Biological wastewater treatment
The biological treatment of high organic polluted wastewater is possible in two ways:
Aerobically, with the support of bacteria, which require oxygen to decompose the organic substances in wastewater. The oxygen must therefore be constantly fed. Since the required settling tanks are limited in their height, they need a lot of space.
Anaerobically, with the help of bacteria which degrade organic matter in wastewater in the absence of atmospheric oxygen. The specific bacteria must be able to separate the oxygen of the H2O molecule for respiration.
Through a series of metabolic intermediate steps, carbon dioxide and methane finally emerge, which can then be used, energetically, as biogas. The space requirement is very low, since the reactors need a significantly smaller volume and can be built very high.
Both systems differ in the operating and investment costs.
The anaerobic degradation, for example, has significant economic benefits and is useful from a COD value of about 1,000 mg/l.