Abstract Summary
Globally, recovery of nutrients and water from municipal wastewater or biorefinery processing wastewater is crucially important for achieving circular economy and coping with the challenges of water scarcity and fertilizer shortage. However, potential presences of pathogens and chemical contaminants in the reclaimed wastewater raise major concerns for its reuse. Pressure-driven membrane-based separation processes, such as microfiltration (MF), ultrafiltration (UF), allow to obtain superior permeate water, offering an alternative solution to produce liquid fertilizers for plant cultivation; while electrodialysis (ED, an electrical-driven membrane process) is capable to concentrate nutrients and facilitate rapid precipitation of struvite when a sacrificial magnesium (Mg) anode is applied in the ED process). In this presentation, several attempts on membrane-based processes to recover nutrient streams or struvite from primary-treated municipal wastewater and microalgal processing wastewater will be presented, and their feasibility as fertilizers to cultivate plants (such as tomato, lettuce, basil) in soil-based and hydroponic-based systems will be examined based on plant growth and heavy metal uptake. The results revealed that the insignificant difference of plant growth using the MF-treated municipal water and commercial fertilizer solution as irrigation water; the MF-treated microalgal processing wastewater as irrigation water led to slightly less plant growth. Nevertheless, the hazard quotient indexes of heavy metals in the plants were less than 1, indicating negligible human health risk. The Mg-anode ED-based nutrient recovery from municipal wastewater was strongly associated with applied crossflow velocity and current density, and long-term operation of the ED process towards achieving high-purity struvite is on-going.
