混合生物质原料的跨季节储存过程及其调控方法研究

Trans-seasonal storage of biomass is critical for a year-round continuous supply of feedstock for the development of regenerated biological energy. The main objective during storage of biomass is to minimize losses and maintain the nutritional value. It is not realistic to produce biological energy from fresh green biomass without a storage facility implemented due to the unavailability of fresh biomass all year long. The fresh biomass have to be stored either in dry or wet form. Compared with dry storage, wet storage is a promising alternative technology, providing several advantages including reduced dry matter loss and ?re risk and improved feedstock conversion efficiency after storage. Wet storage is a way to preserve freshness of biomass making it available for fermentation purpose all year long until the next harvest time. On the basis of strong complementary in terms of physical structure, nutrient content and moisture content, we put forth assume of trans-seasonal storage of different biomass, such as crop straw, fruit and vegetable waste(FVW) or food industry wastes (FIW). In order to solve the problems of preservation of dry matters during long-term storage, research on trans-seasonal storage process of mixed biomasses and its regulation and control method is carried out. Wet airtight storage system was builded according to the storage capacity of different biomass, and qualitative and quantitative impacts of mixing ratio of biomass, material characteristics, storage environment, sealing performance of storage system and supplementary additive on matter change, microstructure, composing pattern of fermentation products were investigated dynamicly. Trans-seasonal storage quality and performance of different biomass were evaluated. The dynamic changes laws of microbial flora structure and quantity, the transfer and conversion mechanism of matter and energy during trans-seasonal storage were illuminated. To provide sustainable high-quality biomass for the development of biological energy, the storage process were optimized and regulated by multi-factor combined effects to meet the requirements of operation stability in storage system and safe storage of biomass.

为了实现多种生物质原料的跨季节储存，保证生物能源生产原料的全年连续稳定高效供给，本项目根据农作物秸秆、果蔬废弃物和食品加工废弃物等生物质原料在物理结构、营养物质、水分含量等方面的互补性，提出了将多种生物质原料进行跨季节混合储存的设想，并就混合生物质原料的跨季节储存过程及其调控方法展开研究。构建混合生物质原料的湿法密闭储存系统，动态考察混合比例、原料特性（水分和游离糖含量等）、储存环境（温度、周期等）、储存体系密封性能、辅助添加剂等因素对储存过程中原料的营养物质、微观结构、发酵产物构成模式的定量或定性影响，评价混合储存品质及其效果，阐释跨季节储存过程中微生物菌群结构和数量的动态演绎规律，揭示混合生物质原料在跨季节储存过程中物质与能量的传递与转换机理。通过多因素耦合优化调控储存过程，实现湿法储存体系的跨季节稳态运行和混合生物质原料的安全储存，为生物能源生产提供高质量生物质原料。

为保证生物能源生产原料的全年连续稳定高效供给，本项目根据作物秸秆、果蔬废弃物和食品加工废弃物等原料在物理结构、营养物质、水分含量等方面的互补性，主要研究了不同混合比例条件下玉米秸秆/白菜废弃物和莴笋叶的混合贮存过程，筛选得到适宜的混合比例；在此基础上分别加入微生物菌剂、酶制剂和有机酸对混贮过程进行优化调控，并考察贮存过程中微生物群落构成及其动态演绎规律，寻找有机组分、发酵品质和微生物群落构成之间的关联性。当玉米秸秆与尾菜的混合比例为21:27时，贮存pH值最低，乳酸含量最高，能使干玉米秸秆连续贮存60d不变质。青贮发酵过程能使尾菜分解消失，使干秸秆原先致密的木质纤维结构瓦解，秸秆表面出现裂缝和孔洞，生物降解可接触面积增加，产甲烷能力明显增强。接种植物乳杆菌、布氏乳杆菌和异常毕赤酵母3种微生物菌剂均能使干物质和可溶性碳水化合物含量显著增加，异常毕赤酵母强化乳酸发酵强度。添加纤维素酶能显著减少干物质损失，使可溶性碳水化合物含量显著升高，纤维组分含量显著下降，明显改善乳酸发酵强度。加入甲酸和乙酸后对增加干物质和可溶性碳水化合物含量具有积极作用，并能使纤维组分含量显著下降，同时添加有机酸能有效抑制贮存中前期的乳酸发酵进程。通过加入不同类型添加剂进行调控，能使秸秆保质贮存170天（近半年）不变质，并获得良好贮存品质。另一方面，秸秆/尾菜混贮过程中乳杆菌属、肠杆菌属和类乳杆菌属等细菌群落丰富，其中腐败菌肠杆菌属在130天时消失，乳杆菌和类乳杆菌属是优势乳酸细菌。贮存后的秸秆厌氧消化产甲烷速率明显增加，产甲烷能力大幅提高，累积甲烷产量是未贮存干秸秆的1.6倍。总之，秸秆/尾菜混合贮存不仅能实现干黄秸秆的长时间跨季节保质贮存，软化秸秆，提高能源转换效率，还能消纳利用叶菜类尾菜资源，减少环境污染，从而实现农业废弃物的资源化利用。通过构建湿法储存体系实现了生物质原料的安全保质储存，为生物能源生产提供高质量生物质原料。