TABLE 2.

Detection of norovirus, rotavirus, reovirus, enterovirus, somatic phages, and F-specific phages in sewage samples (both raw and treated sewage) and the virus removal at the sewage treatment plant

DateSewageConcn (95% confidence interval)
Somatic phages (PFU/liter)F-specific phages (PFU/liter)Enteroviruses (PFU/liter)Reoviruses (PFU/liter)Noroviruses (PDU/liter)Rotaviruses (PDU/liter)
16 November 1998Raw3.5 × 106 (2.9 × 106 to 4.2 × 106)4.0 × 106 (3.4 × 106 to 4.7 × 106)191 (140-253)1,253 (1,114-1,403)7,035 (444 to 6 .3 × 104)4,690 (296 to 4.2 × 104)
16 November 1998Treated3.6 × 105 (2.9 × 105 to 4.4 × 105)1.0 × 105 (9.2 × 104 to 1.2 × 105)39 (31-49)48 (39-59)896 (57-7,999)598 (38-5,333)
    Calculated log 10 removal1.01.60.71.40.90.9
21 December 1998Raw6.8 × 106 (6.3 × 106 to 7.3 × 106)6.8 × 106 (6.9 × 105 to 7.7 × 105)288 (226-361)2,143 (1,964-2,332)1.2 × 105 (7,359 to 1.1 × 106)763 (36-8,804)
21 December 1998Treated3.0 × 105 (2.5 × 105 to 3.4 × 105)6.2 × 103 (5.3 × 103 to 7.2 × 103)7 (4-10)92 (83-102)1,367 (88 to 1.2 × 104)908 (57-8,106)
    Calculated log 10 removal1.42.01.61.41.9−0.1
11 January 1999Raw6.4 × 106 (5.0 × 106 to 8.1 × 104)1.2 × 106 (1.1 × 106 to 1.3 × 106)296 (186-424)555 (414-725)8.5 × 105 (5.3 × 104 to 8.0 × 106)5.5 × 104 (2,592 to 4.9 × 105)
11 January 1999Treated1.0 × 106 (9.3 × 105 to 1.1 × 106)6.7 × 104 (5.9 × 104 to 7.6 × 104)10 (7-13)76 (68-85)7,499 (463 to 7.1 × 104)4,819 (228 to 4.3 × 104)
    Calculated log 10 removal0.81.31.50.92.11.1
4 February 1999Raw3.3 × 106 (3.0 × 106 to 4.0 × 106)7.5 × 105 (6.7 × 105 to 8.4 × 106)140 (99-190)416 (343-499)4.6 × 104 (2,896 to 4.1 × 104)3.1 × 104 (1,931 to 2.7 × 105)
4 February 1999Treated1.5 × 105 (1.3 × 106 to 1.7 × 105)1.3 × 104 (1.2 × 104 to 1.4 × 104)5 (3-7)23 (19-28)4,283 (265 to 4.0 × 1 04)2.9 × 104 (1,763 to 2.7 × 105)
    Calculated log 10 removal1.41.81.51.31.00.03
25 February 1999Raw5.2 × 106 (4.5 × 106 to 6.0 × 106)3.5 × 106 (3.2 × 106 to 4.0 × 106)833 (587-1,141)111 (40-239)5,111 (322 to 4.6 × 104)339 (16-3,027)
25 February 1999Treated1.9 × 105 (1.8 × 108 to 2.1 × 105)5.4 × 104 (4.8 × 104 to 6.2 × 104)12 (9-18)8 (5-12)3,582 (221 to 3.4 × 104)2.4 × 104 (1,475 to 2.2 × 105)
    Calculated log 10 removal1.41.81.81.10.2−1.8