Process Engineering

A modern state-of-the-art wastewater treatment is a result of our well-known principle of downstream treatment steps. The domestic, industrial or agricultural wastewater is mechanically pre-treated in a physical manner, biologically purified, mechanically treated in a physical manner downstream and then recycled into the natural water course. This natural way of wastewater treatment does not require chemical additives. Only in some special wastewaters can a chemical treatment step enormously support the biological processes.
For more in depth requirements, downstream treatment steps, such as disinfection, are also available. The modular concept of System S&P® offers a wide variety of combinations to the above mentioned technologies.


The mechanically performed physical pre-treatment of house treatment plants is normally achieved by multi-chamber pits or with a similar technology. For bigger plants, state-of-the-art technologies such as screenings systems, grit chambers and drum sieves are used. In many cases it is important to foresee a grease trap. The aim of such a grease trap is to remove any kind of particular matter, as this could negatively influence the biological step. With the afore mentioned mechanical technologies, a treatment efficiency of up to 35% can be achieved.


The main part of the wastewater treatment is controlled by the biological step, where micro organisms degrade the organic load, which consists of mainly carbon compounds under oxygen consumption. By adequate process conception it is possible to biologically transform the ammonia nitrogen into the more environmentally friendly nitrate-nitrogen. This process is called nitrification. The next step consists of the removal of the nitrogen through an anoxic process called denitrification.
Highly loaded wastewaters can be treated by additional biological anaerobe steps that are used for phosphate elimination.
The basic activated sludge systems use general technologies of biological treatment. Such a system suspends the biomass in the wastewater where it is supplied by aerators with vital oxygen. In contrast to this, the biomass adheres to the basic fixed film technology on growing surfaces which are continuously or periodically surrounded by an oxygen atmosphere. Combinations of both above mentioned technologies are also possible.


The final clarification step is then necessary as the biologically treated wastewater still contains degradation products from the biological step, the so-called excess sludge. The sludge must be separated out in a mechanically performed physical process. Adequate technologies to use in this application are gravity separators such as Emscher Tank or floatation separators.


A special kind of gravity separator is the specific lamella separator, which is approved in combination with fixed film biology.
The sludge separated out in the pre-treatment is called fecal sludge and cannot be applied on land due to its consistency and stabilization grade. However, the excess sludge of the fixed film technologies is widely stabilized and can be used as valuable fertilizer in agriculture. Other possibilities for sludge disposal are through composting, sludge earthening and burning.


Further amelioration of the quality of the treated wastewater can be achieved through several tertiary treatment steps. This is especially required if the wastewater will be used for irrigation or if the process water will be used for air conditioning or toilet flushing. Common technologies are in this case chemical precipitation for phosphate elimination or heavy metal removal. The mechanically performed physical filtration with such a substance as sand filter can remove the finest suspended particles. By activated carbon filtration, non-biodegradable organic compounds can be removed. UV-disinfection or chlorination removes bacterial contamination of the treated wastewater.

By the use of only tertiary treatment technologies, existing surface or ground water can also be treated up to process water quality.


For drinking water quality of wastewater, ultra and nano filtration, reverse osmosis, and membrane technology are used along with the above mentioned technologies. The aim of these technologies is to provide drinking water for man and beast without noxious side effects.


In particularly sensitive fields such as hospitals or hotels, additional installation of air filters can be useed in order to avoid any unpleasant smell. For this purpose biofilters are mainly used.