酸碱预处理对芦蒿秸秆厌氧发酵的影响

通过对芦蒿秸秆进行酸、碱预处理和厌氧发酵制沼气实验,比较不同的预处理方法对芦蒿秸秆产气性能的影响。结果表明,与对照组相比,碱处理能较好地改善秸秆的产气性能,其中2%NaOH处理效果最好,发酵初期VFA含量高达4882.34 mg·L?1,比对照组提高了705.21%,单位TS固体产气量为288.42 ml·g?1,较对照组提高了17.08%,甲烷含量最高可达61.14%。     

不同温度下氢氧化钠预处理对玉米秸秆甲烷产量的影响

利用农作物秸秆进行厌氧发酵生产沼气是解决我国农村能源紧张的重要途径,然而秸秆中难以降解的木质纤维结构导致在发酵过程中甲烷转化率较低。利用自行设计的可控性恒温发酵装置,以玉米秸秆为发酵原料,分析了在不同温度条件下氢氧化钠（NaOH）预处理对秸秆木质纤维结构以及厌氧发酵产气效率的影响。结果表明,NaOH预处理能够显著降低玉米秸秆的木质纤维素含量,与未预处理的秸秆相比,经NaOH处理后的秸秆纤维素含量降低了24.4%～33.2%,半纤维素含量降低了14.2%～52.4%,木质素含量降低了9.3%～29.3%。在6%、8%和10%浓度中,经8%NaOH处理的秸秆在55℃下的甲烷产量最高,达到188.7 ml CH₄·（g VS）^-1,较未处理的增加了84.2%,因此可作为提高秸秆厌氧发酵产气效率的预处理方法。     

水稻秸秆渗滤床半固态厌氧发酵性能研究

以水稻秸秆为原料,利用自行设计的渗滤床反应器,对比研究了不同温度（20、25、30和35℃）及不同预处理方式（NaOH、生物试剂和沼液）对秸秆厌氧发酵产气性能、物能转化率、发酵后沼液性能和产气成本等方面的影响。实验结果表明：发酵后总固体（TS）质量分数稳定在13%~15%之间,属于半固态厌氧发酵,同时累积产气量与温度、发酵后COD及NH₃-N的变化量均呈极显著正相关。相同温度（20~30℃）条件下,经预处理后的水稻秸秆TS产气率较空白均有所提高;其中沼液预处理效果最为明显,35℃条件下,TS产气率及挥发性固体（VS）产甲烷率分别为154.0和55.2 mL/g,较空白样品分别提高25.1%和52.5%。同时,沼液预处理可显著提升厌氧发酵产气中的甲烷体积分数。各预处理样品TS产甲烷率及VS产甲烷率呈随温度（20~30℃）上升而增加的趋势,但产甲烷提升率随温度的上升而逐渐下降,将系统温度从20℃提升至25℃,各处理产甲烷率可提高90%以上。考虑到沼气工程罐体增温及产能收支平衡等因素,温度控制在25℃是经济性最好的策略模式。从产气成本上分析,自产沼液具有较佳的处理效果和较低的生产成本,每生产1 m³沼气的可变成本1.62元。     

不同温度下氢氧化钠预处理对玉米秸秆甲烷产量的影响(英文)

利用农作物秸秆进行厌氧发酵生产沼气是解决我国农村能源紧张的重要途径,然而秸秆中难以降解的木质纤维结构导致在发酵过程中甲烷转化率较低。利用自行设计的可控性恒温发酵装置,以玉米秸秆为发酵原料,分析了在不同温度条件下氢氧化钠(NaOH)预处理对秸秆木质纤维结构以及厌氧发酵产气效率的影响。结果表明,NaOH预处理能够显著降低玉米秸秆的木质纤维素含量,与未预处理的秸秆相比,经NaOH处理后的秸秆纤维素含量降低了24.4%~33.2%,半纤维素含量降低了14.2%~52.4%,木质素含量降低了9.3%~29.3%。在6%、8%和10%浓度中,经8%NaOH处理的秸秆在55℃下的甲烷产量最高,达到188.7 ml CH4·(g VS)?1,较未处理的增加了84.2%,因此可作为提高秸秆厌氧发酵产气效率的预处理方法。     

