四氯化碳的生产与应用及其淘汰策略

四氯化碳是一种消耗臭氧层物质,其生产和消费都面临着严峻的淘汰形势.简要叙述了四氯化碳的生产技术,以四氯化碳为原料生产大宗化学品和精细化学品的转化技术,四氯化碳作为化工助剂在我国的应用情况以及相应的淘汰方法和技术进展.     

EuroBionet: a pan-European biomonitoring network for urban air quality assessment

EuroBionet, the 'European Network for the Assessment of Air Quality by the Use of Bioindicator Plants', is an EU-funded cooperative project currently consisting of public authorities and scientific institutes from 12 cities in 8 countries. In 2000, the bioindicator plants tobacco (Nicotiana tabacum Bel W3), poplar (Populus nigra 'Brandaris'), spiderwort (Tradescantia sp. clone 4430), Italian rye grass (Lolium multiflorum italicum) and curly kale (Brassica oleracea acephala) were exposed to ambient air at 90 monitoring sites according to standardised methods. Visible injuries and growth parameters were assessed and the accumulation of toxic substances in leaves determined. The exposure of tobacco resulted in a gradient with low levels of ozone-induced foliar injury in N and NW Europe, and medium to high values in the southern and central regions. The results of heavy metal and sulphur analyses in rye grass samples generally showed low to very low sulphur and low to medium heavy metal concentrations in leaves. In some cities, however, local hot spots of heavy metal contamination were detected. Analyses of the PAH contents in curly kale leaves gave low to medium values, with locally elevated levels at traffic-exposed sites.     

异养协同硫自养ABR系统还原高浓度高氯酸盐

构建新型异养硫自养ABR反应器,以处理含高浓度高氯酸盐（ClO₄^-）废水,并探讨该工艺对不同浓度ClO₄^-的还原性能及硫酸盐（SO₄^2-）的产生规律,同时解析ABR系统内生物量及胞外聚合物（EPS）的变化特性.结果表明：在HRT=12h,进水ClO₄^-浓度为300mg/L时,去除率可达99.60%,出水SO₄^2-浓度稳定在150mg/L内.进水pH值为7.8~8.0,随着还原ClO₄^-浓度的升高,异养段出水pH值逐渐升高至8.0~8.3,自养段pH值则逐渐降低至6.6~6.9,异养协同硫自养ABR系统可实现酸碱的平衡.此外,提高进水ClO₄^-浓度可促进EPS的分泌,且异养段第一格室微生物分泌的EPS最多,其含量可达到102.46mg/（g·vss）.EPS的分泌可以形成保护层以抵制外界的压力,同时也起到储备碳源和能源的作用.     

Nitrate removal and extracellular polymeric substances of autohydrogenotrophic bacteria under various pH and hydrogen flow rates

In recent years there has been an increasing interest in the use of autohydrogenotrophic bacteria to treat nitrate from wastewater. However, our knowledge about the characteristics of extracellular polymeric substances (EPS) releasing by these activities is not yet very advanced. This study aimed to investigate the change in EPS compositions under various pH values and hydrogen flow rates, taking into consideration nitrogen removal. Results showed that pH 7.5 and a hydrogen flow rate of 90 mL/min were the optimal operating conditions, resulting in 100% nitrogen removal after 6 hr of operation. Soluble and bound polysaccharides decreased, while bound proteins increased with increasing pH. Polysaccharides increased with increasing hydrogen flow rate. No significant change of bound proteins was observed at various hydrogen flow rates.     

Purification and molecular weight distribution of a key exopolysaccharide component of Bacillus megaterium TF10

Extracellular polymeric substances (EPS) are organic metabolic compounds excreted by microorganisms. They largely impact microbial aggregate structures and functions. Extracellular polysaccharides (EP) in EPS are responsible for the formation of microbial aggregates. In this work, we successfully separated and characterized EP from EPS of the bacterium Bacillus megaterium TF10. Extraction of EP from EPS was optimized using Sevag''s reagent. Chemical characteristics, functional groups, and molecular weight (MW) distribu-tion of EP were compared with the harvested EPS and soluble microbial products (SMP). We found that the polymers of lower MW and free proteins were successfully removed by Sevag''s reagent. The higher MW components of EPS were predominantly polysaccharides, while the polymers of lower MW tended to secrete to the supernatant and were described as SMP. A part of the proteins in the EP was polysaccharide-bonded. Our results can be further used in elucidating the complex flocculation mechanisms in which EP play a major role.     

Insights into sludge granulation during anaerobic treatment of high-strength leachate via a full-scale IC reactor with external circulation system

In this study, a full-scale internal circulation(IC) reactor coupled with an external circulation system was developed to treat high-strength leachate from a municipal solid waste(MSW)incineration plant, in which anaerobic sludge granulation was intensively investigated. Results showed that the IC reactor achieved excellent treatment performance under high organic loading rates(OLR) of 21.06–25.16 kg chemical oxygen demand(COD)/(m3? day). The COD removal efficiency and biogas yield respectively reached 89.4%–93.4% and 0.42–0.50 m3/kg COD.The formation of extracellular polymeric substances(EPS) was closely associated with sludge granulation. Protein was the dominant component in sludge EPS, and its content was remarkably increased from 21.6 to 99.7 mg/g Volatile Suspended Solid(VSS) during the reactor operation. The sludge Zeta potential and hydrophobicity positively correlated with the protein/polysaccharide ratio in EPS, and they were respectively increased from-26.2 m V and 30.35% to-10.6 m V and 78.67%, which was beneficial to microbial aggregation. Three-dimensional fluorescence spectroscopy(3 D-EEM) and Fourier transform infrared spectroscopy(FT-IR)analysis further indicated the importance of protein-like EPS substances in the sludge granulation. Moreover, it was also found that the secondary structures of EPS proteins varied during the reactor operation.     

