Issue link: http://winesandvines.uberflip.com/i/696561
July 2016 WINES&VINES 43 WINEMAKING " When we built our new fermentation tank facility, we selected Wilden® AODD pumps for cap irrigation because their low-sheer product handling is clearly superior in extracting the juices and controlling tannins. They are also very energy effi cient and extremely easy to clean at the end of the season. We're extremely pleased with the outstanding results delivered by Wilden." See why Rodney Strong selected Wilden pumps: psgpumps.com/RodneyStrong Wilden Sanifl o™ Series Advantages: • Gentle product handling for optimum fermentation • Pro-Flo® SHIFT ADS saves up to 60% in air consumption over competitors • Pure-Fuse diaphragms eliminate product trap area between the outer piston of traditional diaphragm assemblies 22069 Van Buren Street Grand Terrace, CA 92313-5607 USA P: +1 (909) 422-1730 wildenpump.com Manuel Villanueva, Cellar Master Rodney Strong Vineyards, Healdsburg, CA, USA Wilden® AODD pumps for cap irrigation because their low-sheer product handling is clearly Improve Your Results, Protect Your Product Sanifl o™ Series AODD Pumps Pure-Fuse Diaphragm Where Innovation Flows 3/16/16 4:13 PM WHAT IS ANAEROBIC DIGESTION? A naerobic digestion is a biological process made by a complex microbial community that works in anaerobic conditions (i.e., in the absence of oxygen). The microorganisms involved are able to break down organic matter and turn it into biogas: a mix of about 60% methane and 40% carbon dioxide. The trans- formation takes place in closed, mixed and heated reactors. The mesophilic (35°-42° C) and thermophilic (52°-55° C) processes can be distinguished accord- ing to the temperature of the reactor. Generally, the thermophilic process has a higher yield of biogas and a better capacity to remove pathogenic bacteria, but it needs more heat and is more difficult to control. The main management parameters of an anaerobic digester are the hydraulic retention time and the organic load. The first is the average time that the substratum remains inside the reactor; the second is how much organic matter is loaded each day per us- able volume of the reactor. The biogas can be burned in a boiler to recover heat or in a trigeneration plant (see diagram): an engine able to produce electricity and recover heat energy, also to produce cooling energy (i.e., cooled water for air conditioning or for industrial processes) up to a temperature of -60° C. Methanation tests: the potential of sludge and lees To better understand the potential of anaero- bic digestion applied to wine waste, the re- sults of methanation tests with different winemaking wastes are reported (see "Methanation Test Results"). Pomace is the most interesting substratum because it has a high level of organic matter, and the pro- duction of methane (152 liters of CH 4 /kg) is comparable, for example, to that of corn silage. Although this waste is available for just a few months of the year, it is an interest- ing substitute for energy crops in autumn in plants fueled by animal farming waste. Lees and sewage sludge, on the other hand, are available for a much longer period throughout the year. They vary depending on the size of the winery and the type of wine production; therefore, though they typically produce less biogas, their avail- ability makes them more interesting. The lees produce methane quickly, reaching 90 liters of CH 4 /kg after about 20 days from the start of the process, whereas the sludge (like the stalks) has a low production of methane (26 liters CH 4 /kg) and needs long retention times inside the anaerobic reactor. CHARACTERISTICS OF SLUDGE, LEES AND DIGESTATE Parameter Unit Sewage sludge Lees Digestate ST (total solids) gST/kg 158.9 ± 49.3 62.0 ± 27.9 24.3 ± 2.9 SV (volatile solids) gSV/kg 143.5 ± 41.6 33.6 ± 15.1 14.2 ± 1.7 SV/ST % 88% ± 3% 57% ± 13% 58 ± 4 COD (chemical oxygen demand) g O 2 /kg 138 ± 11 201 ± 54 16 ± 1 N org (organic nitrogen) g N-NH 4 + /kg 8.4 ± 2.6 1.9 ± 0.8 0.9 ± 0.1 NH 4 + (ammonium) mg N-NH 4 + /l nd 33.9 ± 22.7 400 ± 56 P tot (total phosphorous) g P-PO 4 3- /kg 1.1 ± 0.3 0.4 ± 0.2 0.2 ± 0.0 Polyphenols mg A.Gal./L nd 1537 ± 1189 26 ± 7 The polyphenols are expressed as gallic acid equivalents.