Karl Glucina

Laboratory technique for predicting the scaling propensity of RO feed waters

Abstract This paper describes the further development of a novel laboratory technique for characterizing the scaling potential of RO feed waters. The work is focused on the CaCO3 scaling system, which is of general interest and is encountered in RO purification of Seine River water. Scaling intensity at various water recovery levels is characterized by measuring permeate flux decline and changes in pH, hardness and alkalinity of a solution recycling in the system for a certain period of time, at the tested water compositions. The objective of the present study was to test the reliability of the above intermittent recycle technique for assessing scaling propensity and anti-scalant inhibitory effectiveness by comparing speedily determined laboratory results with long duration field data, measured with Seine River water. Scale deposition thresholds in the presence of four different anti-scalants were determined in the laboratory using simulated Seine River concentrates of compositions corresponding to water recovery levels of 60–90% and of scaling potentials ranging from Langelier saturation index values (LSI) of −0.1 to 2.5. Both field and laboratory results indicated that all four tested anti-scalants enabled a water recovery level of at least 88% at LSI levels exceeding 2.0. The laboratory measurements predicted correctly the field results in three out of four cases in which a comparison was possible. This agreement lends support to the usefulness of the proposed laboratory technique for convenient characterization of scaling propensity of RO feed waters.

QSAR-like models: a potential tool for the selection of PhACs and EDCs for monitoring purposes in drinking water treatment systems--a review.

Recent studies have demonstrated the presence of trace-level pharmaceutically active compounds (PhACs) and endocrine disrupting compounds (EDCs) in a number of finished drinking waters (DWs). Since there is sparse knowledge currently available on the potential effects on human health associated with the chronic exposure to trace levels of these Emerging Contaminants (ECs) through routes such as DW, it is suggested that the most appropriate criterion is a treatment criterion in order to prioritize ECs to be monitored during DW preparation. Hence, only the few ECs showing the lowest removals towards a given DW Treatment (DWT) process would serve as indicators of the overall efficiency of this process and would be relevant for DW quality monitoring. In addition, models should be developed for estimating the removal of ECs in DWT processes, thereby overcoming the practical difficulties of experimentally assessing each compound. Therefore, the present review has two objectives: (1) to provide an overview of the recent scientific surveys on the occurrence of PhACs and EDCs in finished DWs; and (2) to propose the potential of Quantitative-Structure-Activity-Relationship-(QSAR)-like models to rank ECs found in environmental waters, including parent compounds, metabolites and transformation products, in order to select the most relevant compounds to be considered as indicators for monitoring purposes in DWT systems.

Adsorption of Ibuprofen and Atenolol at Trace Concentration on Activated Carbon

Abstract Adsorption isotherms of atenolol and ibuprofen onto activated carbon (AC) at trace concentration in water (initial concentration, 80 μg/L – equilibrium concentration as low as 0.13 μg/L) are presented in this paper. Their adsorption was studied considering two ACs (F400 and Picabiol) showing different textural and chemical characteristics. Experiments were performed in buffered ultrapure water with and without humic acids to evaluate their influence on adsorption. It was found that adsorption was not in agreement with expectations based either on the log Kow or log D values of the target compounds. Adsorption mechanisms were discussed and the experimental isotherms were modelled.

Monitoring and treatment of selected nanoparticles

With their increasing use, nanoparticles will become concentrated in urban effluents in the future. Both adequate monitoring methods and water treatment technologies will be necessary to assess and avoid consumer exposure. This paper reports results in these two challenging areas for both organic and inorganic nanoparticles. Treatment experiments indicate that lamellar settling is better adapted than dissolved air flotation for SiO(2) nanoparticles removal. The use of 120 mg/L of Aqualenc coagulant without flocculant addition allows 99% removal to be achieved for an initial concentration of 1 g/L. On the other hand, the dissolved air flotation process implemented under the usual industrial conditions does not permit removal of SiO(2) nanoparticles. In this case SiO(2) removal occurs only by settling in the flocculator tank. Application of a high resolution liquid chromatography/mass spectrometry (LC/MS) technique to a small selection of treated urban effluents indicates that C(60) fullerenes are not yet widely distributed in effluents; however non-point sources cannot be entirely ruled out.