Dry Weather Sampling Research Articles

Fluorescence spectroscopy for tracking microbiological contamination in urban waterbodies

Dissolved organic matter (DOM) plays a crucial role in freshwater ecosystem function. Monitoring of DOM in aquatic environments can be achieved by using fluorescence spectroscopy. Particularly, DOM fluorescence can constitute a signature of microbiological contamination with a potential for high frequency monitoring. However, limited data are available regarding urban waterbodies. This study considers fluorescence data from field campaigns conducted in the Paris metropolitan region: two watercourses (La Villette basin and the river Marne), two stormwater network outlets (SO), and a wastewater treatment plant effluent (WWTP-O). The objectives of the study were to characterize the major fluorescence components in the studied sites, to investigate the impact of local rainfall in such components and to identify a potential fluorescence signature of local microbiological contamination. The components of a PARAFAC model (C1-C7), corresponding to a couple of excitation (ex) and emission (em) wavelengths, and the fluorescence indices HIX and BIX were used for DOM characterization. In parallel, fecal indicator bacteria (FIB) were measured in selected samples. The PARAFAC protein-like components, C6 (ex/em of 280/352 nm) and C7 (ex/em of 305/340 nm), were identified as markers of microbial contamination in the studied sites. In the La Villette basin, where samplings covered a period of more than 2 years, which also included similar numbers of wet and dry weather samples, the protein-like components were significantly higher in wet weather in comparison to dry weather. A positive relationship was obtained between C6 and FIB. In urban rivers, the high frequency monitoring of C6 levels would support the fecal contamination detection in rivers. In addition, it could help targeting specific field campaigns to collect comprehensive dataset of microbiological contamination episodes.

Microbial source tracking to identify fecal sources contaminating the Toronto Harbour and Don River watershed in wet and dry weather

Identification of sources of fecal pollution in urban areas is critical for protecting public health, the environment, and guiding remediation. We collected 670 water samples at 46 sites in 2018 to study fecal pollution in the Toronto Harbour and Don River watershed. Water samples were analyzed for E. coli, wastewater chemicals, and microbial source tracking DNA markers using a digital PCR technique. Microbial DNA markers were useful for interpreting the sources of elevated E. coli concentrations in the study. The HF183 marker for human sewage was the most frequently detected DNA marker, occurring in 100% of samples taken from the Don River and associated outfalls. It was also frequently detected in the Inner Harbour and outfalls along the Toronto harbour front. It was detected less frequently and at lower levels in the outer harbour. Detection of a human mitochondrial DNA marker and wastewater chemical markers such as caffeine provided additional evidence of widespread sewage contamination. The gull DNA marker was widely detected, but at lower frequencies and levels than human source DNA markers. A wet weather response of increased E. coli and human DNA marker concentrations occurred at most sites. However, human DNA markers were also widely detected on dry weather sampling days, indicating sewage cross-connections in stormwater and dry weather CSO systems. The cumulative impact of cross-connected stormwater outfalls is likely an under-recognized source of sewage contamination. E. coli and HF183 DNA marker levels observed can serve as benchmarks for evaluating future water quality improvements from wastewater infrastructure investments.

In situ removal of four organic micropollutants in a small river determined by monitoring and modelling

Organic micropollutants (OMPs) are widely detected in surface waters. So far, the removal processes of these compounds in situ in river systems are not yet totally revealed. In this study, a combined monitoring and modelling approach was applied to determine the behaviour of 1-H benzotriazole, carbamazepine, diclofenac and galaxolide in a small river system. Sewage treatment plant effluents and the receiving waters of the river Swist were monitored in 9 dry weather sampling campaigns (precipitation < 1 mm on the sampling day itself and <5 mm total precipitation two days before the sampling) during different seasons over a period of 3 years. With the results gained through monitoring, mass balances have been calculated to assess fate in the river. With the DWA Water Quality Model, OMP concentrations in the river were successfully simulated with OMP characteristics gained through literature studies. No removal was determined for 1-H benzotriazole and carbamazepine, whereas diclofenac showed removal that coincided with light intensity. Moreover, modelling based on light sensitivity of diclofenac also suggested relevant degradation at natural light conditions. These two approaches suggest removal by photodegradation. The highest removal in the river was detected for galaxolide, presumably due to volatilisation, sorption and biodegradation. Furthermore, short-term concentration variability in the river was determined, showing that daily concentration patterns are influenced by dynamics of sewage treatment plant effluent volumes and removal processes in the river.

