Micropollutant analysis according to the revised EU Urban Wastewater Treatment Directive

Directive (EU) 2024/3019, known as the revised Urban Wastewater Treatment Directive (UWWTD), entered into force in January 2025. It aims to improve water quality by introducing stricter treatment and monitoring requirements for wastewater, including an obligation to remove at least 80% of certain micropollutants during quaternary treatment.

The change is a significant one, as the previous directive did not impose quaternary treatment requirements on urban wastewater treatment plants. As a result, most existing procedures do not specifically target pharmaceutical residues or other micropollutants, making upgrades necessary to achieve the required removal rate.

Measurlabs offers laboratory analysis services to evaluate the effectiveness of new micropollutant removal processes, helping wastewater treatment plants comply with the revised directive. We can also support local, regional, and national authorities with other monitoring requirements introduced by the new UWWTD, including analyses for PFAS and microplastics.

Micropollutant removal requirement under the new UWWTD

According to Directive (EU) 2024/3019, the term micropollutant covers a broad range of substances that are usually present in urban wastewater and that can be considered hazardous to human health or the environment, even in low concentrations.¹

Due to the broad definition, the effectiveness of micropollutant removal processes is assessed by measuring the concentrations of a set of indicator substances, listed in Table 3 of Annex I to the Directive. The average removal efficiency of quaternary treatment with regard to these substances must be at least 80%.²

The current list of indicator substances contains two categories of organic substances, most of which are active pharmaceutical ingredients (APIs). Category 1 includes substances that can be very easily treated:

• Amisulprid (CAS: 71675-85-9)

• Carbamazepine (CAS: 298-46-4)

• Citalopram (CAS: 59729-33-8)

• Clarithromycin (CAS: 81103-11-9)

• Diclofenac (CAS: 15307-86-5)

• Hydrochlorothiazide (CAS: 58-93-5)

• Metoprolol (CAS: 37350-58-6)

• Venlafaxine (CAS: 93413-69-5)

While category 2 comprises substances that can be easily disposed of:

• Benzotriazole (CAS: 95-14-7)

• Candesartan (CAS: 139481-59-7)

• Irbesartan (CAS: 138402-11-6)

• Mixture of 4-Methylbenzotriazole (CAS: 29878-31-7) and 5-methyl-benzotriazole (CAS: 136-85-6)

For compliance testing, the concentrations of at least six substances, with twice the number from category 1 as compared to category 2, are measured before and after quaternary treatment. The average percentage of removal is then calculated and compared to the 80% threshold.

When is micropollutant analysis required?

The quaternary treatment obligation introduced by the revised UWWTD applies to large wastewater treatment plants responsible for handling a pollution load of at least 150,000 p.e. (population equivalents). All discharges from these plants must meet the criteria for micropollutant removal by the end of 2045, with interim requirements for 20% of plants to comply by 2033 and 60% by 2039. 

Smaller plants (10,000 p.e. and above) must also meet quaternary treatment requirements by 2045 if they discharge water into areas where the accumulation of micropollutants poses risks to human health or the environment. These include drinking water catchment areas, bathing water, and areas where aquaculture is practiced. 

Monitoring should start well before the deadline to ensure that sufficient removal efficiency is achieved in time.

Wastewater monitoring for PFAS and microplastics

Although the revised UWWTD does not specify similar requirements for the removal of microplastics or PFAS, it does require competent authorities to monitor their presence at the inlets and outlets of urban wastewater treatment plants that handle a pollution load of at least 10,000 p.e.³

The PFAS monitoring requirement applies when treated wastewater is discharged into drinking water catchment areas. Analyses should focus on one or both of the indicator parameters specified in the revised Drinking Water Directive (EU) 2020/2184:⁴

• PFAS Total: The totality of per- and polyfluoroalkyl substances measured through proxy methods, such as combustion ion chromatography (CIC) or the total oxidizable precursor (TOP) assay. According to the Commission’s technical guidelines, the definition includes the ultrashort-chain compound trifluoroacetic acid (TFA), which can end up in water from various sources and is currently under evaluation by the World Health Organization (WHO) with respect to potential health effects.⁵

• Sum of PFAS: Sum of 20 individual substances (e.g., PFOS, PFOA, and PFHxS), listed in Part B of Annex III to the Drinking Water Directive. Analysis is typically performed using high-performance liquid chromatography methods, such as LC-MS/MS.

The microplastic monitoring requirement applies to both wastewater and sludge, particularly when sludge is reused in agriculture. The UWWTD does not currently specify a methodology for microplastic analysis, but required data are likely to include particle size, shape, number, and polymer type, as this would be consistent with the approach already established for drinking water.⁶ These parameters can be determined using microspectroscopic methods, of which µFTIR is preferred for wastewater and sludge samples.

Official analysis methods for PFAS and microplastics monitoring under the UWWTD will be established through implementing acts. The methodology for PFAS is due to be published by 2 January 2027, and the one for microplastics by 2 July 2027.

Analytical services for wastewater monitoring in accordance with the UWWTD

Measurlabs offers analyses for various types of wastewater and sludge samples to determine pollution levels in the influent and the percentage of removal achieved during each step of the treatment process. Popular services include the following:

• Pharmaceutical residue analysis of untreated and treated wastewater, covering all indicator substances for assessing the efficacy of quaternary treatment in accordance with the new UWWTD

• Targeted PFAS analysis of wastewater, covering up to 58 individual compounds, including TFA

• TOP assays to determine the concentration of PFAS precursors

• Microplastic analysis of wastewater with µFTIR

• Microplastic analysis of sludge or sediment with µFTIR

Analysis options are also available for a range of other high-priority pollutants, such as PAH compounds, phthalates, and dioxins. Do not hesitate to contact our experts for more information or a quote for your samples.