Water Reuse & Recycling Plants

A water reuse and recycling plant is a facility that treats wastewater or process water to a defined quality standard suitable for a specific beneficial reuse application, rather than discharging it to the environment. Reuse applications range from non-potable urban irrigation and industrial process water through to indirect potable reuse via aquifer recharge. The plant design is determined by the gap between the quality of the source water and the quality required for the target reuse application, with multi-barrier treatment trains providing the necessary level of treatment and pathogen reduction.

Reuse water quality standards vary by application and jurisdiction. WHO guidelines for water reuse set pathogen reduction targets for different reuse categories, from restricted agricultural irrigation through to indirect potable reuse. National and regional standards may also apply, specifying limit values for pathogens, BOD, TSS, nutrients, heavy metals, emerging contaminants and disinfection residuals. IWTE designs all water reuse plants to comply with the specific standards and permit conditions applicable to the reuse application and location.

The treatment train in a water reuse plant is configured around the source water quality and the reuse standard required. Secondary biological treatment removes organic matter and nutrients. Membrane filtration using ultrafiltration provides a reliable barrier against suspended solids and pathogens. Reverse osmosis removes dissolved salts, trace contaminants and emerging pollutants where high reuse quality is required. Advanced oxidation processes address micropollutants and residual organics. UV disinfection and chlorination provide the final pathogen reduction barrier before reuse.

Indirect potable reuse (IPR) involves treating wastewater to a high standard and then introducing it into the environment, typically via managed aquifer recharge or surface water augmentation, before extraction and further treatment as a potable supply. The environmental buffer provides additional treatment and public acceptance. IWTE designs IPR treatment trains that achieve the pathogen reduction, organic removal and trace contaminant targets required by the applicable indirect potable reuse framework, typically incorporating reverse osmosis and advanced oxidation as core treatment barriers.

Yes. Industrial water recycling schemes treat process effluent to a quality suitable for reuse in the same or a different process within the facility, reducing freshwater intake and wastewater discharge volumes. Common industrial reuse applications include cooling tower make-up, boiler feed pre-treatment, equipment washing and dust suppression. For facilities targeting zero liquid discharge, IWTE designs advanced concentration and recovery stages that maximise water recovery and eliminate or minimise liquid discharge.

Agricultural reuse water quality is managed through a combination of treatment process selection and ongoing monitoring. The treatment train is designed to achieve the pathogen and chemical quality targets set by applicable agricultural reuse standards. Continuous online monitoring of key quality parameters, combined with automatic diversion of off-spec water back to the treatment process, ensures only compliant water is supplied for irrigation. IWTE designs automated diversion and alarm systems as standard in all agricultural reuse applications.

Reuse plants that incorporate reverse osmosis or nanofiltration generate a concentrate reject stream containing the removed dissolved solids. This stream must be managed separately, with disposal options including sewer discharge where permitted, evaporation ponds, deep well injection or further concentration by thermal or membrane processes for zero liquid discharge applications. IWTE assesses concentrate management requirements during the design phase and incorporates appropriate handling and disposal provisions within the overall plant design.

Yes. IWTE provides feasibility assessment services for water reuse projects, covering source water quality characterisation, reuse demand and application analysis, technology selection, indicative treatment train design, regulatory pathway review and capital and operating cost estimation. A feasibility study provides the technical and commercial basis for a project investment decision and informs the detailed design brief. IWTE engineers are available to discuss your reuse objectives and scope a feasibility study to your specific needs.