As part of the pilot project awaregio, funded by the BMBF, a semi-technical, modular wastewater treatment plant was built on the grounds of the sewage treatment plant Moers-Gerdt of the Linksniederrheinische Entwässerungs-Genossenschaft (LINEG, Germany). Different product water qualities are produced here from the wastewater of the sewage treatment plant. Afterwards these waters of different qualities are tested in a connected aquaponics (combination of fish farming (aquaculture) and plant cultivation (hydroponics) in a closed cycle system).
The wastewater treatment system was consciously designed to be low‑energy, low‑cost and low‑maintenance. A further developed anaerobic reactor (combination of an Emscher well, an anaerobic baffled reactor (ABR) and an anaerobic filter (AF)), an anoxic-aerobic biofilm stage (MBBRD) and a packed bed filter are used in the primary wastewater treatment. This means that there is no need for pressure aeration, for example.
Several modular technologies are available for post-purification, which produce the following different water qualities:
- As an operationally very simple variant 1 (Q1), an optimised, planted soil filter stage (SF) was realised, which was combined with a second soil filter stage in additional tests. (Qh, SF ≈ 0.15 m³/h).
- In variant 2 (Q2), a periodically operated UV stage was used instead of the soil filter. (Qh, UV ≈ 30 L/h).
- In variant 3 (Q3), the pretreated wastewater was treated in an ultrafiltration stage (UF). (Qh, UF ≈ 0.33 m³/h).
- In variant 4 (Q4), the water from the ultrafiltration or the soil filter cascade was further treated by a low-pressure reverse osmosis (RO). (Qh, RO ≈ 0.33 m³/h).
The clear water from the soil filter, the UV stage and the ultrafiltration stage were tested in an aquaponics greenhouse, which was operated by the project partner TERRA URBANA. Next to these water qualities, also fresh water from a well was testes as a reference. The tests were made in four independent water circuits.
For the analysis of the individual treatment steps, there were 14 sampling points and several gas meters distributed all over the plant. For the study of trace substances passive samplers at the inlets and outlets of the various treatment stages and bioanalytical methods were used. In addition, precipitation tests to produce an N+P recycling product from the RO concentrate were made in the wastewater treatment plant laboratory. Next to this, also tests for further oxidative degradation of the trace substances in the RO concentrate were done there. Finally, biogas recovery from the anaerobic stage was investigated using a vacuum degassing system.
The semi-technical test facility is equipped with a PLC and a DCS for semi-autonomous testing. This allows that the operating values are automatically recorded and sent electronically.
The awaregio development project, funded by BMBF (federal ministry of education and research of Germany) was successfully completed at the end of September 2019. We want to continue using the test and demonstration plant to test, which water qualities can be achieved with which treatment path, to serve different fields for use. In addition, the experimental plant is perfect for training or further education of (inter)national experts and managers, as the knowledge built up on the increasingly important topic of "water reuse" can be visually presented and further distributed here.