Graywater Reuse in Jordan -- continued --

3.0 Graywater Applications Assisted by CSBE

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A number of small simple schemes to reuse graywater have been assisted by CSBE during the course of this project. Some were instigated by CSBE, who carried out the design work, while others were already under development with CSBE providing advice and design assistance. The schemes vary in complexity and some have reached implementation stage. Others are still at design stage, and will continue to receive advice and guidance from CSBE following the completion of this component of the project.

MA – Private Garden Sink

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Figure 5 illustrates this simple application of graywater reuse which serves to demonstrate the simplicity of basic graywater reuse. An external sink has been established in the garden of domestic house to assist with the maintenance of the grounds. Rather than being connected to the municipal sewer, the sink drain has been connected to a row of Firethorn shrubs (Pyracantha coccinea) through a drip irrigation line placed above the soil. Graywater draining from this sink automatically goes to irrigate the garden. Should there be a need to dispose of substances which may cause harm to plants (such as strong cleaning chemicals or paints), the drain can be easily diverted – manually - to a receptacle, thus preventing harmful substances from entering the irrigation network – see Figure 6. The contents of the receptacle may then be disposed of appropriately. 

This system is so simple that it is in danger of being criticized as rather obvious, hardly worth the designation of ‘system’ at all. However, this is graywater reuse at its best. It illustrates the principle underlying graywater reuse in the first place - that the reason why graywater is chosen to be used after minimal treatment is its lack of contamination. This system provides no treatment whatsoever, and none is needed, given that graywater containing contaminants will be diverted away from the plants. No consumer contact with the graywater is required to connect the diversion, provided it is done in advance. However, the system does assume a degree of care and intervention on the part of the user – both regarding what is disposed of in the sink, and in the prompt and careful use of the diversion - and is clearly designed on the assumption of high quality water. The cost of the system was no more than 10 JD (around 14 USD) – the cost of the additional hose required to connect the sink to the irrigation system. This system was installed in the spring of 2003.

RSCN Nature Center

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The Royal Society for the Conservation of Nature (RSCN) has included a graywater reuse unit in its new Nature Center in Jabal Amman. CSBE assisted with the design of this unit, illustrated in Figures 7 (photograph) and 8 (sketch).  

Graywater will come from the hand basins and kitchens of the Nature Center as well as from the bathrooms and laundry of 4 apartments which will be housed above the Center. The actual quantities of graywater will depend on the usage of the center and occupancy of the apartments. The unit consists of 3 chambers as shown. Graywater drains (via the vertical PVC pipe on the left of the photograph) to a mesh screen filter, easily removable for cleaning, which will remove coarser solid material such as hair, lint and food scraps. Graywater will then pass upwards through a graded sand-gravel filter, visible in the right hand window on the photograph. This variable medium will allow for further filtering of finer solids, and will provide a surface for the anaerobic breakdown of organic material trapped in the filter. The filtered graywater will appear above the medium layer and overflow into the third chamber, from where it will drain by gravity to the irrigation network. The design of the unit provides for backwashing of the filter by reverse-connecting a hose to the unit, and also contains a diversion valve which can take all graywater to the municipal sewer if necessary.  

There are a number of issues of interest with this system. Firstly, the system does not serve a single family household. The Nature Center itself will be a non-residential establishment, with little volume of graywater output other than restroom sinks and possible a small kitchen area. It is not thought that meals will be prepared here. However, the building will contain 4 apartments for short term usage by guests of the RSCN and visitors. A degree of care and cooperation will need to be shown by the users of these apartments to avoid the release of strong cleaning materials and bleach etc into the graywater.  

Secondly, the performance of the graywater unit itself needs to be monitored and assessed over time. The amount of solid material intercepted by the filters will be an indicator of the quality of the graywater being produced. Also, the hydraulic operation of the sand filter should be monitored to determine if it is liable to clog.

A third important issue involves the plants to be irrigated by the graywater. The irrigated area is sheltered by the Center building and as such will receive no rainfall which would have had the effect of diluting the graywater and helping to reduce the buildup of contaminants released into the soil from the graywater. In addition, the architect has elected to sow the site using spores and seeds of plants native to that particular urban area of the city. Young plants are particularly sensitive to some of the impurities in graywater, and RSCN may need to supplement the irrigation with mains water for an initial period. However, the type of plants which have survived in such a polluted urban environment will tend to be more drought tolerant and resilient to graywater. 

It is clear that this unit has a degree of complexity not seen in the rural installations, and will require a higher degree of observation and user intervention. CSBE will continue to work with RSCN to monitor the performance of this unit, which at time of writing, has yet to come operational. Further results will be published on the CSBE website in due course.