Start-up performances of dry anaerobic mesophilic and thermophilic digestions of organic solid wastes

Two dry anaerobic digestions of organic solid wastes were conducted for 6 weeks in a lab-scale batch experiment for investigating the start-up performances under mesophilic and thermophilic conditions. The enzymatic activities, i.e., β-glucosidase, N-α-benzoyl-Largininamide （BAA）-hydrolysing protease, urease and phosphatase activities were analysed. The BAA-hydrolysing protease activity during the first 2-3 weeks was low with low pH, but was enhanced later with the pH increase. β-Glucosidase activity showed the lowest values in weeks 1-2, and recovered with the increase of BAA-hydrolysing protease activity. Acetic acid dominated most of the total VFAs in thermophilic digestion, while propionate and butyrate dominated in mesophilic digestion. Thermophilic digestion was confirmed more feasible for achieving better performance against misbalance, especially during the start-up period in a dry anaerobic digestion process.

Co-digestion Of Olive Mill Wastewater and Swine Manure Using Up-Flow Anaerobic Sludge Blanket Reactor for Biogas Production

Swine wastewater (SW) and olive mill wastewater (OMW) are two problematic wastes that have become major causes of health and environmental concerns. The main objective of the current work was to evaluate the efficiency of the co-digestion strategy for treatment of SW and OMW mixtures. Mesophilic batch reac-tors fed with mixtures of SW and OMW showed that the two adapted sludges Gadot and Prigat exhibited the best COD removal capacity and biogas production;therefore both were selected to seed up-flow anaerobic sludge blanket (UASB) continuous reactors. During 170 days of operation, both sludges Gadot and Prigat showed high biodegradation potential. The highest COD removal of 85-95% and biogas production of 0.55 L?g-1 COD were obtained at a mixture consisting of 33% OMW and 67% SW. Under these conditions, an organic load of 28,000 mg?L-1 COD was reduced to 1,500-3,500 mg?L-1. These results strongly suggest that co-digestion technology using UASB reactors is a highly reliable and promising technology for wastewater treatment and biogas production.

Startup and operation of anaerobic EGSB reactor treating palm oil mill effluent

A bench-scale expanded granular sludge bed （EGSB） reactor was applied to the treatment of palm oil mill effluent （POME）. The reactor had been operated continuously at 35℃ for 514 d, with organic loading rate （OLR） increased from 1.45 to 17.5 kg COD/（m^3·d）. The results showed that the EGSB reactor had good performance in terms of COD removal on the one hand, high COD removal of 91% was obtained at two days＇ of hydraulic retention time （HRT）, and the highest OLR of 17.5 kg COD/（m^3·d）. On the other hand, only 46% COD in raw POME was transformed into biogas in which the methane content was about 70% （V/V）. A 30-d intermittent experiment indicated that the maximum transformation potential of organic matter in raw POME into methane was 56%. Volatile fatty acid （VFA） accumulation was observed in the later operation stage, and this was settled by supplementing trace metal elements. On the whole, the system exhibited good stability in terms of acidity and alkalinity. Finally, the operational problems inherent in the laboratory scale experiment and the corresponding countermeasures were also discussed.

Degradation of polyacrylamide (PAM) and methane production by mesophilic and thermophilic anaerobic digestion: Effect of temperature and concentration

Polyacrylamide(PAM)is generally employed in wastewater treatment processes such as sludge dewatering and therefore exists in the sludge.Furthermore,it degrades slowly and can deteriorate methane yield during anaerobic digestion(AD).The impact or fate of PAM in AD under thermophilic conditions is still unclear.This study mainly focuses on PAM degradation and enhanced methane production from PAM-added sludge during 15 days of thermophilic(55°C)AD compared to mesophilic(35°C)AD.Sludge and PAM dose from 10 to 50 g/kg TSS were used.The results showed that PAM degraded by 76%to 78%with acrylamide(AM)content of 0.2 to 3.3 mg/L in thermophilic AD.However,it degraded only 21%to 30%with AM content of 0.5 to 7.2 mg/L in mesophilic AD.The methane yield was almost 230 to 238.4 mL/g VSS on the 8th day in thermophilic AD but was 115.2 to 128.6 mL/g VSS in mesophilic AD.Mechanism investigation revealed that thermophilic AD with continuous stirring not only enhanced PAM degradation but also boosted the organics release from the sludge with added PAM and gave higher methane yield than mesophilic AD.