弱碱性过氧化预处理对稻草秸秆酶解糖化的影响

为了提高稻草秸秆的酶解糖化率,对稻草秸秆弱碱性过氧化预处理条件进行了优化。结果表明:弱碱性过氧化预处理降低了稻草秸秆中木质素的含量,提高了纤维素的含量。最优预处理条件为温度40 ℃,时间24 h,H₂O₂质量分数为2.0 %,在此条件下稻草秸秆的酶解糖化率达到了83.23 %,而在相同酶解条件下,预处理温度30 ℃、时间24 h、 2.0 % NaOH处理后稻草秸秆的酶解糖化率为70.38 %。弱碱性过氧化预处理稻草秸秆的糖化率明显高于碱性预处理稻草秸秆的糖化率。同时试验结果表明,木质素的除去率与H₂O₂质量分数有关。当H₂O₂质量分数大于2.0 %后,H₂O₂对木质素的除去选择性降低,木质素的除去率基本保持不变,却增加了半纤维素的损失。     

酸、碱预处理对泥炭产甲烷影响

泥炭甲烷转化存在甲烷产量低的问题，为促进泥炭生物甲烷转化，探索酸、碱预处理对泥炭产甲烷的影响，先对草本泥炭进行酸、碱预处理，然后进行生物甲烷发酵，解析酸、碱预处理对泥炭甲烷发酵日产气量、总产气量、腐植酸、乙酸、葡萄糖、pH的影响。结果表明，酸预处理泥炭组第5天日产气量最高达8.71 mL/g(以泥炭的挥发性固体含量计，下同),比酸预处理泥炭对照组增加193.27%,碱预处理泥炭组第5天日产气量最高达3.67 mL/g,比碱预处理泥炭对照组峰值增加83.5%;酸预处理泥炭组总产气量达41.95 mL/g,比酸预处理泥炭对照组提高90.68%,碱预处理泥炭组总产气量为44.27 mL/g,比碱预处理泥炭对照组提高61.28%;酸、碱预处理均有利于促进泥炭甲烷发酵，其中碱预处理对泥炭产生物甲烷促进效果更显著，能显著提高泥炭生物甲烷产量。     

碱性臭氧预处理对稻草秸秆酶水解的影响

以稻草秸秆为原料经碱性臭氧预处理后进行酶水解,研究了处理前后稻草秸秆半纤维素、纤维素、木质素含量的变化,通过测定酶水解还原糖含量来判断预处理的效果。结果表明,碱性臭氧预处理与碱预处理相比,在稻草秸秆木质素含量与降解上没有什么差异,但酶水解糖化效果更优。经O3/2%NaOH预处理过的稻草秸秆,在pH值5.0、酶用量31.2mg.（g底物）-1、45℃条件下酶水解120h时,还原糖含量达到了902mg.（g稻草秸秆）-1,糖化率达到了92.57%。     

吐温-80及碱预处理对饲用稻草木质素含量和纤维素酶解产糖的影响

探讨了添加1‰吐温-80非离子表面活性剂和不同浓度碱预处理对稻草秸秆木质素及纤维素的影响,并对预处理前后的稻草进行了X射线衍射光谱(XRD)分析,从结晶度的变化综合分析了预处理对纤维素酶解的影响。实验结果表明:在30℃下添加1‰吐温-80非离子表面活性剂时,用4%NaOH预处理稻草秸秆,木质素含量降至6.5%(较未处理稻草下降了41.9%),灰分值仅占6.9%,具有较好的粗饲料价值;在121℃(0.1 MPa)下添加1‰吐温-80非离子表面活性剂时,用4%NaOH预处理稻草秸秆,木质素含量降至2.8%(较未处理稻草下降了74.5%),酶解还原糖达到393.9 mg/g,纤维素糖化率为59.3%(较未处理稻草提高了2.4倍)。XRD分析显示,在较温和的条件下,低浓度碱预处理稻草秸秆,对纤维素结晶区带来的影响相对于无定形区弱,不足以引起纤维素结晶度的降低。     

