Cooperation between ligninolytic enzymes produced by superior mixed flora

Since the ability to degrade lignin with one kind of white-rot fungi or bacteria was very limited, superior mixed flora‘s ability to degrade lignin was investigated by an orthogonal experiment in this paper. The results showed that superior mixed flora reinforced the ability to degrade lignin, the degradation rates of both sample 9 and 10 were beyond 80% on the day 9. The cooperation between lignin peroxidase(LiP), Mn-dependent peroxidase(MnP) and laccase (Lac) for lignin degradation was also studied. By examining the activities of three enzymes produced by superior mixed flora, it was found that Lac was a key enzyme in the process of biological degradation of lignin but Lip was not; the enzyme activity ratios of Lac/MnP and Lac/LiP were significantly correlative with the degradation rate of lignin at the 0.01 level; and the ratio of MnP/LiP was an important factor affecting the degradation rate of lignin.     

Bioaugmentation with a pyridine-degrading bacterium in a membrane bioreactor treating pharmaceutical wastewater

The bacterial strain Paracoccus denitrificans W12, which could utilize pyridine as its sole source of carbon and nitrogen, was added into a membrane bioreactor （MBR） to enhance the treatment of a pharmaceutical wastewater. The treatment efliciencies investigated showed that the removal of chemical oxygen demand, total nitrogen, and total phosphorus were similar between bioaugmented and non-bioaugmented MBRs, however, significant removal of pyridine was obtained in the bioaugmented reactor. When the hydraulic retention time was 60 hr and the influent concentration of pyridine was 250-500 mg/L, the mean effluent concentration of pyridine without adding W12 was 57.2 mg/L, while the pyridine was degraded to an average of 10.2 mg/L with addition of W12. The bacterial community structure of activated sludge during the bioaugmented treatment was analyzed using polymerase chain reaction-denaturing gradient gel electrophoresis （PCR-DGGE）. The results showed that the W12 inoculum reversed the decline of microbial community diversity, however, the similarity between bacterial community structure of the original sludge and that of the sludge after bioaugmentation decreased steadily during the wastewater treatment. Sequencing of the DNA recovered from DGGE gel indicated that sp., Sphingobium sp., Comamonas sp., and Hyphomicrobium sp. were the dominant organisms in time sequence in the bacterial community in the bioaugmented MBR. This implied that the bioaugmentation was affected by the adjustment of whole bacterial community structure in the inhospitable environment, rather than being due solely to the degradation performance of the bacterium added.     

Process of rice straw degradation and dynamic trend of pH by the microbial community MC1

The process of the rice straw degradation in the fermentor with aeration at 290 ml/h was studied. The results of dissolved oxygen （DO） indicated that the optimum DO during cellulose degradation by microbial community MC1 ranged from 0.01 to 0.12 mg/L. The change model ofpH values was as follows： irrespective of the initial pH of the medium, pH values decreased rapidly to approximate 6.0 after being inoculated within 48 h when cellulose was strongly degraded, and then increased slowly to 8.0--9.0 until cellulose was degraded completely. During the degradation process, 15 kinds of organic compounds were checked out by GC-MS. Most of them were organic acids. Quantity analysis was carried out, and the maximum content compound was ethyl acetate which reached 13.56 g/L on the day 4. The cellulose degradation quantity and ratio analyses showed that less quantity （under batch fermentation conditions） and longer interval （under semi-fermentation conditions） of rice straw added to fermentation system were contributed to matching the change model of pH, and increasing the quantity and ratio of rice straw degradation during cellulose degrading process. The highest degradation ratio was observed under the condition office straw added one time every five days （under semi-fermentation conditions）.     

Photoelectrocatalytic degradation of Rose Bengal

An innovative photoelectrode, TiO2/T1 mesh electrode, was prepared by galvanostaticanodisation. The morphology and the crystalline texture of the TiO2 film on mesh electrode were examined by scanning electronic microscopy and Raman spectroscopy respectively. The examination results indicated that the structure and properties of the film depended on anodisation rate, and the anatase was the dominant component under the controlled experimental conditions. Degradation of Rose Bengal (RB) in photocatalytic (PC) and photoelectrocatalytic (PEC) reaction was investigated, the results demonstrated that electric biasing could improve the efficiency of photecatalytic reaction. The measurement results of TOC in photoelectrocatalytic degradation showed that the mineralisation of RB was complete relatively. The comparison between the degradation efficiency of RB in PEC process and that in aqueous TiO2 dispersion was conducted. The results showed that the apparent first-order rate constant of RB degradation in PEC process was larger than that in aqueous dispersion with 0.1%--0.3% TiO2 powder, but was smaller than that in aaueaus disverslon with 1.0% TiO2.     

