Investigating the impacts of extraneous water on wastewater treatment plants

Abstract

To demonstrate the effects of increased extraneous water on operation, purification, and energy efficiency, two wastewater treatment plants (WWTPs) have been investigated in detail under the research project 'Sealing of sewer pipes - Effects on the purification performance of WWTPs and their impact on the local water balance'. Both treatment plants, after evaluating and analyzing the measurement data and information about them, were compared in the light of existing literature and other practical investigations. Furthermore, the results were assessed with respect to transferability to other treatment plants. In WWTP 1, extraneous water reduction led to lower energy consumption of certain plant components such as the pumping station and aeration. An increased percentage of extraneous water had an impact on the wastewater characteristics (e.g. organic load) in WWTP 2. A decrease in extraneous water increases the concentration of biodegradable matters; however, an increase in extraneous water increases the loads in the effluent. The results are in accordance with the theoretical approaches described in the literature and confirm the correlations between extraneous water and purification efficiency and energy consumption of WWTPs.

Intra‐annual variability of urban effects on streamflow

“…Soil moisture is highest during December–April (Figure 3), thereby maximining I&I and resulting in smaller baseflows in urban watersheds (Figure 7(g,h)). Results from studies in western Europe confirm the peak in I&I during winter and early spring (Braud et al, 2013; Dirckx et al, 2019; Rodel et al, 2017; Weiß et al, 2002). The intra‐annual variation in WWTP effluent throughout the Atlanta area (Figure 6), as well as the detailed analysis of WWTP effluent in the SRW (Figure 7(a–d)), provides strong evidence for I&I as a major cause of reduced baseflows in winter and spring.…”

“…), while infiltration is groundwater seeping into the sewer pipes via cracks, leaky joints, and through aging manholes (Pawlowski, Rhea, Shuster, & Barden, 2014). It is not uncommon for clean water to constitute at least 30% annually of the total water volume entering a WWTP (Bareš, Stránský, & Sýkora, 2012; Rödel, Günthert, & Brüggemann, 2017).…”

Identifying sources of infiltration and inflow in sanitary sewers in a northern community: comparative assessment of selected methods

“…Excluding such locations from method comparisons reduced the number of detected locations from 16 to six for CCTV and from 47 to just two for visual inspections. Misconnected roofs and gully pots (eight locations) did not contribute to I/I during the periods of smoke testing; however, these locations would most definitely generate I/I during rain events (Rödel et al 2017) and were, therefore, included in the comparisons. Seven locations with smoke coming up from the ground were excluded from the comparison for smoke testing.…”

Using Distributed Temperature Sensing (DTS) for Locating and Characterising Infiltration and Inflow into Foul Sewers before, during and after Snowmelt Period

“…The average I/I rate into sewers in Germany has been estimated at 25% of the total flow. Rödel et al [8] have also reported increased I/I rates into 100,000 PE WWTP due to increased rainfall amounts (almost tripling in May as compared to January). Kaczor and Bugajski [9] studied I/I rates during snowmelt into five small-scale WWTPs in Poland (<2000 PE) and found that 43% to 70% of their daily inflows was I/I.…”