Reducing the environmental impact of winery waste

Treasury Wine Estates (TWE) planned to expand the capacity of the Matua Marlborough winery from 13,500 tonnes equivalent (te) to 24,000 te, with capacity to expand further in future. As a condition of approval, Marlborough District Council required a significant reduction in environmental impact. Past practice had been to irrigate the wastewater onto an extensive area of pasture; however, that pasture area was showing degradation and eutrophication.

Factor UTB was thus hired to design and construct a winery wastewater treatment for Matua Marlborough. The new plant required the use of almost every trick and technique the company had learned to deal with high-strength and volatile loads to provide load peaking and achieve high-quality treatment.

The plant used the pre-existing flow balancing system, which collects the flow from the winery area and the new tank farm. An automated diversion system ensures capture of the initial dirty flow and then allows clean stormwater to be diverted in response to sensors indicating safe discharge to on-site soakage, reducing hydraulic loads.

Winery wastewater is loaded in batches into the two ‘lead’ reactors in turn. Those two reactors are about 90% efficient in removal of BOD up to a maximum capacity of about 1250 kg. BOD is typically 5000 mg/L and can be double that. COD can exceed 15,000 mg/L. The treated water from the first stage is then transferred to a secondary reactor, which can remove up to 625 kg of BOD. The system is configured to minimise the BOD load in the final treated effluent.

Untreated effluent is introduced into the third reactor directly only if the first two reactors are at full load. The event-based control system allows real-time measurement of actual oxygen take-up. For most of the time, the third reactor serves a polishing function to ensure that wastewater is discharged at a BOD of less than 100 mg/L and a COD of less than 500 mg/L. This allows the best ‘flow weighted average’ quality of treated water to be produced with small amounts of overload blended with the treated water from the reactors. The water is then passed through 50 µm automatic filters and pumped 3 km to the irrigation area on the banks of the nearby Wairau River, where it irrigates an open woodlot area.

The high daily quantities of biosolids produced by the system are wasted as settled sludge to a thickening tank and on to a Dayco Vfold belt filter press, also supplied by Factor UTB. Since there is no source of human waste entering the system, the thickened sludge can be used as a soil conditioner or fertiliser supplement. A company that packages potting mixes and fertilisers takes all of the waste at no cost to the winery.

The order for the plant was received in mid-November 2015. The design was complete and regulatory approval gained by early January. Site work commenced on 4 February and the plant was turned on by mid-April for the start of Marlborough’s cool climate vintage. The project has also been awarded the Malcolm Kinnaird Award for Engineering Excellence by Engineers Australia.