Posted to News on 5th Dec 2012, 13:27
Tubular membrane technology for food and beverage manufacturers
PCI Membranes, a Xylem brand, is a specialist in filtration technologies using tubular membranes. Recent projects in the food and beverage industry include saving one of the largest independent raisin processors in the world significant sums of money on wastewater disposal and generating an additional source of revenue through the sale of concentrated sugar water to distilleries; saving processing and capital costs for a tomato juice manufacturer and helping wine producers improve vinification.
The raisin company had booming sales but increasingly heavy wastewater costs, and decided to improve its method of washing the raisins and reduce its water usage. Standard disposal methods were not an option, as raisin wash water contains high levels of dissolved sugars, creating a high biological oxygen demand, so it decided to remove sugar from the wash water before disposal. If the grape sugar concentration in the wash water was high enough, this could be sold to local distilleries as an ingredient for grape alcohol. A concentration of eight per cent sugar was required, double or quadruple the two to four per cent normally released.
Trials with PCI's tubular reverse osmosis (RO) membranes proved this was possible. After initial trials, 80 B1 PCI Membrane modules fitted with AFC99 Tubular Reverse Osmosis membranes were installed in a continuous system, with expansion planned for up to 120 modules. Once the full system was running and the concentrated sugar water (the retentate) had been removed, the remaining water (the permeate) was actually lower in dissolved solids than the well water that feeds the raisin company's plant and is re-used for irrigation. ROI was less than two years.
The tomato processor wanted to expand production by 50 per cent over 2 years and considered the cost of an additional large tripe effect evaporator versus PCI's reverse osmosis system. Capital costs and running costs were both factors in its decision to install PCI's RO system, which removes almost 20 tonnes of water an hour and uses150kW of electricity. The process involves crushing the tomatoes, heating them, screening out skins and seeds, reverse osmosis to concentrate the pulp to 8.5 deg. Brix and a final evaporation phase. In the second year, two additional RO lines were ordered which increased capacity to 125 tonnes per hour. Today production has expanded to 150,000 tonnes of process tomatoes a year and new products have been added to the company's range, including chopped tomatoes and passata. The operating costs of PCI's RO technology is about half that of using evaporators for all concentration processes.
Concentration by reverse osmosis
PCI's 12.5mm RO tubular membranes do not block, so are well suited to concentrating grape must prior to vinification as no pre-filtration is required and very high product quality is achieved economically. Red wine must from Cabernet, Merlot and Sauvignon grape varieties can be concentrated by RO up to a sugar content equivalent to 12-13 per cent alcohol. The process does not affect the delicate balance of aroma compounds in the must, as neither freezing nor evaporation is necessary.
Further applications for PCI Membranes technologies include: apple juice clarification; concentration of vegetable extracts; sweetener and sugar clarification and concentration; clarification and de-colouring of natural sugar solutions and starch-derived sugars; flavour and fragrance concentration; desalting and concentration of food colourings; recovery of animal, fish and vegetable proteins; purification and concentration of food products; and recovery of spent cleaning solutions.
At Brau Beviale, PCI Membranes is exhibiting its technologies on Stand 119 in the Process Hall, where technical experts are available to answer further questions. For further information about tubular membranes and filtration technologies, please visit www.xyleminc.com/.