Stormwater treatment evaluation on a commercial site in Nambour, Queensland

Abstract Field monitoring of a stormwater treatment train had been underway between March 2014 and April 2015 at a commercial development located at Nambour, in Queensland's Sunshine Coast hinterland. The research was undertaken to evaluate the effectiveness of a Class 1 proprietary stormwater treatment system for removing total suspended solids and nutrients from runoff. Monitoring was undertaken on all events complying with the sampling protocol. The protocol was developed in collaboration with the University of the Sunshine Coast (USC), reflecting the Auckland Regional Council Proprietary Device Evaluation Protocol (PDEP) and United States Urban Stormwater Best Management Practice (BMP) Performance Monitoring Manual with some minor improvements reflecting local conditions. During the 18 month period, more than 59 rain events have occurred, of which 18 are complying with the protocol. The Efficiency Ratios (ER) observed for the treatment device are 83% TSS, 11% for TP and 23% TN. Dry weather sampling does not show conclusive evidence that pollutants are exported between storms or that concentrations increase significantly over time.

Precipitation influences pathogenic bacteria and antibiotic resistance gene abundance in storm drain outfalls in coastal sub-tropical waters

Stormwater contamination can threaten the health of aquatic ecosystems and human exposed to runoff via nutrient and pathogen influxes. In this study, the concentrations of 11 bacterial pathogens and 47 antibiotic resistance genes (ARGs) were determined by using high-throughput microfluidic qPCR (MFQPCR) in several storm drain outfalls (SDOs) during dry and wet weather in Tampa Bay, Florida, USA. Data generated in this study were also compared with the levels of fecal indicator bacteria (FIB) and sewage-associated molecular markers (i.e., Bacteroides HF183 and crAssphage markers) in same SDOs collected in a recent study (Ahmed et al., 2018). Concentration of FIB, sewage-associated markers, bacterial pathogens and many ARGs in water samples were relatively high and SDOs may be potentially hotspots for microbial contamination in Tampa Bay. Mean concentrations of culturable E. coli and Enterococcus spp. were tenfold higher in wet compared to dry weather. The majority of microbiological contaminants followed this trend. E. coli eaeA, encoding the virulence factor intimin, was correlated with levels of 20 ARGs, and was more frequently detected in wet weather than dry weather samples. The blaKPC gene associated with carbapenem resistant Enterobacteriaceae and the beta-lactam resistant gene (blaNPS) were only detected in wet weather samples. Frequency of integron genes Intl2 and Intl3 detection increased by 42% in wet weather samples. Culturable E. coli and Enterococcus spp. significantly correlated with 19 of 47 (40%) ARG tested. Sewage-associated markers crAssphage and HF183 significantly correlated (p < 0.05) with the following ARGs: intl1, sul1, tet(M), ampC, mexB, and tet(W). The presence of sewage-associated marker genes along with ARGs associated with sewage suggested that aging sewage infrastructure contributed to contaminant loading in the Bay. Further research should focus on collecting spatial and temporal data on the microbiological contaminants especially viruses in SDOs.

Field and Evaluation Methods Used to Test the Performance of a Stormceptor® Class 1 Stormwater Treatment Device in Australia

Field testing of a proprietary stormwater treatment device was undertaken over 14 months at a site located in Nambour, South East Queensland. Testing was undertaken to evaluate the pollution removal performance of a Stormceptor® treatment train for removing total suspended solids (TSS), total nitrogen (TN) and total phosphorous (TP) from stormwater runoff. Water quality sampling was undertaken using natural rainfall events complying with an a priori sampling protocol. More than 59 rain events were monitored, of which 18 were found to comply with the accepted sampling protocol. The efficiency ratios (ER) observed for the treatment device were found to be 83% for TSS, 11% for TP and 23% for TN. Although adequately removing TSS, additional system components, such as engineered filters, would be required to satisfy minimum local pollution removal regulations. The results of dry weather sampling tests did not conclusively demonstrate that pollutants were exported between storm events or that pollution concentrations increased significantly over time.

