Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, 77843-3122, USA.
Appl Biochem Biotechnol. 2023 Jan;195(1):331-352. doi: 10.1007/s12010-022-04149-3. Epub 2022 Sep 9.
The carboxylate platform is a promising biomass-to-energy pathway that uses methane-arrested anaerobic digestion (MAAD) to convert biomass to carboxylic acids, which can be chemically converted to industrial chemicals and liquid fuels. Lignocellulose is an energy-rich carbon source, but lacks nutrients necessary for microbial growth. Chicken manure (rural waste) and sewage sludge (urban waste) are rich in nitrogen and useful macronutrients; therefore, co-digesting these wastes with lignocellulose improves MAAD performance. However, waste nutrients must be digested immediately, or preserved. This study investigated the effects of various preservation techniques - frozen (fresh), air-dried, and baked - on chicken manure and sewage sludge. Batch experiments were performed with office paper (carbon source) and chicken manure or sewage sludge (nutrient source) with different methods of preservation. Fresh substrates produced higher acid yields and biomass conversion (the amount of biomass consumed during digestion) than dried substrates. Baked chicken manure showed reduced conversion and total acid production, which suggests that oven-drying reduces digestibility. From the batch data, the Continuum Particle Distribution Model (CPDM) predicted results of a four-stage countercurrent digestion. The data are displayed on maps showing the impact of liquid residence time (LRT) and volatile solids loading rate (VSLR) on conversion and product concentration. Co-digesting office paper and wet chicken manure at a non-acid volatile solid (NAVS) concentration of 300 g/L, the model predicted a high total acid concentration of 52.8 g/L and conversion of 0.89 g NAVS/NAVS at a volatile solid loading rate of 4 g/(L·day) and liquid retention time of 35 days.
羧酸盐平台是一种很有前途的生物质能源途径，它使用甲烷截留厌氧消化（MAAD）将生物质转化为羧酸，羧酸可以进一步化学转化为工业化学品和液体燃料。木质纤维素是一种富含能量的碳源，但缺乏微生物生长所需的营养物质。鸡粪（农村废物）和污水污泥（城市废物）富含氮和有用的大量营养素；因此，将这些废物与木质纤维素共消化可以提高 MAAD 的性能。然而，废营养物必须立即消化或保存。本研究调查了各种保存技术——冷冻（新鲜）、风干和烘焙——对鸡粪和污水污泥的影响。使用办公用纸（碳源）和鸡粪或污水污泥（营养源）进行批处理实验，采用不同的保存方法。新鲜的基质比干燥的基质产生更高的酸产量和生物质转化率（消化过程中消耗的生物质量）。烘焙鸡粪显示出较低的转化率和总酸产量，这表明烤箱干燥会降低消化率。从批处理数据中，连续粒子分布模型（CPDM）预测了四阶段逆流消化的结果。数据显示在地图上，显示了液体停留时间（LRT）和挥发性固体负荷率（VSLR）对转化率和产物浓度的影响。在非酸性挥发性固体（NAVS）浓度为 300 g/L 的条件下，共消化办公用纸和湿鸡粪时，该模型预测在挥发性固体负荷率为 4 g/（L·天）和液体保留时间为 35 天时，总酸浓度可达到 52.8 g/L，转化率为 0.89 g NAVS/NAVS。
