Wine Industry News

The Aqua Wetland System balances variable wastewater from small wineries

Mar 30, 2022 | Winery Industry News

By Andrew Hellebust, President, Rivercourt Engineering 

Toronto-based Andrew Hellebust, P.Eng., has been collaborating with Lloyd Rozema of Aqua Treatment Technologies for over 20 years to design engineered treatment wetlands that process high-strength agricultural and industrial biodegradable wastewaters. 

Primarily serving Ontario’s main wine growing region in Niagara, Rivercourt and Aqua Treatment Technologies have two decades of experience treating winery wastewater. Small wineries produce relatively low amounts of wastewater for most of the year, mainly from tourism, tank washing, and bottling. At the start of the fall crush period, however, the wastewater abruptly becomes high strength and high volume. The sudden influx of crush wastewater has been challenging historically for suspended growth aeration treatment approaches which need time to re-establish the treatment bacteria population. 

The Aqua Wetland System (AWS) contains a 1.2 metre depth of fine gravel or coarse sand trickle filter media with a high surface area to support bacterial growth. Being attached, the bacteria are not vulnerable to wash out as they are in suspended growth systems. The bottom 0.25 metres of the AWS has standing water which moves horizontally to the discharge pump basin. In treatment wetland terms, there is a vertical trickle filter with aerobic unsaturated media stacked on top of a horizontal flow saturated wetland. The void spaces in the media are used to flow balance by passive means (orifice restriction) and active means (pump control panel with timer program). The retention of bacteria in attached growth, conservative sizing of the media, flow balancing, and long residence time of the standing water all contribute to the AWS being a forgiving technology for the high variability typical of small winery wastewater.

The winery keeps coarse solids, such as grape skins, from entering the wastewater and a septic tank provides physical separation of the remaining settleable or floatable solids. Sampling of the AWS influent and effluent after the first “cell” (the AWS is divided into multiple tanks or cells using plastic liners) showed that the AWS could reduce BOD5 (biochemical oxygen demand) at a rate of 50-70 mg BOD5/L per 1 m2 top area. A two-cell AWS can be used to bring high-strength winery wastewater down to levels that can be discharged into city sewers, for example, below 300 mg/L BOD5. Adding more cells can bring the strength down to a Level IV (<10 mg/L CBOD5 and TSS) quality effluent suitable to discharge into the smallest dispersal beds. Using recirculation of nitrified effluent and providing an anoxic wood chip cell results in total nitrogen concentrations well under 10 mg/L.

Aqua Treatment Technologies has been collecting ten years of weekly samples during the wine crush period at small wineries in the Niagara region and the results have shown that the AWS achieves the target treatment performance within in the first week of crush. 

The AWS has also been used to treat batch distillery and brewery wastewaters, which are high strength and variable due to batch production. The monthly variation of wastewater flows from distilleries and breweries is not harvest related, like wineries, but follows annual trends in market demand. With most projects in the 2,500 to 50,000 L/d range, the AWS has been proven to be a robust and low-maintenance solution for small wineries, distilleries, and breweries.