Previous studies established that a combination of commercially available micro filtration, nano filtration and reverse osmosis units would be capable of recovering water fit for irrigation from waste water at the Altona Waste Water Treatment plant in Melbourne. This study used computer modelling to investigate the costs associated with five different possible recycling treatment plant configurations.
Analysis of effluent from the Altona Secondary Treatment Plant was carried out and the data used to model the performance of five possible recycling plant configurations. Three key variable areas in generating costs were identified. These are: electric power, chemical supplies and invested capital.
Computer modelling of five separate plant configurations was undertaken to obtain estimates of daily throughput, power consumption and recycled water quality. Plant performance modelling was executed with the ROSA, Reverse Osmosis System Analysis Package supplied by Dow Water & Process Solutions.
Cost Modelling was done using electric, chemical and standardised capex models, with plant sized to produce in the order of 1ML per day of recycled water.
Results from the five different plant configurations were reduced to a cost per kilolitre of recovered water for comparison. These were found to range from 30cents to $2 per kilolitre. The most cost efficient plant configuration recovers 67 per cent of the feed water and produces substantially less than 1 ML per day, while the most expensive option recovers 96 per cent of the feed water. These results allow comparison of cost efficiency versus recovery efficiency and are a useful guide to selection of the optimum configuration of water recycling plant installations for particular applications and locations.