FEATURE FILTRATION & SEPARATION


LOOKING INTO THE FUTURE OF WATER TREATMENT


The potential for the use of nanoparticles in water treatment such as water filtration is too compelling to ignore, despite the potential risks. Here, Rachael Benstead, senior aquatic ecotoxicologist at Fera Science, outlines a future where we can take advantage of the benefits of nanotechnology in water and mitigate the drawbacks


N


anoparticles are particles between one and 100 nanometers (nm) in size


surrounded by an interfacial layer consisting of ions, inorganic and organic molecules. A nanoparticle behaves as a whole unit with respect to its transport and properties and is commonly used in many areas of innovation including manufacturing, agriculture, business, medicine and public health. Within water and wastewater treatment


in particular, nanoparticles and other nanotechnology such as nanofilters are now entering the commercial market, which is expected to grow at a compound annual growth rate of 9.7% during the next five years. This is largely due to reducing costs and pressure to supply clean drinking water to the world’s growing population. For example, nanofilters are now being


used for reverse osmosis. Widely accepted as the best way to desalinate water, reverse osmosis involves feeding water through a semi-permeable membrane. Traditionally, this was much too energy


More research is needed to determine the suitability of nanotechnology to water treatment. The E-Flows mesocosm project, developed, designed, managed and operated by Fera Science, in partnership with the Centre for Crop Health and Protection (CHAP), supported by Innovate UK, will provide scientific research opportunities across a wide range of industries


intensive to be viable for most uses. However, much less pressure is required to pass water across nanofilters than traditional filters, making the process up to 50% more efficient using nanotechnology. Other advantages of nanotechnology are


more directly related to the small size. The huge surface area to volume ratio that can only be achieved by such small particles means the material is likely to be much more reactive. This increased reactivity can mean substances that are well understood in their bulk state might respond differently to expectations in its nanoparticle state. They also have a high mobility, allowing them to react with a large number of molecules quickly. This means, in addition to desalination,


nanoparticles can be used to remove sediments, chemical effluents, charged particles and even kill bacteria by releasing silver ions. However, some of these benefits may


also pose risks to the environment if nanoparticles are inadvertently released, either through use or accidentally through


REDUCE CONTAMINATION RISK AND CUT CONSUMABLE COSTS


The dairy industry can reduce the risk of contamination and cut costs thanks to a new innovation by Parker Bioscience. A division of Parker Hannifin, Parker Bioscience has launched the ASEPT-X range of sterilising gas filters


which have been designed to increase microbial security and reduce consumable costs in the aseptic processing of sensitive food and beverage products. They provide sterile gas for critical processes. The filters have been validated to withstand harsh reverse steam sterilisation processes without the need


for condensate management, as they have the ability to pass bulk liquid condensate. Previously, sterile air and gas filters may have failed due to their hydrophobic nature and their inability


to pass bulk condensate under high pressure reverse steam cycles. However, the membrane composition of ASEPT-X is capable of withstanding reverse steam cycles without fail and therefore can offer a greater filter lifetime compared to other sterilising gas filters. The reduction in filter failure and consequential filter replacements means not only can dairy producers save on consumable costs, but ASEPT-X’s robust design also helps to safeguard the sterile gas process and reduce the risk of contamination, as there is less risk of a process running with a damaged filter. ASEPT-X filters are capable of withstanding 100 x Steam In Place (SIP)


cycles in the reverse direction without the requirement to drain bulk condensate and are capable of withstanding aggressive differential pressures at steam temperatures in the reverse direction of up to 1.5barg at 140°C. Parker Bioscience


www.parker.com/bioscience


spills or steam released during the manufacturing process. Some synthetic nanoparticles could be


directly toxic to microbes, plants and animals, where others may provide a secondary risk. For example, silver ions released to kill bacteria during water treatment will devastate biological populations, with knock-on effects to the entire ecosystem. Silver ions effectively kill bacteria, removing a food source for other organisms further up the food chain. The toxic effects of many nanoparticles


are not yet fully understood, especially as they are much more reactive than their large-scale bulk equivalents. The particles are very difficult to properly track and study, with insufficient analytical techniques currently available for the detection and measurement of nanoparticles. This being said, there have not yet been


any reports of adverse reactions to human health and nanotechnologies promise great benefits, especially in environments where clean water is scarce. However, future research into interactions, conducted to closely mimic the natural environment, such as in a large-scale flow-through mesocosm like Fera’s E- Flows mesocosm, is crucial to determine whether nanotechnology really is the panacea of water treatment. Nanoparticles and nanofilters offer great


potential for water treatment, particularly when facing the challenge of how to produce clean water for those in developing countries. However, the risks of using small, reactive particles, which could inadvertently end up in the water system and affect biological ecosystems cannot be overlooked. Further testing must be carried out before nanoparticles can be deemed safe to enter the water supply.


Fera Science www.fera.co.uk


36 SEPTEMBER 2018 | PROCESS & CONTROL / PROCESS&CONTROL


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