有机生活垃圾多组分联合厌氧降解产甲烷性能研究

为了阐明生活垃圾多组分的混合对其厌氧降解产气性能的影响,通过在中温（37±1）℃下对餐厨类、纸类和园林类垃圾组分进行单独和联合厌氧降解产甲烷实验,研究接种物来源对单组分和多组分物料厌氧降解产甲烷性能的影响,应用修正的Gompertz模型拟合和分析物料产甲烷过程动力学特征,并借鉴和发展评价混合物料联合厌氧降解性能的量化指标方法.试验与模型拟合结果均表明：接种物来源对各组分及其组合的厌氧生物可降解程度无显著影响,但对其降解速率存在明显影响.此外,尽管物料的混合对试验初期物料降解产甲烷速率存在促进作用,但仅有3组分混合试验组在最终累计甲烷产率方面表现出显著的协同促进,在2种接种物条件下,相比于3组分单独降解的甲烷产率分别增长了16%和14%.     

预处理及物料配比对有机垃圾厌氧发酵的影响

针对我国推行垃圾分类政策后产生的大量有机垃圾难以有效消纳的问题,开展了厨余、果蔬与园林垃圾连续式厌氧发酵实验,并通过超声与碱热预处理技术改善产甲烷性能,并以厨余垃圾单独厌氧发酵作为对照实验组。根据进料有机负荷（OLR）,将反应周期分为低有机负荷[OLR=1,2 g/（L·d）]和高有机负荷[OLR=4,6 g/（L·d）]2个阶段。结果表明:在低有机负荷阶段,反应体系均表现出较强的稳定性。其中,厨余垃圾实验组的有机质（VS）去除率和甲烷产率最高,分别可达到90.3%,460 mL/g。并且超声与碱热预处理可以使混合物料甲烷产率分别提高7%~8%和3%~7%;在高有机负荷阶段,厨余垃圾实验组稳定性明显降低,具体表现为pH值降低至6.70,挥发性脂肪酸（VFA）和氨氮（TAN）积累浓度分别达到1230,1519 mg/L,且VS去除率与甲烷产率分别降低了2.8%、11%。此时混合物料反应体系表现出较强的抗冲击负荷的能力。与厨余垃圾相比,混合物料的甲烷产率有所提高,可达到420 mL/g。其中,超声预处理后甲烷产率可进一步提高3%,而碱热预处理后甲烷产率降低了4%。     

投加颗粒活性炭强化餐厨垃圾的厌氧处理

通过投加颗粒活性炭（GAC）强化直接种间电子传递（DIET）进而提升餐厨垃圾的厌氧产甲烷处理效能,并研究了GAC投加导致的微生物群落变化.研究发现,投加了GAC的实验组反应器能够在更高的有机负荷下（10.4kgCOD/（m³·d））稳定运行并维持较高的甲烷产率,不投加GAC的对照组在有机负荷7.8kgCOD/（m³·d）时甲烷产率及pH值均明显降低,挥发酸大量积累,反应器酸化崩溃.微生物群落结构分析发现,GAC表面富集了大量可以胞外电子传递的细菌（占细菌丰度的34%）和可以参与DIET的产甲烷菌（占古菌丰度的88%）,表明GAC的加入可以有效富集这两类微生物的生长,并可能通过GAC强化DIET促进了餐厨垃圾的厌氧消化.     

生活垃圾厌氧堆肥产甲烷及古细菌多样性分析

通过厌氧堆肥试验,对厌氧堆肥产甲烷的基本特征进行了研究,结果表明:在厌氧堆肥开始阶段,气体中只有8%的甲烷,二氧化碳产率是甲烷产率的4倍左右;而随着反应的进行,二氧化碳产率呈下降趋势,甲烷产率逐渐升高,并于3个月时达到最高值45%;此后二氧化碳及甲烷产率都逐渐降低。对3个月时的垃圾堆肥渗出液取样,提取总DNA,对古细菌片段进行限制性片段长度多样性分析(RFLP),在60个随机选出的古细菌rDNA克隆子中,可以划分15个不同的谱型。对深入了解产甲烷厌氧微生物过程,加快垃圾稳定化具有重要意义。     

