DEGRADATION AND TRANSFER OF POLYACRYLAMIDE BASED FLOCULENTS IN SLUDGES AND INDUSTRIAL AND NATURAL WATERS Microbial aerobic and anaerobic degradation of acrylamide in sludge and water under environmental conditions—case study in a sand and gravel quarry A. G. Guezennec & C. Michel & S. Ozturk & A. Togola & J. Guzzo & N. Desroche Received: 15 July 2014 /Accepted: 23 October 2014 # Springer-Verlag Berlin Heidelberg 2014 Abstract Polyacrylamides (PAMs) are used in sand and grav- el quarries as water purification flocculants for recycling process water in a recycling loop system where the flocculants remove fine particles in the form of sludge. The PAM-based flocculants, however, contain residual amounts of acrylamide (AMD) that did not react during the polymerization process. This acrylamide is released into the environment when the sludge is discharged into a settling basin. Here, we explore the microbial diversity and the potential for AMD biodegradation in water and sludge samples collected in a quarry site submit- ted to low AMD concentrations. The microbial diversity, analyzed by culture-dependent methods and the denaturing gradient gel electrophoresis approach, reveals the presence of Proteobacteria, Cyanobacteria, and Actinobacteria, among which some species are known to have an AMD biodegrada- tion activity. Results also show that the two main parts of the water recycling loop—the washing process and the settling basin—display significantly different bacterial profiles. The exposure time with residual AMD could, thus, be one of the parameters that lead to a selection of specific bacterial species. AMD degradation experiments with 0.5 g L -1 AMD showed a high potential for biodegradation in all parts of the washing process, except the make-up water. The AMD biodegradation potential in samples collected from the washing process and settling basin was also analyzed taking into account on-site conditions: low (12 °C) and high (25 °C) temperatures reflecting the winter and summer seasons, and AMD concen- trations of 50 μgL -1 . Batch tests showed rapid (as little as 18 h) AMD biodegradation under aerobic and anaerobic con- ditions at both the winter and summer temperatures, although there was a greater lag time before activity started with the AMD biodegradation at 12 °C. This study, thus, demonstrates that bacteria present in sludge and water samples exert an in situ and rapid biodegradation of AMD at low concentration, whatever the season, and in both the aerobic and anaerobic parts of the water recycling system. Keywords Acrylamide biodegradation . Microbial diversity . Proteobacteria . Actinobacteria . Polyacrylamide . Flocculant Introduction Polyacrylamides (PAM) are linear anionic, cationic, or neutral acrylamide (AMD) polymers (or copolymers) that are widely used as flocculants in the industrial field (wastewater, food industry, chemical industry, etc.) to improve water treatment (Haveroen et al. 2005). This is particularly the case in sand and gravel quarries. Most industrial quarries use water recycling loops with PAM to remove fine particles and clarify the process water since PAM flocculants enhance the settling of solids in the clarifier. Although PAM is considered as nontoxic, industrial preparations may nevertheless contain residual AMD monomers that can negatively impact the en- vironment (Guézennec et al. 2014). AMD is classified as a carcinogenic (level 2), mutagenic (level 2), and reprotoxic (level 3) compound (World Health Organization 1985; Molak 1991). It is listed in the Registration, Evaluation, Responsible editor: Gerald Thouand A. G. Guezennec (*) : C. Michel : A. Togola Département Eau Environnement Ecotechnologies, BRGM, 3 avenue Claude Guillemin, BP 36009, 45060 Orleans Cedex 1, France e-mail: a.guezennec@brgm.fr S. Ozturk : N. Desroche Nexidia SAS, 15 Rue de Mayence, 21000 Dijon, France J. Guzzo UMR A « Procédés Alimentaires et Microbiologiques », Equipe VALMIS, Université de Bourgogne, IUVV, Rue Claude Ladrey, 21000 Dijon, France Environ Sci Pollut Res DOI 10.1007/s11356-014-3767-x