Predicting bioavailability of PAHs in field-contaminated soils by passive sampling with triolein embedded cellulose acetate membranes

Triolein embedded cellulose acetate membrane (TECAM) was used for passive sampling of the fraction of naphthalene, phenanthrene, pyrene and benzo[a]pyrene in 18 field-contaminated soils. The sampling process of PAHs by TECAM fitted well with a first-order kinetics model and PAHs reached 95% of equilibrium in TECAM within 20 h. Concentrations of PAHs in TECAM (C_TECAM) correlated well with the concentrations in soils (r² = 0.693-0.962, p < 0.001). Furthermore, concentrations of PAHs determined in the soil solution were very close to the values estimated by C_TECAM and the partition coefficient between TECAM and water (K_TECAM-w). After lipid normalization nearly 1:1 relationships were observed between PAH concentrations in TECAMs and earthworms exposed to the soils (r² = 0.591-0.824, n = 18, p < 0.01). These results suggest that TECAM can be a useful tool to predict bioavailability of PAHs in field-contaminated soils.     

以废纸为原料制备煤尘抑制剂的合成及应用

采用碱化、醚化法制备了以废纸为原料的煤尘抑制剂,借助FTIR、SEM、TG-DTA及XRF等手段对合成物进行了表征,并将其用于抑制煤尘进行性能测试。结果表明,羧甲基纤维素的取代度为0.69;选用羧甲基纤维素含量为0.5g/mL的煤尘抑制剂进行应用实验,效果最佳。9 h内,喷洒含有羧甲基纤维素的煤尘抑制剂的煤样表面已经结壳,抗七级风,抑尘率在130 h都可保持在99%以上。在较高温燃烧条件下,煤尘抑制剂以H2O和CO2的形式失去,不会产生有害物质。     

稻秆负荷与pH对稻秆厌氧发酵产酸系统启动过程的影响

为探讨稻秆负荷（即稻秆VS/污泥VSS）与发酵pH对稻秆厌氧发酵产酸系统启动过程产挥发性脂肪酸（VFAs）效果的影响,利用厌氧搅拌罐反应系统考察在不同的稻秆负荷（0.556、0.945、1.334和1.724 g/g）和不同的发酵pH（8.0、9.0和10.0）启动运行条件下的产酸性能,并分析了系统启动过程产酸与稻秆主要成分降解之间的关系。实验结果表明,VFAs浓度随稻秆负荷提高而增大,随发酵pH的升高而降低;发酵18 d时,发酵pH为9.0时,稻秆负荷1.334 g/g的产酸效果最好,VFAs浓度与稻秆产酸量分别为4 385.10 mg/L和2.19 gVFAs/g稻秆,此时半纤维素、纤维素和酸性洗涤木质素降解率分别为32.69%、22.53%和6.40%;稻秆负荷为0.945 g/g条件下,VFAs浓度在pH为8.0时达到最高值4 409.51 mg/L,此时稻秆降解量也最多,半纤维素、纤维素和酸性洗涤木质素降解率分别为28.60%、47.32%和22.69%。研究表明,稻秆负荷与发酵pH通过影响稻秆半纤维素、纤维素和木质素的降解影响稻秆厌氧发酵产酸的进程和效果。     

常温纤维素降解菌群的筛选及其特性初探

在改良PCS培养基的基础上,通过定期改变传代方法,从污泥、森林土、发酵腐熟牛粪、堆肥处理麦秆中筛选出1组纤维素分解能力强而稳定的纤维素混合菌群(代号为Xc),100 mL培养物在37 ℃静置培养5 d,对滤纸纤维素、脱脂棉、麦秆(片)、牛粪纤维降解率分别达到81%、41%、25%、40%.Xc在37、28 ℃分解滤纸时,分别在第5 天、第7 天时CMC酶活性最高,分别达到104.5、95.3 U·mL-1.在初始pH 5～9的培养基上接种均能表现出较强分解能力.采用变性梯度胶电泳(DGGE)法比较来源于不同时期菌群16S rDNA条带表明,菌群结构稳定.     

Degradation of corn stalk by the composite microbial system of MC1

The composite microbial system of MC1 was used to degrade corn stalk in order to determine properties of the degraded products as well as bacterial composition of MC1. Results indicated that the pH of the fermentation broth was typical of lignocellulose degradation by MC1, decreasing in the early phase and increasing in later stages of the degradation. The microbial biomass peaked on the day 3 after degradation. The MC1 efficiently degraded the corn stalk by nearly 70% during which its cellulose content decreased by 71.2%, hemicellulose by 76.5% and lignin by 24.6%. The content of water-soluble carbohydrates （WSC） in the fermentation broth increased progressively during the first three days, and decreased thereafter, suggesting an accumulation of WSC in the early phase of the degradation process. Total levels of various volatile products peaked in the third day after degradation, and 7 types of volatile products were detected in the fermentation broth. These were ethanol, acetic acid, 1,2-ethanediol, propanoic acid, butanoic acid, 3- methyl-butanoic acid and glycerine. Six major compounds were quantitatively analysed and the contents of each compound were ethanol （0.584 g/L）, acetic acid （0.735 g/L）, 1,2-ethanediol （0.772 g/L）, propanoic acid （0.026 g/L）, butanoic acid （0.018 g/L） and glycerine （4.203 g/L）. Characterization of bacterial cells collected from the culture solution, based on 16S rDNA PCR-DGGE analysis of DNAs, showed that the composition of bacterial community in MC1 coincided basically with observations from previous studies. This indicated that the structure of MC1 is very stable during degradation of different lignocellulose materials.     

