A new database on urban runoff pollution: comparison of separate and combined sewer systems

Abstract

For a long time people have questioned what the "best" sewer system is for limiting the pollution load released into the receiving waters. In this paper the traditional separate and combined sewer systems are compared using a pollution load balance. The investigation is based on measured concentration data for a range of pollutant parameters in the sewer from the new database "ATV-DVWK Datenpool 2001". The approach also accounted for the wastewater treatment plant outflow which contributes to the total pollutant load considerably. In spite of a number of neglected effects, the results show that the separate system is superior to the combined for some parameters only, such as nutrients, whereas for other parameters, e.g. heavy metals and COD, the combined system yields less total loads. Any uncritical preference of the separate system as a particularly advantageous solution is thus questionable. Individual investigations case by case are recommended.

Stormwater Pollutant Process Analysis with Long-Term Online Monitoring Data at Micro-Scale Sites

“…The distribution of TSS concentration also reveals low TSS contribution. Compared to the results of [22], values are lower than TSS concentrations of a separated sewer system in Germany. The mean value of 114.3 mg/L and the standard deviation of 339 mg/L indicates high variation.…”

An empirical investigation of climate and land-use effects on water quantity and quality in two urbanising catchments in the southern United Kingdom

“…Therefore alongside deterministic modelling studies an empirical approach is very valuable and is the subject of this study on two growing towns largely characterised by separate sewer systems in which flood events have been mitigated against at the planning stage by the construction of balancing ponds. Although moderated by site-specific factors combined and separate sewer systems can have very different impacts on receiving water quality (Brombach et al, 2005). Whilst a move to separate systems will likely increase the overall storm water volume and pollutant load it should be beneficial as much of the organic matter reaching receiving waters will be of lower concentration and less biodegradable and therefore less likely to lower oxygen levels (Thorndahl et al, 2015).…”

ZeroWasteWater: short-cycling of wastewater resources for sustainable cities of the future

“…Secondly, infiltration in the sewer systems could be significantly decreased by improved maintenance. With 50% less infiltration, the concentrations will increase with only around 20% in combined sewer systems, but with around 140% in a separate sewer system (Brombach et al, 2005). Thirdly, in the latter system, water conservation of 25% could lead to a concentration increase of around 190%.…”

“…However, because of dilution with storm and infiltration water, this concentration is, in practice, much lower. In average German conditions for instance, the sewage is diluted with a factor 3.4 (Brombach et al, 2005), giving rise to about 225 mg COD L −1 . For energy recovery from anaerobic digestion, considerably higher COD levels are desirable.…”

“…Firstly, a separate sewer system with a sanitary and a storm sewer can increase pollutant concentrations by around 85%, as calculated from typical German flow rates (Brombach et al, 2005). Secondly, infiltration in the sewer systems could be significantly decreased by improved maintenance.…”