Consideration of emerging pollutants in groundwater-based reuse concepts.

Elimination of pathogens and emerging pollutants represents a key factor in integrated water resources management in arid regions. Within the SMART Jordan Valley project it is the objective of this study to assess the occurrence and examine the elimination of selected emerging pollutants and pathogens in waste water treatment and aquifer recharge. In batch and soil column studies non-chlorinated organophosphorous compounds (tri-n-butylphosphate, triphenylphosphate) and endocrine disruptors (e.g. 17-ß-estradiol, bisphenol A) proved to be biodegradable, while the X-ray contrast agents iomeprol and iopromide were eliminated in the soil columns only, and the chlorinated trialkylphosphates showed persistency. Treating waste water in a membrane bioreactor (MBR) in combination with powdered activated carbon (PAC) resulted in considerable removal rates also for the more persistent compounds such as the antiepileptic carbamazepine. Viruses were shown to be present in most of the Jordan Valley surface water samples. MBR treatment resulted in a decrease of MS2 bacteriophages used as model viruses.

Cultivation of hard-to-culture subsurface mercury-resistant bacteria and discovery of new merA gene sequences.

Mercury-resistant bacteria may be important players in mercury biogeochemistry. To assess the potential for mercury reduction by two subsurface microbial communities, resistant subpopulations and their merA genes were characterized by a combined molecular and cultivation-dependent approach. The cultivation method simulated natural conditions by using polycarbonate membranes as a growth support and a nonsterile soil slurry as a culture medium. Resistant bacteria were pregrown to microcolony-forming units (mCFU) before being plated on standard medium. Compared to direct plating, culturability was increased up to 2,800 times and numbers of mCFU were similar to the total number of mercury-resistant bacteria in the soils. Denaturing gradient gel electrophoresis analysis of DNA extracted from membranes suggested stimulation of growth of hard-to-culture bacteria during the preincubation. A total of 25 different 16S rRNA gene sequences were observed, including Alpha-, Beta-, and Gammaproteobacteria; Actinobacteria; Firmicutes; and Bacteroidetes. The diversity of isolates obtained by direct plating included eight different 16S rRNA gene sequences (Alpha- and Betaproteobacteria and Actinobacteria). Partial sequencing of merA of selected isolates led to the discovery of new merA sequences. With phylum-specific merA primers, PCR products were obtained for Alpha- and Betaproteobacteria and Actinobacteria but not for Bacteroidetes and Firmicutes. The similarity to known sequences ranged between 89 and 95%. One of the sequences did not result in a match in the BLAST search. The results illustrate the power of integrating advanced cultivation methodology with molecular techniques for the characterization of the diversity of mercury-resistant populations and assessing the potential for mercury reduction in contaminated environments.