Storm water retention tanks act as a buffer during periods of heavy rainfall. This is increasingly important as areas become more developed, with hard surfaces such as roofs, roads and parking lots that cannot absorb the rainwater. When storm water retention tanks are implemented, gravity or pumps can be utilized to provide a reduced continuous flow into the sewer system. Sulzer expertise makes it possible to avoid peak hydraulic loads and to limit the stresses on existing sewer systems.

Treated wastewater may occasionally require further treatment. Local discharge rules may pose strict limits that cannot be fulfilled by even the most effective process, or a higher quality of effluent may be requested for its reuse. When tertiary treatment is needed, various levels of filtration can be applied, including very fine filtration. Often, however, a final step of mixing and aeration is sufficient to achieve the target. When this is the case, Sulzer's submersible mixer types ABS XRW and RW can be used, along with submersible aerator type ABS TA–TAK and disc diffuser system types ABS PIK, DS and Sucoflow.