La~(3+)对产氢产甲烷厌氧反应器作用的研究

通过3个阶段的实验,第一阶段采用IC厌氧反应器做为产氢反应器的启动过程中,确定了葡萄糖进水COD为2 000 mg/L时,最佳水力停留时间为6 h。COD去除率达到34%,氢气产量达到8 L/d。第二阶段产氢产甲烷反应器的启动,产氢反应器COD去除率为31%～34%,氢气产量7.5～8 L/d,产甲烷反应器的COD去除率为83%～86%。最大比产甲烷活性493～504 m L/(g·d)。实现了同时产氢和产甲烷,达到了能源的最大产出,提高了废水处理效果,具有重要的现实意义。第三阶段稀土元素对产氢产甲烷反应器的促进作用表现在对产甲烷菌的促进,当La3+浓度为0.3 mg/L时,此时产甲烷反应器COD去除率达到最大值92%,比产甲烷活性达到520 m L/(g·d);对产氢反应器的作用不大。稀土元素进一步提高了废水处理效果和产甲烷量,将其用在废水处理中是可行并且有效的。     

AFMBR处理生活污水的功能菌群特性研究

厌氧流化床膜生物反应器(AFMBR)作为一种低耗产能的高效厌氧反应器,在处理生活污水中有着巨大的潜力.本研究主要利用宏基因组测序技术对AFMBR系统内的微生物菌群进行探究,结果表明:与接种菌群相比,AFMBR经过一段时间的连续运行后,在属水平上古菌优势菌属由接种时的甲烷囊菌属变为甲烷八叠球菌属、甲烷杆菌属,细菌的整体菌属结构发生了较大变化;在种水平上,系统内不存在较明显的优势菌种.从相对丰度比例≥1%的菌种来看:水解发酵菌群产氢产乙酸菌群产甲烷菌群,但各菌群之间相对丰度的差距较小.从基因水平来看,系统内与碳水化合物代谢、氨基酸代谢、能量代谢相关的基因丰度较高,二氧化碳、乙酸转化为甲烷是系统产甲烷的主要途径.     

末端产物对乙醇型发酵菌群产氢能力及代谢进程的影响

利用连续流搅拌槽式反应器(CSTR)在一定条件下驯化成功的乙醇型产氢发酵菌群,通过静态培养实验,以葡萄糖为碳源,利用缓冲液控制反应体系pH值,通过不同的pH值环境使产氢发酵菌群末端产物生成比例发生改变,考察了不同的末端产物生成比例对菌群产氢能力的影响.结果表明,在液相末端产物总量相当的情况下,乙醇生成比例高时氢气产量也较高.通过外加乙醇和乙酸进行静态产氢实验发现,乙醇对发酵产氢的抑制作用不明显,同对照组相比,外加40 mmol/L时氢气产量仅下降了34%,而乙酸的存在对菌群的发酵产氢有较强的抑制,外加乙酸浓度为10 mmol/L时即对产氢发酵产生明显抑制,浓度为40 mmol/L时产氢量较对照组降低了84.3%,液相末端产物也大幅降低,混合菌群最终形成乙醇型发酵应是菌群自然选择的结果.     

末端产物对乙醇型发酵菌群产氢能力及代谢进程的影响

利用连续流搅拌槽式反应器(CSTR)在一定条件下驯化成功的乙醇型产氢发酵菌群,通过静态培养实验,以葡萄糖为碳源,利用缓冲液控制反应体系pH值,通过不同的pH值环境使产氢发酵菌群末端产物生成比例发生改变,考察了不同的末端产物生成比例对菌群产氢能力的影响.结果表明,在液相末端产物总量相当的情况下,乙醇生成比例高时氢气产量也较高.通过外加乙醇和乙酸进行静态产氢实验发现,乙醇对发酵产氢的抑制作用不明显,同对照组相比,外加40 mmol/L时氢气产量仅下降了34%,而乙酸的存在对菌群的发酵产氢有较强的抑制,外加乙酸浓度为10 mmol/L时即对产氢发酵产生明显抑制,浓度为40 mmol/L时产氢量较对照组降低了84.3%,液相末端产物也大幅降低,混合菌群最终形成乙醇型发酵应是菌群自然选择的结果.     

