Sources and erosion of organic solids in a combined sewer

Sterols: a tracer of organic matter in combined sewers

“…Three types of in-sewer stocks are identified in the literature (Crabtree 1989;Chebbo et al 2003): gross bed sediment (GBS) found at the invert of the pipes, organic biofilms located on sewers walls at the mean water level and an organic layer (OL) at the water-bed interface. Previous studies on six different catchments in Paris have shown that the major source of organic matter in combined wet weather flows is the erosion of an organic in-sewer deposit (Kafi-Benyahia 2006), whose characteristics are similar to the organic layer identified by Ahyerre et al (2000) on Marais catchments (40 ha, Paris). However, this organic layer has not been localised up to now on wide scale.…”

The experimental urban catchment ‘Le Marais’ in Paris: what lessons can be learned from it?

“…This comparison was carried out initially over the whole catchment area. The conclusions drawn from this comparison (Ahyerre, 1999;Ahyerre et al, 2000;Ahyerre and Chebbo, 2002) are the following: † Type A deposits have a mass greater than the mass of the particles eroded during rainfall events. They have a higher mineral content, for example the volatile matter content of eroded particles is on average 67% whilst that of particles with a diameter of less than 400 mm in type A deposits is 17%, † Biofilms have a mass which is much lower than the mass eroded during storms, organic matter content are similar and however the metal content of the eroded biofilm is much higher than in the biofilm located on the pipe walls…”

Sediment risk analysis of urban drainage pipeline

“…The solid particulate matter in sewage pipe network comes from three aspects [5]: firstly, the small particle size residue of human excreta and organic particulate matter, which is the main source of sediment in sewage pipe; second is the kitchen, domestic waste in the large particle size residue and organic solid material; in addition, there are some paper, discarded clothing and other objects, such as objects, although not many, but the harm is very big, it is easy to cause pipeline blockage. Ahyerre et al [6] based on the physico-chemical properties of the channel sediments, they were divided into bottom coarse-grained sediments (Gross Bed Sediment, GBS) according to their distance from the bottom of the tube, the Organic Layer (OL) and the biomembrane (Biofilm) are three layers, as shown in Figure 1.…”