玉米秸秆产生物燃气及其微生物群落解析

为研究玉米秸秆产沼气及其发酵过程中微生物群落变化,以预处理后的玉米秸秆为原料,采用10 L厌氧反应器进行批式中温发酵产沼气。同时取样利用454焦磷酸测序法测定发酵过程中微生物群落的变化。结果表明：该系统启动迅速,在第3 d就达到产气高峰7.78 L,料容产气率为0.97 L·L^-1·d^-1,46 d原料沼气产率和甲烷产率分别为236.84 ml·（g VS）^-1和132.23 ml·（g VS）^-1。454焦磷酸测序及分析表明系统中古菌主要为甲烷微菌纲（Methanomicrobia,占总OTU的89.63%）,其次为热原体纲（Thermoplasmata,8.51%）古菌。发酵系统中共有22～29个细菌门,其中优势菌群为拟杆菌门（Bacteroidetes,平均含量46.07%）、变形菌门（Proteobacteria,平均含量20.51%）和厚壁菌门（Firmicutes,平均含量13.09%）。玉米秸秆沼气系统微生物群落结构的阐明可为秸秆沼气工程调控提供科学数据。     

氢氧化钠预处理对甘蔗渣酶解和发酵性能的影响

采用氢氧化钠预处理甘蔗渣,通过单因素和正交试验考察了不同预处理条件对甘蔗渣酶解和发酵性能的影响,并进一步分析了比表面积和木质素含量对酶解性能的影响。结果表明：预处理温度、氢氧化钠质量分数及预处理时间对酶解和发酵效率影响较为显著,最佳的预处理条件为：温度85℃、时间11 h、NaOH质量分数4.5%,在此优化条件下预处理的甘蔗渣,含纤维素56.46%,与原料相比提高了46.16%;半纤维素20.30%、Klason木质素5.79%,与原料相比分别降低了15.77%和72.87%,酶解36 h的还原糖得率为0.69 g/g（以甘蔗渣质量计）。经过氢氧化钠预处理后的甘蔗渣比表面积显著增加（由原料的0.07 m²/g最大可增加到1.07 m²/g）,木质素显著降低,有利于提高酶解和发酵效率。当比表面积超过0.30 m²/g时,酶解初始速率和酶解效率达到平衡;当木质素低于11%时,酶解效率达到平衡。     

Improving physicochemical characteristics and anaerobic digestion performance of rice straw via ammonia pretreatment at varying concentrations and moisture levels

Rice straw physicochemical characteristics and anaerobic digestion(AD) performance via ammonia pretreatment at varying ammonia concentrations(2%, 4%, and 6%) and moisture contents(30%, 50%, 70%, and 90%)under a mild condition were investigated. The results showed that the ammonia pretreatment effectively damaged the rice straw structure, increased the soluble organic concentration, and improved rice straw hydrolysis and AD performance. After pretreatment, the ester bond and ether bond were ruptured in lignocellulose and the volatile fatty acids(VFAs) were within the range of 1457.81–1823.67 mg·L~(-1). In addition, ammonia pretreatment had high selectivity on lignin removal, resulting in a maximum lignin removal rate of 50.80%. The highest methane yield of rice straw was 250.34 ml·(g VS)~(-1) at a 4% ammonia concentration coupled with a 70% moisture content, which was 28.55% higher than that of the control. The result showed that ammonia pretreatment of rice straw is technically suitable to enhance AD performance for further application.     