羧甲基纤维素包覆纳米铁的制备及其分散性研究

纳米铁以其较高的活性和较小的尺寸适用于地下水氯代烃污染的原位修复。然而,为达到原位修复的目的,纳米铁必须在水中保持良好的分散性。研究以羧甲基纤维素为分散剂采用液相还原法制备纳米铁来改善其分散性。透射电镜观察得到羧甲基纤维素包覆纳米铁颗粒呈离散状态,且羧甲基纤维素含量为64.2wt%的纳米铁粒径为20nm左右;而未包覆纳米铁颗粒有明显的棱角且粒径为50～100nm。傅立叶红外光谱测试表明羧甲基纤维素通过其分子中羧基的单齿配位作用结合在纳米铁表面。沉降曲线表明,在1mmol/LNaHCO3水溶液中羧甲基纤维素包覆纳米铁的沉降曲线是斜率为-10-4～-10-5s-1的直线,其分散性比未包覆纳米铁颗粒有较大改善。     

分解纤维素的高温真菌筛选及其对烟杆的降解效果

为研制促进烟杆堆肥的微生物菌剂,进行了分解纤维素的高温真菌筛选.结果表明,从不同原料腐熟堆肥中筛选到4株降解纤维素的高温真菌,它们均能在以羧甲基纤维素钠(CMC-Na)或烟杆粉末为唯一碳源的培养基上生长.菌株在2～5d内可长满CMC-Na-刚果红平板和烟杆粉末培养基.菌株摇瓶培养时2d可达到产酶高峰,酶活(CMCase)超过10U.菌株对烟杆的降解效果较好,7d内的降解率最高可达42.2%,对烟杆中的纤维素、半纤维素和木质素的分解率分别可达52.7%、47.9%和37.6%.     

UASB反应器处理CMC废水的启动特性研究

采用上流式厌氧污泥床(UASB)反应器,以高浓度羧甲基纤维素(CMC)废水为处理对象,研究了中温条件下UASB反应器的启动、颗粒污泥特性和废水处理效果.结果表明,采用接种颗粒污泥与消化污泥的混合泥进行培养,并逐步提高进水CMC废水浓度,运行80 d后,可实现UASB反应器的启动;当进水COD值达到4 000 mg/L,容积负荷6.86 kg/(m3.d),COD去除率在80%以上;反应器内污泥实现颗粒化,且颗粒污泥的比产甲烷活性良好.     

醋酸纤维素包埋非水溶性介体催化强化生物反硝化特性

利用醋酸纤维素包埋法固定非水溶性醌类介体,研究其催化强化Paracoccus versutus菌株GW1的反硝化作用。结果表明,醌浓度在26.7 mmol/L时,固定化蒽醌(AQ)、1-氯蒽醌(1-AQ)、2-氯蒽醌(2-AQ)、1,5-二氯蒽醌(1,5-AQ)、1,8-二氯蒽醌(1,8-AQ)和1,4,5,8-四氯蒽醌(1,4,5,8-AQ)催化反硝化效率依次为:1,5-AQ1,8-AQ1,4,5,8-AQAQ1-AQ空白对照2-AQ。反应10 h时,1,5-AQ可使硝酸盐去除率比空白对照提高1.84倍;硝酸盐氮反硝化动力学拟合为零级反应,其速率常数Kx随1,5-AQ浓度的增加均呈线性增加(Kx=0.1885C1,5-AQ+8.378);水中溶解氧会降低GW1菌反硝化的效果;投加1,5-AQ的反硝化体系中亚硝酸盐积累的最大值比不投加介体的低48.3%;醋酸纤维素介体小球经过4次的重复利用,催化效果始终是空白对照的1.5倍以上。醋酸纤维素固定化非水溶性醌可以有效加速生物反硝化,表明其是一种较优的醌固定化方法,具有良好的应用价值。     

一组高效稳定纤维素分解菌复合系MC1的筛选及功能

从4种堆肥样品中分别筛选出纤维素分解能力较强的4组混合菌,再以酸碱反应互补的原则重新优化组合并驯化成1组纤维素分解能力非常强而稳定的纤维素分解菌复合系MC1.100mL培养物在50℃静止培养72h,分别可分解0.48g滤纸、0.49g脱脂棉、0.19g麦秆和0.08g锯末.分解滤纸时,第24h CMC糖化力最高,为122.3U·mL^-在初始pH4～10的不同培养基上接种,均能把pH调到中性,最后稳定在8.0～8.5之间.在连续投放滤纸情况下纤维素分解能力稳定保持20d以上,其发酵液的pH在有滤纸时稳定在6.0～6.5之间,没有滤纸时稳定在8.0～8.5之间.