Research on the degradation mechanism of pyridine in drinking water by dielectric barrier discharge

Pyridine, an important chemical raw material, is widely used in industry, for example in textiles,leather, printing, dyeing, etc. In this research, a dielectric barrier discharge(DBD) system was developed to remove pyridine, as a representative type of nitrogen heterocyclic compound in drinking water. First, the influence of the active species inhibitors tertiary butanol alcohol(TBA),HCO_3~-, and CO_3~(2-)on the degradation rate of pyridine was investigated to verify the existence of active species produced by the strong ionization discharge in the system. The intermediate and final products generated in the degradation process of pyridine were confirmed and analyzed through a series of analytical techniques, including liquid chromatography–mass spectrometry(LC–MS), high performance liquid chromatography(HPLC), ion chromatography(IC), total organic carbon(TOC) analysis, ultraviolet(UV) spectroscopy, etc. The results showed that the degradation of pyridine was mainly due to the strong oxidizing power of ozone and hydroxyl radical produced by the DBD system. Several intermediate products including 3-hydroxyl pyridine, fumaric acid, 2, 3-dihydroxypyridine, and oxalic acid were detected. Nitrogen was removed from the pyridine molecule to form nitrate. Through analysis of the degradation mechanism of pyridine, the oxidation pathway was deduced. The study provided a theoretical and experimental basis for the application of DBD strong ionization discharge in treatment of nitrogen heterocyclic compounds in drinking water.     

Biodegradation of imazapyr in typical soils in Zhejiang Province, China

The degradation of imazapyr in non-sterile and sterile soils from four sampling sites in Zhejiang, China was studied. The results showed that the half-lives of imazapyr in non-sterile soils were in the range of 30 to 45 d, while 81 to 133 d in sterile( by autoclaving) soils. It means the rate constants of imazapyr under non-sterile conditions were 2.3--4.4 times faster than that under sterile(by autoclaving)conditions, evidently indicating that the indigenous microorganisms in soil play an important role in the degradation of imazapyr. The different sterilization methods could result in different degradation rates of imazapyr. The heat of sterilization of soil largely decreased the degradation. However, the sterile treatment of soil by sodium azide had a different effect from that by autoclaving. Further more, the mechanism was also discussed. Biodegradation in four non-sterile soils accounted for 62% to 78% of imazapyr degradation. In contrast, less than 39% of imazapyr degradation was associated with chemical mechanisms. Therefore, the degradation mechanism was predominantly involved in biology including organisms and microorganisms in soil. Two imazapyr-degrading bacterial strains were isolated in enrichment culture technique and they were identified as Pseudomonas fluorescenes biotype [[ ( ZJX-5 ) and Bacillus cereus (ZJX-9),respectively. When added at a concentration of 50μg/g in mineral salts medium(MSM), ZJX-5 and ZJX-9 could degrade 81% and 87% imazapyr after 48h of incubation. For the treatment of incorporation of ZJX-5 or ZJX-9 into soil, the degradation rate enhanced 3-4 fold faster than that for control samples, which showed an important value in quick decontamination of imazapyr in soil.     

Degradation kinetics and mechanism of aniline by heat-assisted persulfate oxidation

Oxidation of aniline by persulfate in aqueous solutions was investigated and the reaction kinetic rates under different temperature, persulfate concentration and pH conditions were examined in batch experiments. The results showed that, the aniline degradation followed pseudo first-order reaction model. Aniline degradation rate increased with increasing temperature or persulfate concentration. In the pH range of 3 to 11, a low aniline degradation rate was obtained at strong acid system (pH 3), while a high degradation rate was achieved at strong alkalinity (pH 11). Maximum aniline degradation occurred at pH 7 when the solution was in a weak level of acid and alkalinity (pH 5, 7 and 9). Produced intermediates during the oxidation process were identified using liquid chromatography-mass spectrometry technology. And nitrobenzene, 4-4’-diaminodiphenyl and 1-hydroxy-1,2-diphenylhydrazine have been identified as the major intermediates of aniline oxidation by persulfate and the degradation mechanism of aniline was also tentatively proposed.     

