Role of calcium oxide in sludge granulation and methanogenesis for the treatment of palm oil mill effluent using UASB reactor

• Main Authors: Anwar, Ahmad, Ghufran, Rumana, Zularisam, A. W.
• Format: Article
• Language: English
• Published: Elsevier Ltd 2011
• Subjects: TA Engineering (General). Civil engineering (General)
• Online Access: http://umpir.ump.edu.my/id/eprint/24776/1/Role%20of%20calcium%20oxide%20in%20sludge%20granulation%20and%20methanogenesis%20for%20the%20treatment%20of%20palm%20oil%20mill%20effluent%20using%20UASB%20reactor.pdf; http://umpir.ump.edu.my/id/eprint/24776/; https://doi.org/10.1016/j.jhazmat.2011.10.008; https://doi.org/10.1016/j.jhazmat.2011.10.008

The granulation process in palm oil mill effluent using calcium oxide-cement kiln dust (CaO–CKD) provides an attractive and cost effective treatment option. In this study the efficiency of CaO–CKD at doses of 1.5–20 g/l was tested in batch experiments and found that 10 g of CaO/l caused the greatest degradation of VFA, butyrate and acetate. An upflow anaerobic sludge blanket (UASB) reactor was operated continuously at 35 °C for 150 days to investigate the effect of CaO–CKD on sludge granulation and methanogenesis during start-up. The treatment of POME emphasized the influence of varying organic loading rates (OLR). Up to 94.9% of COD was removed when the reactor was fed with the 15.5–65.5 g-COD g/l at an OLR of 4.5–12.5 kg-COD/m3 d, suggesting the feasibility of using CaO in an UASB process to treat POME. The ratio of volatile solids/total solids (VS/TS) and volatile fatty acids in the anaerobic sludge in the UASB reactor decreased significantly after long-term operation due to the precipitation of calcium carbonate in the granules. Granulation and methanogenesis decreased with an increase in the influent CaO–CKD concentration.