Reclaimed Municipal Wastewater used for the Irrigation of Green Areas in Jeddah: 1 – Chemical Characteristics

For a better management of water resources, the municipality of Jeddah uses recycled municipal wastewater for the irrigation of parks and green areas. These places are recreational areas and are frequently visited by the population. A comprehensive study was planned to measure the potential health risk that may result from inadequate water treatment through the examination of the chemical and bacteriological characteristics of the recycled wastewater as well as the soil. In this context, 20 water and soil samples were collected from the most frequently visited sites all over the city. Water samples were analyzed for their content of, between others, nitrogen species (ammonium, nitrite, nitrate, organic nitrogen) phosphorus, dissolved oxygen, dissolved organic carbon, pH and suspended particulate matter. The trace elements Cu, Pb and Cd were also measured In order to achieve the major objective, we looked for the regulations regarding the quality criteria for this particular type of application. In the absence of particular guidelines for the irrigation of parks and green areas with recycled water, the reference criteria applied for unrestricted irrigation were used. Concentrations of TSS, Ammonium, nitrate, total nitrogen and phosphate averaged 65.25, 20.8, 3.4, 24.5 and 6.3 mg l–l, while concentrations of the trace elements Cd, Pb and Cu averaged 0.0003, 0.0044 and 0.009 mg l–1. These results indicate that the concentrations of the analyzed parameters are within the limits fixed for the water reuse for irrigation. The health risk may come from the potential contamination with other chemicals and any eventual bacterial contamination particularly with faecal coliform.