In this field we study different strategies to treat industrial wastewater contaminated with toxic or recalcitrant compounds by using advanced biological treatments (granular biomass for example), chemical oxidation processes or combined sequential chemical and biological processes. Despite all processes available for the treatment of industrial wastewater, it is still a difficult task to select a single treatment option for these wastewaters. The selection of the most appropriate treatment depends on several challenging factors: the nature and the concentration of the recalcitrant compounds, the presence of nutrients (see the research line about simultaneous removal of Ammonium and recalcitrant organic matter) and the transient or continuous presence of these compounds in industrial wastewaters. In addition, the load applied to the treatment plays a key role with regard to the technical, economic and environmental performance of the proposed treatment.
This line is nowadays conducting research on xenobiotic compounds which besides being recalcitrant may be detrimental to the common WWTP populations. Phenolic compounds such as: p-nitrophenol, o-cresol, 2-chlorophenol and quinoline, among others, are used as the reference compounds and its treatment is approached using either continuous granular bioreactors or suspended biomass SBR. Moreover, several tools and protocols have been developed, applied and consolidated during the years for this specific research line:
- Fluorescence in-situ hybridization (FISH) coupled to Confocal Laser Scanning Microscopy (CLSM) and, more recently, the pyrosequencing technique using the 454-Roche or Illumina MiSeq platforms. A range of FISH probes are used for monitoring the evolution of target groups of microorganisms and its diversity, while taxonomic analyses at different levels (species, family, group, etc…) provide in-depth information for further correlation with bioreactor performance.
- Respirometry. This technique is used for assessing biodegradability, toxicity and inhibition of the recalcitrant wastewaters. Also this technique is combined with modelling tools to assess, in addition to the biological activity, biological mechanisms, as well as, kinetic and stoichiometric parameters related to a specific enriched microbial culture.
- Bioaugmentation. The introduction of a specific strain or a consortium of microorganisms is used to accelerate and to enhance the removal efficiency of recalcitrant and/or toxic compounds in bioreactors and to promote the development of complex granular biomass for simultaneous removal of nutrients and recalcitrant compounds.