Daniel Deere

Concentrations of Pathogens and Indicators in Animal Feces in the Sydney Watershed

ABSTRACT A fecal analysis survey was undertaken to quantify animal inputs of pathogenic and indicator microorganisms in the temperate watersheds of Sydney, Australia. The feces from a range of domestic animals and wildlife were analyzed for the indicator bacteria fecal coliforms and Clostridium perfringens spores, the pathogenic protozoa Cryptosporidium and Giardia, and the enteric viruses adenovirus, enterovirus, and reovirus. Pathogen and fecal indicator concentrations were generally higher in domestic animal feces than in wildlife feces. Future studies to quantify potential pathogen risks in drinking-water watersheds should thus focus on quantifying pathogen loads from domestic animals and livestock rather than wildlife.

Development of a process-based model to predict pathogen budgets for the Sydney drinking water catchment

Over 1.1 billion people in the world lack access to improved drinking water. Diarrheal and other waterborne diseases cause an estimated 2.2 million deaths per year. The Safe Water System (SWS) is a proven household water treatment intervention that reduces diarrheal disease incidence in users in developing countries. Because the SWS recommends the addition of sodium hypochlorite to unfiltered water sources, concerns have been raised about the potential long-term health effects of disinfection by-products to SWS users. This study investigated the production of trihalomethanes (THMs) in water treated with sodium hypochlorite from six sources used for drinking water in western Kenya. The turbidity values of these sources ranged from 4.23 NTU to 305 NTU. THM concentrations were analysed at 1, 8, and 24 hours after addition of sodium hypochlorite. No sample exceeded the World Health Organization (WHO) guideline values for any of the four THMs: chloroform, bromodichloromethane, dibromochloromethane, or bromoform. In addition, no sample exceeded the WHO additive total THM guideline value. These results clearly show that point-of-use chlorination of a variety of realistic source waters used for drinking did not lead to THM concentrations that pose a significant health risk to SWS users.

Dispersion and Transport of Cryptosporidium Oocysts from Fecal Pats under Simulated Rainfall Events

ABSTRACT The dispersion and initial transport of Cryptosporidium oocysts from fecal pats were investigated during artificial rainfall events on intact soil blocks (1,500 by 900 by 300 mm). Rainfall events of 55 mm h−1 for 30 min and 25 mm h−1 for 180 min were applied to soil plots with artificial fecal pats seeded with approximately 107 oocysts. The soil plots were divided in two, with one side devoid of vegetation and the other left with natural vegetation cover. Each combination of event intensity and duration, vegetation status, and degree of slope (5° and 10°) was evaluated twice. Generally, a fivefold increase (P < 0.05) in runoff volume was generated on bare soil compared to vegetated soil, and significantly more infiltration, although highly variable, occurred through the vegetated soil blocks (P < 0.05). Runoff volume, event conditions (intensity and duration), vegetation status, degree of slope, and their interactions significantly affected the load of oocysts in the runoff. Surface runoff transported from 100.2 oocysts from vegetated loam soil (25-mm h−1, 180-min event on 10° slope) to up to 104.5 oocysts from unvegetated soil (55-mm h−1, 30-min event on 10° slope) over a 1-m distance. Surface soil samples downhill of the fecal pat contained significantly higher concentrations of oocysts on devegetated blocks than on vegetated blocks. Based on these results, there is a need to account for surface soil vegetation coverage as well as slope and rainfall runoff in future assessments of Cryptosporidium transport and when managing pathogen loads from stock grazing near streams within drinking water watersheds.

Quantification of microbial sources in drinking-water catchments.

A detailed literature review was undertaken of pathogen prevalence and concentration in fecal matrices and sewage effluent. Most of the reports described microbial prevalence rather than concentration and the majority of studies were from developed countries in Europe, the Americas, and Australasia. Prevalence varied from nondetected to up to 100% and reported values varied between studies for the same host and matrix. Juvenile animals typically had higher reported pathogen prevalence than adult animals. The reported prevalence of pathogens was usually higher in domestic animals than wildlife. Extensive variation in reported pathogen concentrations was observed covering up to four orders of magnitude for the same matrix. Similar to the trends in prevalence, the reported concentration of pathogens was higher among juvenile animals than among adults and generally higher in domestic animals than in wildlife. The source of variation was highest for reports of concentrations in feces and lowest for reports of the sewage effluent, presumably because the latter is effectively a pooled sample. Reported concentrations of pathogens in similarly treated sewage effluent were reasonably consistent between studies from different parts of the world, although it is noted that the countries from which the reports originated had similar socioeconomic characteristics. The priorities for reducing pathogen presence in water-supply catchments are to adequately treat domestic sewage before discharge and to improve the management of domestic animals to reduce levels of infection.

Environmental inactivation of Cryptosporidium oocysts in catchment soils

Aims:  To generate field‐relevant inactivation rates for Cryptosporidium oocysts in soil that may serve as parameter values in models to predict the terrestrial fate and transport of oocysts in catchments.

Extreme weather events: Should drinking water quality management systems adapt to changing risk profiles?

