Nutrient recovery from treated municipal wastewater for basil production in indoor farming

Climate change and population growth are driving the increasing demand for alternative water sources in agriculture. Nutrient-rich treated municipal wastewater emerges as a potential alternative for agriculture production. Therefore, a pot experiment using zeolite as the growing substrate to simulate hydroponic conditions was conducted to assess the impacts of fully treated municipal wastewater and partially treated wastewater that undergone only mechanical treatment step on basil (Ocimum basilicum cv. Edwina) production, aiming to explore the potential of nutrient recovery from these wastewater sources. Tap water and optimal liquid fertilizer were utilized as negative and positive controls, respectively. Results showed that primarily treated wastewater significantly enhanced basil production compared to the tap water, although the large relative increase was partly attributable to the extremely low biomass under tap-water irrigation. However, with consistently greater production and nutrient concentrations produced by the positive control, nutrient supplementation was still required in the wastewater treatments to achieve greater production and nutrient levels comparable to those with complete mineral nutrient solution. Analysis of selected heavy metals indicated no evidence of excessive accumulation in basil shoots under the conditions of this study, although comprehensive food safety assessment would require evaluation of additional contaminants, including microbiological hazards and emerging pollutants. The findings provide insights into the potential of treated municipal wastewater reuse for nutrient recovery in controlled agricultural systems.