1株转座子插入突变菌株TB34的筛选及产氢分析

以分离自红树林污泥的厌氧发酵产氢细菌Pantoea agglomerans BH18为出发菌株,利用转座子Tn7构建突变体文库.通过卡那霉素抗性筛选与PCR扩增,鉴定转座子插入突变菌株.通过初筛和复筛,获得1株突变菌TB34,其产氢量较野生菌株明显提高.在初始pH为7.0和葡萄糖浓度10 g.L-1的海水培养条件下,产氢量(H2/葡萄糖)为(2.04±0.04)mol.mol-1,相比野生菌株产氢量提高43%.经过5次连续传代培养,突变菌株TB34表现出稳定的产氢特性.测定突变菌株TB34在不同碳源培养条件下的产氢量.结果表明,突变菌株TB34和野生菌株BH18都能利用蔗糖、葡萄糖和果糖发酵产氢.与野生菌株BH18不同,突变菌株TB34在以木糖为底物培养条件下仍能够发酵产氢,产氢量(H2/木糖)为(1.34±0.09)mol.mol-1,扩大了底物利用范围.     

生物载体强化的连续流生物制氢反应器的运行特性

在连续流搅拌槽式反应器(CSTR)中填加比重为1.54 g/cm³,粒径小于2mm的多孔物质,以糖蜜废水为底物利用活性污泥制取氢气.考察了填加生物载体后生物制氢反应器连续流稳定运行的系统特性.研究表明,投加生物载体能够扩大产氢细菌的活性范围,提高系统的抗冲击负荷能力和耐低pH值的能力,增加系统稳定性,并且可使系统在低HRT下保持较高的生物量.此连续流生物制氢反应系统的最佳发酵类型为乙醇型发酵,适宜的pH值范围为3.8～4.4,气相中的氢气含量约为40%～57%,最大产氢速率为0.37L/(g·d).降低pH值可抑制厌氧发酵过程中出现的产甲烷菌群,加速产氢反应器的启动.     

不同阴离子在生物质发酵产氢中的作用研究

为揭示不同阴离子在生物质发酵产氢中的作用规律,以混合菌群发酵产氢为研究对象,采用正交试验设计的方法考察了6种不同的阴离子及添加尿素对发酵产氢过程的影响.通过对不同阴离子浓度及相互关系对发酵产氢的影响的综合比较,获得以下结论:促进混合菌群发酵产氢的阴离子组成为:SO42-1.5 g·L-1,Cl-0 g·L-1,NO3-0 g·L-1,Mo7O246-0.1 g·L-1,C2O42- 1g·L-1,C6H5O73- 5g·L-1,(H2N)2CO 0 g·L-1;以PDB(马铃薯水解液)为基质发酵原料,H2最高含量和平均含量分别比对照组提高了21.4%和24.1%;平均产氢速率由对照组的36.79 mL·L-1·h-1提高到96.25 mL·L-1·h-1;氢气产率由对照组的0.76 mol·mol-1提高到1.17 mol·mol-1.研究同时证明,尿素对H2的产生具有显著的抑制作用,Mo7O246-则可促进混合微生物对原料的利用和转化;阴离子C2O42-和C6H5O73-的交互作用显著,说明两者同时使用可改善发酵产氢.从理论上对上述结果进行了分析探讨.     

缓冲体系对厌氧发酵生物产氢的影响

为了研究碳酸盐和磷酸盐缓冲对于厌氧发酵从葡萄糖中制取H2的影响,将经过热处理的初级消化污泥接种到不同浓度碳酸盐和磷酸盐基质中进行厌氧发酵产氢实验.实验结果表明,碳酸盐和磷酸盐的缓冲对于厌氧发酵制氢有较大影响.当NaHCO3,浓度为4 g·L-1时,每1 mol葡萄糖的产氢量达到最大,最大值为1.68 mol,这比不加NaHCO3时的产氢量提高了282%.磷酸盐的浓度对于厌氧发酵产氢也有较大影响.在NaHCO3浓度为4 g·L-1,NaH2PO4·2H2O和K2HPO4·3H2O浓度均为500 mg·L-1时,葡萄糖的产氢率可达到1.94 mol·mo1-1,这比不加入磷酸盐时提高了56%.实验中产氢一般从接种后12 h开始,历时10 h左右结束,最大产氢速率可达到0.44 mol·h-1·mol-1·     

