Lees and Solids Management
Improving solids management is an essential component of reducing wastewater strength. Wineries can reduce the strength of their wastewater by 90% by diverting this organic material before it enters the wastewater stream. This can reduce wastewater costs and help transform waste into valuable by-products.
Case Study: Developing Value-added Products at Southbrook
Southbrook has taken the philosophy of interconnectedness and balance that informs its organic and biodynamic wines to find additional value in the by-products of the wine-making process. An excellent example of this is Bioflavia, a nutritional additive made from grape skins that is high in antioxidants.
Southbrook takes their pomace, that is typically viewed as a waste product, sends it to a grape seed oil producer who separates the seeds and stems. The remaining skins are then processed to produce Bioflavia which Southbrook sells from their tasting room, online, and through health food stores and nutritional experts across the country.
Keep solids out of drains
Reduce overall wastewater strength by preventing pomace and other solids from being washed down the drain through the use of dry cleaning techniques, screens, or settling.
All floor drains should have apprpriate screens installed to catch any solids and these screens should be cleaned regularly.
Wineries can also explore methods of reducing the used of solids in winemaking. For instance, wineries can take steps to avoid over-use of bentonite in the fining process or explore new approaches, such as enzyme –based fining, to eliminate the use of bentonite.
When removing screens for cleaning, use temporary covers to prevent solids or any other materials from entering the drain that may damage pumps.
Separate lees from the wastewater stream
Wineries can reduce the strength of their wastewater and improve their solid waste management by separating wine and juice lees and removing them prior to washing tanks or barrels. Keeping wine lees out of the drain alone has been shown to reduce BOD levels from 25,000 mg/l to 2,500 mg/l.
The liquid content of lees can be reduced through extended settling, additional racking, or through the use of plate-and-frame, rotary vacuum, membrane, or crossflow filters. Equipment suppliers are developing new solutions to filter high-solids lees with low levels of oxygen introduction that may be economical for smaller wineries.
Juice recovered from lees can be blended back in with the rest of the juice for fermentation. Wine recovered from lees can either be blended back in with the rest of the wine, sold on the bulk market, or used to produce other value-added products such as vinegar.
Wine lees can contain up to 10% of a winery’s production volume.
Develop value-added products
In some cases, wineries may be able to obtain additional value from solid waste by-products. Pomace contains seeds that can be processed into grape seed oil and skins that can be used to produce pomace brandy or nutritional supplements. Wine lees have been used in the aging of beer or in high quality chocolate, bread, mustards, jam, and other food products.
If a winery is not interested in further processing of pomace or lees, it is still possible to take advantage of the nutrients and proteins for use as a soil amendment once the pomace and lees have been composted. The high protein content of lees also makes them suitable as a potential animal feed.
Properly dispose of solids
If there is no potential for the development of value-added products from winery waste streams, they must be disposed of in an appropriate manner.
Pomace, lees, and filtration aids and clarifying agents (such as diatomaceous earth and bentonite) may be composted, used in an anaerobic digester, or land-applied
In the case of direct land application, wineries should follow good practices (including appropriate setbacks from wells, surface water, and adjoining properties, amount of material applied, and other factors).
Wineries that purchase the majority of their grapes from other vineyards are considered commercial operations and must follow the requirements laid out in Ontario’s Nutrient Management Act for the land application of lees, bentonite, DE, and other non-grape materials. This includes the development of a Non-Agriculture Source Material (NASM) Plan. Wineries that obtain a majority of their grapes from their own vineyards are considered agricultural operations under Reg. 347 and are exempt from these requirements.
There may be additional requirements under the EPA or NMA depending on specific circumstances. Wineries should contact their local MOECC district office or OMAFRA to clarify site-specific requirements.