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Increased demand for single-use personal protective equipment (PPE) during the COVID-19 pandemic has resulted in a marked increase in the amount of PPE waste and associated environmental pollution. Developing efficient and environmentally safe technologies to manage and dispose of this PPE waste stream is imperative. We designed and evaluated a hydrothermal deconstruction technology to reduce PPE waste by up to 99% in weight. Hydrothermal deconstruction of single-use PPE waste was modelled using experimental data in Aspen Plus. Techno-economic and sensitivity analyses were conducted, and the results showed that plant scale, plant lifetime, discount rate, and labour costs were the key factors affecting overall processing costs. For a 200 kg/batch plant under optimal conditions, the cost of processing PPE waste was found to be 10 NZD/kg (6 USD/kg), which is comparable to the conventional practice of autoclaving followed by landfilling. The potential environmental impacts of this process were found to be negligible; meanwhile, this practice significantly reduced the use of limited landfill space. [ABSTRACT FROM AUTHOR]

Wet air oxidation (WAO) of the PPE mixture was performed at temperatures ranging from 300 °C to 350 °C, with initial air pressures of 30 bar and 60 bar, respectively. Total suspended solids (TSS) were reduced by up to 99%, while total chemical oxygen demand (tCOD) and soluble chemical oxygen demand (sCOD) were significantly reduced to 360 mg/L and 110 mg/L, respectively. The main products were volatile fatty acids such as acetic and propionic acids and ammonia nitrogen (NH 3 -N) with concentrations of up to 1117 mg/L, 975 mg/L, and 18 mg/L, respectively. Nitrogen and oxygen were the most abundant gaseous products, reaching 72% (w/w) and 14% (w/w), respectively. Semi-batch WAO treatments were carried out at 300 °C and 350 °C to achieve comparable waste reduction. The results suggest that non-catalytic WAO is a viable PPE waste management solution. [Display omitted] • Up to 98.8% of the mixture of selected single-use PPE items was deconstructed. • Up to 18 mg/L ammonia was detected in the resultant reaction mixture. • Volatile fatty acids, mainly acetic acid up to 1117 mg/L was produced. • Nitrogen and oxygen were the primary gaseous products in the off-gas stream. [ABSTRACT FROM AUTHOR]

[Display omitted] • Up to 98% of single-use PPE items was deconstructed. • Up to 547 mg/L ammonia was detected in the resulting reaction mixture. • Volatile fatty acids, primarily acetic acid up to 8974 mg/L was produced. • Carbon dioxide and oxygen were the main gaseous products in the off-gas stream. To minimise the transmission of the SARS-CoV-2 virus, there has been a substantial increase in the production and usage of synthetic personal protective equipment (PPE) globally. Consequently, single-use PPE have been widely adopted without appropriate regulations for their disposal, leading to extensive environmental contamination worldwide. This study investigates the non-catalytic hydrothermal deconstruction of different PPE items, including isolation gowns, gloves, goggles, face shields, surgical masks, and filtering-facepiece respirators. The selected PPE items were subjected to hydrothermal deconstruction for 90 min in the presence of 30-bar initial oxygen pressure, at temperatures ranging between 250 °C and 350 °C. The solid content in form of total suspended solids (TSS) was reduced up to 97.6%. The total chemical oxygen demand (tCOD) and soluble chemical oxygen demand (sCOD) decreased with increasing deconstruction temperature, and at 350 °C the lowest tCOD and sCOD content of 546.6 mg/L and 470 mg/L, respectively, was achieved. Short-chained volatile fatty acids were produced after 90 min of deconstruction, predominantly acetic acid at concentrations up to 8974 mg/L. Ammonia nitrogen content (NH 3 –N) of up to 542.6 mg/L was also detected. Carbon dioxide (CO 2) and unreacted oxygen (O 2) were the main gaseous by-products at up to 15.6% (w/w) and 88.7% (w/w), respectively. The findings suggest that non-catalytic hydrothermal deconstruction is a viable option to process and manage PPE waste. [ABSTRACT FROM AUTHOR]