Surface World January 2019 Surface World January 2019 | Page 18

INDUSTRY NEWS Does lime hold future for waste treatment? By Xavier Mear, Product Manager for Neutralac at Lhoist Add in to the mix the uncertainties surrounding Brexit and, while Lhoist sees continued success for its liquid lime technology, we are being asked questions about the security of its supply chain and how it can contribute to users’ own security of manufactured goods. The good news is that, as Lhoist owns a large lime quarry just south of Buxton, whatever geopolitical uncertainties continue to dog the UK, there’s going to be no issue when it comes to lime dosing supplies! For the water utilities, lime dosing is a proven technology that works, helping them to ensure that they achieve the required consent limits imposed on them by the environmental regulator. As these consent levels show no sign of easing off – indeed, if anything, they are likely to become stricter over time – the water companies are constantly on the look-out for new technologies, hardware, machinery – anything which will help them to reduce contamination levels, ideally, at the same time as reducing chemical use. On a different note, the recycling or reusing of waste streams is becoming very topical. Individual customers, who might have trace elements of heavy metals in their waste, are beginning to understand that it could be economically viable to recycle their sludge and organic waste streams, and subsequently, to modify it. The volume of material now being processed means that there is pressure on to modify and recycle the sludge. Suitable for anaerobic digestion and biogas Agriculture produces slurry and sludge, food manufacturers create quantities of waste from washing and processing vegetables, for example, and abattoirs create an acidic, sludge-based waste. Some of these are suitable for anaerobic digestion and biogas. Long term, there is real potential, and, as gas and electricity prices continue to rise, so ways of using waste to generate energy are going to become more attractive – and are certainly a better option than landfill. For Lhoist, there is potential in this waste-to- energy, biogas market. Taking the food industry as an example, some of the waste is ‘fairly consistent’ and requires no pre- conditioning, while plenty of waste does require pre-conditioning before entering the AD waste stream system. To ensure efficiency, bacteria needs to work in optimal environments, ensuring that gas production is as high as possible, and Lhoist products are applicable here. We have carried out AD research that shows there is a biogas increase when using our products and after the AD process, the sludge fraction goes to agricultural use with treated water going down the drain. Focus on sludge nutrient recovery There has been increasing focus on sludge nutrient recovery – phosphate in particular, which is a key nutrient in fertilisers. Right now, these levels are very high and the water utilities are looking at both phosphate reduction and recovery ideas. The phosphate consent standard is incredibly tight, and is perhaps going to go beyond what standard, known practices can achieve. When it comes to sludge chemistry, there are several start-up companies and various research and development projects that are looking to provide solutions. It is unlikely that one solution will provide the answer for everyone, but a combination of different approaches will, hopefully, provide an overall solution. Lime is an important reagent that has been used for centuries and there are many day-to-day applications of using that chemistry. Amongst other projects, we are working on removal efficiencies and dealing with the implications of both storing and dosing applications. Blockages and dust emissions are two potential issues, but the industry has moved forward in terms of addressing these. In any case, Lhoist encourages potential customers or existing customers with new applications to test the lime dosing solution first. We know that customers want to test materials in real life to check that there will be no negative impact on their plant. So, we set up parallel trials to run alongside the existing sludge and chemical dosing process. This means that the customer can select what they are happy with, and there’s always the option to switch back. Once the trial is set up it stays on without interruption, and the customer can assess such parameters as the cleanliness of the water, the contamination removal and how easy it is to deal with the sludge. We source CONTINUED ON PAGE 20 16 JANUARY 2019 twitter: @surfaceworldmag