Associate Professor Phillip Geary

In managing water quality in catchments and estuaries, faecal contamination is typically assessed using microbial indicators, such as faecal coliform bacteria. Bacteriological indicators however cannot be used to distinguish whether the faecal contamination has been derived from human or animal sources. The ability to track contamination and distinguish between sources is particularly important where water is used for potable supply, recreational purposes and where commercial aquaculture for human consumption is undertaken. Various chemicals associated with human metabolism and activities which are present in faecal material (such as faecal sterol, pharmaceutical and fluorescent whitening compounds present in wastewaters) can be utilized to identify a human signal and therefore whether the faecal contamination in water is likely to have been derived from human sources. This paper demonstrates an approach and methodology for future work using a combination of these methods to distinguish human contaminant sources in stormwater runoff in an estuary where aquaculture is practised.

The secondary metabolites geosmin and 2-methylisoborneol (2-MIB) provide soil with its characteristic earthy-musty odour, being notably produced by the abundant spore-forming filamentous bacterial genus Streptomyces, among other Actinobacteria. Taste and odour (T&O) problems attributed to these compounds affect drinking water supplies worldwide, often occurring sporadically and untraced to their biological origins. A number of prokaryotic and eukaryotic organisms are recognised geosmin and 2-MIB producers in aquatic environments. However, the focus of this paper is to assess the potential contribution of Actinobacteria to this water quality issue. To date, the aquatic ecology of these bacteria remains poorly understood and debate surrounds whether they exist solely as dormant spores of terrestrial origin or are capable of growing and biosynthesising these odourous compounds in aquatic environments. The Actinobacteria which are known to produce geosmin and 2-MIB are identified and a critical assessment of habitats within aquatic environments in which they may be metabolically active residents and thus potential sources of T&O is provided. Current understandings of the chemical ecology and biosynthetic pathways of geosmin and 2-MIB, as well as the conditions under which these secondary metabolites are produced by Streptomyces, are reviewed. © IWA Publishing 2013.

The Probabilistic Urban Rainfall and wastewater Reuse Simulator (PURRS v7.2), the Model for Urban Stormwater Improvement Conceptualisation (MUSIC v3) and Spreadsheet modelling tools were compared for evaluating rainwater harvesting strategies. Input data included climate files, suggested water demands and time-steps. Models were run with climate data of unequal duration and time-step, which highlighted significant differences between modelled outcomes. Using climate data of equal duration still resulted in major differences. The reasons for these differences are explained as a function of the duration and time-step of climate data, the time-step and diurnal patterns of indoor/outdoor water demand and tank configuration. Results imply that the length and time-step of climate inputs, the distribution and time-step of daily water demand and rainwater tank configuration are significant factors in robustly evaluating mains water savings for a range of Australian climates.

This paper reports on the performance of two urban stormwater management systems which incorporate constructed wetland systems in the treatment train. The stormwater runoff is treated prior to its discharge to different estuarine lake systems located on the NSW Central Coast. At Croudace Bay on Lake Macquarie, the system incorporated a surface flow constructed wetland, while at Blue Haven near Wyong, a sub-surface flow constructed wetland was incorporated into the stormwater management system. In each case the local authority was responsible for the design, construction and management of their stormwater treatment system. The removal of pollutants in stormwater runoff was monitored by two Bachelor of Environmental Science Honours students from the University of Newcastle.

A large number and growing proportion of both single lot residential and larger scale new developments in the Hunter Region are not serviced by a conventional reticulated sewerage system. In such cases, wastewater treatment, its possible reuse and final disposal, is on-site, where the effluent is generated. A range of geotechnical factors including the site geology, geomorphology, soils, availability and performance of geo and geosynthetic materials, along with climatic factors, have a bearing on the selection, design, sizing and performance of an on-site wastewater system which will perform adequately and meet regulatory requirements. Geotechnical skills in site and soil assessment are fundamental to and necessary for good on-site wastewater system design and to ensure that the environmental impacts associated with on-site wastewater management are minimised. The Hunter Region displays a number of challenging geological settings and soil types for wastewater management. These include perched and shallow water tables, sensitive aquifers, floodplains and coastal lake and estuary catchments. Soils include sodic, dispersive and duplex soils and high permeability sandy soils with limited capacities for wastewater assimilation. Hydraulic and nutrient loading capacities of some of the region's soils are limiting and present a challenge to designers. An understanding of transport and assimilation of nutrients and pathogens through permeable materials is significant in understanding the potential contribution of on-site wastewater management systems to surface and groundwater contamination and the protection of those sensitive receiving bodies by appropriate design. This paper reviews the geotechnical aspects of on-site wastewater management in the Hunter Region and illustrates, with a number of case studies, both the problems commonly encountered and their possible solutions.