Sequential UV-biological degradation of chlorophenols

The sequential UV-biological degradation of a mixture of 4-chlorophenol (CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP), and pentachlorophenol (PCP) was first tested with each pollutant supplied at an initial concentration of 50 mg l(-1). Under these conditions, the chlorophenols were photodegraded in the following order of removal rate: PCP>TCP>DCP>CP with only CP and DCP remaining after 40 h of irradiation. The remaining CP (41 mg l(-1)) and DCP (13 mg l(-1)) were then completely removed by biological treatment with an activated sludge mixed culture. Biodegradation did not occur in similar tests conducted with a non-irradiated mixture due to the high microbial toxicity of the solution. UV treatment lead to a significant reduction of the phytotoxicity to Lipedium sativum but no further reduction of phytotoxicity was observed after biological treatment. Evidence was found that the pollutants were partially photodegraded into toxic and non-biodegradable products. When the pollutants were tested individually (initial concentration of 50 mg l(-1)), PCP, TCP, DCP, 4-CP were photodegraded according to first order kinetic model (r2>99) with half-lives of 2.2, 3.3, 5.7, and 54 h, respectively. The photoproducts were subsequently biodegraded. This study illustrates the potential of UV as pre-treatment for biological treatment in order to remove toxicity and enhance the biodegradability of organic contaminants. However, it also shows that UV treatment must be carefully optimized to avoid the formation of toxic and/or recalcitrant photoproducts and results from studies conducted on single contaminants cannot be extrapolated to mixtures.     

负载型磷酸氧钒低温脱硝催化剂的制备及其抗硫抗水性能

针对目前低温脱硝催化剂抗硫抗水性较差的不足,以TiO2为载体负载活性组分V2O5,利用磷酸调控表面酸性,制备了磷酸氧钒催化剂VPO/TiO2,并实验研究了SO2和水蒸气对其脱硝活性的影响。结果表明：控制P与V的摩尔比为1/5,活性组分(VPO)负载量为10%,焙烧温度为400 ℃时,催化剂脱硝性能最好,180~400 ℃温度范围内脱硝率高于98%;反应温度为200 ℃,烟气中SO2体积分数为200×10-6~800×10-6和水蒸气体积分数为4%时,催化剂的活性无明显下降。添加磷酸能够促使催化剂表面生成VOPO4、(VO)2P2O7及V4+/V5+氧化还原电对,提高了催化剂的低温脱硝活性。磷酸可增强催化剂的表面酸性,减少了SO2的表面吸附及其与活性组分的反应。另外,催化剂表面以介孔为主,可提高未被水分子占据的活性位点量,FT-IR图谱显示抗硫抗水测试后的VPO/TiO2表面未发现有硫酸根生成,VPO/TiO2表现出较强的抗SO2和水蒸气毒化的性能。负载型磷酸氧钒催化剂具有较高的脱硝活性和较强的抗硫抗水性能。     

Analysis of halogenated polycyclic aromatic hydrocarbons in urban air, snow and automobile exhaust

Urban air, snow and automobile exhaust samples were extensively cleaned up by open column liquid chromatography. The appropriate fractions were analysed for halogenated polycyclic aromatic hydrocarbons (XPAH) by gas chromatography/negative chemical ionization mass spectrometry (GC/NCIMS). XPAH were found in all three sample types. A urban air sample was found to contain chlorinated pyrenes, fluoranthenes and benzopyrene and brominated pyrenes and fluoranthenes. Furthermore, the concentration of 1-chloropyrene in that air sample was estimated to be 10 pg/m³. XPAH were also found in snow samples taken in the vicinity of a motor-way. Ethylene dibromide and ethylene dichloride, are probably the source of the halogen atoms in the XPAH detected in car exhaust.     

乙二胺还原的氧化石墨烯对镉离子的动态吸附

以乙二胺(EDA)还原氧化石墨烯(GO)制得一种吸附剂材料,即还原态氧化石墨烯(RGO)。考察了动态条件下Cd2+溶液的初始浓度、流速及吸附床高度对穿透曲线的影响,同时利用Bed-Depth-Service Time(BDST)模型对吸附床高度与穿透时间的关系进行线性拟合分析,研究了RGO对Cd2+溶液的动态吸附性能。结果表明,RGO可以有效地去除水溶液中的Cd2+,随着吸附床高度的增加,离子的去除率增大,穿透时间延长;当溶液初始浓度增大时穿透时间缩短,离子的去除率减小;而溶液的流速加快,穿透时间和去除率都相应减小。吸附床高度与穿透时间的关系可用BDST模型较好地进行描述,预测新的操作条件下的穿透时间与实验值误差均小于5%。     

TiO2@碳纳米管吸附去除盐酸四环素

采用静电组装法制备了TiO2@碳纳米管复合吸附剂,用以除去水中的盐酸四环素。通过FE-SEM、EDS和XRD进行表征,考察了pH、初始浓度和吸附剂用量对吸附过程的影响,研究了吸附动力学、等温模型和热力学,并对吸附剂的再生进行了评价。结果表明,复合吸附剂对盐酸四环素的最大饱和吸附量为52.33 mg/g;最佳吸附pH值为6,强酸不利于吸附;当初始浓度在15~60 mg/L范围内时,吸附量随着初始浓度的增大而增加;当吸附剂投加量为0.50 g/L时,吸附效率最高。吸附过程符合准二级动力学模型和Langmuir等温模型。热力学参数ΔG H >0,表明该吸附过程是自发、吸热过程。H2O2-TiO2光催化协同效应可有效完成吸附剂的再生。     

