Synthesis and physico-chemical studies of a novel bis [3,5-diamino-4H-1,2,4-triazol-1-ium] dichloride monohydrate

The title new compound, (C2H6N5+)2, 2Cl−.H2O, contains two 3,5-diamino-4H-1,2,4-triazol-1-ium cations, two chloride anions and one water molecule. The crystal structure is stabilized by O - H···Cl, N - H···Cl, N - H···O and N - H···N hydrogen bonds, one of them being a three-center interaction. Strong π - π stacking interactions between neighboring triazolium rings are present, with a centroid - centroid distance of 3.338 (7) Å. The exocyclic N atoms are sp2 hybridized, as evidenced by bond lengths and angles, in agreement with an enamine-imine tautomerism. A dielectric spectroscopic study of the title compound was performed. The 13C CP-MAS NMR spectrum is in agreement with crystallographic data. The infrared spectrum has been recorded at ambient temperature and interpreted on the basis of literature data. The temperature dependence of the imaginary part of the permittivity constant was analyzed with the Cole - Cole formalism in the temperature range 325 - 375 K

Olive mill wastewater treatment in a membrane bioreactor: process stability and fouling aspects

International audienceAn external ceramic membrane bioreactor was used to carry out an experimental study of process stability and fouling aspects for olive mill wastewater (OMW) treatment. Three diluted OMW solutions were used to continuously feed the reactor. An acclimated biomass was employed and the process stability was followed on the basis of the permeate quality and some operating parameters (pressure, temperature, mass flow and dissolved oxygen). Several backpulse combinations were tested to determine the best filtration and backwash time. It appeared that a short backpulse duration was sufficient and that the behaviour, in terms of the permeate flux versus time, stabilized. In terms of increased permeate flux, the effect of the backpulsing depended on the nature of the solution. This improvement was limited, but, in the long-term, backpulsing makes it possible to maintain a constant permeate flux over a period of several days

ASPECTS OF THE LIFE SPAN AND PHENOLOGY OF THE INVASIVE FRESHWATER SHRIMP ATYAEPHYRA DESMARESTII (MILLET, 1831) AT THE NORTHEASTERN EDGE OF ITS RANGE (UPPER RHINE)

Quantitative aspects of the life cycle of the freshwater shrimp Atyaephyra desmarestii were used to investigate its life span at the edge of its distribution area in Central Europe (Upper Rhine) for a period of three years. We estimated the proportion of the population surviving a second hibernation period. The appearance of ovigerous females in late spring was followed by a strong decline in the number of adults, the appearance of a high percentage of juveniles in late summer (0.58 ind./m(2)), and their subsequent disappearance from the shore in winter. A small semivoltine cohort survived a second winter. The average life span was 12-15 (max. 29) months under laboratory conditions. In molecular studies (COX I), the Upper Rhine and Southern France populations clustered within the North Africa/West-Central Europe species clade. Due to its low productivity, this invasive species is unlikely to cause management problems