Wastewater disposal via small-scale treatment plants; notification of test results

State-of-the-art small-scale wastewater treatment plants typically consist of a mechanical treatment stage followed by a biological wastewater treatment stage. The wastewater is first directed into a tank where the solid components settle; the dissolved organic components are broken down by microorganisms in a downstream biological treatment stage. If more stringent treatment requirements must be met in specific cases (e.g., nitrogen removal, phosphorus removal, wastewater disinfection), more complex small-scale wastewater treatment plants must be constructed and operated.

Small-scale wastewater treatment plants on private property are generally built and operated by the homeowner or property owner. To ensure effective treatment performance over the long term, it is necessary to regularly maintain and monitor the small-scale wastewater treatment plants. Often—especially for more technically complex systems—this task is outsourced to specialized companies under a maintenance contract. The sewage sludge from the mechanical treatment stage must be disposed of properly and regularly.

Every 2 years (4 years for systems with no defects found during the last inspection), small wastewater treatment plants must be inspected by a certified private expert in water management (PSW); the inspection results must be certified to the lower water authority (district administrative authority).

• Expert inspection report (2–4 years)