半连续泔脚垃圾与猪粪混合厌氧消化研究

在中温(35℃)条件下,采用逐渐提高有机负荷的半连续进料方式,研究泔脚垃圾厌氧消化规律。在1gVS/(L.d)、1.25 gVS/(L.d)和1.5 gVS/(L.d)的有机负荷下,厌氧消化系统能够稳定运行,实现水解酸化阶段和产甲烷阶段的动态平衡,甲烷产率与日产气量的变化规律一致,pH、VFA、氨氮浓度分别保持在7.2和360mg/L1、500 mg/L左右。当有机负荷为1.5 gVS/(L.d),每克VS的甲烷产率和甲烷百分数出现最大值,分别为1.40 L/g7、1.37%,此时厌氧消化系统处于最佳运行状态。     

厌氧分步生物反应器系统处理城市生活垃圾的试验研究

以生活垃圾中COD溶出量为研究参数,试验研究了厌氧分步生物反应器系统和渗滤液直接回灌填埋场中的有机物降解规律与产甲烷特征.结果表明:厌氧分步生物反应器系统可显著促进生活垃圾及渗滤液中有机污染物的降解,加速填埋垃圾稳定化,其COD溶出总量与填埋时间的对数呈极显著的线性相关性.厌氧分步生物反应器中产甲烷反应器的产气量占总产气量的80%,甲烷含量55%～69%,较适容积COD负荷为6.5～7.5g/(L·d).     

有机垃圾填埋过程产甲烷量化模型研究

垃圾填埋场产生大量甲烷,收集这些甲烷不仅可减少温室气体排放,并且可将其作为能源利用,而填埋场甲烷产量的预测是其利用过程中的首要环节. 笔者介绍并分析了现有几种有关垃圾填埋场甲烷产量预测模型的不足;并从可降解有机组分的厌氧降解机理出发,对降解主要反应方程进行量化,由此推导出产甲烷量化模型. 结果表明:每kg动物、植物、纸类和木竹类垃圾(净垃圾)分别可产生0.578,0.331,0.270和0.319 kg甲烷;在此基础上,推导出有机垃圾填埋过程产甲烷量化预测模型,验证结果显示,该模型预测结果可靠,且结构简单、参数较少、易于量化,由于在计算过程中舍弃了其他不可降解组分的含碳量,因而比现有模型更加精准.      

含固率和有机负荷对厨余垃圾厌氧消化性能及沼渣特性的影响

为提高厨余垃圾厌氧消化性能和促进沼渣资源化利用,以底物降解效能和产甲烷量最大化为目标,分别考察不同进料总固体（TS）含量（含固率）(12%、15%、18%、25%、28%、33%)和有机负荷〔8.5、10.5、13.5 g/(L·d),以挥发性固体(VS)计〕条件下厨余垃圾的中温厌氧消化特性,并对最优进料参数下沼渣特性和资源利用潜力进行分析. 结果表明:进料TS含量是影响厨余垃圾厌氧消化效能的重要因素,调节进料TS含量至25%时可获得最大累计产甲烷量(16.81 L)和最高单位容积负荷累计产甲烷量(42.01 L/L),挥发性固体降解率达72.29%,系统运行稳定. 在进料TS含量为25%的条件下,系统累计产甲烷量随有机负荷的增加呈先升高后降低的趋势,有机负荷为10.5 g/(L·d)时,系统累计产甲烷量和挥发性固体降解率最高,分别为24.04 L和79.64%,未产生酸抑制现象. 厌氧消化过程中产生的副产物沼渣中有机质和总养分含量较高,电导率和重金属含量较低,pH适宜,满足《有机肥料》(NY 525—2021)和《绿化用有机基质》(GB/T 33891—2017)的要求. 研究显示:当进料TS含量为25%、有机负荷为10.5 g/(L·d)时,厌氧消化系统运行效能最优;沼渣营养成分较高、生物毒性较低,具有较大资源化利用潜力,后续经脱水处理并提高腐熟程度后可进行应用.      

