Lignocellulosic biomass is a promising renewable feedstock for the production of bioenergy and platform chemicals; however, its use would not be economically viable without adopting effective transformation technologies. In this work, long-term anaerobic treatment (370 days) of pulp and paper primary sludge (PS) was performed by a thermophilic anaerobic membrane bioreactor (AnMBR) for the first time to investigate the effect of various solid retention times (SRTs) on biogas production and solids reduction ratios. The tested STRs (32–55 days) have shown varying biogas productivity, and it can be concluded that the longer the SRT, the higher is the biogas yield. At the optimum solids retention time of 55 d, an organic loading rate of 2.15 ± 0.10 kg-TSS/L.d, and hydraulic retention time of 5 d, average biogas yield of 106.4 ± 8.5 m³ biogas/tonne TSS _added (approximately 72.7 m³ CH₄/t VS_added) was achieved with an average methane content of 56 ± 4% and the solids reduction ratio ranged between 47% and 54.9%. Besides biogas yield, the quality of the permeates, solids reduction, and digestates characteristic/dewaterability changed by changing the SRT. The mixed liquor suspended solids concentrations and solids reduction increased with increasing SRT, while the effluent COD concentration and sludge dewaterability decreased. The Fourier Transform Infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) findings exhibited that the digestate contains more lignin and cellulose than the other substances, while the nitrogen and carbon concentration decreased with increasing SRT.

木质纤维素生物质是一种很有前景的可再生原料，可用于生产生物能源和平台化学品；然而，如果不采用有效的转化技术，它的使用在经济上是不可行的。在这项工作中，首次采用嗜热厌氧膜生物反应器（AnMBR）对纸浆和造纸初沉污泥（PS）进行长期厌氧处理（370天），以研究各种固体停留时间（SRTs）对污泥的影响。沼气产量和固体减少率。测试的 STR（32-55 天）显示出不同的沼气生产率，可以得出结论，SRT 越长，沼气产量越高。在 55 d 的最佳固体停留时间、2.15 ± 0.10 kg-TSS/Ld 的有机负载率和 5 d 的水力停留时间下，平均沼气产量为 106.4 ± 8.5 m³沼气/吨 TSS_添加（约 72.7 m ³ CH ₄ /t VS_添加) 的平均甲烷含量为 56 ± 4%，固体减少率介于 47% 和 54.9% 之间。除了沼气产量外，通过改变 SRT，渗透物的质量、固体减少和消化物的特性/脱水能力也发生了变化。混合液悬浮物浓度和固体减少量随着SRT的增加而增加，而出水COD浓度和污泥脱水能力降低。傅里叶变换红外 (FTIR) 和 X 射线光电子能谱 (XPS) 研究结果表明，消化液比其他物质含有更多的木质素和纤维素，而氮和碳浓度随着 SRT 的增加而降低。