The comprehensive renovation of the GIZ headquarters in Eschborn carried out from 2004 to 2006 included a concept for the separate collection of grey, yellow and brown water in house no. 1 (fig. 1). The wastewater flows are discharged via three lines that lead into the cellar of the house. The technical plants for the recovery of nutrients (P and N) from yellow water and the production of process water from grey and brown water is provided by HUBER SE within the scope of the SANIRESCH project (SANItaryRecyclingESCHborn). Due to its complexity and innovative character the project is supported by BMBF (grant ID 02WD0952).

A MAP precipitation reactor (HUBER NuRec) is used to recover nutrients from urine, whereas the well-proven MBR system with ultrafiltration is used for the production of process water from grey and brown water. In addition to the technical processes, a special challenge of this project was the very limited installation space.  The room provided for the installation of all technical plant components is located in the cellar and has only 21 m2. After the successful start-up of the MAP precipitation reactor in summer 2010 and the brown water pre-treatment system in April 2011 the start-up of the MBR greywater treatment unit (fig. 2) followed in May. No operating problems have been experienced to date.

38 washing and wash hand basins and 8 dish washing machines are connected to the greywater line, with a volume of 350 l greywater to be treated per day. The following modular components are installed:

• Intermediate storage tank with preceding HUBER Turny screen (3 mm mesh)
• Membrane bioreactor (MBR) with submerged HUBER ultrafiltration module (MCB 1; fig. 3) in a plastic tank
• Permeate storage tank
• Electric measuring and automatic control devices including remote data transmission (incl. fault indication via SMS) and telecontrol

The PE tanks are customized units perfectly tailored to meet specific customer requirements, and they are odour-tight. To ensure as problem-free as possible plant operation, for the first time a telecontrol system is used in addition to the normal remote data transmission including fault messages via SMS. This system allows access to operating status information from a central station and adaption to actual MBR process requirements. This reduces potential standstill times and service requirements to a minimum.

First test results have shown a high cleaning efficiency and proven the stable operation of the plant. Average COD elimination is presently 95%. The applied ultrafiltration with 38 nm separation size guarantees the retention of all bacteria. Due to its microbiological properties the permeate can without problems be used for toilet flushing and irrigation purposes. Reuse of treated greywater considerably reduces water consumption and is therefore the basis for certification to BREEAM (BRE Environmental Assessment Method) and LEED (Leadership in Energy and Environmental Design). Additional information on this project is provided on www.saniresch.de and www.facebook.de/saniresch. 
  

Project overview:

Technical data:

• Bio-tank volume: max. 0.5 m³
• Membrane surface: 3.5 m² (1 x MCB 1)
• Separation size: 38 nm
• Membrane material: PES

Operating parameters:

• Flow rate: 350 l/d
• DS content: 3 - 6 g/l
• BDS ≤ 0.1 kg COD/kg DS*d