Microplastics in industrial wastewater

Definition first: industrial wastewater is water arising from a production process and discharged into a water body or the sewer system. Microplastics are plastic particles up to five millimetres in diameter. In wastewater from the plastics processing industry both features occur together: the particles are generated in the process, their polymer spectrum is known, and the discharge point can be located precisely. This makes such wastewater fundamentally different from municipal wastewater, where origin and composition are diffuse.

With increasing legal regulations for polymers, plastics and microplastics, high costs for water, waste, energy, chemicals, and plant maintenance, as well as complex pollution scenarios - companies that use a lot of water, polymers and other chemicals in their processes are facing the challenge of realigning their environmental, waste and resource management.

The Wasser 3.0 PE-X® process provides an adaptive complete solution for a process upgrade for industrial water treatment. The process focuses on the removal of microplastics and is based on organosilane-based agglomeration–fixation, filter-free separation without a membrane stage and circular economy processes. What is evidenced is the retention performance, the COD reduction and the reusability of the treated water; the figures follow below.

Detecting microplastics: municipal wastewater treatment plants vs. industrial wastewater

Wastewater from plastic manufacturing or processing industries is often highly polluted with microplastics (MPs) and high levels of oxidizable organic matter, which results in a high chemical oxygen demand (COD). Measured values from our own pilot trials: 1,725 ± 377 mg/L of microplastics and 7,570 ± 1,339 mg/L COD at a packaging production line (Clean Technol. 2025, 7, 67), and 8,450 to 9,940 mg/L COD at a plastics processor (Water 2025, 17, 671). When the high microplastic load enters wastewater streams, it is a large burden for municipal wastewater treatment plants (WWTPs).

WWTPs are not designed to remove microplastics, and due to the high volumes of wastewater released, they are important point sources of microplastics into the environment and water cycle. At the time this post was first published, microplastics were not on the regulatory agenda. That has changed: the recast EU Urban Wastewater Treatment Directive, Directive (EU) 2024/3019, entered into force on 1 January 2025 and, under Article 17, obliges Member States for the first time to monitor microplastics in wastewater systems. The transposition deadline is 31 July 2027. There is still no emission limit value for microplastics.

Further, the majority of the microplastics end up in sewage sludge, whereby the problem is only displaced. Our own comparative measurements support this: across the effluents of three municipal plants with two, three and four treatment stages, no significant differences in microplastic concentration were found (Water 2025, 17, 711). Advanced processes such as advanced oxidation or activated carbon target dissolved substances and capture particles only incompletely. It is therefore essential to avoid the input of MPs into wastewater streams by targeting their removal from upstream point sources such as industrial wastewaters. Targeting an upstream removal (start-of-the pipe) is more effective, involves lower costs, and ensures that the polluter bears the costs instead of the public. There is a measurable basis for the greater effectiveness: the agglomeration process works more efficiently at high starting loads. In industrial wastewater with 673 ± 183 million particles per litre, removal reached 99.1 % by particle count, whereas in municipal WWTP effluent with 29.1 ± 15.1 particles per litre it reached 60.9 ± 27.5 % (Clean Technol. 2025, 7, 67; Water 2024, 16, 268). The statement on lower costs refers to the smaller volume of water requiring treatment; a robust total cost comparison against a downstream municipal solution is not available.

Microplastic removal from wastewater: New feasibility study published

As early as 2021, we were able to carry out a long-term trial on the simultaneous removal of microplastics and micropollutants at the municipal wastewater treatment plant in Landau. In 2023, we had the opportunity to test our rental model in an in-house pilot operation at a plastics processor for the removal of microplastics and simultaneous reduction of COD from industrial wastewater. In a total of eight test phases over a period of three months, our research and development work focused on reproducibility, impact analysis, and economic feasibility.

In each test phase, 12 samples were analyzed for five parameters: COD, total suspended solids (TSS), particle count, pH, and turbidity. Microplastic removal is accomplished through the physical-chemical agglomeration fixation of microplastics from the water. We use innovative hybrid silica gels that can form a few large agglomerates from many small particles in a water-induced sol–gel reaction, for which no relevant by-products were detected in the trials carried out. The COD reduction was carried out using a fixed-bed reactor filled with modified absorbent materials. We have now published the results.

