Bacterial indicators are used to indicate increased health risk from pathogens and to make beach closure and advisory decisions; however, beaches are seldom monitored for the pathogens themselves. Studies of sources and types of pathogens at beaches are needed to improve estimates of swimming-associated health risks. It would be advantageous and cost-effective, especially for studies conducted on a regional scale, to use a method that can simultaneously filter and concentrate all classes of pathogens from the large volumes of water needed to detect pathogens. In seven recovery experiments, stock cultures of viruses and protozoa were seeded into 10-liter lake water samples, and concentrations of naturally occurring bacterial indicators were used to determine recoveries. For the five filtration methods tested, the highest median recoveries were as follows: glass wool for adenovirus (4.7%); NanoCeram for enterovirus (14.5%) and MS2 coliphage (84%); continuous-flow centrifugation (CFC) plus Virocap (CFC؉ViroCap) for Escherichia coli (68.3%) and Cryptosporidium (54%); automatic ultrafiltration (UF) for norovirus GII (2.4%); and dead-end UF for Enterococcus faecalis (80.5%), avian influenza virus (0.02%), and Giardia (57%). In evaluating filter performance in terms of both recovery and variability, the automatic UF resulted in the highest recovery while maintaining low variability for all nine microorganisms. The automatic UF was used to demonstrate that filtration can be scaled up to field deployment and the collection of 200-liter lake water samples.

The method detection limit (MDL, 99% chance of detecting a positive result in a single replicate), as per the United States Code of Federal Regulations, was determined for a protocol using an ultrafiltration based automated waterborne pathogen concentration device. Bacillus anthracis Sterne strain spores were seeded at low levels into 100 L reagent water samples. Suspect colonies were confirmed through morphological, chemical, and genetic tests. Samples of 100 L (n=14) of reagent water were seeded with five B. anthracis CFUs each. To confirm the estimated detection limit, a second set (n=19) of 100 L reagent water samples were seeded at a higher level (7 CFUs). The second estimate of the MDL could not be pooled with the first, due to significant difference in variance. A third trial (n=7) seeded with 10 CFUs produced an estimate of the MDL that could be pooled with the higher previous estimate. Another trial consisting of eight 100 L samples of tap water were seeded with approximately 7 CFUs. Recovery in these samples was not significantly different from the pooled MDL. Theoretically a concentration of 4.6 spores/100 L would be required for detection 95% of the time, based on a Poisson distribution. The calculated pooled MDL, based on experimental data was approximately 6 B. anthracis CFU/100 L (95% confidence interval 4.8 to 8.4). Detection at this level was achieved in municipal water samples.

Feasibility studies have been completed for an anaerobic pretreatment system designed to treat hazardous waste leachates in publicly owned treatment works. The system was designed to mitigate many of the problems associated with conventional aerobic treatment of these wastes and other types of dilute waterborne hazardous wastes. In this new approach, a contact/sorption stage consisting of an expanded bed of granular activated carbon (GAC) with an attached anaerobic biomass was used as a pretreatment device after primary clarification before the aerobic treatment portion of the plant. This sorption stage was intended to reduce pass‐through of toxics, retaining them for subsequent treatment in a separate anaerobic stabilization reactor. The organic‐rich GAC/biomass bed from the sorption stage was exchanged with stabilized GAC biomass from the anaerobic stabilization stage, conserving the GAC in the system.
Two 87‐L/d bench‐scale systems were operated for 332 days, one treating unspiked primary effluent and one treating primary effluent spiked with 5% landfill leachate and 14 hazardous organic compounds. In the spiked system, removals in the sorption stage were the highest for the aromatic compounds. Five of the six aromatics added were removed at over 95% and the sixth, phenol, had an 85% removal. Removals of chlorinated aliphatic compounds ranged from 52% for methylene chloride to 95% for trichloroethylene. Removals of phthalate compounds were approximately 60%. Removals of ketones ranged from 24% for acetone to 93% for methyl isobutyl ketone. Chemical oxygen demand removals remained at 40% to 50% throughout the year‐long study in both systems.

Inactivation of Bacillus globigii spores in wash water was studied to simulate chlorine inactivation of Bacillus anthracis spores in water generated during biological cleanups. Eight waters were studied, with six containing detergent. Chlorine levels were approximately 3000 mg/L. Results across different waters showed decreasing inactivation with increasing pH. Inactivation did not appear to be influenced by chemical oxygen demand, suspended solids, turbidity, or dissolved solids. Inactivation efficacy was expressed as the time calculated to yield 6 log10 inactivation at 3000 mg NaOCl/L. This time ranged from 5 to 51 minutes at ~21 °C and from 11 to 209 minutes at ~5 °C. For one wash water, inactivation was conducted when there was no pH adjustment, and when the pH was buffered at 7 and 8. Inactivation in these buffered waters was rapid, but inactivation decreased sharply at a pH above ~9.3.

Ultrafiltration concentration of microorganisms in large volume water samples containing high levels of particulate matter was evaluated in a proof of concept study. The organisms tested were Bacillus atrophaeus subspecies globigii spores and MS2 bacteriophage. To produce the large volume samples, fresh water sediment of a known particle size was added to 51 liters of tap water. Five different concentrations of particulate matter were studied: 0, 50, 100, 150 and 750 mg solids/L. The concentration procedure used a dialysis filter as the ultrafilter configured for axial flow, either with or without recirculation. The target number of organisms spiked was 1 × 10 5 of either spores or bacteriophage per 51 liters. After concentration, the filters were dissected to retrieve the fibers which were then washed using surfactant solution which was then analyzed for the target organisms. Two washes of the filter fibers were carried out sequentially. For axial flow with recirculation, the first wash produced statistically greater recovery of B. globigii spores (26-40 % of spike) compared to the second wash (8-13% of spike). Total recovery (the sum of the recoveries for the first and second washes) ranged from 35 to 53 %. Recovery increased as the solids level increased from 0 to 150 mg solids/L. Recovery at the 100 and 150 mg solids/L loadings was statistically higher at the P < 0.05 level than recovery at 0 mg/L solids. At 150 mg solids/L, axial flow without recirculation (dead end) yielded lower recovery than axial flow with recirculation, however the difference was not significant at the P < 0.05 level. Recovery of B. globigii at 750 mg solids/L averaged 38% using dead end axial flow. The average recovery of MS2 bacteriophage was 45 % at a solids concentration of 150 mg/L using axial flow with recirculation. PhiX174 and Phi8 were also studied, however these bacteriophage appeared to be inactivated in the matrix of concentrated wash water. One hundred liters of water containing 750 mg solids/L was concentrated using dead end axial flow, and only minimal problems with filter clogging were observed. Results described herein suggest axial flow ultrafiltration is an effective concentration method for microorganisms in water containing high levels of particulate matter.