Abstract
South East Queensland is one of the fastest growing regions in Australia with a correspondingly rapid increase in sewage production. In response, local councils are investing in more effective and sustainable options for the treatment and reuse of domestic and industrial effluents. A novel, evaporative solar dryer system has been installed on the Sunshine Coast to convert sewage sludge into a drier, usable form of biosolids through solar radiation exposure resulting in decreased moisture concentration and pathogen reduction. Solar-dried biosolids were analyzed for selected pathogenic microbial, metal and organic contaminants at the end of different drying cycles in a collaborative study conducted with the Regional Council. Although fecal coliforms were found to be present, enteroviruses, parasites, E. coli, and Salmonella sp. were not detected in the final product. However, elevated levels of zinc and copper were still present which restricted public use of the biosolids. Dilution of the dried biosolids with green waste as well as composting of the biosolids is likely to lead to the production of an environmentally safe, Class A end-product.
Highlights
Sewage sludge is an inevitable by-product of wastewater treatment and with the present rate of population increase, the volumes of sludge to be dealt with will continue to grow, constituting a problem for local authorities
The results of this study demonstrate that the dried biosolids product from the Maroochydore Sewage Treatment Plant (STP)
With regard to bacterial indicators, the results of this study indicate that Salmonella sp. and E. coli counts were reduced to acceptable levels for Grade A compliance
Summary
Sewage sludge is an inevitable by-product of wastewater treatment and with the present rate of population increase, the volumes of sludge to be dealt with will continue to grow, constituting a problem for local authorities. The agenda for global sustainability provides a strong mandate for waste streams, such as sewage sludge, to be converted into biosolids of various grades that can be used to restore degraded lands by reintroducing nutrients and soil conditioning agents (Table 1). The reuse of inadequately treated biosolids might present a recognized public health risk [1,2,3]. A i) Home lawns and gardens ii) Public contact sites iii) Urban landscaping iv) Agriculture v) Forestry vi) Soil and site rehabilitation vii) Landfill disposal viii) Surface land disposal
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More From: International Journal of Environmental Research and Public Health
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