有机负荷和进料频率对高含固厨余垃圾厌氧消化系统性能的影响

以系统降解效能和产甲烷量最大化为目标,分别考察不同有机负荷（8.93、10.71、13.39 kg·m^-3·d^-1）及进料频率（1、2、3次·d^-1）下厨余垃圾中温厌氧消化系统运行过程中甲烷产量、SCOD、氨氮、pH和挥发性脂肪酸（VFAs）的变化,旨在明确系统负荷边界及进料频率对系统稳定性的影响.结果表明,系统的有机负荷存在最优值,系统累计产甲烷量随负荷的增加而升高,随后降低,有机负荷为10.71 kg·m^-3·d^-1时获得最大累计产甲烷量37.17 L,VS降解率72.58%.负荷增加系统稳定性下降甚至失稳,各物质出现积累,不利于反应的进行.增加进料频率可优化系统运行参数,显著提高系统产气和产甲烷量,进料频率较高时,运行周期内系统的甲烷产量及产率最高,分别达到45.03 L和0.738 L·g^-1,呈线性增长,增加进料频率可提高系统对氨氮的耐受能力,显著提高系统稳定性,明显改善VFA和丙酸积累问题.     

垃圾渗滤液与厨余垃圾混合厌氧消化研究

对垃圾渗滤液与厨余垃圾进行混合厌氧消化研究,采用中温批式厌氧消化工艺,考察3g/L和30g/L有机负荷(以VS计)条件下厌氧消化过程中pH值、产气量、VFA以及甲烷含量的变化,旨在探索有机负荷对厌氧消化产甲烷效果的影响.结果表明,在30g/L负荷下比3g/L负荷反应过程更为稳定,且累计生物气产量有大幅提高.2种负荷下系统均能进入产甲烷阶段,最高甲烷体积分数分别达到77.14%和74.47%,VFA质量浓度在反应结束时分别为300mg/L和336 mg/L.     

Anaerobic co-digestion of municipal biomass wastes and waste activated sludge：Dynamic model and material balances

The organic matter degradation process during anaerobic co-digestion of municipal biomass waste （MBW） and waste-activated sludge （WAS） under different organic loading rates （OLRs） was investigated in bench-scale and pilot-scale semi-continuous stirred tank reactors. To better understand the degradation process of MBW and WAS co-digestion and provide theoretical guidance for engineering application, anaerobic digestion model No. 1 was revised for the co-digestion of MBW and WAS. The results showed that the degradation of organic matter could be characterized into three different fractions, including readily hydrolyzable organics, easily degradable particulate organics, and recalcitrant particle organics. Hydrolysis was the rate-limiting step under lower OLRs, and methanogenesisis was the rate-limiting step for an OLR of 8.0 kg volatile solid （VS）/（m^3·day）. The hydrolytic parameters of carbohydrate, protein, and lipids were 0.104, 0.083, and 0.084 kg chemical oxygen demand （COD）/（kg COD·hr）, respectively, and the reaction rate parameters of lipid fermentation were 1 and 1.25 kg COD/（kg COD.hr） for OLRs of 4.0 and 6.0 kg VS/（m^3·day）. A revised model was used to simulate methane yield, and the results fit well with the experimental data. Material balance data were acquired based on the revised model, which showed that 58.50% of total COD was converted to methane.     