Off-flavor compounds from decaying cyanobacterial blooms of Lake Taihu

The effect of cyanobacterial bloom decay on water quality and the complete degradation of cyanobacterial blooms in a short period were examined by an enclosure experiment in Gonghu Bay of Lake Taihu,China.Water quality parameters as well as taste and odor compounds during the breakdown of cyanobacterial blooms were measured.Results showed that the decay of cyanobacterial blooms caused anoxic water conditions,decreased pH,and increased nutrient loading to the lake water.The highest concentrations of dimethyl sulfide (DMS),dimethyl trisulfide (DMTS),and β-cyclocitral were observed in the anoxic water,at 62331.8,12413.3,and 1374.9 ng/L,respectively.2-Methylisoborneol was dominant during the live growth phase of cyanobacterial blooms,whereas DMS and DMTS were dominant during the decomposition phase.Dissolved oxygen,pH,and chlorophyll a were negatively correlated with DMS,DMTS,and β-cyclocitral,whereas total phosphorus,total nitrogen,and ammonium (NH4+-N) were positively correlated with DMS,DMTS,β-cyclocitral,and β-ionone.The experimental results suggested that preventing the anaerobic decomposition of cyanobacterial blooms is an important strategy against the recurrence of a malodor crisis in Lake Taihu.     

Heterogeneous Fenton-like degradation of 4-chlorophenol using iron/ordered mesoporous carbon catalyst

Ordered mesoporous carbon supported iron catalysts(Fe/OMC) were prepared by the incipient wetness impregnation method and investigated in Fenton-like degradation of 4-chlorophenol(4CP) in this work. XRD and TEM characterization showed that the iron oxides were well dispersed on the OMC support and grew bigger with the increasing calcination temperature. The catalyst prepared with a lower calcination temperature showed higher decomposition efficiency towards 4CP and H2O2, but more metals were leached. The effect of different operational parameters such as initial pH, H2O2 dosage, and reaction temperature on the catalytic activity was evaluated. The results showed that 96.1% of 4CP and 47.4% of TOC was removed after 270 min at 30°C, initial pH of 3 and 6.6 mmol/L H2O2. 88% of 4CP removal efficiency was retained after three successive runs, indicating Fe/OMC a stable catalyst for Fenton reaction. 4CP was degraded predominately by the attack of hydroxyl radical formed on the catalyst surface and in the bulk solution due to iron leaching. Based on the degradation intermediates detected by high performance liquid chromatography, possible oxidation pathways were proposed during the 4CP degradation.     

Anoxic biodegradation of dimethyl phthalate （DMP） by activated sludge cultures under nitrate-reducing conditions

Worldwide extensive use of plasticized plastics has resulted in phthalates pollution in different environment. Nitrates from industry and agriculture are also widely disseminated in the soils, natural waters and wastewaters. Dimethyl phthalate (DMP) biodegradation by activated sludge cultures under nitrate-reducing conditions was investigated. Under one optimized condition, DMP was biodegraded from 102.20 mg/L to undetectable level in 56 h under anoxic conditions and its reaction fitted well with the first-order kinetics. Using the high-performance liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LC-MS) analysis, mono-methyl phthalate (MMP) and phthalic acid (PA) were detected as the major intermediates of DMP biodegradation. When combined with the determination of chemical oxygen demand (CODCr) removal capacity and pH, DMP was found to be mineralized completely under anoxic conditions. The biodegradation pathway was proposed as DMP → MMP → PA → … → CO2 H2O.The molar ratio of DMP to nitrate consumed was found to be 9.0:1, which agrees well with the theoretical stoichiometric values of DMP biodegradation by nitrate-reducing bacteria. The results of the non-linear simulation showed that the optimum pH and temperature for the degradation were 7.56 and 31.4℃, respectively.     

