Microplastics removal from a primary settler tank in a wastewater treatment plant and estimations of contamination onto European agricultural land via sewage sludge recycling

Lofty, J.; Muhawenimana, Valentine; Wilson, C.A.M.E.; Ouro, Pablo

doi:10.1016/j.envpol.2022.119198

Cited by 50 publications

(16 citation statements)

References 56 publications

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“…This is higher than most previously reported values. Globally, the amount of MPs reported in a gram of biosolid (dry weight) range between 1 and 171 in Australia, China, Ireland, Italy, Spain, and the United Kingdom (Edo et al, 2020;Iyare et al, 2020;Li et al, 2018;Lofty et al, 2022;Magni et al, 2019;Mahon et al,2017;Ziajahromi et al, 2021). Lares et al (2018) have reported levels >200 particles of microplastics in a gram (dry weight) of biosolids from a Finnish WWTP.…”

Section: Discussionmentioning

confidence: 99%

How many microplastic particles are present in Canadian biosolids?

et al. 2023

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Application of treated sewage sludge (biosolids) from wastewater treatment plants (WWTPs) to farmlands is an important pathway through which microplastic particles (MPs) enter terrestrial ecosystems. Yet, microplastic concentrations in Canadian biosolids have only been estimated in samples from four WWTPs previously. We aimed to fill this knowledge gap by quantifying microplastics in biosolids from 22 WWTPs located in nine provinces and two commercial fertilizer producers in Canada. All samples had substantial microplastic concentrations ranging from 228 to 1353 particles per gram dry weight (median = 636 particles), which are orders of magnitude greater than MPs reported from earlier investigations of biosolids from other countries. Fibers (median: 86%) were the most common type of MPs observed, followed by fragments (median: 13%). There were no statistically significant differences in the amount of microplastics observed in the biosolids from different geographical regions, WWTP types, and sludge treatment processes. This suggests that diverse combinations of local sewershed characteristics, site‐specific treatment approaches, and daily flow at WWTPs may be influencing concentrations of microplastics in biosolids. Our results indicate that microplastic concentrations in biosolids are substantially higher than they are in other environmental matrices, and this has important implications to managing microplastic pollution in terrestrial ecosystems.

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Section: Discussionmentioning

confidence: 99%

How many microplastic particles are present in Canadian biosolids?

et al. 2023

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“…The percentage of larger MP particles in the liquid phase remained at the level of 2–10% for most of the C/Fs, only for 2.5 mL FCT/L did this percentage increase to 26.6%. Lofty et al [ 26 ] reported that after a seven-day sampling period, a higher concentration of particles with 1000–5000 μm diameters was present in the scum than in the sludge (1271 vs. 771 MP/L) in the primary settling tank. The higher concentration of MPs in the scum resulted from a lower density than water, or from their flocculation with floating fats, oils, and grease.…”

Section: Resultsmentioning

confidence: 99%

Coagulation and Flocculation before Primary Clarification as Efficient Solutions for Low-Density Microplastic Removal from Wastewater

Jachimowicz

Cydzik‐Kwiatkowska

2022

IJERPH

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Microplastic (MP) removal from wastewater was investigated using various types and doses of commercial coagulants (PIX, PAX) and flocculants (FPM, PEL, FCT) before primary clarification in a wastewater treatment plant (WWTP). Dosing with FPM, PIX, and PEL caused small MPs (180–212 µm) to be transferred mainly to the settled sludge (up to 86.4% of MP at a dose of 5 mL FMP/m3), while dosing of FCT and PAX caused these MPs to be transferred to the floated sludge (up to 64% MP at a dose of 5 mL PAX/m3). The efficiency of MP removal from wastewater was the highest (90%) with 2.5 mL PAX/m3; the generated primary sludge had a low MP content and could be safely managed in subsequent stages of sludge treatment. At the highest doses, PIX significantly increased the removal of P-PO4 (up to 94%) and COD (up to 73%). FPM and FCT resulted in over 40% efficiency of ammonium removal—such disturbance in wastewater composition may negatively affect further biological treatment. Effective removal of MP in the mechanical part of WWTP resulting from coagulation and flocculation enables the safe use of the excess sludge for agricultural purposes.

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“…MPs are sourced from the fragmentation of large plastic waste, the breakdown of textiles, or from purposely manufactured small plastic particles, and can enter the riverine systems through direct disposal (e.g. littering, combined sewage overflows, wastewater treatment plant outflows), airborne dispersal and run-off (Allen et al, 2019;Woodward et al, 2021;Lofty et al, 2022). The varying size, density and shape of MP particles found in the environment impacts on their buoyancy, settling velocity, and critical bed shear stress, making it challenging to predict their transport and distribution (Waldschläger and Schüttrumpf, 2019b;Khatmullina and Chubarenko, 2020;Waldschläger et al, 2022).…”

Section: Introductionmentioning

confidence: 99%