A history of wastewater irrigation in Melbourne, Australia

Reclamation of wastewater for irrigation has had an important role to play in Melbourne’s struggle to manage water resources as effectively as possible. Rapid growth within the first few years of the founding of the city led to a sanitary crisis, which provided the impetus for the construction of a large sewerage system. Interest in using the effluent from sewage treatment plants for irrigation gained attention in the late 1970s, but despite some activity in the early 1980s, it was not until 2005 that large-scale wastewater irrigation schemes became a reality. Successful to a degree, there have also been problems, and the future viability of one large irrigation scheme for commercial vegetable production is threatened by high salt concentrations in the treated wastewater. Greywater irrigation at the household level has also become commonplace in Melbourne over the last decade, but it is difficult to regulate and the health risks urgently need to be quantified. More recently, several third-pipe schemes, where treated wastewater is reticulated to households, have been commissioned with plans for many more, and treated stormwater is growing in popularity, particularly for irrigation of public open spaces.

TREATED

The exhibition and community engagement hub, TREATED (the sublime passage), is at the Wyndham Art Gallery. The show allows a greater number of people to reflect on and engage with the works completed on-site, engage with the practice of the artists, and to consider ideas around process, elimination and purification as seen in the public art event, TREATMENT. There are tensions to explore here for as sewerage is transformed into liquid gold (water), ideas take form through material processes to become artworks. The exhibition also reveals much more about the artists’ research and aspects and factoids about the site. Architectural elements (installed by Bishop and Reis) referencing Melbourne Water’s Information Centre will activate the space – in displays, archival material, discarded materials and unused footage, diary notes and documentation of the project including video interviews with key people involved in the project. Two workshops will run with artists and members of the community, inviting participants to respond to the work, a particular process and prompt. This is a feature of the project that will allow for collaboration with a wide range of community stakeholders as workshops would draw on the histories and technologies of the site to provoke reflection and a material response from participants.

In-situ evaluation of predictive models for H₂S gas emission and the performance of optimal dosage of suppressing chemicals in a laboratory-scale sewer

This in-situ analysis quantifies hydrogen sulfide gas emission from a simulated sewerage system, with varying slopes between 0.5% and 1.5%, under the dosing of certain mitigating chemicals. A portable H₂S gas detector (OdaLog) was employed to record the gaseous phase concentration of hydrogen sulfide. The investigation was comprised of three interrelated phases. In the first stage, precision of four prediction models for H₂S gas emission from a laboratory-synthesized wastewater was assessed. It was found that the model suggested by Lahav fitted the experimental results accurately. Second phase explorations included jar tests to obtain the optimal dosage of four hydrogen sulfide suppressing chemicals, being Mg(OH)₂, NaOH, Ca(NO₃)₂, and FeCl₂. In the third stage, the optimal dosage of chemicals was introduced into the experimental sewerage system, with the OdaLog continuously monitoring the H₂S gas emission. According to a baseline (experiments with no chemical addition), it was found that NaOH and Mg(OH)₂ performed very good in mitigating the release of H₂S gas, while Ca(NO₃)₂ was not effective most probably due to the absence of biological activity. Furthermore, interpretation of OdaLog data through the optimum emission prediction model revealed that higher sewer slope led to more emission.