造纸污泥和餐厨垃圾混合发酵联产氢气和甲烷试验

采用联产氢气和甲烷复合工艺,对造纸污泥和餐厨垃圾进行中温-高温混合厌氧消化,通过设计两种物料的不同配比(质量比,以VS计),研究了不同比例混合的物料联产氢气和甲烷的性能.试验结果表明,造纸污泥和餐厨垃圾混合比例为2:2的反应器总气体产率最高,达496.78mL·g-1(其中,氢气64.48mL·g-1,甲烷432.3mL·g-1,均以VSfed计,下同),其VS去除率也最高,达41.33%,在反应30h后和产甲烷18d后分别完成了80%的氢气产量和甲烷产量,而单纯造纸污泥总气体产率为144.99mL·g-1,单纯餐厨垃圾总气体产率为80.4mL·g-1.综合氢气和甲烷产率、产气速率、VS去除率等指标发现,造纸污泥和餐厨垃圾混合发酵联产氢气和甲烷的最佳配比为2:2.     

两相厌氧处理有机废水快速启动试验研究

针对试验设计的两相厌氧反应器(TPAD)进行启动研究,寻求快速启动的方法. 试验采用人工配水,以淀粉、葡萄糖作为主要碳源. 采用低负荷启动方式,快速提高进水ρ(COD_Cr),缩短水力停留时间(HRT),使产酸相尽快维持在酸性最佳条件下. 间歇投加粉末状CaO调节产酸相出水pH在7.0±0.3,从而保证产甲烷相在最佳条件下. 经过36 d的启动过程,在产酸反应器和产甲烷反应器中均出现了性能良好的厌氧颗粒污泥. 启动后第36天,当两相厌氧反应器的水力停留时间(HRT)为17.03 h,COD_Cr负荷(VLR)为8.46 kg/(m3·d),水力负荷为0.059 m3/(m2·h)时,系统整体COD_Cr去除率达到最优,为96.66%.      

Hydrogen gas production in a microbial electrolysis cell by electrohydrogenesis

Electrohydrogenesis is a bio-electrochemical process where organic material is microbially oxidized to protons and electrons, which in turn are reduced to form hydrogen gas (H₂). The reactor in which these reactions occur is termed a microbial electrolysis cell (MEC). The microorganisms that colonize the anode are known as electricigens and behave as biological catalysts, significantly reducing the energy required to drive this process. Electricigens are capable of complete substrate degradation, leading to very high cathodic H₂ recovery efficiencies from sources previously considered organic waste. In this short review, the origination of the bio-electrochemical system (BES) is introduced, mechanisms for electron transfer between microbe and electrode are discussed, the challenges these electrochemical systems face are presented, and finally an overview of current MEC systems and their respective performance is evaluated. Electrohydrogenesis has established itself as a promising technology for sustainable H₂ production from renewable sources.     

基质COD浓度对单室微生物电解池产甲烷的影响

单室微生物电解池(microbial electrolysis cells,MEC)产甲烷过程中,底物COD浓度可同时影响阳极和阴极微生物的活性.为了探究COD浓度的影响,构建生物阴极型单室MEC,比较COD为700、1 000、1 350 mg·L-1情形下产甲烷速率和COD去除量随外加电压的变化规律,并计算MEC的能量效益.结果表明,随着COD的增加,产甲烷速率和COD去除量均呈增大趋势.随着外加电压的升高(0.3~0.7 V),低COD条件下MEC的产甲烷速率呈增大趋势,而在中、高COD条件下,产甲烷速率随着外加电压的升高先增大后减小;COD去除量的变化规律与产甲烷速率一致.当外加电压为0.5 V时,阴极电势降至最低值(-0.694±0.001)V,有利于产甲烷菌的富集,从而获得最高的产甲烷速率和能量回收率(约42.8%).COD浓度1 000mg·L-1和外加电压0.5 V时,MEC可获得最大的能量收益0.44 k J±0.09 k J(约1 450 k J·m-3).最终结果表明,MEC可利用低浓度COD废水生产甲烷,并且可获得正的能量效益,这为废水中化学能量的回收利用提供了新的研究思路.     

