A study of a modified membrane filter technique for the enumeration of stressed fecal coliforms in urban runoff

Urban runoff samples collected from a parking lot in Blacksburg, Virginia were analyzed by several techniques for fecal coliform recovery. The samples were also analyzed for heavy metal concentrations. Statistical analyses of data by the paired-t test showed that the standard membrane filter technique (MF) yielded significantly lower recoveries (0. 05 level) than the standard MPN procedure. A modified membrane filter technique employing a two-layer agar and a two hour 35°C preincubation period (M-2hr) was found to yield recoveries consistently greater (0.01 level) than the standard MF technique. Increasing the preincubation period to five hours in this modified method (M-5hr) resulted in recoveries that were even greater (0.005 level). The recoveries of the M-5hr method were found to closely approximate the MPN recoveries in most cases. It was concluded that a substantial percentage of the fecal coliform population found in urban runoff may be injured by a host of environmental factors, though no correlations could be made with metal concentrations or elapsed time between rainfalls. The M-5hr method was concluded to be quite useful in the recovery of these stressed organisms. though growth of non-fecal-coliforms was increased and made enumeration of the fecal coliforms more difficult.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Environmental Sciences and Engineering

Department dc:contributor.department

Environmental Sciences and Engineering

Grantor dc:publisher

Virginia Polytechnic Institute and State University

Year dc:date.issued

1977

Author dc:creator

• Brown, Edward Ryland

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/10919/64115

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/64115