Biogas production from microbial-alkali pretreated corn stover by solid-state anaerobic digestion

Corn stover pretreated by Ceriporiopsis subvermispora was used as substrate to enhance biogas production via solid state anaerobic digestion(SS-AD).Effects of temperature,inoculum volume and alkaline concentration on the biogas production profermance were investigated.The results showed that pretreatment of corn stover by C.subvermispora benefited the biogas production.The optimal conditions were temperature 35°C,inoculum 10:1(w/w)and adding 5.0%of alkali,under which the maximum productions were obtained for daily and cumulative biogas of 14.07 L/kg VS and 211.09 L/kg VS.During the SS-AD process,the total solids(TS)and volatile solid(VS)were significantly degraded.The volatile fatty acids(VFA)concentration increased to 106 mmol/L and alkalinity decreased by about 23%.The results collectively suggested that microbial-alkali pretreatment of corn stove combining mesophilic condition could be a promising way to produce biogas in SS-AD.

接种比在中温与低温条件下对猪粪产甲烷潜力的影响研究

为探究猪粪挥发性固体(VS)与接种液VS不同接种比(S/I)对中温与低温条件下猪粪产甲烷潜力(BMP)的影响,在(35±0.5)℃中温条件和(23±0.5)℃低温条件下,将初始VS浓度控制在3%,按照接种比为0.5、1.0与2.0开展猪粪BMP试验,并进行产甲烷过程的动力学分析。各试验组甲烷产生量均为标准状况(1标准大气压,0℃)下的体积。结果:无论中温还是低温条件,累积甲烷产量和最大日甲烷产生量都与猪粪接种比呈显著正相关性(P<0.05),但不同接种比例下猪粪BMP无显著差异(P>0.05);以VS计,中温条件下S/I为0.5、1.0和2.0时猪粪的BMP分别为(252.05±5.12)mL/g、(250.07±16.57)mL/g和(249.65±13.69)mL/g,均值为(250.59±1.28)mL/g;低温条件下S/I为0.5、1.0和2.0时猪粪的BMP分别为(183.42±9.18)mL/g、(189.02±11.25)mL/g和(191.88±3.50)mL/g,其均值为(188.11±4.31)mL/g;动力学研究表明,修正的Gompertz模型较Logistic模型更适合猪粪的厌氧消化动力学分析。本研究表明,初始VS水平控制在3%时,在相同温度条件下(中温或低温),不同接种比猪粪的BMP无显著差异,从缩短BMP测试时间、提高效率的角度考虑,建议进行猪粪BMP测试时选取中温条件下,将S/I设为0.5。

Oxygen tolerance capacity of upflow anaerobic solid-state(UASS) with anaerobic filter(AF) system

In order to investigate the oxygen tolerance capacity of upflow anaerobic solid-state（UASS）with anaerobic filter（AF） system, the effect of microaeration on thermophilic anaerobic digestion of maize straw was investigated under batch conditions and in the UASS with AF system. Aeration intensities of 0–431 m L O2/gvswere conducted as pretreatment under batch conditions. Aeration pretreatment obviously enhanced anaerobic digestion and an aeration intensity of 431 m L O2/gvsincreased the methane yield by 82.2%. Aeration intensities of 0–355 m L O2/gvswere conducted in the process liquor circulation of the UASS with AF system. Dissolved oxygen（DO） of UASS and AF reactors kept around 1.39 ±0.27 and 0.99 ± 0.38 mg/L, respectively. p H was relatively stable around 7.11 ± 0.04. Volatile fatty acids and soluble chemical oxygen demand concentration in UASS reactor were higher than those in AF reactor. Methane yield of the whole system was almost stable at 85 ± 7 m L/gvs as aeration intensity increased step by step. The UASS with AF system showed good oxygen tolerance capacity.

