Rincón B, Borja R, Martín M A, Martín A
Instituto de la Grasa (CSIC), Avda. Padre García Tejero 4, 41012 Sevilla, Spain.
Waste Manag. 2009 Sep;29(9):2566-73. doi: 10.1016/j.wasman.2009.04.009. Epub 2009 May 17.
A study of the second step or methanogenic stage of a two-stage anaerobic digestion process treating two-phase olive oil mill solid residue (OMSR) was conducted at mesophilic temperature (35 degrees C). The substrate fed to the methanogenic step was the effluent from a hydrolytic-acidogenic reactor operating at an organic loading rate (OLR) of 12.9 g chemical oxygen demand (COD) L(-1) d(-1) and at a hydraulic retention time (HRT) of 12.4 days; these OLR and HRT were found to be the best values to achieve the maximum total volatile fatty acid concentration (14.5 g L(-1) expressed as acetic acid) with a high concentration in acetic acid (57.5% of the total concentration) as the principal precursor of methane. The methanogenic stage was carried out in an anaerobic stirred tank reactor containing saponite as support media for the immobilization of microorganisms. OLRs of between 0.8 and 22.0 g COD L(-1) d(-1) were studied. These OLRs corresponded to HRTs of between 142.9 and 4.6 days. The methanogenic reactor operated with high stability for OLRs lower than 20.0 g COD L(-1) d(-1). This behaviour was shown by the total volatile fatty acids/total alkalinity ratio, whose values were always kept 0.12 for HRTs>4.6 days. The total COD (T-COD) removed was in the range of 94.3-61.3% and the volatile solids (VS) removed between 92.8% and 56.1% for OLRs between 0.8 and 20.0 g COD L(-1) d(-1). In the same way, a reduction of 43.8% was achieved for phenolic content. The low concentration of total volatile fatty acids (TVFA) observed (below 1 g L(-1) expressed as CH(3)COOH) in the methanogenic reactor effluents showed the high percentage of consumption and conversion of these acids to methane. A methane yield of 0.268+/-0.003 L CH(4) at standard temperature and pressure conditions (STP) g(-1) COD eliminated was achieved.
在中温（35摄氏度）条件下，对处理两相橄榄油厂固体残渣（OMSR）的两级厌氧消化过程的第二步即产甲烷阶段进行了一项研究。进入产甲烷步骤的底物是来自水解产酸反应器的流出物，该水解产酸反应器的有机负荷率（OLR）为12.9克化学需氧量（COD）L⁻¹ d⁻¹，水力停留时间（HRT）为12.4天；发现这些OLR和HRT是实现最大总挥发性脂肪酸浓度（14.5克L⁻¹，以乙酸计）的最佳值，其中乙酸浓度较高（占总浓度的57.5%），是甲烷的主要前体。产甲烷阶段在一个厌氧搅拌罐反应器中进行，该反应器含有皂石作为固定化微生物的载体介质。研究了0.8至22.0克COD L⁻¹ d⁻¹的OLR。这些OLR对应的HRT为142.9至4.6天。对于低于20.0克COD L⁻¹ d⁻¹的OLR，产甲烷反应器运行稳定性高。总挥发性脂肪酸/总碱度比值表明了这种行为，对于HRT>4.6天，其值始终保持在0.12。对于0.8至20.0克COD L⁻¹ d⁻¹的OLR，总COD（T-COD）去除率在94.3 - 61.3%范围内，挥发性固体（VS）去除率在92.8%至56.1%之间。同样，酚类含量降低了43.8%。在产甲烷反应器流出物中观察到的总挥发性脂肪酸（TVFA）浓度较低（低于1克L⁻¹，以CH₃COOH计），表明这些酸转化为甲烷的消耗和转化率很高。在标准温度和压力条件（STP）下，实现了0.268±0.003升CH₄克⁻¹ COD去除的甲烷产率。
