Study of the Photodegradation of PBDEs in Water by UV-LED Technology.

Polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants that can arrive to water bodies from their use as flame retardants in a wide range of applications, such as electric and electronic devices or textiles. In this study, the photodegradation of PBDEs in water samples when applying UV-LED radiation was studied. Irradiation was applied at three different wavelengths (255 nm, 265 nm and 285 nm) and different exposure times. The best degradation conditions for spiked purified water samples were at 285 nm and 240 min, resulting in degradations between 67% and 86%. The optimized methodology was applied to real water samples from different sources: river, marine, wastewater (effluent and influent of treatment plants) and greywater samples. Real water samples were spiked and exposed to 4 hours of irradiation at 285 nm. Successful photodegradation of PBDEs ranging from 51% to 97% was achieved for all PBDE congeners in the different water samples with the exception of the marine one, in which only a 31% of degradation was achieved.

Recycled corrugated wire hose cover as biological carriers for greywater treatment in a sequential batch biofilm reactor.

Greywater treatment and reuse can be considered a promising option, in particular in water scarcity affected areas. In this work a waste material, namely recycled corrugated wire hose cover, was applied as an alternative and cheap carrier in a sequencing batch biofilm reactor (SBBR) for greywater treatment. The bioreactor performance was studied in terms of organic matter, nitrogen and micropollutant removal. Four operational stages were investigated: i) inoculation of the carriers; ii) greywater treatment with suspended biomass; iii) synthetic and iv) real greywater treatment with inoculated carriers in the SBBR. The SBBR could treat real greywater showing high removal efficiencies for COD (86.5 ±â€¯5.8%), ammonium (98.4 ±â€¯1.4%) and total nitrogen (71.4 ±â€¯8.2%). The obtained efficiencies were similar to the ones obtained with commercial carriers and to other treatments such as MBBR or MBR. In terms of micropollutants, 7 out of 13 detected micropollutants were highly removed (efficiency higher than 85%) while 5 of them (ofloxacin, metoprolol acid, venlafaxine, iopromide and hydrochlorothiazide) were found to be highly recalcitrant to the treatment.

Inactivation kinetics of antibiotic resistant Escherichia coli in secondary wastewater effluents by peracetic and performic acids.

While disinfection processes have been central for public health protection, new concerns have been raised with respect to their ability to control the spread of antibiotic resistance in the environment. In this study, we report the inactivation kinetics by peracetic and performic acids of a typical indicator, Escherichia coli and its corresponding antibiotic-resistant subpopulation, in secondary settled wastewater effluent. Performic acid always showed greater inactivation efficiency than peracetic acid, whether or not the indicator was Ampicillin-resistant. Observed inactivation data, fitted with an exposure-based inactivation model, predicted very well the inactivation profile of both total and ampicillin resistant Escherichia coli. Notably, the antibiotic resistance percentage decreased significantly in treated wastewater compared to untreated wastewater thus making the peracid-based disinfection processes beneficial in controlling antibiotic resistance in secondary settled wastewater. Moreover, the minimum inhibitory concentration values remained unchanged. Finally, antibiotic-resistant-specific inactivation kinetics were used to predict the disinfection efficiency in continuous-flow reactors under ideal and non-ideal hydraulics thus providing useful information for future design and operation of disinfection process in antibiotic-resistance controlling mode.

Tracking and quantification of nitrifying bacteria in biofilm and mixed liquor of a partial nitrification MBBR pilot plant using fluorescence in situ hybridization.

A moving bead biofilm reactor (MBBR) pilot plant was implemented as a partial nitrification process for pre-treatment of ammonium-rich liquors (676 ± 195 mg L(-1)), and studied for 479 days under variations in hydraulic retention time. The main purpose of this work, was the study of dynamics abundance of total bacteria and single-cells nitrifying bacteria belonging to ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in biofilms and mixed liquor of the plant. The microbial monitoring was successfully achieved using fluorescence in situ hybridization combined with flocs disaggregation protocol as a useful microbial monitoring tool. A partial nitrification process with a N-NH4(+) removal rate of about 38.6 ± 14.8% was successfully achieved at 211 days after start-up, with a clear dominance of AOB, which accounted for 11.3 ± 17.0% of total bacterial cells compared with only 2.1 ± 4.0% of NOB. The effluent obtained was subsequently supplied to an Anammox reactor for complete ammonium treatment.