A novel method for organic matter removal from samples containing microplastics. (1st October 2021)

• Record Type: Journal Article
• Authors: Lavoy, Mercedes; Crossman, Jill
• Is Part Of: Environmental pollution. Volume 286(2021)
• Publication Date: 2021-10-01
• Subjects: Microplastics -- Wastewater treatment -- Enzymatic digestion -- Biosolids -- Micro-Raman spectroscopy; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2021.117357
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Sludge and biosolids from wastewater treatment plants (WWTPs), identified as important pathways through which microplastics (MPs) can enter the wider environment, contain high organic content, which can obstruct MP quantification/identification. Time- and cost-effective removal of organics is a significant barrier to MP analysis. This study aims to alleviate these obstacles using a widely available store-bought septic tank cleaner, comprised of enzymes and bacteria. The cleaner was added to sludge samples, obtained from a local WWTP. Digestion was tested across a range of cleaner concentrations and heat treatments, and compared to a control digestion without cleaner. Organic content of samples digested with cleaner was reduced by 93%, representing a 22% greater reduction compared to control samples. Virgin plastic pellets, of a variety of polymers, were subjected to the digestion process and underwent no physical or chemical changes, demonstrating this method does not degrade MPs. As all enzymes were added in a single step, the time required for enzymatic digestion using the cleaner was only two days. Compared to existing methods, which take up to several weeks, this novel enzymatic digestion method offers a viable means of extracting MPs from organic materials without either the long processing times required of chemical (solely Fenton's) methods or high cost of laboratory grade enzyme approaches. Graphical abstract: Image 1 Highlights: High organics sample content typically impedes microplastics analysis. Lab-grade chemical and biological digestions are time consuming and expensive. Commercial septic cleaner was used as an alternative for sludge digestions. Organic reduction by septic cleaner was 22% greater than chemical methods. Septic cleaner did not alter structure of MP controls or contaminate samples.