基于异养-硫自养反硝化耦合技术的陶粒-硫磺混合生物填料对城市污水处理厂尾水的深度脱氮

针对城市污水处理厂脱氮能力的不足,设计了2种不同体积比的陶粒-硫磺混合生物填料反应器(陶粒与硫磺的体积比分别为2∶1和5∶1),并用其对城市污水处理厂尾水进行了深度处理。结果表明,陶粒与硫磺体积比为2∶1的混合生物填料反应器(R2,高硫耦合组)在C/N为4,HRT为4 h的条件下处理模拟废水时脱氮效率最高,TN平均去除率和平均出水质量浓度分别为(92.62±1.36)%和(2.39±0.22) mg∙L^-1。相比于R1(异养对照组),R2在保证脱氮效率的同时,碳源投加量更少;此外,R2在最佳条件下促进了体系内反硝化微生物群落Thauera(陶厄氏菌属)和Thiobacillus(硫杆菌属)的生长,二者的相对丰度之和为39.13%。     

半焦吸附养殖废水中的重金属

采用生物质半焦作为吸附剂处理养殖废水中的重金属,并对半焦吸附重金属的吸附容量及吸附效率进行了分析和评估。实验结果表明,生物质半焦对养殖废水中Cu、Zn、Pb和Cd 4种重金属具有较好的吸附效果,吸附容量分别为22.4、19.03、17.30和16.94 mg/g,且吸附率均达到70%以上,氮磷的影响吸附不超过30%。重金属离子在半焦表面上的吸附过程符合Langmuir等温吸附模型,且主要为单分子层表面吸附。由此生物质半焦作为廉价高效的吸附剂处理养殖废水中重金属技术上可行,为养殖废水中重金属吸附研究及生物质半焦资源化利用提供新途径。     

Health risk assessment of heavy metals in soil-plant system amended with biogas slurry in Taihu basin,China

Biogas slurry is a product of anaerobic digestion of manure that has been widely used as a soil fertilizer. Although the use for soil fertilizer is a cost-effective solution, it has been found that repeated use of biogas slurry that contains high heavy metal contents can cause pollution to the soil-plant system and risk to human health. The objective of this study was to investigate effects of biogas slurry on the soil-plant system and the human health. We analyzed the heavy metal concentrations (including As, Pb, Cu, Zn, Cr and Cd) in 106 soil samples and 58 plant samples in a farmland amended with biogas slurry in Taihu basin, China. Based on the test results, we assessed the potential human health risk when biogas slurry containing heavy metals was used as a soil fertilizer. The test results indicated that the Cd and Pb concentrations in soils exceeded the contamination limits and Cd exhibited the highest soil-to-root migration potential. Among the 11 plants analyzed, Kalimeris indica had the highest heavy metal absorption capacity. The leafy vegetables showed higher uptake of heavy metals than non-leafy vegetables. The non-carcinogenic risks mainly resulted from As, Pb, Cd, Cu and Zn through plant ingestion exposure. The integrated carcinogenic risks were associated with Cr, As and Cd in which Cr showed the highest risk while Cd showed the lowest risk. Among all the heavy metals analyzed, As and Cd appeared to have a lifetime health threat, which thus should be attenuated during production of biogas slurry to mitigate the heavy metal contamination.     

微气泡催化臭氧化深度处理制药废水的效果及DOM组分特性的变化

采用镁铝层状双氢氧化物(MAL)微气泡催化臭氧化(MAL/MB/O₃)体系深度处理实际制药废水,考察了该体系对溶解性有机物(DOM)的深度去除性能及DOM组分的变化特性,并与普通气泡臭氧化(CB/O₃)、普通气泡催化臭氧化(MAL/CB/O₃)、微气泡臭氧化(MB/O₃)工艺进行了比较。结果表明,MAL/MB/O₃处理性能优于CB/O₃、MAL/CB/O₃和MB/O₃,在臭氧投加总量与处理废水初始COD值之比为0.6、气流量0.5 L·min⁻¹、催化剂投加量0.5 mg·L⁻¹的条件下,整体COD去除率可达49.79%,COD去除量与臭氧消耗量的比值为0.83,废水的可生化性得到了一定改善,生物毒性显著下降。废水DOM中疏水性组分氧化去除率高于亲水性组分。臭氧直接氧化可去除疏水性组分,而亲水性组分去除主要依赖HO·氧化。MAL/MB/O₃对DOM的去除效率最高,可达到52.51%,其中疏水性组分整体去除率56.67%,亲水性组分整体去除率46.93%。废水DOM在氧化处理中存在官能团向酸性基团转化、类腐殖质向类富里酸和类胡敏酸转化、其他组分向亲水性酸(HIA)组分转化的趋势。MAL/MB/O₃强氧化能力对于DOM组分不饱和结构和荧光结构的破坏作用最为显著。以上研究结果可为制药废水深度处理提供参考。     

生物强化水解酸化过程前后微生物群落结构变化

通过利用生物强化技术提高水解酸化处理模拟印染废水的处理效果,包括共基质强化和菌剂强化两个方面。菌剂和共基质强化结果表明,菌剂A和菌剂B的加入将脱色率分别提高了2.33%和7.20%,当不加碳源时,脱色效果比较差(低于6.00%),而蔗糖的加入能提高脱色率至45.29%。利用PCR-DGGE技术追踪生物强化前后微生物群落结构信息,结果表明,菌剂和共基质的加入都对水解酸化池的微生物群落结构有较大影响。菌剂A和B强化后,水解酸化池的微生物多样性指数H(Shannon Weaver)由2.38分别增长到2.56和2.69,而共基质调控使得H由2.94增加到3.16。菌剂强化后,优势菌厚壁菌(Firmicutes)得到强化。通过共基质强化,优势菌拟杆菌(Bacteroidetes)和厚壁菌(Firmicutes)得到强化,它们可能在染料降解中起到重要作用。