## 1 Introduction  
In 2018, wine production reached a record volume, with over 293 million hectoliters being produced globally [1]. As the largest consumer, the United States is also the fourth-largest producer of wine globally [1]. Wine produced in the United States comes from wineries of many sizes; wineries that produce over 500,000 cases per year are considered to be large, and wineries producing less than 50,000 cases per year are small [2]. Currently, only 341 of the 10,185 wineries in the United States are classified as medium or large, and the rest are classified as small, very small, or limited production [2]. These smaller wineries dominate the Michigan wine industry. In 2018, there were nearly 150 wineries [3], 71% of which were ten acres or less in size [4]. These 150 wineries bottle more than 11.3 million liters (\(>\)3 million gallons) of wine annually [5]. It is estimated that, for every liter of wine produced, 2.86-4 L of wastewater is generated [6, 7], which suggested that Michigan produced 45.4 million liters (12 million gallons) of winery wastewater in 2018. The composition of winery wastewater is highly variable between wineries as a result of general management practices, the amount of water used, the size and design of the winery, and different wine-making techniques [8; 9; 10; 11; 12]. Winery wastewater quantity and quality vary, even within a single winery due to the various steps in wine-making and the type of wine produced [6; 9; 11; 12]. Wastewater is generated throughout the wine-making process, which has five distinct stages: harvest, crush, fermentation, packing and clarification, and aging and bottling. The harvest period produces the highest chemical oxygen demand (COD) strength wastewater and accounts for the largest volume of winery wastewater produced [8; 13]. Small wineries may generate up to 80% of their wastewater during this period [8]. After the harvest season, wastewater production is at a minimum and it depends on daily activities [8]. Winery wastewater is high in organic matter from grapes and wine [8; 9]. This organic matter contributes up to 85% of all contaminants in winery wastewater. The remaining organic matter includes yeast, alcohol, esters, sugar, soluble organic acids, tannins, lignin, and polyphenols [9; 13]. Table 1 presents a summary of conventional wastewater pollutants in winery wastewater, as reported in the literature. In addition to organic matter, nitrogen and phosphorus are of primary concern. Proteins that are removed during stabilization of wine are the predominant source of these nutrients. The use of phosphate detergents can also drastically increase the phosphorus concentrations [14]. Potassium and sodium are often found in high concentrations in winery wastewater due to cleaning agents and excess grape juice [8]. Without proper treatment, the discharge of winery wastewater can result in adverse health and environmental consequences, such as methemoglobinia in infants [39], eutrophication, cyanobacterial blooms [40], and cyanotoxins [41]. Metal mobilization is an additional environmental concern when wastewater is treated while using land application. Naturally occurring metals in the soil may become chemically reduced as oxygen becomes depleted during microbially mediated oxidation-reduction reactions [42]. Metals in the soil, such as manganese and iron, are water-soluble when chemically reduced, which allows for groundwater contamination [42]. Regulations have been set to mitigate the impacts of wastewater discharges, and new, more restrictive regulations are driving the development of technologies for winery wastewater treatment [6; 43; 44]. Many wineries are located rurally and they do not have access to public sewers.