焦化废水中几种含氮杂环有机物在A1-A2-O系统中的降解特性研究

在对焦化废水中有机物在A1－A2－O生物膜系统中降解转化规律进行分析的基础上，选取焦化废水中6种主要的含氮杂环化合物，吡啶，吲哚，喹啉，异喹啉，8－羟基喹啉，与苯酚共同配制成溶液，在A1－A2－O生物膜系统中运行，结果表明上述几种含氮杂环有机物在A1－A2－O 都可得到较完全的去除，它们在厌氧段的降解速率从大到小依次为，吲哚＞2－甲基喹啉＞8－羟基喹啉＞异喹啉＞喹啉＞吡啶。在厌氧条件下，吲哚和喹啉存在拮抗作用，而吡啶对喹啉有协同作用，啉啶的加入有利于改善由喹啉和吲哚之间产生的拮抗作用。     

新型无极准分子光源深度处理水相中含N-杂环化合物

采用微波激发Kr/I2混合气体产生的206 nm准分子紫外光降解水相含N-杂环化合物,考察了206 nm准分子光直接光解模拟喹啉和吲哚废水的效果.结果表明,初始浓度为20 mg.L-1的吲哚溶液,光照80 min时去除率达62.0%,150 min时TOC去除达50.7%.光照时间、初始浓度和溶液的pH值对喹啉的降解有一定的影响.相同条件下,喹啉的去除率和TOC损失率都明显低于吲哚.光解后的溶液经旋转蒸发提取,顶空注射进入气相色谱/质谱联用仪(GC/MS)定性分析,结果表明,光照下喹啉发生开环降解,生成了甲苯、二甲苯、酸、醛和酯类化合物,而吲哚降解过程中发生了聚合反应.最后,根据中间产物,推断了206 nm准分子光源光解喹啉和吲哚的机制.     

难降解有机物生物抑制特性的研究

对杂环化合物及多环芳烃的好氧生物降解抑制特性研究结果表明：咔唑、联苯等５种物质具有类似的抑制特性,表现在急性持久抑制及抑制强度大２方面,其抑制机理为不逆抑制;喹啉、吲哚等５种物质在高浓度时对苯酚的降解产生明显的初期抑制,历经诱导期,恢复期,最后进入正常降解期,其抑制机理为可逆抑制,萘的抑制属于竞争性抑制范畴。     

焦化废水中有机物在A1-A2-O生物膜系统中的降解机理研究

对焦化废水中有机物在A1 A2 O生物膜系统各段的降解进行了研究 .结果表明 ,废水中主要有机组份为苯酚类和含氮杂环类化合物 ,它们所占比例分别为 5 0 %和 4 0 % .经过厌氧酸化处理后 ,苯酚类中简单酚得到了较大程度的降解 ,随着苯酚甲基取代基数目的增加 ,降解率逐渐降低 ,对三甲酚则没有降解 ;简单的含氮杂环化合物如喹啉、异喹啉、吲哚、吡啶在厌氧过程中也得到了较大的降解 ,而有取代基的含氮杂环化合物则有所增加 ;喹啉和甲基喹啉的降解可生成羟基喹啉和甲基 2(1H)喹啉酮中间产物 .经过厌氧酸化段处理后 ,废水的BOD5 COD有较大提高 .厌氧出水的大部分有机物可在缺氧段得到降解 .最终出水中有机物基本上为大分子难降解物质 .     

6种含氮杂环化合物对发光细菌的毒性研究

研究了吲哚，吡啶，喹啉，异喹啉、2-甲基喹啉和8-羟基喹啉6种含氮杂环化合物对发光细菌的急性毒性作用及上述物质两两混合对发光细菌的联合毒性作用。结果表明，上述物质对发光细菌的EC50分别为11．75、591．50、24．30、8．24、52．26和0．88mg／L，毒性由强至弱依次为8-羟基喹啉、异喹啉、吲哚、喹啉、2-甲基喹、吡啶。所有物质两两混合的联合毒性作用均表现为相加作用。     

Fast photo-catalytic degradation of pyridine in nano aluminum oxide suspension systems

UV light can degrade pyridine to ammonia nitrogen at room temperature. The decomposition of pyridine under UV irradiation with the help of aluminum oxide powders was rarely studied. While with the assist of alumina, fast photo-catalytic degradation of pyridine to 100 percentage ammonia nitrogen was realized within an hour. The promising promotion phenomena were confirmed in opening other nitrogen heterocyclic compounds (NHCs) such as quinoline and 2,2′-bipyridine. Scanning electron microscopy images showed the alumina powder was about 100 nm in size. X-ray diffraction results indicated that the sample was mainly a-Al₂0₃. Specific surface area of the sample was about 280 m²/g determined by BET method. The optimum dosages of catalysts and effects of pH value were also tested. There was no clear absorbance of the alumina sample showed in the range of 200-420 nm. It is believed that the interaction between pyridine and alumina surface hydroxyl caused by chemisorptions weakened the carbon-nitrogen bond and led to the promotion of the decomposition.     

