Bacterial inactivation,DNA damage,and faster ATP degradation induced by ultraviolet disinfection

• Long amplicon is more effective to test DNA damage induced by UV. • ATP in bacteria does not degrade instantly but does eventually after UV exposure. • After medium pressure UV exposure, ATP degraded faster. The efficacy of ultraviolet (UV) disinfection has been validated in numerous studies by using culture-based methods. However, the discovery of viable but non-culturable bacteria has necessitated the investigation of UV disinfection based on bacterial viability parameters. We used quantitative polymerase chain reaction (qPCR) to investigate DNA damage and evaluated adenosine triphosphate (ATP) to indicate bacterial viability. The results of qPCR effectively showed the DNA damage induced by UV when using longer gene amplicons, in that sufficiently long amplicons of both 16S and gadA indicated that the UV induced DNA damages. The copy concentrations of the long amplicons of 16S and gadA decreased by 2.38 log/mL and 1.88 log/mL, respectively, after exposure to 40 mJ/cm² low-pressure UV. After UV exposure, the ATP level in the bacteria did not decrease instantly. Instead it decreased gradually at a rate that was positively related to the UV fluence. For low-pressure UV, this rate of decrease was slow, but for medium pressure UV, this rate of decrease was relatively high when the UV fluence reached 40 mJ/cm². At the same UV fluence, the ATP level in the bacteria decreased at a faster rate after exposure to medium-pressure UV.     

水质工程用紫外光消毒器的CFD数值模拟

紫外光消毒法是一种重要的污水深度处理方法,消毒器内部辐射强度的分布情况、微生物的停留时间及其运动轨迹对灭菌效果起着至关重要的作用。本文首次在国内系统介绍了采用计算流体动力学(CFD)手段对紫外光消毒器进行数值模拟研究的理论基础和技术路线,指出辐射强度的计算和停留时间的确定是其中的关键。以特定结构的紫外光消毒器为对象,对其内部流场进行了模拟计算,讨论了挡板位置不同所引起的消毒器内部速度场的变化情况;应用离散坐标辐射模型(DO)对紫外光辐射强度分布进行了模拟,同时加入离散粒子模型(DPM)来模拟消毒器内微生物的停留时长和运动轨迹,为最终计算微生物所受紫外光辐射剂量奠定了坚实的基础。     

蛋白酶对水环境中病毒的灭活作用

以大肠杆菌噬菌体T₄作为模式病毒,研究了蛋白酶对病毒的灭活作用.试验结果表明:蛋白酶灭活病毒的效果明显. 适宜条件下,67.5u/mL的蛋白酶K处理1h对纯水中病毒(6.2×10⁵PFU/L)和生活污水中病毒(7.2×10⁵PFU/L)灭活率分别达到了99.4%和49.4%,处理3h的灭活率分别是>99.9%和81.1%;工业蛋白酶1398在75.0u/mL酶浓度下处理1h对纯水水中病毒(1.7×10⁵ PFU/L)灭活率达到74.4%.pH和温度对病毒灭活效果的影响不明显.     

新型含氮消毒副产物的生成机制及毒性研究进展

含氮消毒副产物(N-DBPs)具有很高的生物毒性和致癌性,近年来受到广泛关注。本文对目前N-DBPs的研究进展进行了概述,重点总结了典型N-DBPs包括卤乙腈(HANs)、卤代硝基甲烷(HNMs)、卤代乙酰胺(HAcAms)和亚硝胺(NAs)的生成机制;并归纳了N-DBPs的毒性效应和毒性机制。根据N-DBPs的生成途径,应该重点控制水中含胺类氮源前体物,并优化设计消毒剂种类和投加方式,在控制病原体的前提下,尽量削减高毒性N-DBPs的生成。本研究旨在为控制消毒副产物生成、提高饮用水水质提供理论参考。     

饮用水消毒剂二氧化氯研究进展

随着人们对氯消毒副产物毒性的认识,寻求替代消毒荆成为了水处理行业重要的研究课题。本文概述二氧化氯在饮用水消毒应用中的特点,对其在水厂实际应用中的几个热点问题进行研究与分析,最后对其研究发展前景进行了展望。     

有机肥施用下稻田田面水中消毒副产物前体物的赋存规律

稻田有机肥输入会使田面水含有含量的溶解性有机碳(DOC).溶解性有机物(DOM)是具有三致效应的消毒副产物(DBPs)的前体物,而DOC是用于表征DOM浓度的一个指标.本研究旨在评估水稻田田面水的三卤甲烷(THMs)前体物的生成反应性,解析猪粪有机肥对于THMs前体物从水稻田输出的潜在影响.于水稻种植季选取4个猪粪施用梯度(以C计,下同)(0[对照],714.1[低],1428.2[中]与2142.3[高]kg·hm-2),检测了稻田田面水中的DOC,UVA254与三卤甲烷生成潜能(THMFP).结果表明,3个指标两两之间呈线性相关性.田面水中以上3个指标都与有机肥施用量呈正相关性.在施肥后的7d内,DOC的输出潜能降低了32.9%至47.5%.有机肥施用与预期的降雨或灌溉之间的时间间隔相隔一周以上,将能在满足作物营养需求的条件下降低消毒副产物前体物输出的风险,使稻田土壤成为DOC的汇而非DOC输出至周边水体的源.     

