Sunlight inactivation of human polymerase chain reaction markers and cultured fecal indicators in river and saline waters.

Decay rates for sunlight inactivation of polymerase chain reaction (PCR) markers for total Bacteroidales, human-specific Bacteroidales, Escherichia coli, and Bifidobacterium adolescentis relative to cultured E. coli were investigated. The experiment used 100-L chambers of fresh water and seawater (paired with dark controls) seeded with human sewage and exposed to natural sunlight over three summer days.

Transport of microbial tracers in clean and organically contaminated silica sand in laboratory columns compared with their transport in the field.

Waste disposal on land and the consequent transport of bacterial and viral pathogens in soils and aquifers are of major concern worldwide. Pathogen transport can be enhanced in the presence of organic matter due to occupation of attachment sites in the aquifer materials thus preventing pathogen attachment leading to their faster transport for longer distances. Laboratory column studies were carried out to investigate the effect of organic matter, in the form of dissolved organic carbon (DOC), on the transport of Escherichia coli and MS2 phage in saturated clean silica sand.

Survival of Escherichia coli, Enterococci, and Campylobacter spp. in sheep feces on pastures.

The survival of enteric bacteria in 10 freshly collected sheep fecal samples on pastures was measured in each of four seasons. Ten freshly collected feces were placed on pasture, and concentrations of Escherichia coli, enterococci, and Campylobacter spp. were monitored until exhaustion of the fecal samples.

Transport of Escherichia coli and F-RNA bacteriophages in a 5m column of saturated pea gravel.

The relative transport and attenuation of bacteria, bacteriophages, and bromide was determined in a 5m long x 0.3m diameter column of saturated pea gravel. The velocity (V), longitudinal dispersivity (alpha(x)) and total removal rate (lambda) were calculated from the breakthrough curves at 1m, 3m, and 5m, at a flow rate of 32Lh(-1).

Survival of indicator and pathogenic bacteria in bovine feces on pasture.

The survival of enteric bacteria was measured in bovine feces on pasture. In each season, 11 cow pats were prepared from a mixture of fresh dairy cattle feces and sampled for up to 150 days. Four pats were analyzed for Escherichia coli, fecal streptococci, and enterococci, and four inoculated pats were analyzed for Campylobacter jejuni and Salmonella enterica.

Sunlight inactivation of Campylobacter jejuni and Salmonella enterica, compared with Escherichia coli, in seawater and river water.

The inactivation of Campylobacter jejuni and Salmonella enterica, compared with Escherichia coli, was determined in 100 l chambers of seawater and river water located at an outdoor site. The chambers (paired with dark controls) were seeded with waste stabilization pond effluent and laboratory-cultured pathogens, and exposed to sunlight in summer and winter experiments. All sunlight inactivation (k(S)) rates, as a function of cumulative global solar radiation (insolation), were far higher than the corresponding dark (k(D)) rates, with a ranking (and average k(S) rates for seawater and river water, respectively) of: C.

Distance and flow effects on microsphere transport in a large gravel column.

Consumption of microbially contaminated ground water can cause adverse health effects and the processes involved in pathogen transport in aquifers need to be understood. The influences of distance, flow velocity, and colloid size on colloid transport were examined in homogenous pea-gravel media using an 8-m column and three sizes (1, 5, and 10 microm) of microspheres. Experiments were conducted at three flow rates by simultaneously injecting microspheres with a conservative tracer, bromide.

Filtration and transport of Bacillus subtilis spores and the F-RNA phage MS2 in a coarse alluvial gravel aquifer: implications in the estimation of setback distances.

Filtration of Bacillus subtilis spores and the F-RNA phage MS2 (MS2) on a field scale in a coarse alluvial gravel aquifer was evaluated from the authors' previously published data. An advection-dispersion model that is coupled with first-order attachment kinetics was used in this study to interpret microbial concentration vs. time breakthrough curves (BTC) at sampling wells.

Estimation of septic tank setback distances based on transport of E. coli and F-RNA phages.

Setback distances between septic tank systems and the shorelines of Lake Okareka, New Zealand were determined from model simulations for a worst-case scenario, using the highest hydraulic conductivity and gradient measured in the field, removal rates of the microbial indicators (Escherichia coli and F-RNA phages) determined from a column experiment, and maximum values of the design criteria for the disposal system, and assuming an absence of an unsaturated zone, a continuous discharge of the raw effluent from a failed or non-complying treatment system (both indicators at concentrations of 1x10(7) counts/100 ml) into the groundwater and no sorption of pathogens in the aquifer. Modelling results suggest that the minimal setback distances were 16 m to satisfy the New Zealand Recreational Water Quality Guidelines for E. coli <126 per 100 ml (Ministry for the Environment, 1999) and 48 m to meet the Drinking-Water Standards for New Zealand 2000 for enteric virus <1 per 100 l (Ministry of Health, 2000).

Sunlight inactivation of fecal indicator bacteria and bacteriophages from waste stabilization pond effluent in fresh and saline waters.

Sunlight inactivation in fresh (river) water of fecal coliforms, enterococci, Escherichia coli, somatic coliphages, and F-RNA phages from waste stabilization pond (WSP) effluent was compared. Ten experiments were conducted outdoors in 300-liter chambers, held at 14C (mean river water temperature). Sunlight inactivation (k(S)) rates, as a function of cumulative global solar radiation (insolation), were all more than 10 times higher than the corresponding dark inactivation (k(D)) rates in enclosed (control) chambers.