InfLuence of Organic Load, Fill Time and Cycle Length on Biohydrogen Production in an Ansbbr Treating Glucose-Based Wastewater

Abstract

An anaerobic sequencing fed-batch reactor (7.2 L) with recirculation of the liquid phase containing immobilized biomass (AnSBBR) was used to produce biohydrogen from the treatment of glucose-based wastewater, at 30°C. The effect of applied volumetric organic load (AVOL) on biohydrogen production was analyzed by varying influent concentration between 3600 and 5250 mgCOD.L-1, cycle lengths of 4, 3 and 2 h, and feeding times of 2, 1.5 and 1 h, resulting in AVOL of 10.4; 13.2; 15.9; 21.5; 21.7 and 31.1 gCOD.L-1.d-1. For concentration at 5250 mgCOD.L-1, cycle length of 3 h and feeding time of 1.5 h the AnSBBR was operated at 30 and 40°C. Removal of organic matter (COD) ranged from 19 to 23% and of carbohydrates (glucose) from 96 to 99%. Volumetric and specific molar productivity were 81.4 molH2.m-3.d-1 and 7.1 molH2.kgSVT-1.d-1 at 31.1 gCOD.L-1.d-1 (5250 mgCOD.L-1 and 2 h) and the yield between the produced hydrogen and removed organic matter in terms of carbohydrates was 0.76molH2.molGLU-1 at 19.9 gCOD.L-1.d-1 (5250 mgCOD.L-1 and 3 h at 40°C). The most significant metabolic compounds were ethanol and acetic acid. Comparison of the biohydrogen production indicators, of fed-batch and batch operation at the same conditions, reveals the values of fed-batch operation were lower for all indicators at conditions with 3600 and 5250 mgCOD.L-1 and 4 and 3 h cycle lengths. However, the condition with the highest AVOL (31.1 gCOD.L-1.d-1), the condition with the highest concentration (5250 mgCOD.L-1.d-1) and highest temperature (40 °C) showed higher values for all indicators when compared to those obtained for batch mode. Thus, batch operation performs better for AVOL up to 21.7 mgCOD.L-1.d-1. For applied volumetric organic loads exceeding 21.7 gCOD.L-1.d-1, fed-batch operation resulted in improved reactor performance, indicating that this configuration was more suitable. Thus, at higher organic loads gradual availability of the substrate allow for better results in terms of molar and specific hydrogen productivity. © 2015 by Nova Science Publishers, Inc. All rights reserved.