SUPERVISOR: Thomas ERTL

PROJECT ASSIGNED TO: Julian FRÄNKEL

Sulfamic acid, or sulfamate, is a widely used industrial chemical and found in household cleaning products. Tt is a precursor in the synthesis of artificial sweeteners such as acesulfame K as well as in the manufacture of herbicides and fire retardants (Motamedi et al., 2013; Singh et al., 2025). Due to its advantageous properties, such as high solubility, its productions and use increased in the last seventy years, resulting in its continuous release into the environment. Sulfamate cannot be degraded completely in communal wastewater treatment plant, so it is present in the environment as a highly mobile and persistent compound (Castronovo et al., 2017; Freeling et al., 2020; Van Stempvoort et al., 2019). 

Studies conducted in Canada and Germany have demonstrated the presence of sulfamate in various environmental compartments, including wastewater treatment plant effluents, surface waters, bank filtrates, precipitation and drinking water, with reported  concentrations ranging up to 2 mg/L (Freeling et al., 2020; Van Stempvoort et al., 2019). However, data on the occurrence and fate of sulfamate in Austria remain limited.

Recent regulatory developments have increased attention towards substances such as sulfamate. Sulfamic acid and sulfamate are considered toxicologically harmless, however, they exhibit high persistence and mobility and are therefore increasingly under scrutiny, as environmental exposure is considered inevitable (Arp & Hale, 2023; Hale et al., 2020). This is reflected in the introduction of the „very persistent, very mobile“(vPvM) hazard class under the REACH regulation. 

The widespread environmental presence of sulfamate, combined with recent regulatory developments, highlights the need for effective and reliable removal technologies. However, existing studies indicate that neither commonly applied treatment techniques in waterworks nor biological treatment in wastewater treatment plants are effective in removing sulfamate (Castronovo et al., 2017; Freeling et al., 2020). 

To address this gap, preliminary investigations were conducted in a wastewater treatment plant to assess the occurrence and potential removal of sulfamate under real conditions. 
Sulfamate was detected in influent, effluent and sludge digestion unit of a wastewater treatment plant, with notably lower concentrations observed in the anaerobic digestion stage, suggesting potential anaerobic degradation of sulfamate. 

These findings highlight the potential of anaerobic processes for sulfamate removal and motivate further investigation into the underlying mechanisms and their applicability in water treatment systems, forming the basis of this study.

This research will focus on two primary objectives:

  1. Investigation of sulfamate concentrations in various water sources in Austria, including wastewater treatment plant effluents, surface waters, bank filtrates, precipitation and drinking water.
  2. Evaluation of sulfamate removal strategies from aqueous matrices with particular emphasis on their feasibility and potential implementation in wastewater treatment plants

To address these objectives, the doctoral study is guided by the following research questions

  • Occurrence and distribution of sulfamate in Austria:
    • What are the concentration levels of sulfamate across different water matrices in Austria?
    • What are the main sources and influencing factors governing its presence in aquatic environments?
  • Anaerobic degradation:
    • Can sulfamate be removed through anaerobic degradation?
    • Which factors promote the degradation process?
    • Which microorganisms are involved in sulfamate degradation and can they be isolated, identified and cultivated?
    • Are there indicator parameters for the degradation of sulfamate?
  • Physicochemical treatment processes:
    • Can sulfamate be removed using UV-light-based treatment processes?
    • Can sulfamate be removed using ozone-based treatment processes?
  • Technical feasibility and scale-up potential
    • A theoretical consideration of whether the degradation can be implemented in a wastewater treatment plant

References:

Arp, H., & Hale, S. (2023). REACH: guidance and methods for the identification and assessment of PMT/vPvM substances. UBA TEXTE, 19, 2023. 

Castronovo, S., Wick, A., Scheurer, M., Nödler, K., Schulz, M., & Ternes, T. A. (2017). Biodegradation of the artificial sweetener acesulfame in biological wastewater treatment and sandfilters. Water research, 110, 342-353. 

Freeling, F., Scheurer, M., Sandholzer, A., Armbruster, D., Nödler, K., Schulz, M., Ternes, T. A., & Wick, A. (2020). Under the radar–Exceptionally high environmental concentrations of the high production volume chemical sulfamic acid in the urban water cycle. Water research, 175, 115706. 

Hale, S. E., Arp, H. P. H., Schliebner, I., & Neumann, M. (2020). Persistent, mobile and toxic (PMT) and very persistent and very mobile (vPvM) substances pose an equivalent level of concern to persistent, bioaccumulative and toxic (PBT) and very persistent and very bioaccumulative (vPvB) substances under REACH. Environmental Sciences Europe, 32(1), 155. 

Motamedi, M., Tehrani-Bagha, A. R., & Mahdavian, M. (2013). Effect of aging time on corrosion inhibition of cationic surfactant on mild steel in sulfamic acid cleaning solution. Corrosion science, 70, 46-54. 

Singh, A., Choubey, A. K., & Nandan, K. (2025). Sulfamic acid: A risk to both the environment and human health. In Hazardous Chemicals (pp. 505-513). Elsevier. 

Van Stempvoort, D., Spoelstra, J., Brown, S., Robertson, W., Post, R., & Smyth, S. (2019). Sulfamate in environmental waters. Science of the Total Environment, 695, 133734.