ANACAD: Analysis and fate of concrete admixtures in wastewaters

• Unité de recherche: PCRD EU
• Numéro de projet: 97.0342-1
• Titre du projet anglais: ANACAD: Analysis and fate of concrete admixtures in wastewaters

Mots-clé (Anglais)

Naphthalenesulfonates; concrete admixtures; superplasticizers; liquid chromatopgraphy; mass spectrometry; waste waters

Autre Numéro de projet (Anglais)

EU project number: ENV4-CT97-0474

Programme de recherche (Anglais)

EU-programme: 4. Frame Research Programme - 3.1 Environment

Description succincte (Anglais)

See abstract

Partenaires et organisations internationales (Anglais)

BMG Engineering, Schlieren-Zurich (CH),
Università di Venezia (I),
Technologiezentrum Wasser, Karlsruhe (D), University of Crete, Heraclion-Crete (GR)

Résumé des résultats (Abstract) (Anglais)

Through construction activities, large quantities of polymeric organic compounds used as concrete admixtures are potentially introduced into the environment. The majority of these chemicals are xenobiotic compounds such as sulfonated naphthalene-formal-dehyde-condensates (SNFC), sulfonated melamine-formaldehyde-condensates used as super-plasticizers, and more recently polycarboxylates or other copolymers. Although SNFC are considered to have little direct environmental impact, they are a potential hazard for the aquatic environment because of their high solubility in water and their ability to remobilize hydrophobic compounds. Thus, their fate and behavior in the environment need to be better assessed.
In this project SNFC were characterized by direct infusion/electrospray ionisation mass spectrometry (ESI-MS) and by liquid chromatography mass spectrometry (LC/ESI-MS). Both methods allowed the identification of individual oligomers.
Emphasis was put on the determination of octanol water partition coefficients Kow which are often used to predict the physico-chemical dispersion of chemicals in the environment. These coefficients were determined as individual chemicals and in technical mixtures.
Waste water samples released from a concrete work after a typical day of work, were analyzed. The composition of the wastewater collected before an on site WWT was compared to the composition of the corresponding treated effluent. The treatment sequence of this WWT consists of three stages: first the solid removal with settling tank, then special treatment with flocculation and finally neutralization with adjustment of the pH value. The corresponding treated effluent contained oligomers only up to 7 units. Larger oligomers disappeared after the WWT flocculation step, but high amounts of SNFC can be released in the environment even after WWT. In previous work mostly smaller oligomers were found in aquatic systems. Since biodegradation is moderate, ionic interactions are likely cause underlying the removal of the high molecular weight SNFC in WWT.
Wastewater and sludge samples from the wastewater treatment plant Zurich-Werdhölzli were analyzed. Monomeric naphthalene sulfonates were degraded in the biologcal treatment. Dimeric and trimeric SNFC could still be detected in the treated effluents.

Références bases de données (Anglais)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 97.0342-1