Wines & Vines

July 2016 Technology Issue

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42 Wines&Vines July 2016 winemaking W aste flows from the winemaking supply chain contain wastewater (generally treated inside the win- ery or sent to municipal plants via sewage systems or by truck) and solid waste such as stems, pomace and lees. In Italy the stems were traditionally used as soil amendments, while for years the pomace and lees have been delivered compulsorily to distilleries for the production of alcohol and the recovery of tartaric acid. Regulation EC 479\2008 of the European Union introduced important new elements to the legal framework of the wine sector, offering member states the possibility of defining the end use of pomace. Italy implemented the above regulation by means of a ministerial decree, which, as an alternative to distillation, allows it to be collected under control for the recovery of enocyanins (anthocyanins responsible for the color of red grapes), the production of agricul- tural products (direct or indirect agronomical use), energy recovery (using byproducts such as biomass for the production of biogas or for fueling energy-production plants) and the ex- traction of molecules with a high added value for pharmaceutical and cosmetic purposes. Direct agronomical use of these waste flows is a choice to be made under careful control and is inevitably subject to the dictates of legislation related to nitrates. In fact, it should be taken into account that the presence of polyphenols (antimicrobials), salts, heavy metals and nitro- gen in these highly biodegradable wastes can compromise the quality of the receiving soil in the long term. Moreover, polyphenols inhibit germination and immobilize nitrogen in the soil. Treatment of these wastes is fundamental, but it can be a significant cost for a winery. In fact, the high chemical and biological oxygen demand values highlight the high consumption of oxygen associated with their decomposition and there- fore the risk of establishing conditions of anoxia in soils and rivers. Biogas from anaerobic digestion Of the technologies that can be applied to the treatment of organic residues, anaerobic diges- tion (see "What is Anaerobic Digestion?") is the most suitable process for their stabilization concomitant to the recovery of a renewable energy source such as biogas. Production of biogas by anaerobic digestion is a mature and widely applied technology that can provide a sustainable approach from an economic and environmental point of view. Today there are more than 10,000 anaerobic digestion plants in farms all over Europe (EBA data). The anaerobic process enables us to ob- tain a biologically stabilized effluent with fertil- izing properties that is hygienically safe. The production of biogas convertible into heat and electricity guarantees the energy self- sufficiency of the process and provides an en- ergy surplus that can be used to produce heat or cooling (trigeneration systems), which can be used within the cellar or in adjacent rooms. Capitalizing on Winemaking Waste Anaerobic digestion produces methane from sludge and lees By Cinzia da Ros, Cristina Cavinato, Paolo Pavan, Franco Cecchi and David Bolzonella KEY POINTs The availability of sludge and waste lees throughout the year in wineries presents an interesting resource for energy production. Researchers in environmental science and bio- technology at the Universities of Venice and Verona (Italy) studied the potential benefits. Their results showed that about 75% of or- ganic matter was transformed into biogas, while nitrogen and phosphorous became more bioavailable as they became more concentrated, making the digestate a valid soil amendment. TRIGENERATION anaerobic digestion with a trigeneration plant and the reuse of digestate on agricultural soils ORGANIC WASTE DIGESTATE BIOGAS ThERmAl ENERGy • Heating • Cooling • Hot water ElECTRICITy ANAEROBIC DIGESTION 1. Hydrolysis 2. Acidogenesis 3. methanogenesis Particulate compounds Soluble compounds Volatile fatty acids methane and carbon dioxide lEAKS 55% 30% 15%

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