Salem Sludge Reed Bed System
In 1998, Archer Engineers completed the design for the expansion of the City of Salem, Missouri's wastewater treatment plant. Included in this expansion was the addition of a sludge reed bed system. Prior to this upgrade the City aerobically digested the sludge, and land applied it on nearby fields. Due to lack of adequate storage facilities, especially during wet weather, the City would have to reduce wasting rates in the activated sludge system, building the MLSS up to higher than recommended levels.
The reed bed system now gives them the flexibility to dispose of sludge year-round during all types of weather. The only annual maintenance the City incurs is the harvesting and disposal of reeds that can be easily handled in one week by two people. Reed beds allow the sludge to accumulate and dewater on the reed bed for 5 to 10 years. The resultant material generally meets Class A sludge requirements. An added bonus is the fact that the reeds uptake metals that can cause problems in meeting 40 CFR requirements. The reed bed system was able to reduce the amount of zinc in the sludge, which had been a concern for the City.
Although reed beds are common in the states of Indiana, Wisconsin and Minnesota, the reed bed system in the City of Salem is the first of its kind in Missouri. Archer responded to the State's questions concerning the system's performance and treatment capabilities. Ultimately, the State approved the concept and design of the reed bed system. Reed beds generally produce a Class A sludge.