Effects of mixture ratio on anaerobic co-digestion with fruit and vegetable waste and food waste of China

The biochemical methane potentials for typical fruit and vegetable waste (FVW) and food waste (FW) from a northern China city were investigated, which were 0.30, 0.56 m3 CH4/kgVS (volatile solids) with biodegradabilities of 59.3% and 83.6%, respectively. Individual anaerobic digestion testes of FVW and FW were conducted at the organic loading rate (OLR) of 3 kg VS/(m3 day) using a lab-scale continuous stirred-tank reactor at 35°C. FVW could be digested stably with the biogas production rate of 2.17 m3/(m3 day) and methane production yield of 0.42 m3 CH4/kg VS. However, anaerobic digestion process for FW was failed due to acids accumulation. The effects of FVW: FW ratio on co-digestion stability and performance were further investigated at the same OLR. At FVW and FW mixing ratios of 2:1 and 1:1, the performance and operation of the digester were maintained stable, with no accumulation of volatile fatty acids (VFA) and ammonia. Changing the feed to a higher FW content in a ratio of FVW to FW 1:2, resulted in an increase in VFAs concentration to 1100–1200 mg/L, and the methanogenesis was slightly inhibited. At the optimum mixture ratio 1:1 for co-digestion of FVW with FW, the methane production yield was 0.49 m3 CH4/kg VS, and the volatile solids and soluble chemical oxygen demand (sCOD) removal efficiencies were 74.9% and 96.1%, respectively.     

Effect of manganese oxide-modified biochar addition on methane production and heavy metal speciation during the anaerobic digestion of sewage sludge

Low organic matter content and high heavy metal levels severely inhibit the anaerobic digestion (AD) of sewage sludge. In this study, the effect of added manganese oxide-modified biochar composite (MBC) on methane production and heavy metal fractionation during sewage sludge AD was examined. The MBC could increase the buffering capacity, enhance the methane production and degradation of intermediate acids, buffer the pH of the culture, and stabilize the sewage sludge AD process. The application of MBC positively impacted methane production and the cumulative methane yield increased up to 121.97%, as compared with the control. The MBC addition can improve metal stabilization in the digestate. An optimum MBC dose of 2.36?g was recommended, which would produce up to 121.1?L/kg volatile solids of methane. After the AD process, even though most of the metals accumulated in the residual solids, they could be transformation from the bio-available fractions to a more stable fraction. The total organic- and sulfide-bound and residual fraction content at a 3?g dose of MBC that is 0.12?g/g dry matter were 51.06% and 35.11% higher than the control, respectively. The results indicated that the application of MBC could improve the performance of AD and promote stabilization of heavy metals in sewage sludge post the AD process.     

Enhanced anaerobic digestion and sludge dewaterability by alkaline pretreatment and its mechanism

To investigate the influences of alkaline pretreatment on anaerobic digestion (AD) and sludge dewaterability after AD, waste activated sludge was adjusted to different pH values (8, 9, 10, 11, 12) and placed at ambient temperature for 24 hr. The samples were then adjusted to the initial pH and subjected to 25 days of AD. The results showed that, when compared with the control (pH 6.8), total suspended solids (TSS) and volatile suspended solids (VSS) reduction following pretreatment at pH 9-11 increased by 10.7%-13.1% and 6.5%-12.8%, respectively, while biogas production improved by 7.2%-15.4%. Additionally, significant enhancement of sludge dewaterability after AD occurred when pretreatment at pH 8-9 was conducted. The proteins and carbohydrates transferred from the pellet and tightly bound extracellular polymeric substances (TB-EPS) fractions to the slime and loosely bound EPS (LB-EPS) fractions after pretreatment and during the AD process, and the concentrations of proteins and carbohydrates in the slime fraction had a good linear relationship with the normalized capillary suction time (CST). During the AD process, the normalized CST was positively correlated with the organic materials in the loosely bound fraction of the sludge matrix (R^{2≥qslant 0.700, p < 0.01), while it was negatively correlated with the organic materials in the tightly bound fraction (R2≥qslant 0.702, p < 0.01). These results suggest that alkaline pretreatment could break the EPS matrix and release inner organic materials, thus influencing the efficiency of the AD process and dewaterability after AD.}     

梧州市生活垃圾高固体厌氧发酵产甲烷

以梧州市的生活垃圾为原料,针对其难降解部分含量相对较高的特点,进行高浓度中温[(35±2)℃]批式厌氧消化实验,主要研究TS的3个设置浓度对厌氧消化稳定性及性能的影响.结果表明,分别为20%、25%和30%的3种TS均能实现稳定的产甲烷过程,在整个过程中没有明显产生挥发性脂肪酸的抑制,pH能实现自稳态调控;TS为20%、25%和30%的厌氧消化的累积产甲烷量为93.06、105.92和117.23L/kgVS;较低的总固体浓度有助于缩短厌氧发酵周期,而较高浓度可提高产甲烷效率.     