Salt Marsh Reduces Fecal Indicator Bacteria Input to Coastal Waters in Southern California

Abstract We investigated fecal indicator bacteria (FIB) concentrations in water and sediment from Carpinteria Salt Marsh, a medium-sized (93 ha), mostly natural southern California coastal wetland. High FIB concentrations, exceeding recreational water quality standards, were found at inlet sites after winter storm events and during a summer dry weather sampling event. Runoff entering the wetland had the highest concentrations of FIB after large rain events and after rain events following extended periods without rain. The watersheds with the greatest agricultural and urban development draining into the wetland generally contributed the highest loads of FIB, while the largest and least developed watershed contributed the lowest FIB concentrations. Surface water exiting the wetland at the ocean contained relatively low concentrations of FIB and only exceeded recreational water quality standards after the largest rain event of the year. Bacterial concentrations in sediment were only elevated after rain event...

Relationships between stream phosphorus concentrations and drainage basin characteristics in a watershed with poultry farming

In the Illinois River watershed (Arkansas and Oklahoma) poultry litter is routinely applied to pasture lands as fertilizer supplements. The objective of this study was to quantify the impacts of this practice on water quality in small streams in the watershed. Total phosphorus concentrations in small streams were quantified during a 15 month intensive sampling program for small tributaries, un-impacted by point sources, and covering a range of upstream poultry farming intensities throughout the watershed. Base flow samples were also collected from the tributaries during multiple dry weather sampling events. Correlation analysis was performed for various measurable drainage basin characteristics and phosphorus concentrations. Results show significant positive correlations between total phosphorus concentrations and the intensity of poultry farm operations upstream of sample sites. This relationship is supported by a supplemental synoptic sampling event upstream and downstream of a field applied with poultry litter and by a watershed-scale mass balance analysis. The latter identifies poultry as the single largest contributor of phosphorus inputs to the basin, accounting for over 76 % of the total watershed load. Study results also show significant, but generally weaker, positive correlations between phosphorus and upstream density of septic tanks and soil conservation service curve number of the drainage basin, but these appear likely to be primarily due to cross-correlations with poultry farm presence. This study demonstrates the use of readily-observed basin characteristics in simple water quality predictive tools and has implications for management of poultry-dominated watersheds.

Assessing Settleability of Dry and Wet Weather Flows in an Urban Area Serviced by Combined Sewers

Settleability of dry and wet weather flow samples from a combined sewer system was examined by settling column tests, in order to improve understanding of settling processes and obtain information for design of settling tanks. In fact, these tests mimic the actual settling processes and allow evaluating total suspended solids (TSS) removal by settling. Therefore, it is also possible to assess, indirectly, removals of other pollutants, such as heavy metals, which are generally transported by solid particles in sewage. Towards this end, dry and wet weather flow samples were collected in the Liguori Channel catchment and analyzed in the laboratory for Water Supply and Sewerage (Acquedotti e Fognature) of the University of Calabria for TSS concentrations according to the Standard Methods. The settleability study revealed that removals of TSS in dry weather samples (i.e., sanitary sewage) were greater than in wet weather samples (WW), using the same experimental procedures. In particular, 65% of TSS was removed in dry weather samples at a depth of 3 m for a detention time of 40 min; while in wet weather samples the comparable removal efficiency was less than 60%.

Dry and wet weather microbial characterization of the Chicago area waterway system

The Chicago Area Waterway System (CAWS) is a man-made channel, which serves the Chicago area for the drainage of urban storm water and the conveyance of secondary treated effluent from the Metropolitan Water Reclamation District of Greater Chicago's (District) North Side, Stickney and Calumet water reclamation plants (WRPs). A microbial characterization of the CAWS upstream and downstream of the WRPs and from the WRP outfall was initiated by collecting dry and wet weather samples and analyzing for indicators and pathogens. During dry weather, indicator bacteria (fecal coliform [FC], E. coli [EC], enterococci [EN]) were the most abundant microbial species detected in the CAWS compared to pathogens (Salmonella spp [SA], enteric viruses [EV], adenovirus [AV], norovirus [NV] and Giardia and Cryptosporidium). Pseudomonas aeruginosa [PA] levels in the outfall samples were either lower or equivalent to the CAWS. The wet weather samples had a higher frequency of detection of indicator bacteria and pathogens compared to dry weather samples. Overall, the concentrations of pathogens in the CAWS, representing the weather conditions experienced in a recreational year, were relatively low. The study concluded that the presence of pathogens in the CAWS downstream of the WRPs were due to secondary loading of the waterway under wet weather conditions from combined sewer overflows (CSOs) and other discharges.