Effect on anaerobic digestion performance of corn stover by freezing–thawing with ammonia pretreatment

In order to enhance the biomethane production from corn stover, choosing effective pretreatment is one of the necessary steps before starting anaerobic digestion(AD).This study was aimed to analyze the effectiveness of freezing–thawing with ammonia pretreatment on substance degradation and AD performance of corn stover.Three ammonia concentrations(2%, 4%, and 6%) with two different moisture contents(50% and 70%) were used to pretreat the corn stover at two temperatures(-20 ℃ and 20 ℃).The result showed that an optimum pretreatment condition for corn stover was at the temperature of -20 ℃, moisture content of 70% and ammonia concentration of 2%.Under the optimum pretreatment condition, the maximum biomethane yield reached 261 ml·(g VS)~(-1), which was 41.08% higher than that of the untreated.Under different pretreatment conditions,the highest loss of lignin at -20 ℃ with 2% ammonia concentration was 63.36% compared with the untreated.The buffer capacity of AD system was also improved after the freezing–thawing with ammonia pretreatment.Therefore, the freezing–thawing with ammonia pretreatment can be used to improve AD performance for corn stover.This study provides further insight for exploring an efficient freezing–thawing with ammonia pretreatment strategy to enhance AD performance for the practical application.     

厌氧发酵起始阶段通氧对玉米秸秆产甲烷特性的影响

基于厌氧发酵起始阶段的氧供应量控制,研究了厌氧发酵起始阶段通氧对玉米秸秆产甲烷特性的影响。当氧气供应量为10 ml·(g VS)^-1时,甲烷产量达到最大为299.8 ml·(g VS)^-1,相对于不做处理的样品甲烷产量提高了8.4%。但是,氧气供应量的继续提高并没有带来甲烷产量的升高,当氧气供应量大于40 ml·(g VS)^-1时,甲烷产量相对于不做处理的秸秆样品轻微下降。modified first order equation 模型拟合分析表明起始阶段微好氧处理可以加快底物的水解速度,但氧气供应量过大会延长厌氧发酵的延滞时间。另外,经过起始阶段通氧处理,秸秆厌氧发酵的VS降解率也有所提高。     

低有机质污泥投加药剂联合低温热水解及后续厌氧发酵研究

污水厂污泥量日益增加,所含的有机物可用于厌氧发酵产甲烷,但目前多数污水处理厂多为低有机质污泥。本文围绕低有机质污泥投加不同药剂联合低温热水解对污泥溶解性物质变化及厌氧发酵规律的影响情况进行研究。结果表明,投加药剂联合低温热水解不仅有助于有机物[可溶糖、可溶蛋白和TVFA（挥发性有机酸（]的溶出与生成,而且有助于后续厌氧发酵产甲烷。在本实验所研究的低温热水解（污泥含固率为8%,热水解处理温度为90℃,处理时间为24 h）及药剂投加量[NaOH：0.018 g·（g DS（^-1、Ca（OH（₂：0.016 g·（g DS（^-1、CaCl₂：0.0375g·（g DS（^-1]的条件下,有机物溶出与生成的效果为NaOH> Ca（OH（₂> CaCl₂,其中热水解联合NaOH中可溶糖、可溶蛋白和TVFA浓度分别达到3051 mg·L^-1、10686 mg·L^-1和5740 mg·L^-1。对于产甲烷促进效果为NaOH> CaCl₂> Ca（OH（₂,其中投加NaOH后最大累积产甲烷量可达到101.9 ml·（g VS（^-1。     

Lower temperature hydrothermal pretreatment improves the anaerobic digestion performance of spent cow bedding

The anaerobic digestion (AD) performance of spent cow bedding was investigated with different hydrothermal pretreatment (HP) conditions. Spent cow bedding was pretreated with low temperatures (50, 70, and 90℃) and different pretreatment times (2-72 h) with ammonia and without ammonia. The results showed that spent cow bedding was a good raw material for AD. After pretreatment, the concentration of volatile fatty acids (VFAs) in the group of hydrothermal pretreatments with ammonia (HPA) was higher than that in the HP group at the same pretreatment temperature and time. The optimal pretreatment condition was achieved with an HPA of 50℃ holding for 72 h. At the optimal condition, the highest concentration of VFAs was 1.58-10.85 times higher than that of the other pretreated groups. The highest hemicellulose and lignin removal rates were 58.07% and 10.32%, respectively. The highest methane yield was 163.0 ml·(g VS)^-1, which was 48.9% higher than that of the untreated group. The VFAs, pH, and reducing sugars showed positive relationships with the methane yield. Therefore, HP at low temperature can enhance the AD performance of spent cow bedding.     

