Exploitation of Treated Municipal Wastewater in Arid Regions Irrigation for Volatile Oils Production

To avoid any contamination risk of edible crops, the safety use of treated municipal wastewater is growing industrial non-food crops such aromatic plants to produce volatile oils for manufacturing soaps, cosmetics and perfumes, etc. Two field experiments were conducted in a sandy soil in western Giza (Abourwash district), Egypt to investigate the influence of treated domestic sewage effluents on the essential oils of geranium, peppermint, fennel, marjoram, and chamomile plants. In the first experiment, the plants were irrigated with treated domestic sewage effluents, while in the second the plants irrigated with fresh water and received the chemical fertilizers. Biological analyses of both irrigation water and rhizosphere of tested plants were determined. Heavy metals accumulation in plant organs and the nutrient status of plants were studied. Results indicated that the treated municipal wastewater contain obvious amount of nutrients sufficiently for growing the tested crops and the plants had higher herb yield than that irrigated with fresh water. Irrigation of geranium and fennel plants with wastewater caused a significant increment in the essential oils concentration by 10.9 and 15.7 % compared to irrigation with fresh water, respectively. The oil yields of five crops were higher under wastewater irrigation and with geranium plants exceeded by 64.5% than that irrigated with fresh water. Uptake and accumulation of heavy metals in plant parts was varied according to element, plant species and organ. No detectable amount of the potential toxic elements was recorded in the essential oils of the aromatic plants. From this standpoint, treated municipal waste water can be used for growing aromatic plants in the arid area to produce volatile oils without causing any reduction in quantity and quality of volatile oils.