接种比对猪粪中温条件产甲烷潜力的影响

为探究不同接种比对猪粪中温产甲烷潜力(BMP)的影响,在(35.0±0.5)℃和3%初始挥发性固体(VS)浓度条件下分别按照猪粪与接种液比例为1∶2、1∶1和2∶1的接种比开展猪粪中温BMP实验,实验期间对各反应瓶的日甲烷产生量和发酵液上清液的pH、氨氮、总氮、葡萄糖等理化指标进行连续监测,并在反应结束后对不同接种比实验体系的微生物群落进行16SV4测序。各处理组甲烷产生量均为标准状况(1个标准大气压,0℃)体积。结果表明:累积甲烷产量和最大日甲烷产生量都与猪粪接种比呈显著正相关关系(P<0.05),但不同接种比例下猪粪BMP(以VS计)无显著差异(P>0.05)。在1∶2、1∶1和2∶1三种接种比例下猪粪的BMP分别为(252.05±5.12)、(250.07±16.57)mL·g^(-1)和(249.65±13.69)mL·g^(-1),其均值为(250.59±1.28)mL·g^(-1);在微生物群落中,厚壁菌门、拟杆菌门与Cloacimonadota是猪粪厌氧消化系统中相对丰度最高的三类细菌,Halobacterota在产甲烷古菌中占绝对优势,变形菌门和Methanobacterium相对丰度的下降水平与接种比呈负相关关系。修正的Gompertz模型较Logistic模型更适合中温条件下猪粪的厌氧消化动力学分析。研究表明,在中温[(35.0±0.5)℃]和3%初始VS条件下,不同接种比的猪粪BMP值无显著差异(P>0.05),从缩短BMP测试时间、提高效率考虑,建议猪粪BMP测试的接种比选取1∶2。

有机垃圾组分中温厌氧消化产甲烷动力学研究

以土豆、生菜、瘦肉和花生油为原料,采用批式中温厌氧消化产甲烷实验,研究了城市生活有机垃圾中淀粉类、纤维素类、蛋白质类和脂类4种典型组分的厌氧消化产甲烷特性。利用修正Gompertz方程对累积产甲烷量进行拟合,并对厌氧降解过程用一级动力学进行分析。结果表明:土豆、生菜、瘦肉和花生油的最终甲烷产量为260.1、145.7、258.4和757.2mL·gVS^(-1),延滞期分别为0、1.3、1.6和13.1d,累积甲烷产量达到最终甲烷产量80%所需的时间分别为7.2、9.6、8.1和59.7d,可生物降解度分别为74%、31%、51%和85%。从厌氧消化过程中液相的挥发性脂肪酸浓度和气相的氢气浓度以及pH监测结果表明,所有厌氧消化过程均没有中间产物的积累,适合一级动力学方程。土豆、生菜、瘦肉和花生油的厌氧降解速率常数分别为0.183、0.147、0.190和0.020d^(-1)。

玉米秸中温与常温厌氧生物气化的比较研究(英文)

为解决玉米秸的资源化利用问题 ,提出通过厌氧消化的方法把其转化成生物气体。比较了在中温和常温条件下 ,不同负荷率 (35、5 0、6 5 g/L )对玉米秸秆日产气量、累积产气量、总干物质 (TS)和挥发性有机物 (VS)消化率的影响。试验结果显示 ,不论是在中温还是在常温条件下 ,5 0 g/L TS负荷率都获得了较高的累积产气量 ;相对于常温而言 ,中温厌氧消化的累积产气量提高了 6 3%,总干物质 (TS)和有机物 (V S)消化率分别增加 33%和 49%,产气速率也明显提高。因此 ,使用 5 0 gTS/L 负荷率 ,在中温条件下对玉米秸秆进行厌氧消化是比较好的。该试验结果可为玉米秸秆的大规模生物气化提供重要设计依据。

氨氮和林可霉素对有机物厌氧消化的抑制效应

以含高蛋白质和抗生素的林可霉素生产残渣产沼利用为背景,通过中温厌氧消化批式实验,研究不同的氨氮浓度（300~4500 mg·L-1）和林可霉素浓度（0~100 mg·L-1）对含氮含抗生素类生物质废物的厌氧消化产甲烷能力的抑制作用。结果表明,氨氮和林可霉素浓度均与累积产甲烷量显著负相关。经过240 h的培养,氨氮和林可霉素对厌氧消化产甲烷量的半抑制浓度（EC50）分别为1445 mg·L-1和35 mg·L-1;游离氨的EC50在27~28 mg·L-1之间。在25 mg·L-1林可霉素存在下,氨氮对厌氧消化的抑制趋势和抑制程度并未明显改变,说明氨氮的抑制作用独立于林可霉素。

