Upcycling of alkaline maize wastewater: Evaluating fresh food production and crop resilience through a circular economy pathway

The tortilla industry generates substantial volumes of alkaline maize cooking wastewater (nejayote). This study evaluates the fermentation of nejayote with an alkaliphilic microorganism consortium (AMC) in a high-rate algal pond (HRAP) to reuse it in fresh food production. Nejayote was inoculated with AMC (2 g/L) and fermented during 0–1 (M1), 2–3 (M3), or 4–5 days (M5). Nejayote, M1, M3 or M5 were used to replace one-third of irrigation water for lettuce ( Lactuca sativa ) cultivation over eight weeks. Growth parameters such as length and weight, total phenolic content (TPC), and metabolomic profiles were compared against chemical fertilizer, nejayote, and water controls. M3 increased lettuce fresh weight by 109.9 % and TPC by 313.2 % in comparison with water, while M5 also enhanced TPC by 173.8 %. In contrast, nejayote reduced lettuce fresh weight by 33.7 %, highlighting its detrimental effects. Inoculation with AMC leads to the accumulation of phenolic and polyphenolic compounds, along with stress-associated fatty acids that support membrane fluidity and enhance plant tolerance to environmental stress. This is a promising agro-industrial wastewater upcycling strategy, promoting sustainable agriculture by minimizing reliance on synthetic agro-inputs, conserving freshwater, and aligning with circular economy principles. • 2–3 days fermented nejayote increased lettuce fresh weight and phenolic compounds. • Nejayote without fermentation process reduced lettuce fresh weight by 33.7 %. • Metabolomic profile revealed modulation of hormonal/developmental pathways. • Water holding capacity remained unchanged in fermented treatments.