Impact of improved primary sedimentation efficiency on operations at the Rosedale WWTP

Following the recent Rosedale Wastewater Treatment Plant Stage 5 upgrade and the associated construction of two additional primary sedimentation tanks there have been some noticeable improvements in operational efficiencies and process stability. These efficiency improvements translate into increased primary suspended solids removal which now averages 74% and stable primary sludge fractions in the anaerobic digester feed stream which have increased by an average of 10% from 58% to 68%. Downstream analysis has also shown that the production of digested sludge is much more stable and predictable; however as yet there is no apparent improvement in sludge dewaterability. Internal electricity generation has increased to over 500 MWh per month resulting in energy cost savings of approximately $8,000 to $10,000 per month.

Now that these improvements have resulted in a more stable and predictable treatment process, further process analysis will be undertaken with the intention to exploit further optimisation opportunities where possible.