麦秸生物炭添加对猪粪中温厌氧发酵产气特性的影响

为探明不同热解温度生物炭添加对猪粪中温厌氧消化产气的影响,以400、500、600℃热解制成的麦秸生物炭(BC400、BC500、BC600)为研究对象,采用批次发酵试验,探讨了生物炭添加对猪粪中温(37±1)℃厌氧发酵产气特性的影响。研究结果表明:麦秸热解生物炭可显著(P<0.05)提高猪粪发酵系统的产气潜力和甲烷含量,其影响从大到小依次为BC600>BC500>BC400。厌氧发酵49 d期间,添加生物炭处理的产气量和产甲烷量分别为260.7~288.7 m L·g^(-1)VS和163.7~185.5 m L·g^(-1)VS,较纯猪粪处理提高了77.1%~96.1%和78.1%~101.8%。同时,添加生物炭可明显提高猪粪厌氧发酵系统的消化效率(T90),缩短厌氧发酵的延滞期。不同热解温度麦秸生物炭对猪粪厌氧消化产气特征的影响明显不同,对畜禽养殖场沼气工程运行中的物料选择和条件优化有实际的指导意义。

餐厨垃圾与污泥两相中温厌氧消化试验研究

研究了混合比例和污泥停留时间对餐厨垃圾与污泥联合两相中温厌氧消化过程的影响。相较于餐厨垃圾与污泥TS比为1∶3的条件,TS比为1∶1时两相系统具有更好的产气效果、有机物去除效果和运行稳定性。随着SRT的延长,两相系统有机负荷逐步降低,产甲烷速率相应降低,单位体积进料产沼气量以及有机物去除率逐步提高。在餐厨垃圾与污泥TS比为1∶1的条件下,两相厌氧消化系统最佳SRT为25 d(产酸相和产甲烷相分别为5 d和20 d);此时,沼气中甲烷含量高达71%,产甲烷速率和甲烷产率分别为0.7 L/L·d和0.69 L/gVS去除,两相系统VS去除率达到64.7%。

含固率和接种比对叶菜类蔬菜垃圾厌氧消化的影响

通过叶菜类蔬菜垃圾中温批式厌氧消化实验,比较了含固率(3%、5%、7%)和接种比(1.5、2.5、3.5)对产甲烷效果的联合影响.结果表明,在研究实验参数范围内,含固率越低、接种比越高,越有利于缩短产甲烷反应迟滞期,平均日产甲烷速率越快.经过52d的培养,在含固率为3%、接种比为3.5的工况中,平均日产甲烷速率最快,达到9.5mL/(gVS·d),日最大产甲烷速率最快,达到49.8mL/(gVS·d),最早进入快速产甲烷期.当接种比为3.5时,随着含固率的升高,产甲烷速率下降,迟滞期延长,但单位底物累计产甲烷量增大,含固率7%时单位底物累计净产甲烷量为481mL/gVS.而当接种比为1.5时,含固率为5%和7%的工况均无法启动甲烷化反应,含固率为3%的工况的产气迟滞期达15d.挥发性有机酸的累积抑制甲烷化反应的启动,迟滞期随着液相中有机酸浓度的增加而延长,当有机酸浓度低于1260mg/L,甲烷化反应没有明显的迟滞期.

污水污泥高温与中温厌氧消化对比研究

研究了不同HRT条件下污泥高温（50℃）厌氧消化效果,并与中温（35℃）厌氧消化效果进行对比分析。结果表明,与中温条件相比,高温厌氧消化对有机物的去除率显著提高;高温厌氧消化沼气产量高于中温,但沼气产率差异并不明显（1.13～1.25L/gVS去除）;高温和中温厌氧消化系统运行稳定性良好,挥发酸/碱度比值仅为0.02～0.03;高温和中温厌氧消化出泥的毛细吸水时间（CST）均增加,并且高温消化污泥的CST高于中温消化污泥,厌氧消化过程可能导致污泥脱水性能变差。

猪粪及奶牛粪中温厌氧发酵对Cu和Zn的影响

以猪粪和奶牛粪为发酵原料,在中温〔(37±2)℃〕条件下采用完全混合式厌氧反应器进行了158 d的室内试验研究,分析厌氧发酵过程中Cu和Zn在沼液中质量浓度的变化及其在沼渣中的赋存形态.结果表明:1猪粪沼液中ρ(TCu)和ρ(TZn)(TCu和TZn分别为总Cu和总Zn)随发酵时间的增加逐渐升高,而奶牛粪沼液中二者变幅不明显.2整个发酵过程中,猪粪沼液中ρ(TCu)和ρ(TZn)的平均值极显著低于进料(P<0.001),降幅分别为80%和43%;而奶牛粪沼液中二者降幅分别仅为11%和13%.3猪粪和奶牛粪沼液中ρ(溶解性Cu)占ρ(TCu)的53%和43%,与进料相比有小幅降低;而猪粪和奶牛粪沼液中ρ(溶解性Zn)占ρ(TZn)的35%和19%,极显著高于进料(P≤0.01),增幅分别为109%和37%.4猪粪和奶牛粪沼渣中Cu主要以可氧化态存在,Zn主要以残渣态和酸溶态/可交换态存在.中温厌氧发酵对猪粪和奶牛粪中溶解性Cu和Zn的削减效果有限,并且沼渣中残渣态Cu和Zn的减少可能增加二者的生物有效性,因此不利于农田的直接利用.

