Validating Pond and Lagoon Treatment Systems

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	Guidelines and Validation

Ponds/lagoons are used world-wide as secondary or tertiary treatment steps for wastewater; in some cases they are the only treatment. Hundreds of Australian municipal treatment systems, particularly in smaller towns and rural areas, rely on pond technology as a disinfection process, holding treated wastewater in effluent ponds for several days to weeks before being recycled or released back to the environment. However, there are very few studies that quantify and qualify the efficacy of this technology on pathogen reduction, and no study has comprehensively assessed the fate of pathogens and chemicals in treatment ponds. This project investigated and sought to validate the efficacy of ponds to provide safe water recycling, and aimed to optimise regional and remote water security by modelling the movement of pathogens in treatment ponds and lagoons.

WORK UNDERTAKEN AND OUTCOMES TO DATE

Research was conducted at Maningrida and Ngukurr in the Northern Territory and Helidon in Southeast Queensland. Results of the project were encouraging, with ponds in South East Queensland demonstrating up to a 99% (2 log) reduction of E.coli, 1.8 log reduction of enterococci and 2.5 log reduction of Giardia. Assessment of pond effluent showed that pond treatment removes limited amounts of emerging organic contaminants. Concentrations of chemicals of concern were generally below limits set out in the Standards, however risk prioritisation identified nine compounds that are important to target for improved removal. The performance of the Helidon pond was modelled using the MIKE3 software package, with the model found to be capable of simulating overall pond dynamics as well as pathogen removal. The incorporation of baffles and the influence of wind direction were shown to be important contributors to pathogen removal performance.

ADOPTION AND IMPACT

The validated hydrodynamic model developed by the project team incorporated water quality data and provides industry practitioners and regulators with guidance and a tool to better design, manage and validate maturation pond treatment systems to protect public and environmental health and to optimise uses of the treated water. Further research on treatment ponds will continue following funding support provided by the Queensland government.

PROJECT PARTNERS
Lead organisation:	Griffith University – Smart Water Research Centre
Partner organisations:	Charles Darwin University
	Central Queensland University
	University of the Sunshine Coast
	SA Water Australian Water Quality Centre
	Queensland Urban Utilities
	Power and Water Corporation (PowerWater NT)
	Deniliquin Council
	Tamworth Regional Council
	Department of Health (NT)

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