海水淡化超滤-反渗透工艺沿程溴代消毒副产物变化规律

研究了海水淡化超滤-反渗透(UF-RO)工艺沿程有机物和溴代消毒副产物(Br-DBPs)变化特征.该海水中含有较高浓度的Br-(45.6~50.9 mg·L-1)和较多的芳香类化合物[比紫外吸收值SUVA为3.6~6.0 L·(mg·m)-1];色氨酸类芳香族蛋白质、富里酸类有机物和溶解性微生物代谢产物是海水中主要的荧光特征有机物.UF-RO工艺进水海水经Na Cl O消毒后,DBPs的种类和浓度显著增加,且增加的主要为Br-DBPs,其中三溴甲烷(CHBr3)占总三卤甲烷(THMs)的70.48%~91.50%,二溴乙酸(Br2CHCO2H)占总卤乙酸(HAAs)的81.14%~100%,二溴乙腈(C2HBr2N)占总卤乙腈(HANs)的83.77%~87.45%.UF膜对THMs、HAAs和HANs的去除率分别为36.63%~40.39%、73.83%~95.38%和100%.RO膜可以完全去除HAAs,但是对THMs不能完全去除.进水海水的抗雌激素活性为0.35~0.44 mg·L-1,氯消毒后增加了32%~69%.海水淡化UF-RO系统生成的DBPs和其他生物毒性物质最终被截留到了UF浓水和RO浓水中.     

Development and modelling of realistic retrofitted Nature-based Solution scenarios to reduce flood occurrence at the catchment scale

Decentralized Nature-based Solutions such as Urban Green Infrastructures (UGI) are increasingly promoted to reduce flooding in urban areas. Many studies have shown the effectiveness of flood control of UGI at a plot or neighbourhood level. Modelling approaches that extrapolate their flood reducing impact to larger catchment scales are often based on a simplistic assumption of different percentages of UGI implementation. Additionally, such approaches typically do not consider the suitable space for UGI and potential implementation constraints. This study proposes a scenario development and modelling approach for a more realistic upscaling of UGI based on empirical insights from a representative neighbourhood. The results from this study, conducted in the metropolitan area of Costa Rica, show that upscaling the full potential for UGI could significantly reduce surface runoff, peak flows, and flood volumes. In particular, the permeable pavement has the highest potential for flood reducing in public space while cisterns perform best at the property level. These results can guide the formation of policies that promote UGI.Supplementary InformationThe online version of this article (10.1007/s13280-020-01493-8) contains supplementary material, which is available to authorized users.     

焦化废水尾水O3氧化消除消毒副产物生成潜能的影响分析

焦化废水经生化处理后的尾水中含有多种溶解性有机物(DOM),可能成为消毒副产物的前体物,进而影响受纳水体下游给水厂的水质安全.因此,对焦化废水外排水(尾水)的消毒副产物生成潜能进行了分析,以实际焦化废水厂尾水为基质,采用气相色谱(GC)考察了O3氧化深度处理前后卤乙腈和三卤甲烷的生成潜能,并结合分子质量分布法和三维荧光光谱法分析了O3氧化处理尾水过程中前体物的转化规律.GC结果表明,焦化废水尾水各个分子质量范围的卤乙腈和三卤甲烷生成潜能分别达到1950.5～3965.1μg.L-1和1498.2～2571.2μg.L-1,表明工业废水排放之前需要考虑其对水体消毒副产物生成潜能的贡献.O3氧化作用可以实现尾水中消毒副产物前体物的削减,相同反应时间的条件下O3浓度越高其削减越有效.溶解性有机碳(DOC)及在254nm波长下的吸光度值(UV254)分析结果表明,O3氧化能部分矿化尾水中的有机物,并优先分解不饱和芳香性有机组分.分子质量和荧光光谱分析结果表明,O3氧化优先矿化小分子组分(<1kDa),并将尾水中大分子有机物分解为小分子(<1kDa),对活泼基团进行预氧化,从而实现氯消毒副产物生成潜能的削减.