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A Field Study of Virus Removal in Septic Tank Drainfields
Author(s) -
Nicosia L.A.,
Rose J.B.,
Stark L.,
Stewart M.T.
Publication year - 2001
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2001.1933
Subject(s) - septic tank , effluent , wastewater , dilution , environmental science , infiltration (hvac) , sewage , environmental engineering , materials science , composite material , physics , thermodynamics
Two field studies were conducted at a research station in Tampa, Florida to assess the removal of bacteriophage PRD1 from wastewater in septic tank drainfields. Infiltration cells were seeded with PRD1 and bromide and the effects of effluent hydraulic loading rate and rainfall on virus removal were monitored. Septic tank effluent samples were collected after passage through 0.6 m of unsaturated fine sand and PRD1 was detected over an average of 67 d. Bacteriophage PRD1 breakthrough was detected at approximately the same time as bromide in all three cells except for the low‐load cell (Study 1), where bromide was never detected. Log 10 removals of PRD1 were 1.43 and 1.91 for the high‐load cells (hydraulic loading rate = 0.063 m/d) and 2.21 for the low‐load cell (hydraulic loading rate = 0.032 m/d). Virus attenuation is attributed to dispersion, dilution, and inactivation. Significant increases in PRD1 elution with rainfall were observed in the first 10 d of the study. Approximately 125 mm of rainfall caused a 1.2 log 10 increase of PRD1 detected at the 0.6‐m depth. Current Florida on‐site wastewater disposal standards, which specify a 0.6‐m distance from the drainfield to the water table, may not provide sufficient removal of viruses, particularly during the wet season.