Wastewater disposal via small wastewater treatment plants; notification of the test result

State-of-the-art small-scale sewage treatment plants usually consist of a mechanical treatment stage followed by a biological wastewater treatment stage. The wastewater is first directed into a tank where the solid matter settles; the dissolved organic matter is then broken down by microorganisms in the subsequent biological treatment stage. If, in individual cases, more stringent treatment requirements need to be met (e.g. nitrogen removal, phosphorus removal, wastewater disinfection), more complex small-scale sewage treatment plants must be installed and operated. Small-scale sewage

treatment plants on private property are generally built and operated by the homeowner or landowner. To ensure good treatment performance in the long term, it is necessary to maintain and monitor the small-scale sewage treatment plants regularly. Often – particularly in the case of more technically complex systems – this task is outsourced to specialist companies under a maintenance contract. The sewage sludge from the mechanical treatment stage must be disposed of properly and regularly.

Every two years (four years for systems found to be fault-free during the last inspection), small sewage treatment plants must be inspected by a recognised private water management expert (PSW); the results of the inspection must be certified to the lower water authority (district administrative authority).