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44 WINES&VINES July 2016 WINEMAKING Toll-Free: 877-552-4828 909-464-1373 • Fax: 909-464-1603 For your nearest dealer, contact: BRANCHLOK™ Used for lateral training of trellised branches and cordons to 12-14 gauge wire. Branchlok™ is available in three lengths: 2½", 3¼", 3 ¾". Patent No. 4,665,000 WineVineBranchLokAD.qxp_Layout 1 12/1/14 2:46 Use Code July on your first order for an extra 10% off! 510-732-7010 A Division of Bay Seal Company Providing Sealing Solutions for over 50 Years wineryseals.com VC Tank Wine Brew Spirit Considering the availability of the waste, most of the applications of the process are concentrated on the treatment of the lees and sewage sludge, leaving open the possibility of integrating the other substrata for brief periods of the year. Numerous studies (Riaño et al., 2011; Rodriguez et al.,2007; Melamane et al., 2007) have demonstrated that anaerobic di- gestion of different types of substrata (co-di- gestion) favors the stability of the process thanks to the contribution of alkalinity (buffer capacity) and nutrients to the system, thus creating a favorable environment for the growth of microorganisms without the addi- tion of synthetic compounds. Another advantage of co-digestion is reduc- tion of the inhibiting or toxic effect of com- pounds such as polyphenols deriving from the processing of grapes, but also of heavy metals (copper and zinc) and organic micropollutants coming from sewer sludge, by effect of the dilution of these substances (Chen et al., 2008). The experiment In order to assess the applicability of anaerobic digestion with these winemaking wastes, an experiment was carried out using lees and sew- age sludge produced by a cellar that sells more than 3.3 million cases of wine per year. The study showed that for every 100 liters of wine pro- duced, 196 liters of wastewater has to be treated, which, in turn, determines the formation of 0.5kg of sewage sludge with 15%-20% dry matter. The treatment of wastewater and the cost for disposal of sludge are significant expenses on the winery's balance sheet and are difficult to recover over time. The winery in question also produces 1.6 kg of lees per hectoliter, a lower value than the national average (6 kg/hl), since it does not directly process grapes but wines bought from third-party wineries. A process of co-digestion of sewage sludge and lees has been simulated on the basis of these assumptions. The tests were carried out in pilot reactors with 230 litres of usable volume by applying different retention times of the substratum in the reactor (23 or 40 days) and temperatures. Both the mesophilic and thermophilic condi- tions were tested. Reactors operating at 55° C highlighted the instability of the process and the accumulation of volatile fatty acids until the inhibition of the anaerobic process. Both of the operating processes at 37° C, on the other hand, proved to be very stable with comparable yields. The study showed that degradability does not increase if the retention time is prolonged to 40 days. Therefore, the most interesting conditions for the full-scale application of the process are a temperature of 37° C and a retention time of about 20 days, since the dimensions of the reac- tor—and therefore the management costs—are limited, but the same mix is supplied. This process worked continuously for more than 200 consecutive days without any prob- lems arising and showed an average produc- tion of 1.2 m 3 of biogas per m 3 of reactor (with 65% methane). Conclusions More than 75% of organic matter (expressed as chemical oxygen demand) was converted ARTICLE FROM IL CORRIERE VINICOLO Editor's note: This article is published as part of Wines & Vines' cooperative editorial effort with Il Cor- riere Vinicolo, the leading Italian wine industry publication (corrierevinicolo.com). Il Corri- ere Vinicolo is edited by Unione Italiana Vini, the largest Italian wine trade association. On a regular basis, our two publications will share key articles in order to give readers a broader view of important wine industry topics in Italy and North America. METHANATION TEST RESULTS 160 140 120 100 80 60 40 20 0 L CH4 / kg 0 5 10 15 20 25 30 Time (days) n Stems n Virgin Pomace n Fermented Pomace n Lees n Sludge Fermented pomace and virgin (unfermented) pomace produced the most methane (CH 4 ) starting around 10 days.