Biodegradation of phytosanitary products in biological wastewater treatment.

Agricultural activity generates two types of waste: firstly, biodegradable organic effluents generally treated by biological processes and, secondly, phytosanitary effluents which contain residues of plant protection products. The latter are collected and treated. Current technological solutions are essentially based on concentration or physical-chemical processes. However, recent improvements in the biodegradability of pesticides open the way to the consideration of alternative, biological, treatment using mixed liquor from wastewater plant activated sludge. The feasibility of the biological treatment of viticultural effluents has been evaluated by the application of pesticides to activated sludge. The necessity for selection of a pesticide-resistant biomass has been highlighted. The elimination of the phytosanitary products shows the potential of a resistant biomass in the treatment of pesticides. The aerated biological storage ponds at three wineries, followed by a sand or reed-bed filter, were used for the treatment of the total annual volume of the viticulture effluents and validate the laboratory experiments. The results show that the biological purification of pesticides by activated sludge is possible by allowing approximately 8 days for biomass adaptation. Stability of purification occurs between 20 and 30 days.

Co-epuration of winery and pesticides effluents, activated sludge with tertiary nanofiltration, two new technologies for pesticides effluents treatment.

Wine-related activities produce significant volumes of wastewater characterized by high concentrations in organic matter. The term of pesticides effluents defines the water coming from the emptying and the rinsing of the equipment used to pulverize the phytosanitary products on the vines. Pesticide pollution of surface waters from vineyards applications represents a considerable hazard for the aquatic environment. The nature of these wastes is very variable, indeed more than 150 active molecules can be employed. So, the main characteristic of these effluents is their toxicity towards the environment. In this study, an approach was developed to estimate the possibility of developing two biological wastewater treatment process for pesticides effluents treatment. The first one is particulary designed for small vineyard and is a co-epuration process combining winery wastewater treatment with pesticides effluents treatment. The second one is an activated sludge with tertiary nanofiltration and is particularly suited for large vineyards or regroupings of wine growers.

A Saccharomyces cerevisiae-based bioassay for assessing pesticide toxicity.

This study evaluates the toxic effect of three pesticides (Azoxystrobin, Cymoxanil, and Diuron) on the yeast Saccharomyces cerevisiae for the development of a new bioassay based on inhibition of S. cerevisiae metabolic activity at the level of adenosine-5-triphosphate (ATP) synthesis, as compared with two different toxicity tests based on inhibition of Daphnia magna mobility (NF EN ISO 6341) and inhibition of Vibrio fisheri activity (NF EN ISO 11348). The S. cerevisiae bioassay is cheaper and 96 times faster than the D. magna toxicity bioassay, but has lower sensitivity. It is as fast as the V. fisheri bioassay and more sensitive. Thus, this new toxicity test can be proposed for rapid detection of pesticide residues in environmental samples as a complement to the more expensive and time-consuming D. magna toxicity test.

Degradation of pesticide residues in vineyard effluents by activated sludge treatment.

The study evaluates the feasibility of the degradation of thirteen pesticides by an activated sludge aerobic treatment, used for the purification of wastewater effluents produced from a winemaking process. Chemical analyses were used to determine the capacity of the treatment to eliminate the implied pollution hazard. The results show that the biological treatment of such pesticides by activated sludge is possible if a minimum adaptation period of approximately 8 days is applied. System stability is reached in 30 days. The related degradation of twelve pesticides was 97%, the exception being anilinopyrimidin. However, the sludge biomass is dispersed (the pesticides destroyed the biomass flocs) and it was necessary to add a flocculation stage to concentrate and remove the free micro-organisms by using sedimentation.

Electrical impedance brain scanner: principles and preliminary results of simulation.

In previous studies, the authors have shown the importance of impedance recording by stereotactic procedures for brain tumor detection. In this study they report the principles and the first results of an attempt to obtain the impedance value of any given point inside the brain by an external way. The experimental device is mainly made of a set of 128 electrodes, surrounded by an electrode guarding monitored by an operational amplifier the purpose of which is to made the electric field uniform and to enable a focused measure of the impedance by each of the 128 electrodes. The effect of this electrode guarding is demonstrated, and the present sensitivity of the prototype is shown on various obstacles. conductive or non-conductive; the influence of an impedance barrier on this sensitivity is the project of an impedometric scanner is described, and the problems due to the non-linear propagation of electric currents and to the anisotropic properties of the brain tissue are evaluated.