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Technical Papers
Figure 2. Nowra Wastewater Treatment Plant.
WATER REUSE
FIT FOR PURPOSE The works originally planned for augmentation of the REMS was the upgrade of Shoalhaven Water’s two remaining WWTPs in the area, Bomaderry and Nowra, and their connection to REMS (Stage 1B). Addition of these two WWTPs will double the reclaimed water available for beneficial reuse as well as significantly reduce future discharges from Nowra and Bomaderry WWTPs to the Shoalhaven River. The effluent quality of the water that is discharged will be of a much higher quality to protect the estuarine environment and downstream oyster-growing regions. Reviewing the augmentation of the REMS has involved discussion about
fit-for-use treatment for the entire scheme, both the existing Stage 1A works and the proposed Stage 1B works. It has also been underpinned by environmental discharge water quality requirements for the Shoalhaven River, including the oyster-growing zones and the benefits and drawbacks of ‘treatment’ versus ‘end use’ control. Shoalhaven Water has opted for treatment control for the REMS stages: • Stage 1A works: AGWR were introduced more than four years after commissioning of the REMS. Treatment at the four Stage 1A plants, although meeting historical regulatory needs, does not fully meet the enhanced requirements outlined by the AGWR. Plans to augment and expand the REMS include upgrading the existing
Figure 3. Bomaderry Wastewater Treatment Plant.
WATER SEPTEMBER 2014
connected four WWTPs to align with the AGWR; • Stage 1B works: Treated highquality effluent from Bomaderry and Nowra WWTPs will be supplied primarily to the REMS and, during prolonged periods of wet weather, may be secondarily discharged to the Shoalhaven River. Thus, when designing the WWTP it is important to consider the two outflow water qualities required: – for water recycling and reuse; and – for discharge to the Shoalhaven River. The approach taken for the design is discussed in the following sections.