Beenyup Groundwater Replenishment Scheme
Advanced water recycling and managed aquifer recharge in Perth, Western Australia
Beenyup receives secondary-treated wastewater from the adjacent wastewater treatment plant and further treats it before recharge to the Leederville and Yarragadee aquifers. The project is valuable to MBR practitioners because it shows how membrane pretreatment, RO performance, disinfection, critical-control-point monitoring, hydrogeology, and public-health regulation must operate as one reuse system.
1. Site context and treatment objective
Perth’s groundwater replenishment program was developed as a climate-independent water source in a drying climate. The scheme produces highly treated recycled water for controlled injection into deep aquifers that can later contribute to drinking-water supply. The three-year trial injected 2,533 ML between November 2010 and December 2012 while technical, regulatory, hydrogeological, and community-acceptance questions were assessed.
Stage 1 was described as 14 GL/year. Stage 2 doubled the annual treatment capacity to 28 billion litres per year, although the owner notes that actual treatment depends on wastewater availability. These are annual capacity figures and should not be converted into an assumed constant daily flow.
2. Documented treatment and control barriers
flowchart TB A[Secondary-treated effluent from Beenyup WWTP] --> B[Pre-treatment, screens and filters] B --> C[Ultrafiltration UF] C --> D[Reverse osmosis RO] D --> E[Ultraviolet disinfection] E --> F[Final conditioning and CCP verification] F --> G[Recharge bores] G --> H[Leederville and Yarragadee aquifers] D --> I[RO performance and cleaning controls] C --> I
The public-health framework uses multiple barriers, control points, fail-safe diversion or shutdown, and notification requirements when treatment barriers fail. The environmental licence also requires groundwater-quality and potentiometric-pressure monitoring to manage geochemical change and avoid excessive aquifer pressure.
3. Engineering decisions and operational learning
- Regulatory design from the beginning: the trial was used to establish a regulatory framework compatible with health guidance and drinking-water guidelines, rather than treating approvals as a final paperwork step.
- Multiple membrane barriers: UF protects the RO process from suspended solids and colloidal loading; RO supplies the principal dissolved-contaminant barrier; UV provides a further pathogen-control barrier.
- RO fouling response: a 2022 technical paper reports severe RO lead-element biofouling during the trial. The response included reverse-cleaning capability and controlled/pre-formed chloramine dosing after UF and before RO, followed by a longer interval between cleans.
- Recharge as part of the treatment system: well integrity, aquifer pressure, geochemistry, monitoring wells, and fail-safe diversion are not optional accessories to the membrane plant.
4. Reported outcomes
| Outcome | What the cited source supports |
|---|---|
| Trial objectives | Technical feasibility, regulatory/policy arrangements, and community acceptance were reported as achieved by Water Corporation. |
| Stage 2 capacity | Doubled from 14 to 28 billion litres/year; actual rate depends on wastewater availability. |
| Historical process performance | A 2022 technical paper reports Stage 1 met permeate-quality specifications over almost six years, while also noting residual front-end biofouling and gradually increased normalized salt passage. |
| Environmental compliance | The 2023–24 Ministerial Statement report recorded no non-compliances or complaints for that reporting scope and period; this is not a blanket claim about every process or water-quality parameter. |
| Water-supply contribution | The owner currently states that groundwater replenishment contributes 5% of Perth’s Integrated Water Supply Scheme. |
5. Limitations and transferability
- Beenyup’s success depends on site-specific secondary-effluent quality, UF/RO operation, aquifer properties, recharge-well performance, groundwater chemistry, pressure limits, and a formal regulator/operator monitoring regime.
- The case is not fouling-free. RO biofouling was a material trial issue, and the 2022 technical account still noted some front-end biofouling.
- Reported compliance for a particular Ministerial Statement period should not be extrapolated to current membrane integrity, current water quality, or future performance without current records.
- Do not copy Beenyup’s capacity, chloramine strategy, cleaning practice, or recharge design without local pilot work, hydrogeological assessment, water-quality risk assessment, and regulatory approval.
6. Transferable lessons for MBR and reuse projects
- Define the required water-quality barrier train from the end use backward; do not assume an MBR alone determines reuse suitability.
- Design membrane fouling control, cleaning access, chemical compatibility, and fail-safe diversion as part of the process safety case.
- For aquifer recharge, integrate process monitoring with well pressure, groundwater quality, geochemistry, and environmental compliance monitoring.
- Present capacity, actual production, compliance, and public-health claims with their dates, boundaries, and source definitions.