Wet and Dry Weather Toxicity in the San Gabriel River

The lower San Gabriel River is an urban watershed located on the border of Los Angeles and Orange Counties. It has a diversity of potential pollutant sources including five water reclamation plants (WRPs) that discharge treated wastewaters and more than 100 storm drains that discharge largely untreated urban runoff to the river. The goal of this study was to assess the magnitude of toxicity to Ceriodaphnia dubia throughout the lower San Gabriel River watershed during wet and dry weather, identify the responsible toxicants, and compare the magnitude of toxicity over time to evaluate the effectiveness of previous watershed management actions. Wet weather runoff was sampled from sites located at the end of the four main reaches of the lower San Gabriel River; Walnut Creek, San Jose Creek, Coyote Creek, and San Gabriel River mainstem. None of the samples collected over two wet seasons exhibited acute or chronic toxicity. Dry weather samples were tested from 16 locations distributed throughout the lower watershed for up to 18 months. None of the dry weather samples from Walnut Creek, San Jose Creek, or the San Gabriel River mainstem exhibited acute or chronic toxicity. Acute and chronic toxicity was intermittently measured in the Coyote Creek tributary. Toxicity identification evaluations suggested nonpolar organic constituents, likely diazinon and perhaps surfactants, as possible toxicants. Toxicity observed in this study was significantly reduced compared to a similar study of the watershed 12 years previously, especially in the San Gabriel River mainstem. Much of the reduction in toxicity was associated with upgrades in WRP treatment. Little to no change in toxicity was observed in Coyote Creek upstream of the WRP discharge where little to no control of dry weather urban runoff had occurred.

Quantitative Detection of Hepatitis A Virus and Enteroviruses Near the United States-Mexico Border and Correlation with Levels of Fecal Indicator Bacteria

For decades, untreated sewage flowing northward from Tijuana, Mexico, via the Tijuana River has adversely affected the water quality of the recreational beaches of San Diego, California. We used quantitative reverse transcription-PCR to measure the levels of hepatitis A virus (HAV) and enteroviruses in coastal waters near the United States-Mexico border and compared these levels to those of the conventional fecal indicators, Escherichia coli and enterococci. Over a 2-year period from 2003 to 2005, a total of 20 samples were assayed at two sites during both wet and dry weather: the surfzone at the mouth of the Tijuana River and the surfzone near the pier at Imperial Beach (IB), California (about 2 km north of the mouth of the Tijuana River). HAV and enterovirus were detected in 79 and 93% of the wet-weather samples, respectively. HAV concentrations in these samples ranged from 105 to 30,771 viral particles/liter, and enterovirus levels ranged from 7 to 4,417 viral particles/liter. The concentrations of HAV and enterovirus were below the limit of detection for all dry weather samples collected at IB. Regression analyses showed a significant correlation between the densities of both fecal bacterial indicators and the levels of HAV (R2>0.61, P<0.0001) and enterovirus (R2>0.70, P<0.0001), a finding that supports the use of conventional bacterial indicators to predict the levels of these viruses in recreational marine waters.

