Feasibility of superabsorbent polymer recycling and reuse in disposable absorbent hygiene product
The objective of this work is to evaluate the life cycle impacts of recovering superabsorbent polymers from absorbent hygiene products (AHPs). AHPs, which include baby diapers, feminine hygiene products, and adult incontinence pads, have a considerable environmental impact. While convenient, the vast majority of these products, which typically contain combinations of polypropylene, polyethylene, elastics, cellulose, and superabsorbent polymers (SAPs), are single use. Current practice of AHP disposal results in the loss of valuable materials like SAPs, generation of large volumes of municipal solid waste, and increased manufacturing burdens. While recognition of AHP impacts is increasing, it is important to consider that the most significant life cycle impacts of AHPs stem from resource extraction and manufacturing, not disposal itself. The SAPs in these products are of particular importance as they contribute substantially to these upstream life cycle impacts. We aim to shed light on how we might lessen upstream impacts by focusing on the potential for SAP recovery and re-use.
This research evaluates end-of-life options for baby diapers in Europe using a life cycle approach to explore alternative options to conventional disposal of AHPs. We analyze the environmental trade-offs under the following scenarios: 1) diaper disposal via landfill or incineration; 2) diaper recycling without SAP recovery; and 3) diaper recycling with theoretical SAP recovery. Each recycling scenario is analyzed under two allocation conditions for a total of five scenarios. Environmental impacts were modeled in the LCA software SimaPro using the ReCipe 2016 impact assessment framework. Results show that SAP recovery has potential to decrease life cycle emissions by 54% compared to standard landfilling and incineration and by 35% when compared to the recycling technologies assessed in the study. SAP recovery and reuse also results in large potential offsets of energy and water burdens involved in SAP manufacturing. By assessing these environmental impacts, we aim to clarify the point at which SAP recovery demonstrates potential for circular economy.