Anaerobic Digestion of Cassava Pulp with Sewage Sludge Inocula

Jun Zhang, Jun-Yang Xu, Dun-Qiu Wang, Nan-Qi Ren

Abstract


The effectiveness of sludge inocula from a municipal carrousel oxidation ditch wastewater treatment plant was studied for both batch and semi-continuous anaerobic digestion (AD) of cassava pulp. In 1.25-L batch experiments, the following sludge inocula were used: I1 sludge from the hydrolysis acidification tank pre-acclimated with cassava pulp; I2, predigested sludge from the hydrolysis acidification tank; and I3, predigested sludge from the gravity thickening tank. In 1.0-L semi-continuous tests, mesophilic AD of cassava pulp inoculated with I3 was carried out at organic matter loading rates (OLRs) of 1.5 to 12.5 kg volatile solids (VS)/(m3 d), whereas 1.5 to 18.0 kgVS/(m3 d) was used for thermophilic AD. For batch operations, all sludge types could be used as the inoculum for the mesophilic AD of cassava pulp, whereas only I1 was used for thermophilic AD. The maximum specific methane yields were 0.333 and 0.395 m3/kgVSadded, respectively, for mesophilic and thermophilic batch digestion with I1. During semi-continuous AD of cassava pulp inoculated with I3, high specific methane yields of 0.334 to 0.336 m3/kgVSadded were obtained under both mesophilic and thermophilic conditions. For thermophilic AD of cassava pulp with sludge inocula, the range of optimum OLR was 2.5 to 15.0 kgVS/(m3 d), and that was 2.5 to 8.7 kgVS/(m3 d) for mesophilic AD.

Keywords


Anaerobic digestion; Cassava pulp; Sludge inocula; Biogas production

Full Text: PDF

Welcome to BioResources! This online, peer-reviewed journal is devoted to the science and engineering of biomaterials and chemicals from lignocellulosic sources for new end uses and new capabilities. The editors of BioResources would be very happy to assist you during the process of submitting or reviewing articles. Please note that logging in is required in order to submit or review articles. Martin A. Hubbe, (919) 513-3022, hubbe@ncsu.edu; Lucian A. Lucia, (919) 515-7707, lucian.lucia@gmail.com URLs: bioresourcesjournal.com; http://ncsu.edu/bioresources ISSN: 1930-2126