The use of F-specific coliphages to assess effluent treatment and reuse schemes

This study reports on the use of naturally occurring F-specific coliphages, as well as spiked MS-2 phage, to evaluate a land-based effluent treatment/reuse system and an effluent irrigation scheme. Both the natural phages and the spiked MS-2 phage indicated that the effluent treatment/reuse system (FILTER - Filtration and Irrigated cropping for Land Treatment and Effluent Reuse) achieved a reduction in phage levels over the treatment system by one to two log10. FILTER reduced natural F-specific phage numbers from around 10(3) to below 10(2) 100-ml(-1) and the spiked phage from 10(5) to around 10(4) 100-ml(-1) (incoming compared with outgoing water). In the effluent irrigation scheme, phage spiked into the holding ponds dropped from 10(6) to 10(2) 100-ml(-1) after 168 h (with no detectable levels of natural F-specific phage being found prior to spiking). Only low levels of the spiked phage (10(2) gm(-1)) could be recovered from soil irrigated with phage-spiked effluent (at 10(6) phage 100 ml(-1)) or from fruits (around 10(2) phage per fruit) that had direct contact with soil which had been freshly irrigated with the same phage-spiked effluent.