sewage inflow to the wastewater treatment plant (WWTP) consists of some extraneous water (or external). Share of infiltration was in a range between 18 and 68%, depending on the year and the method used. ![]() Share of infiltration and accidental water is changing in different methods. The total amount of extraneous water was estimated as in the range from 38 to 53% of annual sewage supply to wastewater treatment plant, depending on the year. In this investigation, accidental water (basically rainwater inflow) poses a significantly less share in the total volume of sewage compared to infiltration water. ![]() Merely the moving minimum method results differ from the others. It was established that the main source of extraneous water was infiltration, because three methods which concern both streams (triangle method, minimum night flow, variability in wet and dry weather) confirm the conclusion. The study covered data from 6 years from 2014 to 2019. Also, some analysis of sewage discharge during wet and dry weather was carried out. The annual balance of water consumption and sewage supply to the wastewater treatment plant were calculated. Three well-known methods were used: the triangle method, the minimum night flow method, and the moving minimum method. Five different quantitative approaches were applied. The aim of the research was to assess the amount of extraneous water inflow to the considered system. Extraneous water that inflow to the sewage system is basically divided into two streams-accidental water (mainly rainwater) and infiltration water.
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