Background: The scarcity of water throughout the world dictates utilization of marginal water for irrigation. Secondary treated municipal wastewater is a common alternative water source for irrigation in arid and semiarid regions. Perennial aromatic plants are cultivated as cash-crops for fresh or dry herb production, or as a source of essential oil(EO). Cultivation of aromatic plants for EOs is suitable for irrigation with treated effluents because the heat applied during oil extraction eliminates human bacterial pathogens originating in the effluents and alleviates health concerns. The EOs can play a role as natural antioxidants and enzyme inhibitors targeting human diseases, eg., Alzheimer’s disease (AD). Such agents can prevent oxidative deterioration of foods, minimize oxidative injury of living cells, treat AD and enhance memory. Replacement of fresh water with treated effluent for irrigation of these plants could promote the development of large-scale production systems for biomass, and EO in these regions. In this study, we aimed to evaluate the applicability of treated wastewater for agricultural crops, assess the effects of continuous use of treated water on soil and crops, and analyze the biological activity of these plants and their essential oils under irrigation with secondary treated effluents (STE).
Materials and Methods: To compare responses of selected aromatic plants to irrigation with potable water (PW) and STE an experimental field has been established, each treatment consisted of 4 replicated plots. The plants were exposed to the water treatments for two consecutive seasons. EO from fresh plant leaves of both treatments was obtained during the two seasons (summer and fall 2016) by hydrodistillation. The extracted EOs and methanolic leaf extracts were tested for their antioxidant activity using DPPH