We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
The fate of microplastics when making sludge into crude oil – the impact of a hydrothermal liquefaction process on microplastics in wastewater treatment plant sludge.
AI summary Read the abstract
Researchers investigated what happens to microplastics in wastewater sludge when the sludge is converted to bio-crude oil using hydrothermal liquefaction (HTL). They found that HTL processing transformed most microplastics into organic compounds incorporated into the crude oil product, effectively mineralizing them rather than leaving them as persistent particles. The study suggests HTL could serve a dual purpose of both producing biofuel and destroying sludge-bound microplastics.
Microplastics (MPs) are entering wastewater treatment plants (WWTPs) from various sources such as primary MPs in consumer products and secondary MPs from wear of plastic items and textiles. There is a scientific consensus that the efficiency of WWTPs in retaining MPs is high, with up to 99% being retained and ultimately ending up in the sludge. Within a totally different research diciplin, scientist are also working on producing bio-crude oil from the sludge by processing it at pressures around 30 Mpa and temperatures around 400°C known as hydrothermal liquefaction (HTL). In an interdisciplinary study, we have studied the fate of MPs in WWTP sludge fed into a continuous HTL reactor. The HTL products as a mixture of bio-crude, aqueous, and solid residues have been investigated. Duplicate samples of each matrix were analyzed for MP. Wet-oxidation (H2O2), sodium dodecyl sulfate, and enzymatic treatment were performed to remove natural organic materials such as cellulose, protein, and lipid compounds. Inorganic particles were removed by density separation using sodium polytungstate solution. The bigger particles (> 500 µm) were separated by sieving and potential MP candidates handpicked and analyzed by ATR-FTIR (Agilent Cary 630, diamond ATR). The smaller particles (10-500 µm) were analyzed by FPA-µFTIR (Agilent Cary 620/670) and the particles identified using the software siMPle for automated analysis of the generated spectral image. 13 polymer types, comprising particles of 11-3207 µm, were observed in the sludge with Polyurethane (PU), Polyethylene (PE), Polypropylene (PP), Polyester (PEsT), alkyd, and cellulose acetate as the dominant ones. In the HTL products, only a few olefins such as PP and PE with sizes of 13.3-81.6 µm were observed. Furthermore, the MP removal efficiency of the HTL process was between 99.65% and 99.99% by particle numbers and mass respectively.
More Papers Like This
Microplastics degradation through hydrothermal liquefaction of wastewater treatment sludge
AI summary Read the abstract
Researchers tested whether hydrothermal liquefaction (HTL) — a high-temperature, high-pressure process that converts sewage sludge into bio-crude oil — could also destroy microplastics in the sludge, finding it reduced microplastic numbers by 76% and mass by 97%, with no microplastics detected in the bio-crude product. This suggests HTL could serve a dual purpose: producing renewable fuel while significantly reducing microplastic pollution from the sludge that would otherwise be spread on farmland.
Effect of Microplastics in Hydrothermal Liquefaction (HTL) of Real Municipal Sludge (RMS)
AI summary Read the abstract
Researchers studied how adding microplastics to real municipal sludge affects the yield and quality of biocrude oil produced by hydrothermal liquefaction, and found that microplastics altered product yields in the presence of different catalysts. The findings are relevant to waste-to-energy processing of sludge that contains microplastics from wastewater treatment.
Fate of microplastics during conventional and hydrothermal treatments of sewage sludge: a short review
AI summary Read the abstract
This review examines the fate of microplastics during conventional and hydrothermal treatment of sewage sludge, noting that approximately 90% of microplastics entering wastewater treatment plants are retained in sludge. Researchers found that while conventional disposal routes concentrate microplastics in sludge destined for land application, hydrothermal treatments offer potential pathways to degrade or transform microplastics, though the efficiency and byproducts of these processes require further investigation.
Fate of microplastic during pyrolysis of sewage sludge
AI summary Read the abstract
Researchers investigated what happens to microplastics embedded in sewage sludge when sludge is treated by pyrolysis, a high-temperature thermochemical process. Pyrolysis effectively destroyed most microplastic particles, but some residual polymer-derived compounds partitioned into the pyrolysis products.
Changes in physicochemical and leachate characteristics of microplastics during hydrothermal treatment of sewage sludge
AI summary Read the abstract
Researchers examined hydrothermal treatment of sewage sludge containing microplastics and found that while the process degraded polyethylene, polystyrene, and PET to varying degrees, it also generated potentially harmful leachates, highlighting trade-offs in this treatment approach.
Research digests by email
When a large batch of papers lands in the Atlas, we read through it and send a short write-up of what stood out.