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Abstract

It is estimated that between 40% and 60% of on-site systems in Australia are not
treating domestic wastewater to acceptable levels. This study investigates the viability
of constructed wetlands as an alternative form of on-site treatment of domestic
greywater in temperate climates. A case study wetland was constructed to treat domestic
greywater from a single household, providing an insight into the design, construction,
operational performance, hydraulic flow and reed growth of a small-scale wetland
operating in Tasmania. A review of current literature provides an insight into
constructed wetlands, emphasising their use as a form of on-site wastewater treatment.
Interviews with officers from five local government councils indicates that knowledge
of constructed wetlands is very limited, but a great deal of interest was shown by the
interviewed environmental health officers, who suggested that they may be willing to
trial wetlands within their municipalities. All the local governments interviewed were
experiencing problems with the current and accepted forms of on-site wastewater
treatment. Testing of the case study wetland over a nine-month period showed that pollutant
removal processes were occurring across all testing parameters except ammonia and
phosphorous. Significant findings from the case study that would improve the quality of
the final effluent include the importance of healthy reeds with deep root systems,
improving hydraulic flow within the Wetland to prevent short-circuiting, and the
necessity of additional pre and post wetland treatment. Greywater alone does not have
sufficient nutrients and trace elements to sustain vigorous growth for the common reed,
Phragmites australis. A combined flow of black and greywater led to vigorous and
healthy reed growth.
The wetland produced an effluent with an average of 64 mg/L BOD5 (60% removal),
48.5 mg/L suspended solids (88% removal), 18,427 FCU/100mL faecal coliforms
(99.2% removal), 0.008 mg/L nitrite (65% removal), 2.9 mg/L nitrate (6% removal), 2.2
mg/L ammonia, 6.7 mg/L phosphorous, 537 pS/cm conductivity, and a pH of 7.7. It is
expected that treatment would improve as the reeds and root systems mature and the
design improvements are implemented.

Item Type:	Thesis - Coursework Master
Authors/Creators:	Bayley, Sam
Keywords:	Land treatment of wastewater, Constructed wetlands
Copyright Holders:	The Author
Copyright Information:	Copyright 1998 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).
Additional Information:	Thesis (M.Env.St.)--University of Tasmania, 1998. Includes bibliographical references
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