类芬顿调理污泥用于微生物电解池产氢与磷回收的研究

为提高微生物电解池(MEC)利用剩余污泥产氢气和磷回收的效率,采用Fe~(3+)、原儿茶酸(PCA)和H_2O_2体系预调理污泥,探究中性PCA/Fe~(3+)/H_2O_2体系的试剂投加量对污泥液相总磷含量和溶解性化学需氧量(SCOD)的影响.在单因素试验的基础上,通过表面响应法(RSM)优化得到Fe~(3+)和H_2O_2投加量分别为12.96 mmol·L~(-1)和0.45 mol·L~(-1),液相总磷含量和SCOD含量实际值分别为(60.14±0.08) mg·L~(-1)和(3357.67±66.37) mg·L~(-1),模拟效果显著.与未处理的剩余污泥MEC反应器出水相比,经过调理后的剩余污泥MEC反应器出水中的总化学需氧量(TCOD)、多糖和蛋白质的去除率分别提高了30.03%、50.16%和97.31%,氢气转化率提升了1.31倍,有效提升了MEC产氢效率.通过鸟粪石结晶回收MEC污泥上清液中的磷,发现在初始pH值为10、Mg~(2+)浓度为0.056 mol·L~(-1)和NH~+_4浓度为0.08 mol·L~(-1)时效果最佳.鸟粪石晶体质量浓度最高可达7.6 g·L~(-1),晶体纯度最大为88.30%,上清液中77.55%的磷以鸟粪石的形式得到回收.在本研究最优化条件下进行中性PCA/Fe~(3+)/H_2O_2体系调理剩余污泥微生物电解池产氢与磷回收全过程中产出经济价值达到2.36元.实验研究最终表明,经过Fe~(3+)/PCA/H_2O_2体系调理污泥可促进污泥中磷的释放和MEC处理污泥的产氢效率,为探究污泥资源化提供了新的研究思路.     

Photochemical degradation of nonylphenol in aqueous solution：The impact of pH and hydroxyl radical promoters

The degradation of nonylphenol (NP) in aqueous solution with UV, H₂O₂/UV, and Fenton/photo-Fenton processes was studied. The efficacy of direct and hydrogen peroxide photolysis proved to be dependent on the pH value. The addition of H₂O₂ to UV treatment improved NP degradation. The application of UV photolysis and the H₂O₂/UV system at pH 7 resulted in low pseudo first-order rate constants at 10^-4 sec^-1. In the experiments at elevated pH values the pseudo-first order rate constants increased to 10^-3 sec^-1. The efficacy of the Fenton process was lower in comparison with UV and hydrogen peroxide photolysis. The addition of UV irradiation to the H₂O₂/Fe²⁺ system substantially improved NP degradation efficacy. In terms of performance, the photo-Fenton process was similar to the H₂O₂/UV process. The most favourable process for complete nonylphenol degradation considering both operational cost and treatment efficacy was H₂O₂/UV at pH 11 and 250 mol/L H₂O₂.     

Biphasic production of hydrogen and methane from waste lactose in cyclic-batch reactors

The biphasic production of the energy gases hydrogen and methane was possible in a fed batch culture resulting in a volumetric mix of approximately 20% H₂ and 80% CH₄ and an energy conversion efficiency of 95%, based on the measured Chemical Oxygen Demand and theoretical calculations assuming that the substrate (a dairy waste permeate) was lactose. Gas production showed a rapid initial phase over 0–20 h in which the composition was up to 50% hydrogen with the balance mainly carbon dioxide. This was accompanied by the accumulation of volatile fatty acids (VFA) in which butyric was predominant. A slower second phase of gas production produced a mixture of methane and carbon dioxide with a reduction in the accumulated acids. The duration of this second phase depended on the initial load applied to the reactor, and in the experiments carried out lasted between 6 and 12 days. Where the applied initial load led to an acid accumulation such that the pH fell below 5.5, the second phase of gas production was inhibited. Where pH control was exerted to prevent the pH dropping below 6.5, ethanol accumulated alongside VFA as a first phase product, with the gas comprised entirely of carbon dioxide. Despite the excellent energy conversion and the production of biogas fuel elements matching those for hythane (a mixture of hydrogen and methane, with improved combustion characteristics), the overall process loading was considered too low for efficient volumetric conversion of the feedstock to energy. The concept could be further developed based on high rate reactor systems with granular or immobilised biomass either as a single tank biphasic system or in a split tank two phase production process.     

