FILTRATION, SEPARATION & PURIFICATION FEATURE COULD RECYCLING MEET YOUR WATER NEEDS?


With the right choice of treatment technologies, and a careful cost- benefit analysis, reusing water can increase your industrial operation’s profits. Mark Bosley of SUEZ Water Purification Systems explains...


O


ver 80% of the world’s wastewater is simply discharged to the environment


untreated, according to the UN. This not only damages ecosystems, natural water quality and human health but wastes a potentially valuable resource. Many industries need large volumes of


water in their product make-up or for related activities such as wash-down equipment. Despite increasingly efficient cleaning-in-place (CIP) and sterilisation- in-place (SIP) systems, water consumption remains high and much of it drains wastefully away. That wasted water could instead be collected and recycled, with appropriate purification, for reuse in the same industrial processes or for a variety of alternative purposes. Recycling immediately reduces the


amount of raw water you need to buy, and it may also cut costs relating to wastewater disposal. Regulators or municipal authorities often charge industrial customers according to the volume and condition of their discharges. If limits on quantity and quality are exceeded, there may be excess fees or fines to pay. Before discharging, you may already be


having to pay someone to treat your waste stream. In cases where the wastewater is being pumped to another site for treatment, equipment and energy costs can be lowered by recycling it close


The Centurion 1500 Decon is a water purification solution for supplying a direct feed of RO water to decontamination equipment


to its point of use. If the quality of the recycled water is insufficient for your operations, someone nearby might buy and use it for theirs. These savings must be weighed


The Select HP Lab Pure Water Deionization Unit can be used to supply water for clinical analyser feed


against the set-up and running costs of water recycling facilities, with consideration of how long you can


afford to wait for a return on your investment. For many businesses, the ROI has turned out to be surprisingly fast. As water prices and discharge fees rise,


and regulations on discharged water quality become more stringent, the business case for recycling is strengthening. At the same time, growing public concern over environmental issues is putting extra pressure on businesses to act responsibly. In assessing the economic viability of reusing your wastewater you should factor in the PR value of maintaining a reputation for sustainable practices and social responsibility. A key question is how clean the water needs to be after treatment. There is no


AD PLANT ORDERS MORE PUMPS AND SEPARATORS


A new order from Future Biogas is set to bring the total number of Börger pumps and separators at its AD/Biogas plants to over 20. The company invested in its first Börger pump back in 2015 for its site near Swaffham. The latest Börger Separator, the sixth for Future Biogas, is heading for Doncaster. Designed with its drainage and press channels positioned one after


the other in order to preserve the filter, the Bioselect RC Separator’s rotating clearing auger does not come into contact with the screen. Abrasive parts cannot cause any damage to the surface area here, increasing the service life of all components. Neil Bushell, head of engineering at Future Biogas, said: “The Börger Separators are excellent. We very


much like the plug-sealing system, which takes away the risk of any liquid escaping...” Converting a wide range of feedstocks into clean, renewable energy at 13 AD plants, Future Biogas has


gradually replaced pumps that caused issues with a large range from Börger, including the small AL-series (1.5 kW), right up to the 15 kW FL-series. Bushell added: “Unlike the pumps we’ve been phasing out, we don’t have to spend anywhere near as


much time or money on the Börger pumps. Just like the separators, they are reliable and very easy to work on with just basic tools. The mechanical seals never seem to fail. Spares are always readily available – and unlike before – at a sensible cost. And as a company, Börger are always there for us when we need help and advice.”


www.boerger.com / PROCESS&CONTROL


commercial value in improving water purity beyond the demands of the process needs. For example, if recycled water is to be used for irrigation of agricultural or amenity areas, toxins must be low but suspended inorganic solids are unlikely to be a problem. Similarly, water reused for flushing toilets and other sanitary systems need not be of drinking quality. Purification costs will depend on these


considerations and on the content of the wastewater. The most costly and specialised purification techniques are often used to remove contaminants which are harmful even in small amounts. Key purification options include: Clarification - Organic and inorganic


particles suspended in cloudy water are clumped using coagulant chemicals, then separated out by sedimentation or filtration. Dissolved air flotation - Air dissolved


into water under pressure is released as small bubbles. Suspended oils and solids stick to these, float to the surface and are removed by skimming. Digestion - Organic material is broken


down into simpler constituents by micro- organisms. Anaerobic digestion (AD) (without oxygen) can generate methane as a useful by-product. It may be followed by AD to reduce organic content further. Distillation - This separates water from


substances with higher boiling points. Filtration - Mechanical filters may


remove large items such as grit, dirt and fibres. Finer filtration systems capture particles larger than a micron. Microfiltration and ultrafiltration -


Membrane filters remove very small particles and, if necessary, prepare water for reverse osmosis and/or deionisation. Reverse osmosis - Water is forced


through a semi-permeable membrane which traps very small particles and larger molecules. Deionisation - Ion-exchange resins


replace unwanted ions like calcium and magnesium with relatively harmless ones like sodium. Electro-deionisation increases effectiveness by electrically regenerating resins. Adding softeners such as calcium hydroxide, can remove targeted solutes by precipitation. Disinfection - Micro-organisms can be


killed by UV radiation, ozone filters or traditional chlorination. To be sure of the most efficient and


cost-effective combination of wastewater treatments, you should consult a water purification specialist, such as SUEZ Water Purification Systems. Having established the initial and ongoing costs, it should be easy to decide whether recycling is economically viable for your operation.


SUEZ Water Purification Systems www.suezwatertechnologies.com


PROCESS & CONTROL | SEPTEMBER 2020 17


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