Acidogenesis/methanogenesis from acid cheese whey in hybrid-UASB reactors

Abstract

The cheese industry produces residues such as acid cheese whey. The latter has a high organic-matter concentration and other nutrients that are severe environmental contaminants. The aim of this study was to evaluate the acidogenesis / methanogenesis of acid cheese whey with short Hydraulic Retention Times (HRT) in Hybrid-UASB reactors, following the evolution of the organic matter, ammonium, and orthophosphate. The acidogenic reactor was operated at an HRT of 0.5 days, while for the methanogenic reactor, this ranged from 1-2 days; both reactors were operated in series. Results showed that the overall HRT of 1.5 days allowed optimal removal (89-96.8%) with organic loading rates of between 2.5 and 10.7 g COD / L-d, while at 14.2-24.9 g COD / L-d, best results were achieved at 2.5 days of overall HRT. Highest methane productivity ranged from 0.99-1.15 L CH 4 / L reactor -d (0.238-0.308 L CH 4 / g COD degraded ). Ammonium formation was only significant in methanogenesis (85 mg / L), while orthophosphates showed no change throughout the entire process. In conclusion, Hybrid-UASB reactors operated at short HRT were suitable for the acidogenesis / methanogenesis of this wastewater. Furthermore, methane can be utilized for energy generation, and ammonium and orthophosphate might be employed for the development of high value-added products. L CH 4 / g DQO degradado ). La formación de amonio únicamente fue significativa en metanogénesis (85 mg / L); los ortofosfatos no mostraron cambio a través de todo el proceso. En conclusión los reactores UASB-híbridos operados a cortos TRH fueron adecuados para la acidogénesis / metanogénesis del agua residual ensayada. Además, el metano puede ser usado para la generación de energía; el amonio y ortofosfatos podrían emplearse para el desarrollo de productos de alto valor agregado. Palabras clave : Lactosuero ácido, acidogénesis / metanogénesis, reactor UASB-híbrido, efluentes industriales, nutrientes.