362
W. Neubrand et al.
A number of pilot projects follow a different approach based on separation of
wastewater streams with different levels of contamination and separate treatment
of individual streams, like it is current practice in industrial water treatment. Pilot
projects in Germany are described by Londong (Lon dong 2000). Greywater is
collected separately and then treated in a wetland system. The effluent can be
reused for gardening or is discharged to a river. Separate treatment of blackwater
and urine is also part of the project.
Especially in urban regions such a scheme cannot be implemented and thus onsite reuse, e.g., for toilet flush is one way to reduce the overall water consumption.
This is also the approach followed by the installation described in the following
sections.
From the figures on water consumption, it becomes evident that the reuse
potential for greywater is high and savings of30% of total water consumption can
be reached.
3 Requirements for On-Site Greywater Recycling
Recycling systems for on-site treatment do not fit into the scheme of centralized
treatment because the major target is to avoid mixing of different water qualities
and transport of excessive water volumes.
The major concern of the authorities is control of water quality and hygienic
standards (Maier et al. 2000). The standards to be met are rather different.
Whereas water reuse in Austria requires microbiological quality according to the
guideline of water for human consumption (EWG 1980, GroB et al. 1996) several
publications consider the application of EC Guidelines for water quality in
recreational areas (EWG 1976) as adequate (Jackson and Orb 2000). In Japan,
similar requirements are valid (Osoghi et al. 2000). Some people even suggest
direct reuse for gardening (Berry 1999) without any treatment.
In addition to hygienic requirements, it is necessary to avoid unpleasant
appearance and color as well as odors to prevent complaints by consumers.
Greywater contains significant organic contamination and thus is a substrate for
bacterial growth, especially when it is stored. This can lead to a significant
increase in the number of microorganisms and, especially when anaerobic
condition prevail, this leads to the formation of hydrogen sulfide and related smell
and odor problems (Berry 1999).
4 Treatment Processes
To meet the strict requirements for water quality the treatment process is based on
nanofiltration (NF) technology in combination with disinfection systems.
W. Neubrand et al.
A number of pilot projects follow a different approach based on separation of
wastewater streams with different levels of contamination and separate treatment
of individual streams, like it is current practice in industrial water treatment. Pilot
projects in Germany are described by Londong (Lon dong 2000). Greywater is
collected separately and then treated in a wetland system. The effluent can be
reused for gardening or is discharged to a river. Separate treatment of blackwater
and urine is also part of the project.
Especially in urban regions such a scheme cannot be implemented and thus onsite reuse, e.g., for toilet flush is one way to reduce the overall water consumption.
This is also the approach followed by the installation described in the following
sections.
From the figures on water consumption, it becomes evident that the reuse
potential for greywater is high and savings of30% of total water consumption can
be reached.
3 Requirements for On-Site Greywater Recycling
Recycling systems for on-site treatment do not fit into the scheme of centralized
treatment because the major target is to avoid mixing of different water qualities
and transport of excessive water volumes.
The major concern of the authorities is control of water quality and hygienic
standards (Maier et al. 2000). The standards to be met are rather different.
Whereas water reuse in Austria requires microbiological quality according to the
guideline of water for human consumption (EWG 1980, GroB et al. 1996) several
publications consider the application of EC Guidelines for water quality in
recreational areas (EWG 1976) as adequate (Jackson and Orb 2000). In Japan,
similar requirements are valid (Osoghi et al. 2000). Some people even suggest
direct reuse for gardening (Berry 1999) without any treatment.
In addition to hygienic requirements, it is necessary to avoid unpleasant
appearance and color as well as odors to prevent complaints by consumers.
Greywater contains significant organic contamination and thus is a substrate for
bacterial growth, especially when it is stored. This can lead to a significant
increase in the number of microorganisms and, especially when anaerobic
condition prevail, this leads to the formation of hydrogen sulfide and related smell
and odor problems (Berry 1999).
4 Treatment Processes
To meet the strict requirements for water quality the treatment process is based on
nanofiltration (NF) technology in combination with disinfection systems.