activated sludge produced during waste water treatments

由于生活废水中可能含有由感染者释放的致病性肠道病毒，因此了解废水净化过程中病毒的行为是很重要的，然而，人们对它的了解仍然很少。在本研究中，我们报道了脊髓灰质炎病毒（Sabin 1株）在污水净化厂活性污泥样品上的粘附及其粘附机制。每克（湿）活性污泥上附着10^8个以上的病毒颗粒，与游离病毒颗粒相比，附着的病毒颗粒保持感染性的时间更长，耐热性更高。通过增加盐浓度或碱性pH缓冲液将附着的病毒颗粒作为感染性颗粒释放。虽然脊髓灰质炎病毒颗粒有2个等电点，一个在大约。pH值为4.3（主要种群），其他种群的pH值约为4.3。当pH值为7.2时，颗粒对阳离子交换色谱柱的吸附比阴离子交换色谱柱的吸附强得多，螯合剂干扰了病毒对活性污泥样品的吸附，表明活性污泥主要通过静电相互作用吸附病毒颗粒，充当阳离子交换吸附剂，多价阳离子在病毒吸附中起重要作用。这些数据表明，病原病毒可以通过静电相互作用附着在活性污泥上，在一定条件下富集并保持传染性，释放到环境中。

Since domestic wastewater could be contained pathogenic enteric viruses released from infected persons the knowledge of the viral behavior in wastewater purifying process is important : it is, however, still poorly understood. In this study, we reported that the adhesion of Poliovirus (Sabin 1 strain) to activated sludge samples taken from wastewater purifying plants and the mechanism of the adhesion. More than 10^8 particles adhered to one gram (wet) of activated sludge, and the adhered viral particles maintained infectivity for longer period of time and showed higher thermo-resistant than the free viral particles. The adhered viral particles were released by increase of salt concentration or alkaline pH buffer as infectious particles. Although the Poliovirus particles have 2 isoelectric points, one at approx. pH 4.3(major population) and the other at approx. pH 7.2(minor population), the particles adsorbed much more strongly to a cation-exchange chromatography column than to an anion-exchange one at pH 7.2 and chelating agents interfered with the viral adsorption to activated-sludge samples, suggesting that activated sludge adsorbed the viral particles mainly through electrostatic interaction, acting as a cation-exchange adsorbent, and that multivalent cations play an important role in the viral adsorption. These data suggest that pathogenic viruses could adhere to the activated sludge by electrostatic interaction, be enriched, maintain the infectivity, and released to environments under certain conditions.