Graywater Reuse in Jordan -- continued --

King Abdullah Mosque

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As was noted in the previous report, ‘Graywater Reuse in Other Countries and its Applicability to Jordan’, wastewater from the ablutions of worshippers at the King Abdullah Mosque in Amman is collected, pumped to a rooftop storage system where it is filtered, and reused to irrigate areas of ornamental plants in the grounds of the mosque. The system has been installed for around 5 years, and has resulted in significant savings on the mosque’s water bills. The capital costs for the installation of the system were recouped within the first year of operation.  

Water quality testing on the water before and after filtering was carried out by CSBE in May 2003 and the results are presented below. 

Table 1:  Results of water quality tests conducted on the graywater collected from the place of ablution at King Abdullah Mosque

EC:  electrical conductivity - a measure of water salinity.  

pH:  a measure of acidity or alkalinity (less than 7 is acidic, greater than 7 is alkaline). 

SAR: sodium adsorption ratio in the water.  

Faecal Coliforms:  a measure of the degree of bacterial contamination from humans and animals. 

BOD:  biochemical oxygen demand – a measure of the amount of organic matter.  It specifically measures the demand for dissolved oxygen from microorganisms as they attempt to break down organic material.

As expected, these results show very low levels of contaminants in the graywater to begin with.  The guidelines given in Jordanian Standard 893/1995 for irrigation of cooked vegetables and fruit trees by treated wastewater have also been included in the table for comparison.  It is clear that this type of graywater is suitable for the irrigation of cooked vegetables and fruit trees, or of ornamental plants in the grounds of the mosque even before filtering.  It is interesting to note that the main effect of filtering on the parameters in question is to reduce the BOD load and the faecal coliform count, mainly through the removal of organic material form the water. However, even the unfiltered graywater would be suitable for use in irrigation of ornamental plants.

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A second example of urban graywater reuse which was recorded in the Phase 1 report is where a householder in Amman has installed a simple graywater system where graywater from one bathroom in the house is intercepted at an external manhole and is taken to a horizontal underground pipe supplying the water to a row of plants. There is no pumping or filtering of any kind. No change of behavior was necessary on the part of the householders, since all the water from the bath, shower, and bathroom sink is applied directly and automatically onto the plants. This system has been operating for over 2 years and there are no signs of stress on the plants or the soil. The cost of the manhole divert and the piping are reckoned to be of the order of 20 JD (around 28 USD), and there is little or no ongoing maintenance required.  

Soil quality tests were carried out at this site by CSBE in order to determine if there has been a buildup of indicator contaminants over this period of time. Samples were taken in June 2003 (following the end of the winter rains) and again in October 2003, after a period of summer drought, but before the first rains of the autumn period. The soil tested was gathered from the entire area to which the graywater has been applied, and could be considered representative of the general characteristics of the soil over a wide area, and not just as a spot sample taken in one place. The results are presented below;

Table 2:  Results of soil quality tests conducted on the soil at HB House - Amman

These results are interesting and indicate two important trends. Firstly, by comparing the graywater-positive results from June and October, it is apparent that the winter rains have a significant flushing effect on the soil. There is a rise in concentration of all the major parameters (with the exception of faecal coliforms). The rise in salinity (from 0.79 to 1.48 dS/m), in chloride (from 1.88 to 7.10 mg/l), sodium (from 26.9 to 31.7 mg/l), in SAR (from 0.65 to 1.86) and in boron (from 0.33 to 0.44 mg/l), all reveal a buildup in these parameters during the summer months. Although more comprehensive testing over a number of summer-winter cycles would be advisable in order to provide a more long term pattern, it is likely that the buildup in the concentration of these substances is due to the application of graywater. During these months, the soil in question has been irrigated by graywater in the absence of rainfall. All the substances listed above, whose concentrations increased, are constituents of soap and detergent products used in showers and bathrooms, and would be expected to be present in the graywater (although no specific tests on this bathroom graywater were conducted). It is likely that a proportion of the substances in graywater are remaining in the soil, following irrigation. The significant rainfall during the winter months would have the effect of flushing out much of the increased concentration of such substances, and effectively cleansing the soil. This may well prove to be a significant factor in reducing the detrimental effect of graywater irrigation in Jordan. 

The second point to note is also important. The soil at this site has been irrigated by graywater for a number of years – a number of summer/winter cycles. It is interesting to note that at the end of the winter rains, the concentrations of these key parameters in the soil irrigated by graywater, are generally not excessively above that in the adjacent sample of soil which has not been irrigated by graywater. In addition, they are substantially below the maximum levels set out in the Agricultural Handbook. This demonstrates that in this case, there has been no long term buildup of contaminants in the soil, as a result of irrigation by graywater. As discussed above, this may be due to the annual flushing of the soil by the winter rains (around 500 mm/year on average, at the site in question).  

The lower concentration of faecal coliforms in the soil in October 2003 is unexplained, but may be a result of the significantly drier soils conditions at the site, which would disfavour the growth of such coliforms.