Winery wastewater management and treatment in the Niagara Region of Ontario,Canada: A review and analysis of current regional practices and treatment performance

The winemaking process produces a large volume of wastewater with highly variable characteristics. Methods in place to manage winery wastewater (WWW) vary, with some wineries treating their WWW on-site, while others direct the WWW to municipal wastewater treatment plants (WWTPs). Despite the significant presence and growth of the wine industry in the Niagara Region of Ontario, Canada, few data are available regarding the characteristics and treatment of WWW in this geographic region. This work presents a comprehensive review of full-scale treatment methods currently in place to manage and treat WWW at 53 wineries in the Niagara Region. The most common type of on-site treatment is the constructed wetland process, providing overall removal rates of >98% for chemical oxygen demand (COD) and >98% for total suspended solids (TSS) for the combined treatment of WWW and site-generated sanitary sewage. Subsurface effluent discharge is the most widely used disposal strategy, while larger systems treating WWW alone also reuse the effluent for vineyard irrigation. The construction and operation of on-site treatment systems at wineries does not address all WWW treatment needs, requiring a portion of the WWW to be co-treated at WWTPs. While full-scale operating data indicate that anaerobic co-digestion with municipal sludges is effective (89% COD removal), the co-digestion capacity is limited. Co-treatment in the municipal WWTPs' liquid treatment train leads to negative operational and performance impacts. No efficient WWW co-treatment options, viable in the long-term, are currently available at municipal WWTPs. Improved co-treatment strategies are required to address WWW treatment needs in the Niagara Region.