Bacteriological indicators of faecal contamination: result of a loading experiment with untreated urban wastewater

Abstract

Some observations were made on the behaviour of total coliforms, faecal coliforms, enterococci, numbers of aerobic bacteria, salmonellas and sulphur-reducing clostridia as bacterial indicators of faecal contamination of groundwater. A controlled irrigation experiment was carried out with untreated residual water in the alluvial aquifer of the Vega of Granada (Spain). The results obtained confirm the value of these parameters are useful indicators of very recent faecal contamination; and changes were detected as the level of the freatic layer increased and the chemical composition of the groundwater changed. These groups of micro-organisms persisted for about 200 h, with the exception of the aerobes which survived for much longer. Salmonellas were present at levels too low to calculate the extent of faecal contamination and sulphur-reducing clostridia were not detected. The results obtained show that irrigation with untreated wastewater offers a lower risk of microbiological contamination of groundwater compared with the direct addition of waters decanted and/or previously filtered.

Comparison of release and transport of manure-borne Escherichia coli and enterococci under grass buffer conditions

“…The much earlier appearance of enterococci in groundwater wells when compared with E. coli was attributed to the better mobility of enterococci in unsaturated soil. Ramos‐Cormenzana et al. (1994) observed that enterococci possessed better resistance to dryness and an excellent ability to move with the infiltrating water when compared with E. coli .…”

Physiological response of Enterococcus faecalis JH2-2 to cold shock: growth at low temperatures and freezing/thawing challenge

“…Enteroccocus faecalis, a ubiquitous Gram-positive microaerophilic bacterium (Schleifer and Kilpper-Balz 1984), lives in the intestinal tract of humans and most animals and is present at low temperature environments such as water, soil and chilled foods (Skinner and Quesnel 1978 ;Board 1983 ;Ramos-Cormenzana et al 1994). The resilient bacterium, which is an indicator of faecal contamination, is of major interest for its ability to resist to high temperatures, high salt concentrations, and to grow at pH 9.6, on 40% (w/v) bile agar and on 0.1% (w/v) methylene blue milk agar (Boutibonnes et al 1993 ;Devriese et al 1993;Flahaut et al 1996).…”

Differentiation between cold shock proteins and cold acclimation proteins in a mesophilic gram-positive bacterium, Enterococcus faecalis JH2-2

“…It is an allochthonous, grampositive bacterium (31) which lives in the intestinal tracts of many animals and is commonly present in cold biological environments (3,29,32).…”