Water and Waste–Water–Treatment More than Just a Spill: How to Turn Waste Water into Ressource

Editor: M.A. Manja Wühr

There are better things to do with treated waste water than just discharging it – in fact, it could become a valueable ressource: Reseachers at Darmstadt Technical University have demonstrated with industrial partners from Microdyn-Nadir this fact at a hotel complex in China.

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First Resource Recovery Center in Qingdao
First Resource Recovery Center in Qingdao
(Bild: est/TU Darmstadt)

Qingdao/PR China – Following the motto “wastewater is not a waste but a resource” Dr. Peter Cornel and his team at the Technical University Darmstadt, Germany developed an innovative and integrated approach. In line with this approach wastewater is seen as a resource for water, energy and nutrients. Conventional wastewater treatment plants do treat the wastewater but do not use the treasures it holds as the water streams are just discharged into the canals after treatment.

With the right infrastructure solutions our resources can be treated and reused much more efficiently: instead of wastes, products like non-potable service water, irrigation water, biogas/electricity as well as biosolids can be produced out of wastewater. The project´s name already shows the solution: Semizentral – not centralized nor decentralized but an in-between infrastructure solution that grows with the cities – might be the key to a sustainable future! The concept combines water and wastewater treatment with anaerobic sludge digestion.

Semizentral Resource Recovery Center

In Qingdao, PR China, the first Semizentral Resource Recovery Center (RRC) was opened in April 2014. Its catchment area comprises three hotels, housing areas for staff and guests, new developed housing areas and office buildings adding up to approximately 12, 000 people to serve.

Material Flows Within the semi-centralized system in Qingdao
Material Flows Within the semi-centralized system in Qingdao
(Picture: Technical University Darmstadt)

The modular approach of the RRC incorporates 4 sections: greywater treatment (-> is reused as non-potable service water), blackwater treatment (->is reused as irrigation water), foodwaste pre-treatment (-> mechanical pre-treatment) and an energy sector (->anaerobic thermophilic treatment, electric energy). The different wastewater streams are treated separately according to the degree of contamination. The whole system is completely energy self-sufficient.

The greywater (wastewater from the sink or shower) section is equipped with 4 Bio-Cel BC 400 modules and treats 718 m3 of wastewater per day. The treated water is reused as non-potable service water, e.g. for the toilet flush. The blackwater (wastewater from toilet flush) section houses 8 Bio-Cel BC 400 modules treating 860 m3 of water daily. After its treatment the water is reused for irrigation purposes. The RCC building is located nearby the residential area and is very compact and a completely closed system (odor control) that does not at all look like a wastewater treatment plant from the outside.