Water Journal : Current May 2016
98 www.awa.asn.au executive summary wastewater treatment Maintenance for WA aerobic and greywater treatment systems A REVIEW OF AREAS THAT COULD BE IMPROVED AND SPECIFIC RECOMMENDATIONS OFFERED. T McGrath, N Shishkina, R Theobald, C Rodrigues Aerobic Treatment Units (ATU) and Greywater Treatment Systems (GTS) are electrically driven onsite wastewater treatment systems (OWTS) designed to treat wastewater to secondary effluent quality standards. ATU are designed to treat wastewater -- both blackwater and greywater -- either wholly or partially, from all areas of the house by aerobic means. All ATU incorporate the following processes: primary sedimentation, biological treatment, secondary sedimentation, and, usually, disinfection. GTS are designed to treat greywater only and typically consist of the following treatment processes: filtration or screening, biological treatment and disinfection. Despite the usefulness of OWTS, they can present a risk to human health and the environment when they fail or are used inappropriately. This is due to the contaminants that are present and the nature of the wastewater they treat. Therefore, maintenance of the electrical, mechanical and chemical components of these OWTS is important for ensuring their consistent and reliable operation to the required standards. ON THE GROUND In Western Australia, the Department of Health Western Australia (DOHWA) approves each system design prior to system sale and installation, and sets out the regulatory requirements for the maintenance of OWTS as well as when and how maintenance is to occur. All service personnel must be accredited by either the DOHWA or the system manufacturer; once accredited, they must also abide by the DOHWA-issued Conditions of Approval. Once the basic product approvals from the DOHWA are in place, the management of individual domestic systems is controlled by local government Environmental Health Officers (EHO). The guidelines and regulations provide a framework that assists EHO in overseeing the management of domestic systems. Management includes approving the installation of systems, issuing permits to use systems and enforcing the maintenance requirements. This paper reviews the maintenance requirements for ATU and GTS in WA and provides recommendations for the proposed changes in guidelines and regulations. DELVING INTO THE DATA State and national guidelines were reviewed and information from industry and regulators was obtained through surveys. Surveys were sent to those most heavily involved in the domestic wastewater treatment systems industry to give the opportunity to express any dissatisfaction, opinions and recommendations and to allow PATHOGENIC ORGANISMS Bacteria Domestic wastewater contains a wide variety and concentration of pathogenic bacteria. Infectious doses of disease- causing bacteria in wastewater can lead to illness. Parasites Domestic wastewater has the potential to contain a range of parasites. Of greatest concern are protozoan parasites, Cryptosporidium and Giardia, and helminths or intestinal worms. Protozoan parasites are often resistant to standard disinfection methods, while helminths release millions of environmentally resilient eggs throughout their lifespan. Viruses Domestic wastewater has the potential to contain viruses. Viruses are more common and diverse than bacteria and can cause widespread illness.
Current Feb 2016
Current August 2016