Feedback Control-Based Strategy Applied for Biohydrogen Production from Acid Cheese Whey

Purpose A control strategy was developed to help with the cheese whey (CW) revalorization through dark fermentation and manipulating operating parameters such as the organic loading rate and the hydraulic retention time (HRT) aiming to increase the hydrogen production rate. Therefore, the main objective of this study was to evaluate the use of an automatic control strategy on hydrogen production from raw acid CW. Methods The control strategy was performed with a programmable logic controller connected to an expanded granular sludge bed reactor fed with raw acid CW (10 g(carbohydrates)/L). The operating pH and temperature were 4.5 and 35 degrees C, respectively. The control strategy automatically alternates between two values of HRT, one above (HRThigh) and one below (HRTlow) a reference HRT, based on the measurements of the biogas flow rate, inducing different organic loading rates (45.8-114.3 g/L-reac.d). Results The average HPR was 4.12 L H-2/(L-reac.d) using the controller (mean HRT of 4.1 h) was 14% higher than the one obtained with conventional operation with the fixed HRT of 5.24 h. A maximum hydrogen production rate of 7.1 L H-2/(L-reac.d) was obtained with an average HRT of 3.1 h, using raw CW with a lactic acid concentration of 13.8 g/L. The high relative abundance Lactobacillus kefiranofaciens induced the hydrogen production, whereas when Lactobacillus delbrueckii dominated, the system failed. Clostridium tyrobutyricum was detected in both conditions. Conclusion The use of the proposed controller increased the H-2 productivity. The lactate-driven dark fermentation pathway played a key role in hydrogen production from CW. Conclusion The use of the proposed controller increased the H-2 productivity. The lactate-driven dark fermentation pathway played a key role in hydrogen production from CW. [GRAPHICS] .