The Castello Banfi winery, where the famous Brunello di Montalcino wine is produced, needed a new aeration system for its wastewater. With a solution from Xylem, including Sanitaire Silver Series II membrane disc diffusers and a Sanitaire TurboMAX turbo blower, the winery was able to cut the energy used by its wastewater treatment plant in half.
The winery is located in Montalcino, Italy, known for its unique soil and microclimate. The Castello Banfi estate covers 2,830 hectares, one third of which is cultivated with vineyards, while the rest has olive groves, orchards with plum trees, and forest. The winery, producing 10 million bottles per year, must find the right balance between technological innovation and protecting the enviroment.
The winery produces wastewater from seasonal cleaning activities associated with winemaking. This wastewater has a high chemical oxygen demand (COD), which if not properly treated would damage the delicate environmental balance of the surrounding area.
Since the estate is not connected to a municipal wastewater treatment plant, it built its own plant to ensure its wastewater was always below the legal requirements. In 2017, however, the treatment plant needed to be updated, both due to its age and the growth of the company. The managers of the estate decided to invest in updating the plant, with specific attention to the quality of treated water and the amount of energy used.
“We first focused our attention on replacing the old diffusers installed on the bottom of the aeration tank,” says Claudio Rivella, the winery’s technical director. “The previous diffusers had reached the end of their useful life, and we wanted to invest in more efficient technologies. Our research showed us that Xylem’s Sanitaire diffusers were the right solution.”
The aeration solution also needed to support seasonal changes in the amount of wastewater produced. In the harvest season, between August and October, the winery is at full capacity. The containers used for the grapes need to be systematically cleaned, as well as the yard where vehicles from the countryside stop. This means that up to 40 square meters of wastewater must be treated per hour for a few months. During the rest of the year, the workload is drastically reduced.
The winery installed 622 Silver Series II membrane disc diffusers on the bottom of the aeration tank. The diffusers use an advanced membrane perforation technique that creates an extremely fine, uniform bubble pattern for optimal oxygen transfer. They also help lower energy consumption and increase operating efficiency with their unique membrane shape, integrated O-ring, and top-sealing threaded retainer ring, which eliminates leakage.
When the winery’s wastewater arrives at the aeration tank its chemical oxygen demand (COD) can be as high as 1,000 mg/liter. The Sanitaire diffusers lower the COD to 10 mg/liter, well below the legal limit of 160 mg/liter for discharge into surface waters. This high-quality treatment, and the removal of other pollutants, enables the winery to reuse part of the water for industrial processes and for the irrigation of its plum trees. This water reuse helps the winery limit its environmental impact and operating costs.
When redesigning the aeration tank, the winery also decided to update its blower. The previous blower was very noisy and not easy to operate. The winery also wanted to see if it could save energy by automating the blower’s operation.
The Sanitaire TurboMAX blower was installed, a highly efficient, high speed, direct-drive turbo blower developed for superior reliability. Unlike magnetic bearing blowers, the TurboMAX blower is totally oil free with low maintenance requirements due to self-adjusting contactless bearings. It also operates quietly.
The blower has a programmable logic controller (PLC) that is connected to a sensor in the aeration tank. This enables the blower to automatically optimize the amount of air sent to the diffusers. This feature allows the right level of oxygenation to be obtained at all times, with the lowest possible energy consumption.
“During the design phase, Xylem technicians had suggested we could reduce energy consumption by more than 30 percent, giving us a very fast ROI,” says Rivella. “However, once installed, we saved even more energy than expected. The automated control of the TurboMAX blower, combined with the effectiveness of the diffusers, meant that the equipment only needed to operate for a few hours a day. As a result, at the end of the first full year of operation, energy consumption was reduced by more than 50 percent. This is a significant cost savings for Castello Banfi, and above all the system leads to almost zero environmental impact, perfectly in line with our company policies.”
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