Compliance of Aerated Wastewater Treatment Systems: A Quantitative and Qualitative Analysis

A survey was conducted of the compliance with permit requirements of effluent quality of Aerated Wastewater Treatment Systems (AWTS) located in a rural municipality in Victoria. The study was prompted by anecdotal reports of high levels of non-compliance, concerns about performance after installation of the systems, and a lack of information about the factors affecting non-compliance. Twenty one of the 45 AWTS identified in the municipality were sampled to investigate their compliance with the Victorian EPA effluent water quality requirements (EPA Victoria 2002). Only one of the 21 systems was compliant with EPA permit effluent water quality requirements. Eighty six percent (86%) of systems were found to have a chlorine residual below the minimum requirement of 0.5 mg/L and 67% of the systems had Escherichia coli levels above the EPA prescribed limit. Fifty two percent (52%) and 33% of the systems were above the BOD and suspended solids prescribed limits, respectively. The presence of chlorine tablets was a major determinant of compliance with both chlorine residual and E. coli levels. A relationship between the number of non-compliances and the number of residents in the household was found, as was a relationship between the number of residents and Biochemical Oxygen Demand (BOD). A survey assessing household knowledge of their system indicated that many residents had little knowledge about their AWTS and its maintenance. A need for accessible, understandable educational material to inform the owners about their system was identified.