缺氧条件下含氮杂环化合物吲哚和吡啶的共代谢研究

以含氮杂环化合物吲哚和吡啶为研究对象,在传统的缺氧反硝化机理研究基础上,通过向配制废水中加入硝酸盐氮,研究吡啶和吲哚在缺氧条件下的共代谢作用.结果表明,吡啶和吲哚缺氧共代谢的最佳碳氮比为8.4～8.9之间.硝酸还原酶适宜作用的环境条件为:温度28℃,pH值7.0～7.5.吡啶的加入有利于硝酸还原酶活性的提高,吡啶对吲哚的缺氧降解有协同作用.在最佳碳氮比条件下,当吲哚起始浓度为150mg/L,吲哚和吡啶的浓度比例为1～10之间时,吲哚的降解符合零级动力学规律,反应过程中亚硝酸盐氮基本没有积累.当吡啶和吲哚的浓度比小于0.25时,随着吡啶浓度比例的提高,硝酸还原酶活性及吲哚降解速率的增长较快;当吡啶和吲哚的浓度比大于0.25时,硝酸还原酶活性及吲哚降解速率的增长变得比较缓慢.     

厌氧反硝化产甲烷体系中喹啉与吲哚共基质的降解特性

研究了厌氧反硝化产甲烷体系中,典型含氮杂环化合物喹啉、吲哚作为共基质碳源,厌氧生物对二者的降解特性,及群落分析.结果表明：在共基质条件下,喹啉的存在对吲哚的生物降解有抑制作用,且抑制随喹啉浓度的升高而升高;吲哚的存在对喹啉的生物降解有促进作用,但吲哚浓度过高（150mg/L）抑制了喹啉的降解;喹啉、吲哚共基质时,二者的降解都遵循零级反应动力学;通过GC-MS分析,喹啉的主要中间代谢产物分别为2（1H）喹诺酮与8-羟基-2（1H）喹诺酮;吲哚的主要代谢产物为2-吲哚酮与靛红;通过高通量测序对共基质体系的微生物群落进行分析,发现厌氧功能菌群得到富集,细菌菌门以变形菌门Proteobacteria为主,菌纲以Gammaproteobacteria和Betaproteobacteria为主,菌属以Acinetobacter,Candidimonas,Azospira,和Desulfomicrobium为主.     

不同共代谢基质对白腐菌降解吲哚的作用研究

选用氨氮、苯酚和喹啉作为吲哚的共代谢基质,通过白腐菌BP对共基质体系的降解研究了白腐菌在秸秆滤出液培养基中对不同共基质体系的代谢过程,并进行了动力学分析,考察了不同共代谢基质物质对白腐菌漆酶分泌和吲哚降解的影响.结果显示,不同降解体系中的白腐菌都可去除99%以上的吲哚.充分的氮源可提高白腐菌的活性和漆酶酶活的峰值;共基质苯酚和喹啉可以增加白腐菌漆酶产量,为吲哚的降解提供较多的电子,同时苯酚和喹啉也能得到较高的去除.在秸秆滤出液中,白腐菌在pH为6～8之间对吲哚都具有较强的降解能力.吲哚在白腐菌的代谢过程中,可能首先在吡啶环的2和3位发生一步羰基化.     

焦化废水中几种难降解有机物的厌氧生物降解特性

在试验室条件下,采用厌氧间歇试验,分别研究了焦化废水中几种有代表性的难降解有机物——喹啉、吲哚、吡啶、联苯的厌氧生物降解特性.文中突出了以厌氧预处理改善焦化废水中难降解有机物生物降解性的工程实用背景,对这四种有机物的厌氧处理的动力学特性、共基质作用、厌氧处理下去除效果的改善等,进行了较为深入的研究.