Liquid industrial chemical wastes are often treated with complex and integrated chemical and biological processes to attain the required standard for water discharge into the environment. Such wastewaters are potentially dangerous and of unknown composition. Biological treatment represents the cheapest means of pollution abatement. In the present work, a microbiological and genetic analysis was performed for the biological pool of an industrial wastewater treatment plant located in Civita Castellana (Viterbo, Italy). This study focused on active sludge treatment and on the subsequent secondary sedimentation system. The parameters of the biological section (the sludge active plant) are normally constantly monitored, but the biological efficiency of the microbial community should be better evaluated to understand the dynamics of the microbial community and its relationship to the overall standard quality parameters that are usually monitored. For this study, Biolog community level physiological profiling (CLPP) on EcoPlates and PCR-amplified 16S rRNA denaturing gradient gel electrophoresis (DGGE) were used in comparison and combined as ecological techniques to characterize an anthropic closed ecosystem. Biolog CLPP provides the potential metabolic pattern and DGGE analyses helps to explain the structure and complexity of the microbial community. The results suggest that these techniques could be predictive and more useful when used together than alone. In addition, a principal component analysis (PCA) performed on the Biolog assay over time can relate principal components predictive wells to the biological and standard chemical analysis used to control and monitor the activity of this type of industrial wastewater treatment plant, providing a selection method for further DGGE community analysis.

Aerobic treatment of wastewater containing Tetramethylammonium hydroxide (TMAH) and photoresist was investigated using a lab scale reactor inoculated with activated sludge coming from urban wastewater treatment that never received TMAH before. The consumption of TMAH was monitored by liquid ion chromatography. Biodiversity indices were calculated from Denaturing Gradient Gel Electrophoresis (DGGE) bands distribution and used to estimate changes in community composition related to adaptation to the new feeding compound. The first week of adaptation was crucial, and it was analyzed in detail: many organisms died, and the microbial community suffered a great shock. TMAH levels remained constant through the first four days, and then suddenly dropped to undetectable, and at the same time NH4+ increased. When the community showed complete adaptation, predominant groups of bacteria were obtained by the Illumina sequencing of 16s rDNA amplicons, to provide insights on ecology of the adapted community, focusing on the main actors of TMAH abatement. Richness of species (Rr) peaks suggest that the development of TMAH-consuming bacteria leads to persistent consortia that maintain toxicity resistance over time. This showed adaptation and changes of the population to the different feeding conditions, and it opens new perspectives in the in situ treatment of these important residues of industrial processes without relying on external processing plants.

Methanogens are responsible for the last step in anaerobic digestion (AD), in which methane (a biofuel) is produced. Some methanogens can cometabolize chlorinated pollutants, contributing for their removal during AD. Methanogenic cofactors involved in cometabolic reductive dechlorination, such as F 430 and cobalamin, contain metal ions (nickel, cobalt, iron) in their structure. We hypothesized that the supplementation of trace metals could improve methane production and the cometabolic dechlorination of 1,2-dichloroethene (DCE) by pure cultures of Methanosarcina barkeri. Nickel, cobalt, and iron were added to cultures of M. barkeri growing on methanol and methanol plus DCE. Metal amendment improved DCE dechlorination to vinyl chloride (VC): assays with 20 µM of Fe 3+ showed the highest final concentration of VC (5× higher than in controls without Fe 3+), but also in assays with 5.5 µM of Co 2+ and 5 µM of Ni 2+ VC formation was improved (3.5-4× higher than in controls without the respective metals). Dosing of metals could be useful to improve anaerobic removal of chlorinated compounds, and more importantly decrease the detrimental effect of DCE on methane production in anaerobic digesters. C

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