In Practice: water’s influence on plastics in manufacturing

Manufacturers challenged with purging waste plastics from production should look to water for answers, says Gary Sewell, general manager, Clearwater  

The growing demand to end the use of waste plastics should have manufacturers exploring the alternatives. For some, it’s simply about adhering to government-defined targets and consumer demand. For others, it’s a genuine want to instigate environmental change. Either way, manufacturers are challenged to find greener means of production without forfeiting significant time, cost and resource. A worthy solution must deliver healthy return on investment.

The outright elimination of virgin plastics (new plastics created from non-recycled materials) and NRPs (non-recyclable plastics) would be a step back for so many of the sectors in manufacturing unless a suitable replacement is introduced. The minimal weight of plastic packaging has reduced transportation costs in Food and Beverage. Meanwhile plastic components have reduced weight, improved fuel consumption and reduced pedestrian collision impact for automotive manufacturers.

Shifting to the use of recycled plastic will not only reduce the volume of waste going to landfill, it will diminish reliance on oil which is a significant cost factor in the production of virgin plastics. Further cost savings can also be achieved in the processing of recyclable plastics when compared with the costs of producing virgin plastics from raw material.

With China, previously an avid consumer of the UK’s waste plastic, now refusing to import any more waste material from overseas, and the emergence of the UK Plastics Pact (a collaborative initiative between UK governments and NGOs that aims to keep plastics in a circular economy and out of the environment), the time is right for manufacturers to explore the measures they can take. Those perceived to be resistant to embracing recycled plastic could all too easily lose business from customers seeking to de-toxify their supply chains.

HDPE Ready

Incorporating High Density Polyethene (HDPE) into the production process in the place of virgin plastic will have a significant environmental impact for manufacturers. HDPE is created by shredding waste plastics into flakes which are then put through a ‘hot wash’ to separate the plastics from any other materials such as paper labels, glues or other bonding agents.

Beyond ensuring the end product is easily recyclable and kept out of the natural environment, the process of creating HDPE should also have minimal impact on the environment. This can be achieved by optimising the consumption of water in the process. Methods can be applied that effectively re-use the hot wash water a maximum number of times, reducing the amount of influent water used and the amount of waste water created.

Water is also key to the heating and cooling of the HDPE on its journey through the manufacturing process. Significant energy savings can be achieved in the optimisation of the steam boilers that generate the heat required. By analysing and optimising on-site boilers and implementing a turn-key pre-treatment plant, manufacturers can accomplish energy savings upwards from 5% while reducing the expenditure traditionally associated with disposing of waste water generated during the process.

When it comes to cooling HDPE during the manufacturing process, further optimisation can be made in the cooling towers. Firstly, cooling tower systems should be analysed for water leaks and losses as these are typically rarely managed. When losses and leaks are managed and addressed, cooling towers are noticeably more efficient. Ensuring the make-up water that runs into the cooling towers is off consistently high quality is also important and this can be achieved by reviewing the chemical treatment processes put in place.

Capacity for Improvement

Traditionally, water treatment has required the use of liquid chemicals supplied in plastic drums up to 250L in capacity. Not only do these large quantities of chemicals drive up the carbon footprint and the overall cost of operation by being expensive to transport – their containers are created from virgin plastic.

Unsurprisingly, there is a growing movement towards the use of new solid chemical solutions that provide the same volume of chemicals in packages a fraction of the size of traditional liquid chemicals. What makes solid chemicals an even more attractive option is the fact they are supplied in HDPE packaging.

The UK Plastics Pact estimates that by 2025, 100%of plastic packaging can be reusable, recyclable or compostable. By implementing solutions that are already available, including HDPE in place of virgin plastics and the associated water management and water treatment solutions, manufacturers could accelerate progress beyond plastic packaging, in the wider use of plastics in new products and components.

Gary Sewell

General manager, Clearwater

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