The key measured values of that study (Water 2024, 16, 268): the microplastic load fell on average by 98.26 ± 2.15 % measured via total suspended solids and by 97.92 ± 2.31 % measured via particle count. COD fell by 94.3 ± 8.9 %. Per cubic metre of treated water, 1.1 kg of microplastics were retained; projected to the site, that corresponds to roughly 2.7 tonnes per year. The projection is based on the pilot operation’s wastewater volumes and is labelled as an estimate in the publication.

Three further studies have appeared since this post. A life cycle assessment accounts for construction, operation and end-of-life of the plant and reports 25.4 kg CO₂ equivalents per m³ of treated wastewater for the pilot plant and 1.0 kg CO₂ equivalents per m³ for an optimised circular concept (Water 2025, 17, 671). An automated successor plant at a packaging production line achieved, across 25 test runs, 97.4 % removal by mass and 99.1 % by particle count, with 78.8 % COD reduction and water reuse of up to 80 % (Clean Technol. 2025, 7, 67). At a two-stage municipal plant on Mykonos, removal was 86 ± 8 % by particle count with 95 ± 3 % retention of total suspended solids (Clean Technol. 2026, 8, 32). The range across sites results from differing starting loads and water matrices and is deliberately not condensed into a single percentage.

Briefly summarized: In addition to microplastic removal and COD reduction, this treatment also enables the reuse of wastewater and agglomerates, which lowers demand for fresh water and primary raw materials. On the climate effect a clarification is needed: the treatment itself causes greenhouse gas emissions. The life cycle assessment reports 25.4 kg CO₂ equivalents per m³ for the pilot plant and 1.0 kg CO₂ equivalents per m³ for an optimised circular concept. The reduction of more than 96 % is a comparison between these two of the company’s own plant concepts, not a comparison with untreated wastewater and not a competitor comparison.

Link to the EU project UPSTREAM

FACT-CHECK NOTE

The percentages from UPSTREAM cited in this section (50 %, 30 %, 83 %) are targets of the funded project, not measurement results. No published final figures are available so far.

Since mid-2023, we have been an active research and development partner of the EU-funded UPSTREAM project.

We support the project consortium in addressing the challenges related to the monitoring, prevention, elimination, and valorization of waste/litter (L), plastics (P) and microplastics (MP).

Objectives of the EU Upstream project (adapted ©Upstream Consortium)

We are one of four WWTP-integrated demo sites addressing pollution at each stage of the water system, connected to seven rivers in five countries. The figures that follow are targets of the funded project, not results achieved. The UPSTREAM consortium aims to establish circular value chains, to which the consortium attributes a reduction potential of 50 % for plastic waste and 30 % for microplastic pollution. Progress in UPSTREAM is based on several technology building blocks, for which the project proposal sets out the following target values:

Standardized, rapid monitoring techniques that can detect microplastics down to > 25 μm in size.
Bio-based, biodegradable plastics that are intended to prevent the formation of MP in consumer products and wastewater treatment plants themselves. For context: biodegradability is tied to defined environmental conditions and does not mean that no microplastics arise in water bodies
Innovative floating platforms intended to remove more than 83% of L, P and MP directly from rivers, both on the surface and in the riverbed. This value is a project target.

Overview of the Upstream project areas (adapted ©Upstream Consortium)

UPSTREAM represents a pan-European consortium with five demonstration plants across Europe, including four wastewater treatment plants (UK, ES, DE, IT) and a test site on the Danube in Serbia.

Photo from the first UPSTREAM project meeting in the UK (©Upstream Consortium)

TRANSPARENCY NOTE ON SOURCES AND DATA STATUS

The trial description states five analytical parameters; filterable solids and total suspended solids denote the same measurement under DIN 38409-2. The UPSTREAM figures of 50 %, 30 % and 83 % are consortium targets, not measurement results. The life cycle assessment values refer to one cubic metre of treated wastewater and compare two plant concepts with one another. Research status: September 2026.

Further information on the EU project Upstream