QUANTIFICATION OF &lt;I&gt;ESCHERICHIA COLI&lt;/I&gt; AND ENTEROCOCCI LEVELS IN WET WEATHER AND DRY WEATHER FLOWS

Forty percent of rivers, 45% of lakes and 50% of estuaries assessed by the National Water Quality Inventory (2000) were not clean enough to support designate d fishing and swimming uses. Pathogens were found to be one of the leading causes of impairments in these waters. Urban runoff is recognized as a leading source of organisms potentially indicating the presence of pathogens. Urban runoff can be defined as any discharge from a separate storm drainage system. Urban runoff traditionally had been defined to in clude precipitation and wash off from lawns and other landscaped areas, buildings, roadways and parking lots. However, other flows may enter the storm drainage system from such sources a s infiltrating groundwater, leaking domestic water supplies and sewage, washwaters, and other inappropriate entries to the storm drainage system. This research was conducted to quantify th e levels of indicator bacteria, and their sources, in urban areas. The main objective of t his research was to identify possible sources of E. coli and enterococci bacteria in dry and wet-weather flows in storm drainage systems. An urban area consists of many different kinds of land uses such as residential, institutional, commercial, industrial open spaces, etc. Each type of la nd use consists of various types of source areas, such as roofs, parking lots, landscaped areas, play grounds, driveways, undeveloped areas, sidewalks. Four representative source area types were sa mpled during this research; including rooftops, parking lots, open spaces, and streets. Two paralle l sites were sampled for each source area type; one affected by birds and other animals, and an other set with less influence from birds and other animals. A section of Cribbs Mill Creek in Tusc aloosa, Alabama, was also selected for dry weather sampling at outfalls. The section of the cr eek was selected such that the drainage areas contributing to outfalls had either commercial or residential land uses. Potential inappropriate discharge water samples were also obtained, including influent samples from the Tuscaloosa sewage treatment plant, local springs, irrigati on runoff water, domestic water taps, car wash, and laundry water. Overall, total coliforms, E. coli and enterococci bacterial analyses were conducted on 202 wet weather and 278 dry weather flow water samples. All samples were analyzed using IDEXX Quantitray enumeration procedures. E. coli and enterococci levels larger than 2,400 and 24,000 MPN/100 mL, r espectively, were observed in wet weather samples collected from various source areas which could not possibly be contaminated with sanitary sewage. The levels of ind icator bacteria present in the urban runoff source area samples exceeded the EPA 1986 single sa mple maximum value water quality criteria in 31% of the samples for E. coli and in 74% of the samples for enterococci. The geometric mean criteria were exceeded in 100% of the source area samples. Since both the indicator organisms studied ( E. coli. and enterococci) only originate in intestines of warm

Observed and simulated effect of rain events on the behaviour of an activated sludge plant removing nitrogen

This study deals with wastewater treatment plant (WWTP) loading and performance when receiving combined sewage. A yearly data set from an activated sludge plant operating at very low food-to-mass ratio (F/M) and being intermittently aerated was analyzed statistically to compare loading and discharge during dry and wet weather. The results show that despite some loading increase, the nitrogen removal performance is only slightly affected by rain, whereas higher soluble COD load discharge is observed. This approach was supplemented with dynamic simulations with the Activated Sludge Model No 1 (ASM1). It was first calibrated on data from an intensive 48-h dry weather sampling campaign at 20 °C. A good fit between simulated and measured variables was obtained after adjusting five parameters of the ASM1. This parameter set was then validated on a wet weather sampling campaign. Once the confidence in the simulations' results was established, several wet-weather scenarios were simulated, with maximum flow and variable pollutant loading. They show that the higher COD load discharge is due to a hydraulic flush of soluble inert compounds, and how the biological potential can be used to treat almost any realistically possible carbon and nitrogen overload.Key words: biological wastewater treatment, activated sludge, rain, combined sewage, nitrogen removal, soluble COD, oxygen demand, ASM1, simulation, calibration.

Coastal Pollution from Septic Tank Drainfields

Wet weather and dry weather sampling is utilized to monitor densities of coliform bacteria in waters draining residential areas of coastal North Carolina. The bacterial levels are compared to different densities of unsewered residences in each watershed and the limitations of the developed soils for assimilating septic tank effluent. An analysis of the data implicates septic tank drainfields installed in unsuitable soils as a major source of contamination of these shellfish waters. In order to reduce the threat to public health and the multimillion dollar economic loss to the fishing industry, several options are presented for rehabilitating concentrations of failing septic tank systems and for modifying overdesigned drainage systems that carry the contamination directly to shellfish waters. In addition, several common sense management practices that minimize the delivery of bacterial contamination to estuarine waters are suggested for use in siting future coastal residential development.