California has been experiencing a series of droughts, which has meant increased water-use restrictions, and a subsequent need for wineries to reclaim and reuse their treated wastewater. When its leach field failed, the owners of Napa Valley winery Castello di Amorosa knew it was time to update their wastewater treatment system to address both these issues.

“A major drought in 2014 led us to be proactive and look for a replacement wastewater treatment system that would save water,” says Tim Dexter, maintenance manager at Castello di Amorosa.

The winery chose a treatment system that uses fiberglass tanks due to their corrosion resistance.

“Tanks made of fiberglass can safely hold any type of winery wastewater, which can contain a variety of chemicals and varied pH levels,” explains Sheldon Sapoznik of BioMicrobics, who supplied the winery’s wastewater treatment system.

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The tanks are watertight, which prevents infiltration that could reduce the treatment quality of wastewater and leaks that could jeopardize the environment.

“Fiberglass was also a more economical option than concrete,” says Dexter. “The installation process is more straightforward and cost-effective. Large concrete tanks often require extensive road infrastructure for access and costly cranes. Neither are necessary for moving lightweight fiberglass.”

A precise treatment system

“A major advantage of pairing ZCL Xerxes tanks with the BioMicrobics treatment system is that together they are scalable and modular,” says Sapoznik. “Fiberglass tanks are easier to customize, so we can obtain a seamless integration with the BioBarrier system.”

Aeration grids
Aeration grids below the membrane modules promote aerobic microbes that metabolize and digest the wastewater.

Three ZCL Xerxes 83,000-litre fiberglass wastewater tanks (3 m diameter) replaced the existing plant’s concrete ones. A BioMicrobics BioBarrier high strength membrane bioreactor treatment system was installed inside each tank. Aeration grids below the membrane modules promote aerobic microbes that metabolize and digest the wastewater. It then passes through the membranes.

The BioBarrier system’s flat-sheet membranes have 0.03 – 1.3 micron pores, providing ultrafiltration. This physically separates the wastewater and treated water so solids and bacteria remain in the tank. Treated water (high-quality effluent), with nearly all contaminants removed, exits the tanks via a small submerged filtrate pump.

The three tanks operate independently to address the winery’s wastewater flows, which can vary significantly from day to day. During the most water-intensive times, when wine is bottled and barrels are washed, all three tank systems run. The BioBarrier system in each tank can treat up to 20 litres per minute. In a 24-hour period, the three tanks can treat up to 34,000 litres of water. The tanks are designed to accommodate the surge protection needed for this high volume of flow, so the treatment process is not disrupted.

The Castello di Amorosa wastewater system is designed for low maintenance, and requires membrane cleaning and sludge removal only once per year. The resulting clean water can be reused in numerous ways, including vineyard irrigation.

“In our first year of operation, the winery treated and reused over 5 million litres of water. That’s water we would have had to source from somewhere else. Our water now has two life cycles,” says Dexter.

Both the winery and land have recently been Napa Green-certified, which means they meet all the regulatory components needed for environmental sustainability, including water conservation and efficiency.

This article appears in ES&E Magazine’s June 2019 issue.

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