As good as new: solvent recovery
31 Aug 2017
Manufacturing medical membranes, which are essential for dialysis patients, involves a huge amount of water-solvent mixture. Thanks to our multiple-effect distillation technology, valuable solvents can now be recovered at the levels of purity required for reuse in medical technology, with reduced energy consumption.
The percentage of elderly people in the population is growing year by year. With associated risk factors including diabetes, obesity, and high blood pressure, the prevalence of chronic kidney disease (CKD) looks set to rise. By 2020, more than 3.8 million people worldwide will need regular hemodialysis, according to the healthcare company Fresenius.
The core component of a dialysis machine is the dialyzer – a mostly single-use disposable tool that filters waste and excess fluid from patients’ blood. This artificial kidney is actually a plastic tube housing thousands of small hollow fibers of 20–30 cm in length, running parallel to one another. The fibers are mainly made from a very thin semi-permeable polysulfone membrane, providing a total filter surface of around 1.0 – 2.5 square meters.
The production of these membranes, i.e. the hollow fibers, requires a wet spinning process and a vast amount of water-solvent mixture.
Up to 98% solvent recovery
During the membrane manufacturing process, solvents are diluted with water and contaminated with by-products, making a direct reuse impossible. Disposal of the contaminated solvent, however, is due to ecological and economic aspects not an option. Our multiple-effect distillation (MED) technology enables manufacturers of medical membranes to recover up to 98% of the solvents with high purity, while minimizing energy consumption. “MED consists of multiple stages or ‘effects’, with each stage essentially reusing the energy from the previous stage,” explains Norbert Strieder, Application Marketing Chemical. In this way, every kilowatt of heat that is fed into the plant is used multiple times at different temperature and pressure levels.
Our advanced calculation methods allow us to design MED plants that are recognized for the high degree of thermodynamic efficiency and high distillate purities achieved. Each MED plant is designed to meet our customers’ exact needs, taking into account factors such as available or preferred energy sources.
— Norbert Strieder, Application Marketing Chemical
