Enhancement of biohydrogen production efficiency in dark co-fermentation of sewage sludge and fruit processing wastes through ultrasonic, alkali, acid, and thermal pretreatment

Akbay, Habibe Elif Gülşen | Deniz, Fatma

The development of urbanization and related treatment/infrastructure systems has increased the number of wastewater treatment plants in cities and the amount of sewage sludge (SS) with high organic matter content coming out of them. Dark co-fermentation (DcF) of such wastes with industrial wastes of food origin with high carbohydrate (CH) content is quite attractive to produce biohydrogen, which is considered as an efficient alternative fuel of the future. This study aimed to improve batch biohydrogen production by ultrasonic (US), thermal (T), acidic (AC) and alkali (AL) pretreatment of feedstock consisting of SS and various fruit processing industry wastes (3:1 mixing ratio based on total solids (TS)). Biohydrogen production yields were 96.48, 143.95, 121.79, 119.80, 114.73, and 100.32 mL/gCHadded for untreated, T (70 °C), AC (pH: 3), AL (pH: 10), US (5 min), and US (10 min) pretreatments, respectively. However, AC (pH:4), T (100 °C), and AL (pH:8) pretreatments decreased the biohydrogen production yield by 20.2 %, 9.9 %, and 3.4 %, respectively. In this study, it was revealed that there is no linear relationship between the increase in organic matter dissolution after pretreatment and biohydrogen production efficiency after the DcF process. However, kinetic model data designed...