The IWA specialised group on anaerobic digestion (AD) is one of the oldest working groups of the former IAWQ organisation. Despite the fact that anaerobic technology dates back more than 100 years, the technology is still under development, adapting novel treatment systems to the modern requirements. In fact, most advances were achieved during the last three decades, when high-rate reactor systems were developed and a profound insight was obtained in the microbiology of the anaerobic communities. This insight led to a better understanding of anaerobic treatment and, subsequently, to a broader application potential. The present “state-of-the-art” paper, which has been written by members of the AD management committee, reflects the latest achievements and sets future lines for further development.

Terephthalate (TA) is one of the top 50 chemicals produced worldwide. Its production results in a TA-containing wastewater that is treated by anaerobic processes through a poorly understood methanogenic syntrophy. Using metagenomics, we characterized the methanogenic consortium inside a hyper-mesophilic (that is, between mesophilic and thermophilic), TA-degrading bioreactor. We identified genes belonging to dominant Pelotomaculum species presumably involved in TA degradation through decarboxylation, dearomatization, and modified b-oxidation to H 2 /CO 2 and acetate. These intermediates are converted to CH 4 /CO 2 by three novel hyper-mesophilic methanogens. Additional secondary syntrophic interactions were predicted in Thermotogae, Syntrophus and candidate phyla OP5 and WWE1 populations. The OP5 encodes genes capable of anaerobic autotrophic butyrate production and Thermotogae, Syntrophus and WWE1 have the genetic potential to oxidize butyrate to CO 2 /H 2 and acetate. These observations suggest that the TA-degrading consortium consists of additional syntrophic interactions beyond the standard H 2 -producing syntroph-methanogen partnership that may serve to improve community stability. The ISME Journal (2011) 5, 122-130; doi:10.1038/ismej.2010; published online 5 August 2010Subject Category: integrated genomics and post-genomics approaches in microbial ecology Keywords: metagenomics; methanogenesis; syntroph; microbial diversity; carbon cycling Introduction Terephthalate (TA) is used as the raw material for the manufacture of numerous plastic products (for example, polyethylene TA bottles and textile fibers). During its production, TA-containing wastewater is discharged in large volumes (as high as 300 million m 3 per year) and high concentration (up to 20 kg COD (chemical oxygen demand) m À3 ) (Razo-Flores et al., 2006). This wastewater is generally treated by anaerobic biological processes under mesophilic conditions (B35 1C). However, anaerobic processes operated at hyper-mesophilic (46-50 1C) and thermophilic (B55 1C) temperatures may be preferable because of the ability to achieve higher loading rate (van Lier et al., 1997;Chen et al., 2004), which reduces the reactor volume. Moreover, TA wastewater is usually generated at 54-60 1C, and does not require additional energy input for maintaining reactor temperature (Chen et al., 2004). The microbial biomass usually occurs in the form of granules or biofilms attaching on the surface of porous media. Under such environments, TA degradation has been hypothesized (Kleerebezem et al., 1999) to be based on a syntrophic microbial relationship whereby fermentative H 2 -producing bacteria (syntrophs) convert TA through benzoate to acetate and H 2 /CO 2 , and acetoclastic and hydrogenotrophic methanogens further convert the intermediates to methane by physically positioning themselves close to the syntrophs to overcome the www.nature.com/ismej thermodynamic barrier (Stams, 1994;Conrad, 1999;Dolfing, 2001).In practice, the complexities of TA-degrading communities are not...

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 15973 Abstract Chlordecone (CLD) was an organochlorine insecticide whose previous use resulted in an extensive pollution of the environment with severe health effects and social consequences. A closely related compound, 5b-hydrochlordecone (5b-hydroCLD), has been searched for and often detected in environmental matrices from the geographical area where CLD was applied. The current consensus considered that its presence was not the result of a biotic or abiotic dechlorination of CLD in these matrices but rather the consequence of its presence as impurity (synthesis by-product) in the CLD released into the environment. The aim of the present study was to determine if and to what extent degradation of CLD into 5b-hydroCLD occurred in the field. To test this hypothesis, the ratios of 5b-hydroCLD and CLD concentrations in a dataset of 810 soils collected between 2006 and 2012 in Martinique were compared to the ratios measured in 3 samples of the CLD dust commercial formulations applied in the banana fields of French West Indies (FWI) and 1 sample of the technical-grade CLD corresponding to the active ingredient used in such formulations. Soil data were processed with a hierarchical Bayesian model to account for random measurement errors and data censoring. Any pathway of CLD transformation into 5b-hydroCLD occurring over the long term in FWI soils would indeed change the ratio of 5b-hydroCLD/ CLD compared to what it was in the initially applied formulations. Results showed a significant increase of the 5b-hydroCLD/CLD ratio in the soils-25 times greater in soil than in commercial formulations-which suggested that natural CLD transformation into 5b-hydroCLD over the long term occurred in these soils. Results from this study may impact future decisions for the remediation of the polluted areas.