Honduran Imhoff Tanks: Potentials and Pitfalls

An Imhoff tank is a structure originally designed to provide primary wastewater treatment. It is a sedimentation tank with a steeply sloped floor resting above a sludge digester. During the 1930s, Imhoff tanks represented 50 % of all waste-water treatment facilities in the United States. The majority of Imhoff tanks within the U.S. have since been abandoned or modified to adapt to changing treatment objectives and regulations. However, within the Central American country of Honduras they continue to represent a significant portion of the wastewater treatment infrastructure and are routinely designed and constructed where populations are small and terrain is limited. In Honduras, stormwater inflow and infiltration into wastewater treatment systems pose significant challenges. The drainage flows in urban areas mix with raw sewage creating dilute, but large volumes of, wastewater that requires treatment. Imhoff tanks in Honduras use design parameters more suitable for dryer regions of the world that do not experience such consequences of storm-water. These tanks are therefore currently not successful in providing treatment