Optimisation of the coagulation-flocculation process of raw water by optimal design method.

In the present paper, a systematic study of the influence of raw water quality and operating conditions on the effectiveness of the coagulation-flocculation process using aluminium sulphate (AS) is presented. The influence of raw water composition is studied at two levels, fractional factorial designs and a Doehlert uniform shell design to determine the influence of the operating conditions. The analysis of the experimental responses (residual turbidity and minimally AS dose are denoted as (Tu(m)) and (AS(m)), respectively) shows that the parameters which have the greatest influence change depending on the response. It is not always possible, for a given water composition, to obtain simultaneously low residual turbidity and minimally AS dose. However, under the conditions of this study, the search for a criterion of optimisation must bear the minimisation of residual turbidity, because it remains the principal criterion of effectiveness of the process, even, if in a few cases, it results in an increase in the cost of treatment.

Use of mixed perfluorinated ion-pairing agents as solvents in ion-pair high-performance liquid chromatography for the preparative purification of aminoglycoside antibiotics.

The possibility of using mixed ion-pair reversed-phase high-performance liquid chromatography for the preparative purification of aminoglycoside antibiotics was investigated. Retention can be satisfactorily defined in aqueous conditions but efficiency is critical. The analysis of a polynominal model allowed ion-pairing agents compositions to be designed leading to improved efficiency. Inexpensive aqueous mobile phases using volatile buffers can be defined for the satisfactory ion-pair preparative chromatography of aminoglycosides.