Odour
Sewage odour is generally a regulated cost to the industry. Sewage odour, mainly rotten egg (H2S) gas:
- Is offensive
- Upsets your Customers
- Is a Health Hazard
- An Occupational Health & Safety Risk
- Can lead to heavy fines
- Leads to costly infrastructure corrosion
- Increases Greenhouse Gas Emissions
- Is an explosive risk.
How and where are sewage odour and methane gas formed?
Sewage odour (H2S gas), dissolved sulfides (HS-) and methane gas (CH4) are formed in the biofilm / sediment (slimes) layer on the invert of the sewer pipe as shown in the photo’s below (see Ref: below)
Note how Biosol products have removed or reduced the biofilm / sediment or slimes complexes in the base of the sewer pipe. This means the cause of sewage odour, sulphide and methane gas generation within the sewer pipe has been eliminated or minimised. The rate of removal of the biofilm / sediment matrix (slimes complex) and thus the time interval to control sewage odour, corrosion and methane gas production depends on the:
Depth of the biofilm sediment matrix in the sewer main
Surface condition of the sewer pipe
Water scour velocity
Selected dose rate of the Biosol products
Length of the sewer main and the sustained water scour velocity for each pumping interval
Sediment inputs to the sewer.
In general sewer odour reductions will be observed within one month of dosing but where a combination of factors as shown in the list above occur, the process may take from 1 to 4 or 5 months to achieve optimal results.
Sewage odour as a Health Issue
Sewage odour can range from a nuisance, objectionable odour to a serious health hazard, which kills a number of people every year. More information
Sewage odour as the cause of infrastructure corrosion
Sewage odour is the cause of most sewage infrastructure corrosion. It results from the conversion of hydrogen sulphide (H2S) gas to sulphuric acid (H2SO4). Stopping or minimising the formation of sewage odour, also minimises infrastructure corrosion from sulfuric acid. More information
Sulphide’s at the treatment plant
At the treatment plant, sulphides (HS) need to be converted to sulphates (SO4). That requires 4 atoms of oxygen for every sulfate molecule entering the treatment plant. Stopping or minimising the formation of sulfides in the sewage catchment by removing the biofilm sediment complexes as shown above, can save a lot of energy at the treatment plant in supplying this oxygen and thus save on cost and greenhouse gas emissions.
Biosol products are unique in that they treats the cause of sewage odour, infrastructure corrosion and methane gas production in sewers.
Most opposition products treat the symptom and not the cause.
Return to Sewers & Cost
References for above:
1 Bowker Robert P.G. et al. Design Manual, Odour and Corrosion in Sanitary Sewerage Systems and Treatment Plants Pg.9 United States EPA Publication N-497
Mishina,F., Nonaka, T., Hikosaka, Y., .Koga, M., Mori, T. “Microbial Corrosion of Concrete Pipes, H2S production from Sediments and Determination of Corrosion Rates”, Water Science and Technology WSTED4 Vol.23 No.7/9 p1275 1282, 1991.
3 Guisasola,A. et al. “Methane formation in sewer systems” WATER RESEARCH 42 (2008) 1421–1430
