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WINERY & VINEYARD EQUIPMENT July 2017 WINES&VINES 49 TANGENT MEMBRANES INC. Tangent Membranes specializes in custom-built crossflow sys- tems. On their standard list of equipment are two unique sys- tems especially for those want- ing to try experimental applications. They have created the XF Mini and RO Mini, which are lab bench units that can do small (several liter) size batches in either microfiltra- tion or reverse osmosis filtra- tion levels. The RO10 standard unit comes in two- to eight-cartridge elements. They can be manual or auto- mated and can have either stain- less steel or fiberglass housings. Some of their custom-built systems for their customers in- clude a large tubular high sol- ids ultrafilter for wine clarification, a fully automatic 120 m 2 reverse osmosis system as well as lab-scale carbon and resin-testing devices. tangentmembranes.com GUIDE TO MEMBRANE TYPES T he suppliers in this article offer many types of membranes for use in the wine industry. The information below is a quick review of the different types of membranes and their separation parameters. Membrane construction The choice of filtration equipment with differ- ent types of membrane construction material and form is partly economic and partly personal preference. While most membrane construction is from organic materials, a substantial amount is inorganic, which does have some advantages. Within organic membrane construction materi- als, there are two formations: hollow tube and flat sheet. The hollow tube fibers, which are made from polymers, have a 2 mm ID (inside diameter) and 0.2µ pore size. In the wine indus- try, hollow tube membranes can only be used effectively in microfiltration. The other classes of separation require too great a pressure differen- tial, and the tubes cannot handle it. Flat sheets have no structural integrity and must be supported on both sides of the mem- brane. Flat sheet membranes come in the full range of membrane pore sizes, from 0.2µ to reverse osmosis porosity of 150 to 100 molecu- lar weight cut-off (MWCO). In the organic membrane group, the polymer material used for hollow tube microfiltration in the wine industry usually is polyethylene. While polyethylene is thought to have a lower fouling potential, it cannot withstand temperatures above 60° C. Polysulfone is still used and has a higher temperature limit (70° C), which allows for better cleaning potential but also fouls more easily. The inorganic membrane material is constructed into ceramic tubes. The base material is usually alumina coated with titania or zirconia. In this membrane style, the various oxide materials are fired into tubes with varying IDs, path ar- rangements and pore sizes. These membranes are more expensive per unit membrane area but make up for the increased cost with higher throughput and greater longevity. Membrane pore sizes The more critical issue in selecting filtration PARTIAL LISTING OF COMMON WINE COMPOUNDS AND MEMBRANE SEPARATION FACTORS Compound Approximate Molecular Weight Range Range Operating Pressure Bar PSI Ethanol 46 Tight RO 70 bar 1,029 Acetic acid 60 Tight RO 70 bar 1,029 Ethyl acetate 88 Tight RO 70 bar 1,029 4-ethylphenol 122 Loose RO Nanofiltration 60 bar 882 Malic acid 134 Loose RO Nanofiltration 60 bar 882 Limonene 136 Loose RO Nanofiltration 60 bar 882 Tartaric acid 150 Loose RO Nanofiltration 60 bar 882 Potassium sorbate 150 Loose RO Nanofiltration 60 bar 882 Citral 152 Loose RO Nanofiltration 60 bar 882 4-ethylguiacol 152 Loose RO Nanofiltration 60 bar 882 Wine lactone 166 Nanofiltration 60 bar 882 Ascorbic acid 176 Nanofiltration 60 bar 882 Citric acid 192 Nanofiltration 60 bar 882 Melatonin 232 Nanofiltration 40 bar 588 7-hydroxyflavone 238 Nanofiltration 40 bar 588 Catechin 290 Nanofiltration 40 bar 588 Quercetin 302 Nanofiltration 40 bar 588 Sucrose 342 Nanofiltration 40 bar 588 Saccharose 342 Nanofiltration 40 bar 588 Anthocyanone 344 Nanofiltration 40 bar 588 Condensed tannins 950 -1300 Nanofiltration Ultrafiltration Hydrolysable Tannins 950 – 1300 Nanofiltration Ultrafiltration Polyphenols 500 – 4000 Nanofiltration Ultrafiltration Polysaccharides 1000- 500,000 Nanofiltration Ultrafiltration Polyphenol and color Variable Nanofiltration Ultrafiltration Hydration shell molecules 500 – 600,000 Nanofiltration Ultrafiltration KOCH MEMBRANE SYSTEMS Koch Membrane systems has a wide variety of filtration solu- tions for the wine industry, all of which use various forms of crossflow filtration, from micro- filtration to reverse osmosis and everything in between. If your business is in areas where waste- water recovery or reclamation of other waste streams is important or necessary, they have systems that can handle the range of input streams, retentate concen- tration and purity of the filtrate to handle just about any issue in the wine industry. Their flagship is the WineFilter system. It can be supplied in manual or automated versions that start at filtrate volumes of 10-20 hL per hour and can be built to handle outputs of more than 230 hL per hour. They also offer custom-built systems. kochmembrane.com This table outlines membrane types and pressure required to separate molecules from a wine medium. —continues on page 50