Production and Sanitary Quality of Kale (Brassica oleracea L. var. acephala) Irrigated with Domestic Wastewater Treated in Vertical Anaerobic Filters

Wastewater (WW) reuse has been identified as an alternative with the potential to reduce the pressure of irrigated agriculture on water resources. However, the limitation of WW reuse in agriculture is its poor quality. Thus, it is recommended to pretreat WW prior to their application. The objective of this study was to evaluate the production and sanitary quality of kales irrigated with effluent from domestic wastewater treated in vertical anaerobic filters. The performance of the wastewater treatment plant (WWTP) was evaluated by analyzing the pH, electrical conductivity (EC), total nitrogen (TN), total phosphorus (TP), potassium (K) and fecal coliforms (Escherichia coli) in the influent and treated wastewater (TWW). Kale cultivation was performed in conventional (CCS) and vertical cultivation systems (VCS) in two cycles. Three treatments were used: T1, 100% TWW; T2, 100% of underground well water (UWW); and T3, 50% TWW and 50% UWW. The number of matured leaves (NML), commercial leaves fresh mass (CLFM) per plant, commercial leaves length (CLL) and sanitary quality of leaves were determined. The WWTP performed satisfactorily, providing TWW with acceptable quality for reuse in crop irrigation, with EC, TN, TP and K significantly below than that observed in influent. The NML, CLFM and CLL per plant were high in the T1 both for CCS and VCS, and significantly different than T2 in the cycle 2. The VCS had highest productivity and irrigation water use efficiency than CCS in both cycles. These observations highlight the positive benefits of application WW in irrigation crops.