An innovative greywater treatment system for urban areas ... - SuSanA

Table 2: Microbiological load of greywater from typicall housholds; (fbr, 2005)
2.1.3 REUSE OF GREYWATER
From the various sources available (sewage water, greywater and rainwater), which could
cover the demand for an inner household’s water reuse, greywater is the most appropriate
option. The availability of rainwater that could be collected from roof drainage, which has in
general a low load, depends on the weather. In many regions of the world rainfall is usually
limited and, due to climatic conditions not consistent (Paris, 2009b). In contrast, in every
household greywater occurs regularly, but in-house installations for separate collection and
treatment are necessary, to make it available for reuse.
In principle, there are many possibilities of water recycling, which enable a sustainable
handling of water resources. In many places, purified wastewater is used for agricultural
irrigation. Water saving techniques in industrial production are widespread due to the
monetary benefits. A common practice is, to collect the relevant process water separately
and prepare it specifically for reuse. For the reduction of drinking water consumption it is also
useful in the urban context, to use water several times. Any use, both in the building as well
as outside, requires a defined process water quality to avoid health risks. The usual innerurban
applications of recycled water include: air conditioning, laundry wash, toilet flushing,
irrigation of private and public green areas, car cleaning and quenching water reserve as
shown in Figure 1 (Asano et al., 2007).
2.1.4 LEGAL FOUNDATIONS
In Germany there are different requirements for the quality of recycled greywater
according to the field of reuse.
Irrigation:
In the DIN 19650 there are hygiene parameters for irrigation water defined.
Toilet flushing:
The two common directives in Germany, the leaflet „Betriebswassernutzung in Gebäuden -
process water use in buildings“ (Senatsverwaltung für Bau- und Wohnungswesen, 1995) and
EU directive for bathing water quality RL 76/160/EWG (1975) and RL 2006/7/EG (2006).
Partial use in washing machines and dishwashers:
There are no exact references specified, therefore recourse to EU directive for bathing water
quality RL 76/160/EWG (1975), RL 2006/7/EG (2006) and drinking water ordinance TrinkwV
(2011) is taken.
In the international context, some countries released directives or standards with specific
requirements for the inner-urban process water quality to ensure safe water reuse (an
overview is given in Table 3. The relevant quality parameters are regularly the BOD
concentration (regarding the storage capacity), the turbidity (due to the aesthetic concerns)
and the microbiological pollution (because of health risks). The specified limit values can vary
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