NA-05 - Cleaning: Solids in Drain and Sewer Systems (Demo)

Consequences of solids entry

Example - annual input and output of sewer solids (The municipality of Entzheim)

Input and output (mass balance) of solids in sewers, and their composition (organic, mineral) using the example of the combined sewer system of the municipality of Entzheim (Germany) [Artie1988].

The investigation by Artières revealed that after the initial survey year approximately 54% (15 t/a) of registered mineral solids remained as deposits in the sewers.

This amounts to approximately 1 t/ha∙ a based on a paved surface area of 16 ha. The organic solids consisted of 87% (20 t/a) from households and only 13% from road surface runoff. Of these, 13% (3 t/a) remained as organic deposits in the sewer system, with the remaining (87%) being discharged.

The amount of deposits in this combined system amounted to approximately 18 t/a, corresponding to 1.125 t/ha ∙ a or 35% of the registered solid mass (see table).

 

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Annual balance of solid entry and discharge into the combined sewer system of the municipality of Entzheim [Artie1988][SteinR2005]

Artières investigations of particle size distributions of 8 sediment samples have led to the conclusion that "the sediment deposits from the Entzheim combined sewer system consist mainly of mineral particles transported by precipitation runoff from the road surface." [Artie1988] [SteinR2005]

Solids type   1. Surface runoff through catch basins 2. Household waste Deposits in the sewer channel (from 1. and 2.)
  [t/a] [%] [t/a] [%] [t/a] [%] [t/a]
Mineral 28 46 12,9 54 15,1 54 15,1
Organic 23 13 3 87 20 13 3
Total 51 - 15,9 - 35,1 35 18,1
Table: Annual balance of solid entry and discharge into the combined sewer system of the municipality of Entzheim [Stotz]
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