Advanced water treatment plant constructed

MBR and RO technology used

Viterra is an agribusiness providing premium quality ingredients to leading global food manufacturers and its Tamworth malt facility has a grain capacity of 45,000 tonnes, supplying malt both domestically and internationally.

With Viterra’s holistic approach to water management and conservation of this precious resource, an advanced water treatment plant (AWTP) was required by the company to treat malting steep water to a quality suitable for re-use within the facility.

Ovivo Australia designed and constructed an AWTP using MBR (membrane bioreactor) and RO (reverse osmosis) technology.

MBR technology was used as it is suitable for the treatment and filtration of municipal and industrial waste. The MBR and RO perform all the necessary steps to treat the influent to a condition suitable for re-use within the client’s facility and to maintain discharge agreement conformance for the reject stream generated.

The malting steep waste is initially screened, balanced, pH corrected and biologically treated to reduce BOD/COD, nitrogen and phosphorous. Permeate is drawn through two immersed membrane trains reducing TSS levels and pathogens. The MBR permeate is further treated through a dual-stage RO system to remove dissolved content and pH corrected before being stored for re-use. The process designed by Ovivo incorporates the use of a bioselector that conditions the wastewater prior to biotreatment and enhances biological phosphorous removal.

The AWTP, which is capable of treating a hydraulic load of 300 kL per day, can recover 75% of the wastewater, which equates to approximately a 50% reduction in the client’s reliance on local potable water supply.

Ovivo was able to provide the client with capital cost savings over conventional activated sludge systems. The AWTP performed the same function but with a reduced footprint and associated civil installation costs. The technology used resulted in a compact and efficient means of improving water quality and is well suited to re-use applications.

The AWTP, which was delivered as design, build and operation (DBO), enables water savings of 50 ML per year.

Since commissioning, plant reliability has been stable with minimal requirement for process adjustments. The aeration system uses Ovivo’s Aerostrip Fine Bubble Diffusers, a high-performing membrane diffuser that has provided high SOTR against power input. The efficiency has been shown as 4 to 4.2 kg O₂/h per kW input. Optimisation of the positive displacement blowers is achieved through Ovivo’s DO control strategy.

With proper management of the sludge age and MLSS, permeability of the submerged membrane modules has been found to be consistent and well above accepted levels of 300 LMH/bar. The membrane flux rate selected reflects the high residual COD that is commonly experienced in industrial trade waste, when compared to sewage, due to slow or non-biodegradable organic fractions.

Performance data:

As can be seen, even though the designed influent data is much lower than actual influent loads, the recovered water surpasses design estimates.

The excess biomass generated by the aeration phase is wasted through the MBR tank and dewatered using a horizontal solid bowl decanter centrifuge. The output of the centrifuge is a spadable cake that is beneficially re-used within the region. Centrate is captured and returned to the head of the plant.

The plant is controlled via a SCADA system that allows for remote monitoring and trending. Automation is seen as critical to the long-term success of the wastewater treatment plant.

This type of advanced water plant is the fifth of its kind that Ovivo has completed for the Australian food and beverage sector.