超声灭活水中隐孢子虫影响因素及机制

采用超声灭活隐孢子虫卵囊,超声频率为19.8kHz,功率为151W,温度控制在(20±1)℃, 探讨了浊度、ρ(腐殖酸)及无机离子质量浓度对超声灭活隐孢子虫的影响,并通过扫描电镜观察及动力学分析探究了超声灭活隐孢子虫的机制. 结果表明:在浊度为0~21.46NTU范围内,隐孢子虫的灭活率先升后降,浊度为1.13NTU时灭活率最高,为94.7%;隐孢子虫灭活率随ρ(腐殖酸)的增加而降低,当ρ(腐殖酸)为50.0mg/L时灭活率降至78.4%. Cu2+、Mn2+和SO₄2-对灭活率影响较小,当ρ(Cu2+)为0.5mg/L时,隐孢子虫灭活率(93.2%)比未添加Cu2+时增加了0.7%;ρ(CO₃2-)增加,隐孢子虫灭活率下降,当ρ(CO₃2-)为150mg/L时灭活率降至82.5%. 扫描电镜形态学观察表明,超声可破坏隐孢子虫细胞结构;动力学分析表明,自由基氧化作用对灭活率的贡献为15.6%,说明超声灭活隐孢子虫的主要机制为空化作用产生的机械剪切作用.      

Tracking Cryptosporidium in urban wastewater treatment plants in a cold region: Occurrence,species and infectivity

• Cryptosporidium in WWTPs in a cold region was investigated in different seasons. • The overall removal efficiency of Cryptosporidium in WWTPs was over 84%. • The infectivity rate declined below 53% in effluents mainly due to disinfection. • The infectivity of Cryptosporidium increased with a seasonal drop in temperature. • Low temperature promotes binding protein retention and virulence genes expression. This study investigated the occurrence, species, infectivity and removal efficiency of Cryptosporidium spp. across typical wastewater treatment train. Samples from different process units were collected seasonally and synchronously from four wastewater treatment plants (WWTPs) in Northeastern China. Live Cryptosporidium oocysts were identified in most samples from both influent (97.50%) and effluent (90.00%) wastewaters of the four WWTPs, at an average density of 26.34 and 4.15 oocysts/L, respectively. The overall removal efficiency was 84.25%, and oocysts were mainly removed (62.01%) by the modified secondary sedimentation process. Ten Cryptosporidium species were identified in the effluent samples. C. andersoni, C. bovis, and C. ryanae were the three most prevalent species. Oocyst viability assays indicated no reduction of excystation rate during the primary and secondary wastewater treatments (varied in the range of 63.08%–68.50%), but the excystation rate declined to 52.21% in the effluent after disinfection. Notably, the Cryptosporidium oocysts showed higher infection intensity in the cold season (winter and spring) than that in summer and autumn. The influences of environmental temperature on virulence factors of Cryptosporidium were further examined. It was observed that more extracellular secretory proteins were bound on the oocyst surface and several virulence genes were expressed relatively strongly at low temperatures, both of which could facilitate oocyst adhesion, invasion, and host immune evasion. This research is of considerable interest since it serves as an important step towards more accurate panoramic recognition of Cryptosporidium risk reduction in WWTPs, and especially highlights the potential health risk associated with Cryptosporidium in cold regions/seasons.     

隐孢子虫病及其水媒传播控制

综述了隐孢子虫和隐孢子虫病的特性，症状和传播途径，水媒传播的重要案列及其为水工业和水源保护带来的启示。介绍了隐孢子虫的检测方法和相应水质指标的研究现状；给水工业中控制隐孢子虫病传播的主要手段。     

免疫荧光法测定水中贾第鞭毛虫孢囊和隐孢子虫卵囊

采用滤囊过滤、振荡洗脱、离心浓缩、免疫磁珠分离、荧光染色和微分干涉相衬镜检计数等技术，检测水体中贾第鞭毛虫孢囊和隐孢子虫卵囊，介绍了其显微特征，方法加标回收率〉35．0％，相对标准偏差≤13．0％。     

污水中隐孢子虫和贾第鞭毛虫病原学检测方法研究

为了提高污水中隐孢子虫和贾第鞭毛虫的检测效果,降低检测成本,对其检测关键环节浓缩、分离和染色进行了方法改进研究.结果表明,以1:25稀释的Giemsa染液染色15-20min更利于对隐孢子虫卵囊和贾第鞭毛虫包囊的观察;对于杂质较多的污水处理出水,筛网预处理不但能减少镜栓时的背景杂质干扰,还能提高卵囊和包囊的检出率;在过滤速度明显变慢时,更换滤膜可大大提高实验效率;采用涡旋振荡器剧烈振荡可有效提高卵囊和包囊的回收率;而乙酸乙酯-福尔马林可实现较好的分离效果.使用改进的方法可以有效提高检出率和回收率.