A novel and simple procedure for concentrating adenoviruses from sea water samples is described. The technique entails the adsorption of viruses to pre-flocculated skimmed milk proteins, allowing the flocs to sediment by gravity, and dissolving the separated sediment in phosphate buffer. Concentrated virus may be detected by PCR techniques following nucleic acid extraction. The method requires no specialized equipment other than that usually available in routine public health laboratories, and due to its straightforwardness it allows the processing of a larger number of water samples simultaneously. The usefulness of the method was demonstrated in concentration of virus in multiple seawater samples during a survey of adenoviruses in coastal waters.
Emerging countries frequently afflicted by waterborne diseases require safe and cost-efficient production of drinking water, a task that is becoming more challenging as many rivers carry a high degree of pollution. A study was conducted on the banks of the Yamuna River, Delhi, India, to ascertain if riverbank filtration (RBF) can significantly improve the quality of the highly polluted surface water in terms of virus removal (coliphages, enteric viruses). Human adenoviruses and noroviruses, both present in the Yamuna River in the range of 10(5) genomes/100 mL, were undetectable after 50 m infiltration and approximately 119 days of underground passage. Indigenous somatic coliphages, used as surrogates of human pathogenic viruses, underwent approximately 5 log10 removal after only 3.8 m of RBF. The initial removal after 1 m was 3.3 log10, and the removal between 1 and 2.4 m and between 2.4 and 3.8 m was 0.7 log10 each. RBF is therefore an excellent candidate to improve the water situation in emerging countries with respect to virus removal.
New disinfection procedures are being developed and proposed for use in drinking-water production. Authorising their use requires an effective test strategy that can simulate conditions in practice. For this purpose, we developed a test rig working in a flow-through mode similar to the disinfection procedures in waterworks, but under tightly defined conditions, including very short contact times. To quantify the influence of DOC, temperature and pH on the efficacy of two standard disinfectants, chlorine and chlorine dioxide, simulated use tests were systematically performed. This test rig enabled quantitative comparison of the reduction of four test organisms, two viruses and two bacteria, in response to disinfection. Chlorine was substantially more effective against Enterococcus faecium than chlorine dioxide whereas the latter was more effective against the bacteriophage MS2, especially at pH values of >7.5 at which chlorine efficacies already decline. Contrary to expectation, bacteria were not generally reduced more quickly than viruses. Overall, the results confirm a high efficacy of chlorine and chlorine dioxide, validating them as standard disinfectants for assessing the efficacy of new disinfectants. Furthermore, these data demonstrate that the test rig is an appropriate tool for testing new disinfectants as well as disinfection procedures.
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