餐厨垃圾固相物料与厨余垃圾混合中温厌氧消化工程中试研究

试验采用有效容积为4 m^3的全混式反应器,在中温(35℃)的条件下,分别进行了单一餐厨垃圾固相物料(S1)、餐厨垃圾固相物料(S1)与厨余垃圾(S2)的混合物料(S3)(混合比为2∶1)厌氧消化工程中试。结果表明,单一餐厨垃圾固相物料(S1)厌氧消化最佳运行工况为进料有机负荷(OLR)为80 kg·d^(-1),停留时间(HRT)为50 d;当OLR增至115 kg·d^(-1)时,其平均容积产气率由2.04 m^3·m^(-3)d^(-1)降至2.02 m^3·m^(-3)d^(-1),气体甲烷含量由61.1%降至38.4%。混合物料(S3)日进料量由80 kg提升至120 kg时,平均容积产气率由2.11 m^3·m^(-3)d^(-1)升高至2.30 m^3·m^(-3)d^(-1),甲烷含量亦由61.9%升高至63.8%。因此,将餐厨垃圾固相物料与厨余垃圾进行混合可以有效改善物料厌氧性能,其有机负荷以及甲烷产率均表现出明显优势。

沼渣水热炭添加对猪粪中温厌氧消化的促进作用

为探明沼渣水热炭添加对猪粪中温厌氧消化产气的影响,该研究以190℃水热炭化制备的猪粪沼渣水热炭(H-190)为研究对象,采用批次发酵实验,探讨H-190添加对猪粪中温(37℃)厌氧消化产气特性的影响。结果表明,TS=4.0%的猪粪中温厌氧消化系统中,添加H-190后系统的平均产气量和产甲烷量分别为313.07和191.35 m L·g^(-1)VS,较纯猪粪处理提高了29.81%和26.22%;而TS=8%的体系中,添加H-190后,二者分别为233.59和145.00 mL·g^(-1)VS,较纯猪粪处理提高了12.08%和13.39%。添加H-190可提高TS=4%猪粪中温厌氧发酵系统的消化效率,缩短厌氧消化的延滞期,但对TS=8.0%的系统则相反。沼渣水热炭优良的表面特性是缓解猪粪厌氧消化过程中中间代谢物质的抑制、促进微生物间的电子传递、提高系统消化产气和产甲烷的主要原因。该研究对养殖场粪污厌氧消化高效处理具有工程指导意义。

不同VS比例的黄花和污泥联合厌氧消化的研究

采用完全混合式反应器R1～R3（加拿大一枝黄花与脱水污泥的有机质配比分别为0：1、1：3和1：1），研究了污泥停留时间为30d，半连续中温（35±1）℃的运行状态下，脱水污泥和加拿大一枝黄花联合厌氧消化的系统稳定性和厌氧消化性能。结果表明：添加黄花进行共发酵，不但降低了游离氨的浓度和VFA的积累，使系统维持更好的稳定性；而且明显改善厌氧消化性能，与污泥单独厌氧消化相比，最佳条件下单位体积甲烷产率、比沼气产率、甲烷产率分别可以提高79．5％，61．7％，29．2％。随着黄花比例的提高，VS降解率呈现出逐渐上升的趋势。R3和R2的VS降解率稍微高于R1，分别为33．8％、31．2％、30．3％。随着黄花VS比例逐渐增加到50％，沼气中的甲烷和H2S含量稍微有所下降，VFA组分中戊酸的浓度升高，而乙酸和丙酸的浓度则有所下降。

IC反应器中剩余污泥的厌氧消化试验研究

利用IC反应器对抚顺三宝屯污水处理厂的剩余污泥进行中温与高温厌氧消化试验,考察厌氧消化工艺的可行性。结果表明,中温、高温连续出泥分别为12d,8d后,出泥COD去除率开始稳定,产气量也逐渐达到稳定,气体中的甲烷含量在70%以上。絮凝试验结果表明,与生污泥相比,消化污泥经絮凝后等量干固体的泥饼体积仅为原来的56%。