Combined pretreatment using CaO and liquid fraction of digestate of rice straw:Anaerobic digestion performance and electron transfer

To improve anaerobic digestion (AD) efficiency of rice straw,solid alkaline CaO and the liquid fraction of digestate (LFD) were used as pretreatment agents of rice straw.The results showed that AD performance of rice straw with CaO-LFD pretreatment was optimal in different pretreatment methods of the CaO + LFD,CaO-LFD,LFD + CaO,CaO,and LFD.The maximum methane yield (314 ml·(g VS)-1) and the highest VFAs concentration (14851 mg·L-1 on day 3) of the CaO-LFD pretreatment group were 81％ and 118％ higher than that of the control group,respectively.Under the action of solid alkaline CaO,the bacteria of Clostridium,Atopostipes,Sphaerochaeta,Tissierella,Thiopseudomonas,Rikenellaceae,and Sedimentibacter could build up co-cultures with the archaeal of Methanosaeta,Methanobacterium,and Methanosarcina performing direct interspecies electron transfer (DIET) and improving AD perfor-mance of rice straw.Therefore,the combined pretreatment using CaO and LFD could not only pretreat rice straw but also stimulate co-cultures of microorganism to establish DIET enhancing AD efficiency.     

Wheat straw pretreatment with KOH for enhancing biomethane production and fertilizer value in anaerobic digestion☆

Wheat straw biodegradability during anaerobic digestion was improved by treatment with potassium hydroxide(KOH)to decrease digestion time and enhance biomethane production and fertility value.KOH concentrations of1%(K1),3%(K2),6%(K3)and 9%(K4)were tested for wheat straw pretreatment at ambient temperature with a C:N ratio of 25:1.86% of total solids(TS),89% of volatile solids(VS)and 22% of lignocellulose,cellulose and hemicellulose(LCH)(22%)were decomposed effectively with the wheat straw pretreated by 6% KOH.Enhanced biogas production and cumulative biomethane yield of 258 ml·(g VS)~(-1)were obtained increased by 45% and 41%respectively,compared with untreated wheat straw.Pretreated wheat straw digestion also yielded a digestate with higher fertilizer values potassium(138%),calcium(22%)and magnesium(16%).These results show that TS,VS and LCH can be effectively removed from wheat straw pretreated with KOH,improving biodegradability biomethane production and fertilizer value.     

芒草酸/碱预处理副产物的生成及对乙醇发酵的影响

研究了不同浓度酸/碱预处理下芒草预处理上清液中副产物的生成和预处理上清液发酵产乙醇的规律,并对预处理副产物与乙醇发酵的关系进行了相关性分析。结果表明:酸/碱预处理上清液中预处理副产物浓度差异较为明显,酸处理产生的糠醛、5-羟甲基糠醛浓度明显高于碱处理,而碱处理上清液中丁香酸、香草醛、对香豆酸、阿魏酸浓度明显大于酸处理;预处理上清液补糖发酵中,1%H₂SO₄预处理上清液糖醇转化效率高于10 g/L NaOH预处理,半纤维素含量高和木质素含量低的材料具有较高的糖醇转化效率;糖醇转化效率与相应预处理上清液中副产物浓度相关性分析显示,糖醇转化效率与5-羟甲基糠醛呈极显著正相关,相关系数达0.795,与香草醛和丁香酸分别表现为极显著和显著负相关,相关系数分别为-0.811和-0.671。