Greywater recycling systems in Germany — results, experiences and guidelines

Abstract

Although Germany is not considered a water-poor country, there exist regional differences in water supply and consumption. During the past 15 years, the greywater aspect has been dealt with in Germany with a greater interest and variable success. In addition to an increased environmental awareness, water costs also play an important role in increasing the demand for advanced greywater treatment plants nstalled in buildings. Under favourable conditions, the amortisation costs usually lie between 5 and 7 years. Systems that have been extensively tried and tested and have been shown to be most reliable are those employing an advanced biological treatment followed by an UV disinfection. Systems based on membrane technology are being developed and researched intensively in Germany for municipal wastewater treatment. However, so far they play no role in greywater recycling. Greywater systems operating under low energy and maintenance requirements without the use of chemicals are mostly favoured. In Germany, greywater recycling systems should be registered at the Health Office in order to guarantee that no cross-connections exist with the drinking water network and that pipes are labelled according to regulations. The hygienic requirements for recycled greywater, which is primarily used for toilet flushing, are oriented towards the EU-Guidelines for Bathing Waters. The use of recycled greywater for irrigation purposes is minor. As to the use of recycled water for laundry, the first promising investigation results are now available.

Urban futures and the code for sustainable homes

“…This exists currently in other European and non-European countries -for example, Germany (Nolde, 2005(Nolde, , 2007 and Australia (Brennan and Patterson, 2004).…”

Comparison of Three Systems for Biological Greywater Treatment

“…Greywater in this study had a relatively high concentration of COD compared to other studies previously performed in regions of similar climate and customs. For example, in Germany COD concentrations of 640 mg/L [6] and 420 mg/L [10] have been measured. In Sweden concentrations have been reported of 588 mg/L [11] and at another location in the Netherlands 450 mg/L [8].…”

Reuse of laundry greywater as affected by its interaction with saturated soil

“…Australian public have increasingly acknowledged the benefits of greywater reuse, particularly laundry and bathroom water for garden/lawn watering. Manual bucketing and diverter valve are the two commonly used methods of untreated greywater application (DLGPSR, 2007) as treatment, storage and subsurface application of greywater into soil can be expensive (Nolde, 1999;Jeppesen, 1996).…”