Aims: To determine the persistence of the faecal indicator organism Escherichia coli in recreational coastal water and sediment using laboratory-based microcosms and validation with in situ measurements. Methods and Results: Intact sediment cores were taken from three distinct coastal sites. Overlying estuarine water was inoculated with known concentrations of E. coli and decay rates from both overlying water and sediment were determined following enumeration by the membrane filtration method at fixed time intervals over a 28-day period. It was demonstrated that E. coli may persist in coastal sediment for >28 days when incubated at 10°C. Escherichia coli survival was found to have an inverse relationship with temperature in both water and sediment. In general the decay rate for E. coli was greater in water than in sediment. Small particle size and high organic carbon content were found to enhance E. coli survival in coastal sediments in the microcosms. Conclusions: Results of this microcosm study demonstrated the more prolonged survival of E. coli in coastal sediments compared with overlying water, which may imply an increased risk of exposure because of the possible resuspension of pathogenic micro-organisms during natural turbulence or human recreational activity. Significance and Impact of the Study: A more accurate estimate of exposure risk has been described which may subsequently be used in a quantitative microbial risk assessment for recreational coastal waters.

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The experience and perceptions of 80 people residing in four separate sites, which feature reclaimed water systems, are considered in this paper in relation to the benefits and costs of residential water reuse applications. Reclaimed water is used for non-potable applications by residents in Florida mainly for garden irrigation and in Australia for both irrigation and toilet flushing. All respondents value reclaimed water and although the benefit of water conservation is identified they are more enthusiastic about the personal cost benefit involved in using this cheaper alternative to potable water. Many are willing to handle the water but the extent to which this increased exposure is seen as a good development depends on the quality of information provided to users. In relation to reclaimed water for toilet flushing, there is a strong indication that the water conservation and cost saving benefit is small compared to the initial cost and the increased cross connection risk.

Aims: To identify the most efficient techniques for the separation of micro-organisms from coastal sediments and, using these techniques, to determine the concentration of faecal indicator organisms in recreational coastal water and sediment. Methods and Results: Sediment samples were taken from a range of recreational coastal sites and subjected to various physical techniques to separate micro-organisms from sediment particles. Techniques investigated included manual shaking, treatment by sonication bath for 6 and 10 min, respectively, and by sonication probe for 15 s and 1 min, respectively. The use of the sonication bath for 10 min was the most successful method for removing microorganisms from sediment particles where sediments consisted mainly of sand. When sediments contained considerable proportions of silt and clay, however, manual shaking was most successful. Faecal coliforms were then enumerated by membrane filtration in both water and sediment from three recreational coastal sites, chosen to represent different physical sediment characteristics, over a 12-month period. Faecal coliform concentrations were generally greater in sediment compared with overlying water for all samples. This was most evident in sediment consisting of greater silt ⁄ clay and organic carbon content. Conclusions: This study demonstrated the importance of sediment characteristics in determining the most efficient method for the separation of micro-organisms from coastal sediments. Sediment characteristics were also found to influence the persistence of microorganisms in coastal areas. Significance and Impact of the Study: Recreational coastal sediments can act as a reservoir for faecal coliforms; therefore, sampling only overlying water may greatly underestimate the risk of exposure to potentially pathogenic micro-organisms in recreational waters.

Over the last 20 years, there has been a growing requirement by governments around the world for organisations to adopt more sustainable practices. Wastewater treatment is no exception, with many currently used systems requiring large capital investment, land area and power consumption. High rate algal ponds offer a sustainable, efficient and lower cost option to the systems currently in use. They are shallow, mixed lagoon based systems, which aim to maximise wastewater treatment by creating optimal conditions for algal growth and oxygen production-the key processes which remove nitrogen and organic waste in HRAP systems. This design means they can treat wastewater to an acceptable quality within a fifth of time of other lagoon systems while using 50% less surface area. This smaller land requirement decreases both the construction costs and evaporative water losses, making larger volumes of treated water available for beneficial reuse. They are ideal for rural, peri-urban and remote communities as they require minimum power and little on-site management. This review will address the history of and current trends in high rate algal pond development and application; a comparison of their performance with other systems when treating various wastewaters; and discuss their potential for production of added-value products. Finally, the review will consider areas requiring further research.