氧化钙强化消落带植被厌氧消化产甲烷的探究及作用机制

为了探究CaO预处理对消落带植被（VE）厌氧消化产甲烷的影响,采用4种不同质量分数的CaO对VE进行中温厌氧预处理,并考察了CaO预处理后VE的厌氧消化性能。结果表明:CaO预处理能提高VE中溶解性COD的含量,降低纤维素及木质素的含量,为后续消化过程提供物质基础。当CaO投加量为3%时,甲烷最大积累量为（229.8±6.3）mL/g,显著高于其他组别。此外,CaO预处理VE组别中甲烷的体积分数随消化时间呈现上升趋势。CaO能促进挥发性脂肪酸（VFA）的积累,当CaO投加量为3%时,VFA的最大积累量为（964±45）mg/L。CaO预处理可加速VE中总悬浮固体及挥发性悬浮固体的减量率。     

F/M及HRT对果蔬垃圾厌氧发酵产氢的影响

通过中温半连续厌氧消化实验,考察了果蔬垃圾在不同食微比(0.5、0.75、1.0和1.5)及不同水力停留时间(2、3和4d)下的产氢性能.结果表明,当食微比较低(0.5和0.75)时,各水力停留时间下均不适宜连续产氢,且在水力停留时间为3 d和4 d时容易产生大量甲烷;当食微比较高(1.0和1.5)时,可以实现稳定连续产氢,发酵过程中几乎无甲烷产生.当食微比及水力停留时间分别为1.0及3 d时可获得最佳连续产氢效率,其最高容积产氢量和平均容积产氢量分别为451m L·(L·d)~(-1)和(186±29)m L·(L·d)~(-1),最高挥发性固体产氢率和平均挥发性固体产氢率(以VS计)分别为133 m L·g~(-1)和(27±5)m L·g~(-1),氢气含量可达20%~30%.     

基于厌氧膜生物反应器的剩余污泥-餐厨垃圾厌氧共消化性能

采用厌氧膜生物反应器(anaerobic membrane bioreactor,AnMBR)进行剩余污泥与餐厨垃圾的共消化,研究其有机物的去除特性、产气性能和微生物群落组成等运行性能.结果表明,反应器运行过程中有机负荷(organic loading rate,OLR,以VS计)稳定在0.59～0.64 kg·(m~3·d)~(-1),挥发性固体(volatile solids,VS)降解率由单消化17.5%上升至共消化40%,COD截留率为95.3%.消化液含固率提高了3.9倍,最终CH_4体积分数稳定在60%,CH_4产量(以COD_(added)计)为78.7 mL·g~(-1).跨膜压差(transmembrane pressure,TMP)和平均Flux分别维持在-3.1～-2.7 kPa和0.106 L·(m~2·h)~(-1),膜污染较轻.16S rRNA微生物多样性分析表明,AnMBR内部厌氧消化细菌主要是Proteobacteria(变形菌门)、Bacteroidetes(拟杆菌门)和Cloacimonetes(阴沟单胞菌门),产甲烷菌中的优势菌科为Methanobacterium(甲烷杆菌科),优势菌属为Methanosaeta(甲烷鬃毛菌属)和Methanolinea(甲烷绳菌属).这将为AnMBR处理污泥及其它高含固率废物流的稳定性和运行性能研究提供有力的理论参考依据,进而为生物质资源化和能源危机提供有效解决途径.