Fe2+和零价铁活化过一硫酸盐降解酸性橙7

采用环境友好的Fe~(2+)和零价铁(ZVI)作活化剂,活化过一硫酸盐(PMS)来降解水中酸性橙7(AO7).结果表明,在Fe~(2+)-PMS体系中,AO7的降解效果不佳,但通过添加适量的络合剂,AO7的去除率会大幅提高.ZVI在PMS存在下被腐蚀,并能够缓慢、持续不断地释放Fe~(2+).ZVI-PMS体系可以在比较宽泛的pH范围(3～9)有效、快速地降解AO7,并且在酸性条件下降解速率较快.淬灭实验结果显示,硫酸根自由基(SO_4~(·-))对AO7的降解起主要作用.除了Cl~-和高浓度(50 mmol·L~(-1))的NO_3~-能够促进AO7的降解外,其他水中共存的阴离子对AO7在ZVI-PMS体系中的降解具有抑制作用,而腐殖酸(HA)则无明显影响.AO7在超纯水中的去除率高于其他实际水体,但反应90 min后,污水厂出水过滤水和胶体浓缩液中的AO7去除率也可高达98.6%和87.6%,说明ZVI-PMS可能可以有效地去除含有较高DOC含量的污水中的AO7.利用GC-MS检测到辐照后溶液中有3种中间产物,推测主要是通过AO7偶氮键断键后的中间产物进一步氧化形成.此外,TOC在一定程度上降低,说明部分AO7被矿化.     

溶菌酶和硫酸铝联用优化污泥脱水性能的研究

以污泥沉降体积、污泥比阻和污泥泥饼含水率为指标,考察了溶菌酶和硫酸铝联用时加药方式和加药剂量对活性污泥沉降性能及脱水性能的影响。结果表明,先投加溶菌酶后投加硫酸铝时污泥的脱水性能更佳,硫酸铝和溶菌酶的最佳投加量均为0.10 g/g TS(总固体),此时,污泥泥饼含水率和污泥比阻分别可达71.84%和0.68×1012m/kg,相比于硫酸铝单独调理分别降低了约5%和0.23×1012m/kg。污泥胞外聚合物(EPS)含量分析表明,溶菌酶和硫酸铝联用时显著降低了污泥中LB-EPS(松散附着性EPS)含量,在最佳投量下可将原污泥的LB-EPS中的蛋白质和多糖依次从(13.44±2.11)mg/L和(23.97±3.44)mg/L降至(1.72±0.32)mg/L和(8.69±0.15)mg/L,表明联合处理使得EPS中的水分得到释放,提高了脱水性能。     

白腐真菌组合培养提高漆酶酶活的作用机制研究

采用白腐真菌组合培养的方式提高漆酶酶活,并对组合后菌株相互作用机制进行了研究.菌株55(Trametes trogii)和菌株m-6(Trametes versicolor)组合后漆酶酶活较菌株55和m-6分别提高了24.13倍和4.07倍;组合后菌株间不存在抑制作用;平板培养时,两菌株菌丝生长止于菌丝交界处,该处漆酶酶活最高并分泌褐色色素;液体培养时,菌株m-6对组合后漆酶酶活的提高起着更为重要的作用:向菌株55的培养物中添加菌块m-6,其酶活比向菌株m-6培养物中添加菌块55时的酶活高7.03倍,并且菌株m-6胞外物对菌株55的漆酶分泌也有明显的刺激作用,其中加入20 mL过滤灭菌胞外物可使菌株55漆酶酶活提高6.79倍,而且胞外物高温灭菌后仍能刺激菌株55的漆酶分泌,加入20mL后酶活比对照高4.60倍;Native-PAGE活性染色结果表明组合后同工酶种类未发生变化,但有3种同工酶的浓度升高.     

曝气强度对膜生物反应器污泥混合液可滤性的影响

主要研究了曝气强度对膜生物反应器(MBR)膜污染的影响.2套MBR采用恒流出水模式连续运行60 d,曝气强度分别为500及100 L/h,应用死端过滤装置来检测不同阶段污泥混合液的可滤性.实验中对不同曝气强度下的溶解性微生物代谢产物(SMP)分子质量分布、颗粒粒径分布、胞外聚合物(EPS)含量进行了测定.结果表明,过高的曝气强度将恶化污泥混合液的可滤性,增加了膜污染速率.进一步研究表明,曝气强度的增加导致了污泥混合液上清液中相对分子质量>10000的SMP浓度的增加,此部分大分子有机物浓度直接影响了污泥混合液的可滤性.过高的曝气强度也导致了污泥絮体中1～10μm细小颗粒和EPS含量的增加.