Treatment of nixtamalization wastewater (nejayote) using electrocoagulation and combined chemical coagulation/electrocoagulation processes

Nejayote is a wastewater byproduct of traditional processes used to make corn tortilla flour, and needs to be treated to protect the environment. In this work, nejayote was treated by subjecting it to coagulation/flocculation and electrocoagulation processes. These two processes were evaluated independently and in combination. In the coagulation/flocculation process, the dose of coagulant/flocculant and the influence of pH were determined. The electrocoagulation process was carried out using an Al/Fe (anode/cathode) system, and the effectiveness of the electrocoagulation as a function of pH and electrolysis time was studied. The control variables were the cell potential difference and NaCl concentration. The nejayote treatments was analyzed by measuring the resulting color, turbidity, and chemical oxygen demand (COD), and carrying out a UV-Vis analysis. The results showed that exclusive application of the electrocoagulation process to the nejayote was the most effective, having nearly completely eliminated color (99.4%), turbidity (98.08%) and COD (84.0%) after 150 min of electrolysis. The coagulation/flocculation process using the Sudflock P-63/Sumex Biofloc A-01 system was the least effective in reducing color (86.7%), turbidity (82.7%) and COD (34.2%), while the combined process (coagulation/flocculation–electrocoagulation), at a pH of 9.0 and 195 min of electrolysis, managed to remove 98.5% of the color, 97.7% of the turbidity and 78.0% of the COD.