Founded in 1911 as a craft enterprise for sanitation and heating equipment the company developed already during the 1920s to a real waste water specialist: With the installation of the first pressured aeration for activated sludge plants in 1924 and only one year later with the first heated anaerobic sludge digestion system in continental Europe for the Ruhrverband in Germany, OSWALD SCHULZE became one of the technology leaders in the field of municipal and industrial waste water treatment. This means now nearly one century of technological leadership and experience.

From the start-up phase until the mid 1960s the company was formed under the leadership of the Person Oswald Schulze himself. After the death of Oswald Schulze his senior engineer for many years Ing. Werner Oles took over the comapany as managing partner and was responsible for a continuous development. Many techological improvements in the process engineering of waste water and sludge treatment were initiated and created by these two personalities.

Further major development steps in sludge digestion are directly linked to OSWALD SCHULZE: In 1956 OSWALD SCHULZE designed and installed the process technology of the worldwide first egg-shaped digester in Frankfurt-Niederrad; for big digesters the egg-shape became then the prefered design due to ist advantages in construction and fluid mechanics for mixing. In 1998 followed the process design and mechanical equipment installation for the still biggest egg-shaped digesters in the world (3 x 17.000 m3) for the waste water treatment plant Emschermündung in Germany.

Also outside of Germany and Europe the expertise of OSWALD SCHULZE was used for the design and Installation of  the first egg-shaped digesters in South Africa (Pietermaritzburg, 1975), Taiwan (PaLi, Taipeih, 1992/2005) and Australia (Perth, 1998).