Among the most widely predicted and accepted consequences of global climate change are increases in both the frequency and severity of a variety of extreme weather events. Such weather events include heavy rainfall and floods, cyclones, droughts, heatwaves, extreme cold, and wildfires, each of which can potentially impact drinking water quality by affecting water catchments, storage reservoirs, the performance of water treatment processes or the integrity of distribution systems. Drinking water guidelines, such as the Australian Drinking Water Guidelines and the World Health Organization Guidelines for Drinking-water Quality, provide guidance for the safe management of drinking water. These documents present principles and strategies for managing risks that may be posed to drinking water quality. While these principles and strategies are applicable to all types of water quality risks, very little specific attention has been paid to the management of extreme weather events. We present a review of recent literature on water quality impacts of extreme weather events and consider practical opportunities for improved guidance for water managers. We conclude that there is a case for an enhanced focus on the management of water quality impacts from extreme weather events in future revisions of water quality guidance documents.

Recovery and Enumeration of Cryptosporidium parvum from Animal Fecal Matrices

ABSTRACT Accurate quantification of Cryptosporidium parvum oocysts in animal fecal deposits on land is an essential starting point for estimating watershed C. parvum loads. Due to the general poor performance and variable recovery efficiency of existing enumeration methods, protocols were devised based on initial dispersion of oocysts from feces by vortexing in 2 mM tetrasodium pyrophosphate, followed by immunomagnetic separation. The protocols were validated by using an internal control seed preparation to determine the levels of oocyst recovery for a range of fecal types. The levels of recovery of 102 oocysts from cattle feces (0.5 g of processed feces) ranged from 31 to 46%, and the levels of recovery from sheep feces (0.25 g of processed feces) ranged from 21% to 35%. The within-sample coefficients of variation for the percentages of recovery from five replicates ranged from 10 to 50%. The ranges for levels of recovery of oocysts from cattle, kangaroo, pig, and sheep feces (juveniles and adults) collected in a subsequent watershed animal fecal survey were far wider than the ranges predicted by the validation data. Based on the use of an internal control added to each fecal sample, the levels of recovery ranged from 0 to 83% for cattle, from 4 to 62% for sheep, from 1 to 42% for pigs, and from 40 to 73% for kangaroos. Given the variation in the levels of recovery of oocysts from different fecal matrices, it is recommended that an internal control be added to at least one replicate of every fecal sample analyzed to determine the percentage of recovery. Depending on the animal type and based on the lowest approximate percentages of recovery, between 10 and 100 oocysts g of feces−1 must be present to be detected.

Fate and transport of viruses during sewage treatment in a mound system

Studies undertaken to assess the performance of filter materials to remove phosphorus in decentralised sewage systems have not reported on the broader performance of these systems. This study aimed to identify virus fate and transport mechanisms at the laboratory scale for comparison with field experiments on a mound system amended with blast furnace slag. Inactivation was a significant removal mechanism for MS2 bacteriophage, but not for PRD1 bacteriophage. Column studies identified rapid transport of PRD1. Laboratory studies predicted lower removal of PRD1 in a full scale system than was experienced in the field study, highlighting the importance of considering pH and flow rate in pathogen removal estimates. The results highlight the necessity for studying a range of organisms when assessing the potential for pathogen transport.

The Risk of Cryptosporidium to Sydney's Drinking Water Supply

Publisher Summary To protect the quality of drinking water in Sydney, the Sydney Water Corporation (SWC) and the recently created Sydney Catchment Authority (SCA) have adopted a catchment to customer risk management approach after the Cryptosporidium water crisis in 1998. In Sydney such an approach involves close collaboration with the New South Wales Department of Health (NSW Health), as well as the consortia managing several of Sydneys large water filtration plants (WFPs) under Build-Own-Operate (BOO) contracts. This chapter presents a paper, which aims to provide an update of the main actions that have been taken since the water crisis in Sydney in 1998. These updates need to be in: the catchments, water treatment plants, distribution system, and analytical laboratories for Cryptosporidium analysis.

Lessons and guidance for the management of safe drinking water during extreme weather events

Extreme weather events have presented significant challenges to drinking water quality managers in Australia and elsewhere. Examples of extreme weather events include droughts, floods, cyclones, and wildfires. With global climate change, an increased frequency and severity of diverse extreme weather events is projected for many parts of the world. As such, the need to effectively prepare for and manage these types of extreme events is increasing. Previous experience with managing water supplies before, during and after extreme weather events can provide valuable lessons to aid planning for future events. By surveying Australian water utilities, detailed experiences and lessons from ten case studies of the management of extreme weather events was compiled. The weather events and their impacts to water quality management are described. The lessons learned from these events were used to establish a series of recommendations intended to be used as guidance for future management of extreme events. An important finding was the need to lead change and coordinate effort by the development of a formal whole-of-organisation strategy for building resilience to extreme events. Effective components of such a strategy include the implementation of a water quality management system and the development of specific incident response plans. The development and maintenance of inter-agency relationships was also found to be important and the use of inter-agency hypothetical scenario testing was identified as an effective way to support this. Strategies identified to assist in maintaining operations during and immediately following extreme weather events include the enactment of incident response plans, effective communication and, where possible, the implementation of short-term risk management controls. Post-event activities were also identified, including event recovery, learning from experiences and knowledge dissemination. The guidance presented in this paper will be of value to water quality managers throughout the world as they plan to enhance resilience within their organisations and services.