Charles A. Sorber

Coliphages as indicators of enteric viruses in activated sludge

Abstract The use of indigenous coliphage as indicators of enteric viruses during activated sludge treatment of domestic wastewater was examined. Enteric viruses, coliphage attacking three strains of Escherichia coli and a number of wastewater parameters were monitored in the primary effluent, secondary effluent and secondary sludge of a wastewater treatment plant. Removal of viruses during secondary treatment appeared to be the result of rapid adsorption of influent virions to mixed liquor suspended solids. Adsorption was followed by inactivation of the viruses during aeration of the mixed liquor. A larger proportion of influent enteric viruses than coliphage was recovered from the secondary sludge. This suggests that activated sludge treatment was less antagonistic towards enteric viruses than towards the coliphage. Coliphage plaques of less than or equal to 1 mm in diameter were composed of large viruses (approx. 100 nm in diameter). Plaques greater than 3 mm in diameter appeared to be the result of host infection by a much smaller virus (approx. 45 nm in diameter). Plaques between 1 and 3 mm in diameter were composed of both small and large coliphages. Coliphage concentrations could not be correlated with enteric virus concentrations in either primary or secondary effluent. However, it was found that coliphage giving rise to plaques greater than 3 mm in diameter were positively related with enteric viruses in the secondary effluent. This result suggests that this group of coliphage may serve as an indicator of the efficacy of activated sludge treatment of enteric viruses.

Viral transport through soil columns under conditions of saturated flow

Abstract Movement of poliovirus 1, reovirus 3, and bacteriophage OX174 was studied in 8 different soils. Soils were sampled to a depth of 100 cm in three 33 cm profiles, and packed into acrylic cylinders, 10 cm in dia. and 33.66 and 100 cm in length according to the vertical distribution and bulk density of the soil as found in the field. Sequential flooding of the columns with wastewater and distilled water resulted in a cyclical pattern of viral release in column percolates. The total number of viruses detected in percolates differed among the soils tested. This was due to the differences among soil properties. Poliovirus recovery correlated most favorably with low soil cation exchange capacity and high organic carbon and clay content. The recovery of OX174 was related to low soil organic carbon and residence time of liquid within a column in combination with either high soil pH or per cent clay. As with poliovirus, detection of reovirus in soil column percolates was negatively correlated with soil cation exchange capacity.

The Survival of EK1 and EK2 Systems in Sewage Treatment Plant Models

In March 1977 the National Academy of Sciences (USA) convened a Forum on Research with Recombinant DNA. It was clear to participants that this potentially was an opportunity to affect national science policy. In trying to assess the benefits and risks inherent in recombinant DNA technology, some argued the risks were not different than any in the microbiology laboratory; others warned that such research was the first step towards the manipulation of human genetics, that it could contaminate the biosphere irrevocably.

A method for evaluating the mixing characteristics of u.v. reactors with short detention times

Abstract Ultraviolet (u.v.) light disinfection of municipal wastewaters is rapidly gaining popularity as an alternative to chlorination. However, little information is available which correlates the disinfection efficiencies with the various types of u.v. reactor system designs. This study presents the results of research carried out on a particular u.v. reactor design: a Teflon®-tube wastewater carrier externally irradiated by a parallel u.v. lamp. An innovative experimental method was developed to obtain concentration-time distribution curves for reactors of detention times of