The headspace in domestic wastewater collection and treatment systems is a severe environment that can impact even high performance protective coatings. A proposed new ASTM International standard covers an apparatus and set of procedures that are used to create and maintain a simulated sewer headspace environment to be used to test potential coatings.
ASTM WK33537, Practice for Operating the Severe Wastewater Analysis Testing Apparatus, is being developed by Subcommittee G01.05 on Laboratory Corrosion Tests, part of ASTM International Committee G01 on Corrosion of Metals.
The apparatus described in ASTM WK33537 is designed to simulate the pertinent attributes of a typical domestic sewer wastewater headspace found in a sewer. Testing is done within two phases in the chamber: a liquid phase containing a prescribed acid and saline solution; and a vapor phase consisting of air, humidity and concentrated sewer gas, which is composed of hydrogen sulfide, carbon dioxide and methane gases.
The temperature of the test chamber is elevated to create accelerated conditions and reaction rates.
While certain chemical and physical properties of coating systems can be determined in laboratories, testing with the apparatus and procedures described in ASTM WK33537 will provide a more accurate simulation of the environment of an actual sewer system.