0
Article Tier 2 Environmental Sources Remediation Sign in to save

Occurrence of Microplastics in Waste Sludge of Wastewater Treatment Plants: Comparison between Membrane Bioreactor (MBR) and Conventional Activated Sludge (CAS) Technologies

Membranes 2022 63 citations

AI summary Read the abstract

Microplastics were compared in sludge from wastewater treatment plants using conventional activated sludge and membrane bioreactor technologies, finding that both produced sludge with significant plastic contamination and that the MBR system showed somewhat different microplastic profiles. The results indicate that sludge disposal is a key route by which microplastics captured in treatment plants are transferred to agricultural land.

Study Type Environmental

In this study, the presence of microplastics in the sludge of three wastewater treatment plants (WWTPs) was examined. The investigated WWTPs operated based on a conventional activated sludge (CAS) process, with (W1) or without (W2) primary clarification, and a membrane bioreactor process (MBR) (W3). The microplastics (MPs) concentration in the samples of W3 was approximately 81.1 ± 4.2 × 103 particles/kg dry sludge, whereas MPs concentrations in W1 and W2 were 46.0 ± 14.8 × 103 particles/kg dry sludge and 36.0 ± 5.2 × 103 particles/kg dry sludge, respectively. Moreover, MPs mainly consisted of fragments (66-68%) in the CAS plants, whereas the fractions of MPs shapes in the MBR sludge were more evenly distributed, although fiber (47%) was the most abundant fraction. Furthermore, samples from the MBR showed a greater diversity in MPs composition. Indeed, all the main polyesters (i.e., textile fibers and polyethylene terephthalate), polyolefins (i.e., polyethylene and polypropylene) and rubber (i.e., polybutadiene) were observed, whereas only polybutadiene, cellulose acetate and polyester were detected in the CAS plants. These findings confirmed that MPs from wastewater are transferred and concentrated in the waste sludge. This is a critical finding since sludge disposal could become a new pathway for microplastic release into the environment and because MPs might affect the fouling behavior of the membrane.

More Papers Like This

Article Tier 2

The Occurrence and Risk Assessment of Microplastics: different treatment technologies for wastewater treatment plants in Oman

AI summary Read the abstract

A study of three wastewater treatment plants in Oman — using conventional activated sludge, membrane bioreactor, and sequencing batch reactor technologies — quantified and characterized MPs at multiple treatment stages, including sludge. Membrane bioreactor technology achieved the best MP removal from effluent, but all plants concentrated MPs in sludge, highlighting an underregulated route for microplastic release back into the environment.

Article Tier 2

[Microplastics in wastewater treatment: current status and future trends].

AI summary Read the abstract

This review summarizes current research on microplastic occurrence, removal, and fate in wastewater treatment plants, noting that while plants capture most microplastics in activated sludge, significant numbers still escape into effluent. The sludge itself then becomes a major pathway for microplastics to enter agricultural soils when applied as fertilizer. Future treatment improvements and sludge management policies are needed to reduce these release pathways.

Article Tier 2

The Effect of Wastewater Treatment Methods on the Retainment of Plastic Microparticles

AI summary Read the abstract

This review examined how different wastewater treatment methods retain or remove plastic microparticles, finding that treatment plant design significantly affects how many microplastics escape to the environment. Advanced treatment processes such as membrane bioreactors outperformed conventional activated sludge systems in removing microplastics.

Article Tier 2

Effects of microplastics on substance transformation, sludge characteristics, toxicological effect, and microbial communities in different biochemical sludge systems: A review

AI summary Read the abstract

This review synthesizes evidence that microplastics impair the biological and physical processes in wastewater treatment sludge systems, inhibiting nutrient removal, disrupting microbial communities, and degrading sludge structure—with smaller particles and higher concentrations causing greater damage. Because sludge is widely applied to agricultural land, any microplastic-driven impairment of treatment efficiency also increases the risk of plastic particles and associated pollutants reaching soils and food crops.

Article Tier 2

Abatement of Microplastics from Municipal Effluents by Two Different Wastewater Treatment Technologies

AI summary Read the abstract

Researchers compared two wastewater treatment technologies for microplastic removal: membrane bioreactors and rapid sand filtration after activated sludge treatment. Both achieved high removal efficiencies for most of the 14 identified polymer types, but some microplastics still pass through to receiving waters.

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.

Email me about

Share this paper