1Renal Unit, University Hospital Geelong, Geelong, Australia, 2Renal Unit, Royal Melbourne Hospital, Parkville, Australia, 3School of Engineering, Deakin University, Waurn Ponds, Australia

Background: A global annual estimate of >900,000 tonnes of post-dialysis plastic waste (pdPW) is either incinerated or chemically disinfected for landfill – both at vast financial and environmental cost. But, as novel waste management systems [eg: a SteriMed 700®] can shred then sterilize pdPW, we have explored incorporating pdPW into concrete as a potential re-use end product.
Method: All p-dPW [lines, dialysers, saline bags, syringes, bi-bags etc.] were shredded and sterilized to a polypropylene plastic fiber ‘shreddate’ (PPfs). This was added as 0.5% and 1% by weight to concrete slurries. Pre-separated hard, soft, and all-mixed PPfs were separately tested in a 1% concentration for compressive strength (CS), tensile strength (TS), and water absorption (WA).
Results: The mixed PPfs additive increased TS (0.5% mix = 0.8% increase: 1% mix = 8% increase). 1% PPfs modestly decreased CS (hard 9.9%: soft 16.9%: mixed 11.5% respectively). Added 1% PPfs did not immediately alter the rate of WA, but the mean delayed rate decreased by 30% across all three PPfs-concrete mixes.
Discussion: The % mix, shape and size of PPfs fibers significantly influenced final concrete characteristics. The small reduction in CS is unlikely to have significant impact, but the increase in TS and the 30% reduction in WA are likely significant factors in reducing water penetration and corrosion.
Conclusion: Concrete sequestration of pdPW may: (1) help solve the financial/environmental costs of pdPW disposal; and (2) significantly improve specific concrete characteristics. Improved long-term concrete behavior, water resistance, durability, and steel reinforcement corrosion protection may prove valuable, especially for coastal construction/building, or in marine structures (piers/retaining walls) that contact seawater. The potentially far-reaching implications of this research have prompted further testing.

John Agar is Conjoint Professor of Medicine and Consultant Nephrologist at Deakin University School of Medicine and University Hospital Geelong. In addition to his commitment to grow and improve home dialysis therapies – in particular, home nocturnal haemodialysis – he has been a long-time advocate for improved resource management, better environmental practices, and a lesser carbon footprint in dialysis through the use of recycled/re-used reject water and the augmentation of dialysis power demands from power renewables. His ultimate dream is to complete the water-power-waste eco-loop trio by finding better ways to manage the mountainous waste generation of dialysis.

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