高温条件下初始pH值对污泥-餐厨垃圾联合厌氧发酵产氢余物产CH4的影响

污泥-餐厨垃圾厌氧消化产氢产CH₄可将城市有机废弃物转化为可再生能源H₂、CH₄,对实现碳减排发挥着重要作用。通过批式试验探究高温条件下(55±1℃),不同初始pH值对污泥和餐厨垃圾联合厌氧发酵产氢余物产CH₄的影响。研究结果表明:适度地增加产氢余物的碱度会提高产CH₄效能,而过低的初始pH则抑制了产氢余物产CH₄效能。初始pH=8时,CH₄最高浓度(79.08%)、累积产甲烷量(101 mL/g DS)和最大CH₄生产速率(12.21 mL/d)均达到最大。不同初始pH下,总糖和总蛋白质的降解量跟累积产甲烷量呈正相关,其中总蛋白的降解量及降解率均高于总糖。初始pH=8时,总糖和总蛋白质的降解量及降解率最高,分别为6078 mg/L、55.70%和4710 mg/L、69.67%。不同初始pH值下,产氢余物厌氧消化后的pH都趋于7.5左右。     

阴极原位产H2O2强化光电催化降解水中EDTA的研究

本研究构建了以活性碳纤维(Activated Carbon Fiber,ACF)为阴极,TiO_2/Ti与Ru O_2/Ti为双阳极的光电催化体系.该体系中,Ru O_2/Ti电阳极和TiO_2/Ti光阳极均有氧化作用,可同时氧化降解污染物;且电阳极具有较强析氧作用,能产生大量O_2;ACF阴极具有还原作用,可将体系中产生的O_2原位还原为H_2O_2;H_2O_2在紫外光下产生·OH,进而强化光电催化与电催化氧化过程,实现对水中乙二胺四乙酸二钠(EDTA)的高效去除.本论文详细考察了电流密度、pH、曝气等因素对EDTA降解效果的影响.结果表明,在EDTA初始浓度为300 mg·L~(-1)、溶液初始pH=4.84、电流密度为12 m A·cm~(-2)和光电流密度为0.012 m A·cm~(-2)的条件下,反应90 min后,EDTA降解率高于90%.该催化体系实现了EDTA的高效降解.     

Degradation kinetics and mechanism of trace nitrobenzene by granular activated carbon enhanced microwave/hydrogen peroxide system

The kinetics of the degradation of trace nitrobenzene (NB) by a granular activated carbon (GAC) enhanced microwave (MW)/hydrogen peroxide (H₂O₂) system was studied. Effects of pH, NB initial concentration and tert-butyl alcohol on the removal efficiency were examined. It was found that the reaction rate fits well to first-order reaction kinetics in the MW/GAC/H₂O₂ process. Moreover, GAC greatly enhanced the degradation rate of NB in water. Under a given condition (MW power 300 W, H₂O₂ dosage 10 mg/L, pH 6.85 and temperature (60±5)℃), the degradation rate of NB was 0.05214 min^-1 when 4 g/L GAC was added. In general, alkaline pH was better for NB degradation; however, the optimum pH was 8.0 in the tested pH value range of 4.0-12.0. At H₂O₂ dosage of 10 mg/L and GAC dosage of 4 g/L, the removal of NB was decreased with increasing initial concentrations of NB, indicating that a low initial concentration was beneficial for the degradation of NB. These results indicated that the MW/GAC/H₂O₂ process was effective for trace NB degradation in water. Gas chromatography-mass spectrometry analysis indicated that a hydroxyl radical addition reaction and dehydrogenation reaction enhanced NB degradation.     

Enhanced methane production in an anaerobic digestion and microbial electrolysis cell coupled system with co-cultivation of Geobacter and Methanosarcina

The anaerobic digestion(AD)and microbial electrolysis cell(MEC)coupled system has been proved to be a promising process for biomethane production.In this paper,it was found that by co-cultivating Geobacter with Methanosarcina in an AD–MEC coupled system,methane yield was further increased by 24.1%,achieving to 360.2 m L/g-COD,which was comparable to the theoretical methane yield of an anaerobic digester.With the presence of Geobacter,the maximum chemical oxygen demand(COD)removal rate(216.8 mg COD/(L·hr))and current density(304.3 A/m_3)were both increased by 1.3 and 1.8 fold compared to the previous study without Geobacter,resulting in overall energy efficiency reaching up to 74.6%.Community analysis demonstrated that Geobacter and Methanosarcina could coexist together in the biofilm,and the electrochemical activities of both were confirmed by cyclic voltammetry.Our study observed that the carbon dioxide content in total gas generated from the AD reactor with Geobacter was only half of that generated from the same reactor without Geobacter,suggesting that Methanosarcina may obtain the electron transferred from Geobacter for the reduction of carbon dioxide to methane.Taken together,Geobacter not only can improve the performance of the MEC system,but also can enhance methane production.