by clicking the arrows at the side of the page, or by using the toolbar.
by clicking anywhere on the page.
by dragging the page around when zoomed in.
by clicking anywhere on the page when zoomed in.
web sites or send emails by clicking on hyperlinks.
Email this page to a friend
Search this issue
Index - jump to page or section
Archive - view past issues
EHA : Yearkbook 2009
EHA YEARBOOK 2009 Tyrone Marini Ballarat City Council The Ballarat City Council has had increasing interest from the community in regard to reusing on-site secondary treated effluent for surface irrigation, particularly on their gardens. This interest has increased over recent times due to the drought and current water restrictions. This paper examines the performance of aerated on-site wastewater treatment systems (AWTS), which are approved by the Environment Protection Authority Victoria (EPA Victoria) to dispose of the treated effluent on the surface. Due to environmental and public health concerns, the Ballarat City Council does not permit any wastewater effluent to be disposed of via surface irrigation. The effluent from 14 AWTS and one sand filter located in the Ballarat municipality were sampled over a two-week period for compliance with the Environment Protection Authority Victoria effluent quality standards for secondary treated onsite sewage. The water quality parameters tested for this research were biochemical oxygen demand (BOD) and suspended solids (SS). The samples were collected over five days from 31 July 2007 to 8 August 2007. The results of the sur vey indicated that of the 15 systems sampled, four complied with the EPA Victoria effluent standard for both BOD and SS equating to a 73% failure rate. This result supports the Council’s position on surface irrigation of treated effluent. The results highlight the need for further investigation into the performance of AWTS including the owner’s knowledge of AWTS and their maintenance requirements. The Ballarat City Council’s Environmental Health Unit has been receiving increasing interest and pressure from the local community for alternative reuse options for their onsite sewage effluent. This pressure has been exacerbated by the current drought and water restrictions. From 1 November 2006, the Ballarat water supply systems moved to the highest level of water restrictions, Stage 4, which restricted all outside garden water use (Caldwell 2006). Ballarat’s water supply is at an all time l o w, with a current capacity as at 16 October 2007 of 11.9% (Central Highlands Water 2007). These restrictions have provided an impetus for the local community to explore alternative water sources to sustain their gardens. According to Ballarat’s Environmental Health Officer, most enquiries have centred on surface disposal of onsite sewage effluent directly to the garden ( P. Garry, November 2 0 0 7, Ballarat City Council, Pers. Comm.). The only effluent quality that has been approved by EPA Victoria for surface disposal is secondary treated effluent. There are a range of secondary treatment systems on the market and these include aerated on-site wastewater treatment systems (AWTSs) and sand filters (EPA Victoria 2003a). However, it is Ballarat City Council policy not to permit a ny treated sewage (domestic wastewater contaminated by faeces or urine) to be disposed of by this method and it requires that all treated wastewater is to be disposed of below ground (W. Swards, November 2 0 0 7, Ballarat City Council, Pers. Comm.). The manufacturers of AWTSs specifically market their product as being designed as safe and environmentally friendly, however, Council as the permitting authority needs to be sure that these systems are able to meet the design performance requirements in normal operating or field conditions. Aim of the Research Project The project aim was to measure the performance of a random sample of onsite aerated wastewater treatment systems in the Ballarat municipality to ascertain whether the quality of treated effluent complied with the EPA Victoria effluent standards. Methodology Participants for the project were selected by extending a written invitation to all owners of AWTS contained within the Council permit data base. The data base revealed that a total of 85 permits had been issued for AWTS, however, for seven of these systems the types and models were unknown due to incomplete records and were not included in the survey. An owner of a sand filter system was also invited by mistake, however, it was decided to include the owner of this system in the project as, according to the E PA Victoria’s Septic Tanks Code of Practice (2003a), sand filters systems have the ability to treat wastewater to the same standard as that for BODs (BOD5 is the actual parameter as the test is conducted over 5 days) and SS, as an AWTS. Table 1 provides the water quality standard for AWTS effluent required for sub-surface irrigation (EPA Victoria 2002). The letter of invitation to AWTS owners was themed around environmental sustainability focusing on what the results of the project could provide in terms of reuse options for residents’ wastewater (i.e. a valuable all-year round resource for their garden). In addition, the invitation stated that the residents would be provided with a free copy of the effluent quality testing results and explanation to facilitate understanding and interest. To simplify the response process, all the residents had to do was tick the response sheet provided stating whether they did, or did not, wish to Table 1: Secondary treated effluent quality for sub-surface irrigation Parameter Criteria For all discharges BOD5 <20mg/L SS <30mg/L Aerated Wastewater Treatment Systems: Do they treat wastewater to the EPA Victoria approved standard?
Annual Review and Yearbook 2008
EHA Yearbook 2010