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首页> 外文学位 >Evaluation of nutrient extraction and membrane processes to facilitate the reuse of water, chemical consumables and macronutrients during lignocellulosic biomass-to-fuel processing in rural communities.
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Evaluation of nutrient extraction and membrane processes to facilitate the reuse of water, chemical consumables and macronutrients during lignocellulosic biomass-to-fuel processing in rural communities.

机译：对营养提取和膜处理的评估，以促进农村社区木质纤维素生物质燃料转化过程中水，化学消耗品和大量营养素的再利用。

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In the 1970s and early 1980s, interest in United States energy self-sufficiency prompted research into using herbaceous crop residues for energy production, such as cellulosic ethanol. Sustainable feed stocks for cellulosic ethanol production include low-cost agricultural residues such as corn stover. Corn stover removal from the soil surface may lead to soil erosion and macronutrient loss. Following harvest, the corn stover is delivered to a lignocellulosic processing facility (aka biorefinery) for pretreatment or pre-hydrolysis (delignification), which (in this study) involves the sequential addition of strong acid and base. For cellulosic ethanol to become a realistic alternative to conventional liquid fuels such as gasoline, there are important economic and environmental barriers to overcome.;This study investigated several processes to facilitate the reuse of water, macronutrients and chemical additives during lignocellulosic biomass-to-fuel processing. This study was conducted in three sections: (1) wet stover storage and macronutrient recovery prior to biomass pretreatment, (2) fractionation of pre-hydrolysis products and (3) concentration and reuse of alkaline species in the pre-hydrolysis waste stream.;The first section evaluated bench scale sequential leaching-ultrafiltration (UF)-hyperfiltration (HF) operations on fresh wet stover. Two extraction (water-leaching) techniques were investigated, stirred and packed bed. Both methods were shown to successfully remove approximately 85% or greater of the water-soluble nutrients in the stover. The approximate overall water and nutrient recovery from the integrated packed bed extraction-UF-RO system were ∼35% water recovery as the RO (reverse osmosis) permeate and ∼80% PO43- , ∼55% Cl-, ∼40% TOC, ∼35% Na+ and ∼0.45% K+ in the RO retentate.;The second section evaluated a bench-scale gamma-alumina ultrafiltration ceramic tubular membrane (CTM) membrane unit for the separation of high molecular mass organics, such a lignin, and alkaline chemical consumables, such as sodium hydroxide (NaOH). This filtration method rejected 100% of the total suspended solids (TSS) and 43% of total organic carbon (TOC), and recovered 80% Na +ions from the pre-hydrolysis waste stream.;The third section evaluated a bench-scale electrodialysis unit for the fractionation of alkaline species (such as sodium) and small molecular mass lignin fragments recovered during ultrafiltration. The sodium ion and TOC recovery (in the concentrate stream) was ∼80-100% and ∼60%, respectively, and the average Na+/TOC selectivity ratio was ∼1.6 and 0.45 for the IonicsRTM and SelemionRTM ion-exchange membrane arrangements, respectively.
机译：在1970年代和1980年代初期，对美国能源自给自足的兴趣促使人们进行研究，以使用草本作物残留物来生产能源，例如纤维素乙醇。纤维素乙醇生产的可持续原料包括玉米秸秆等低成本农业残留物。从土壤表面去除玉米秸秆可能导致土壤侵蚀和大量营养素流失。收获后，玉米秸秆被运送到木质纤维素加工设施（又名生物精炼厂）进行预处理或预水解（脱木素），这在本研究中涉及先后加入强酸和强碱。为了使纤维素乙醇成为汽油等传统液体燃料的现实替代品，有许多重要的经济和环境障碍需要克服。;本研究研究了在木质纤维素生物质燃料转化过程中促进水，大量营养素和化学添加剂再利用的几种方法处理。这项研究分三个部分进行：（1）在生物质预处理之前进行湿秸秆的存储和大量营养素的回收；（2）预水解产物的分级分离；（3）预水解废物流中碱性物质的浓缩和再利用。第一部分对新鲜湿秸秆上的台式规模的连续浸出-超滤（UF）-超滤（HF）操作进行了评估。研究了两种萃取（水浸）技术，搅拌床和填充床。两种方法均能成功去除秸秆中约85％或更多的水溶性养分。集成填料床萃取-UF-RO系统的总水分和养分回收量约为RO（反渗透）渗透水约35％，PO43-，Cl-约55％，TOC约40％， RO截留液中〜35％Na +和〜0.45％K + 。；第二部分评估了台式规模的γ-氧化铝超滤陶瓷管式膜（CTM）膜单元，用于分离木质素和碱等高分子有机物化学消耗品，例如氢氧化钠（NaOH）。这种过滤方法可去除100％的总悬浮固体（TSS）和43％的有机碳（TOC），并从预水解废水中回收80％的Na +离子。超滤过程中回收的碱性物质（例如钠）和小分子木质素碎片的分离装置。离子交换膜装置的钠离子和TOC回收率（在浓缩液中）分别为〜80-100％和〜60％，平均Na + / TOC选择性比分别为〜1.6和0.45。 。

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