Effect of Minimizing d-Limonene Compound on Anaerobic Co-digestion Feeding Mixtures to Improve Methane Yield
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The purpose of this work was to assess the enhancement of the anaerobic digestion process of sewage sludge by the addition of orange peel as co-substrate. In this experimental study, an evaluation of the co-digestion process in a semi-continuous stirred tank reactor was carried out under mesophilic conditions (37 ± 0.2 °C) during an operation time up to 315 days. All trials were performed at a hydraulic retention time of 15 days and the AD reactor was fed daily with a mixture of sewage sludge and orange peel pulp, previously prepared. The organic loading rate was kept at 1.80 ± 0.31 g VS L−1 day−1 in all trials. A reference scenario (T0), mono-digestion, was performed using sewage sludge as substrate (primary sludge and activated sludge, 40:60, v/v). Thereafter, two different anaerobic co-digestion trials were carried out, one with pre-treated orange peel (T1) and the other with reduced d-limonene content (T2). Trials with pre-treated orange peel (T1 and T2) led to two- and threefold improvements in biogas and methane yields, compared with the reference scenario (T0). Furthermore, the reduction of d-Limonene content (T2) increased the methane yield by around 70% compared with T1. Therefore, it was proved that the sieving pre-treatment is effective to avoid the inhibitory effect of d-limonene.
KeywordsAnaerobic co-digestion Municipal sludge Orange peel d-Limonene Methane yield Inhibition
This work was supported by the Linking Landscape, Environment, Agriculture and Food (LEAF) research unit (UID/AGR/04129/2013); and Centro de Estudos Florestais (CEF) (PEst-OE/AGR/UI0239/2014).
- 11.Luo, H., Liu, X., Anderson, B., Zhang, K., Li, X., Huang, B., Li, M., Mo, Y., Fan, L., Shen, Q., Chen, F., Jiang, M.: Carbon sequestration potential of green roofs using mixed-sewage-sludge substrate in Chengdu World Modern Garden City. Ecol. Indic. 49, 247–259 (2015). doi: 10.1016/j.ecolind.2014.10.016 CrossRefGoogle Scholar
- 27.APHA: American Public Health Association: Standard Methods for the Examination of Water and Wastewater, 22nd Edition. American Public Health Association, Washington DC (2012)Google Scholar