Wastewater from maize lime-cooking as growth media for alkaliphilic microalgae-cyanobacteria consortium to reduce chemical oxygen demand and produce biomass with high protein content

Wastewater from maize lime-cooking (nejayote) was fermented with an alkaliphilic microalgae-cyanobacteria consortium (AMC) or mixed with a mineral salt medium (MSM) to reduce its chemical oxygen demand (COD). Four sets of experiments in 1 L Erlenmeyer flasks were done with and without previous nejayote sterilisation (NE and N) inoculated with AMC and as controls MSM (M) and non-sterile without AMC (NB). Total soluble carbohydrates (TSC), proteins and COD were analysed in the culture broth and in dried biomass. The pH decreased for N, NE and NB to 8.8 & PLUSMN; 0.1, 9.2 & PLUSMN; 0.2 and 8.9 & PLUSMN; 0.1, respectively, but increased to 10.4 & PLUSMN; 0.1 for M. NE showed more than 50% COD removal efficiency after 12 days. NB had a protein content (ICP) of 24% & PLUSMN; 2% DW, followed by NE with 19% & PLUSMN; 0.4%, N with 16% & PLUSMN; 1% and M with 1% & PLUSMN; 0%. COD reduction was not related to AMC growth but to TSC consumption. Intracellular protein contents for NE (19%) or N (16%) were higher than the observed for M (1%), but further analysis of the amino acid profile, functionality and stability of this potential single-cell protein (SCP) should be considered to promote its use in functional foods. Maize lime-cooking wastewater fermented with an alkaliphilic microalgae-cyanobacteria consortium to reduce chemical oxygen demand.image