Traitement tertiaire d'eaux usées municipales par culture de Scenedesmus sp. en installation pilote

Deux installations pilote destinées au traitement d'effluents secondaires par culture de micro-algues (Scenedesmus sp.) ont été opérées à Valcartier (effluents domestiques) et Vaudreuil (effluents semi-industriels). Des bassins de 15 000 L ont servi aux cultures en vrac sous conditions naturelles, avec apport de CO2 atmosphérique par huilage. Les paramètres physiques, chimiques et biologiques ont été mesurés.Les résultats montrent que, malgré les limitations en CO2 et en azote, un enlèvement moyen d'environ 95 % pour l'azote (N-NH4+, N-NO2-, N-NO3-) et de 60 % pour le phosphore (P-PO4-3) a été possible à Valcartier durant l'été; les données correspondantes sont de 92 % et de 98 % à Vaudreuil où la production de biomasse (1,02 mg/L-h) a été plus forte qu'à Valcartier (0,39 mg/L-h). Les facteurs pouvant expliquer les différences observées aux deux sites sont présentées. Les résultats montrent la faisabilité technique, durant l'été, de ce type de traitement tertiaire.Two experimental pilot-scale culture systems have been operated at Valcartier (domestic effluent) and Vaudreuil (semi-industrial urban effluent) in order to test the feasibility of a tertiary treatment using microalgae (Scenedesmus sp.). Tanks with a capacity of 15 000 L were used for batch cultures conducted outdoors; CO2 being provided through atmospheric air bubbling. Physical (temperature, relative insolation, solar radiation), chemical (pH, NH4+, NO2-, NO3-, PO4-3, heavy metal, pesticides) and biological parameters (biomass dry weight, cell counts) were mesured.Results show that cultures were limited for CO2 (high final pH) and for nitrogen flow N/P ratio with value of 3-7). During the summer period, nutrient removal from the Valcartier effluent was ~ 95 % for N and ~ 60 % for P; corresponding figures at Vaudreuil were 92 % and 98 %.Biomass productivity was lower (0,39 mg/L-h) at Valcartier compared to that obtained at Vaudreuil (1,02 mg/L-h). Among the differences that could explain the results at both sites, one may suggest a better CO2 input, a more favorable N/P ratio, slightly higher average temperature and light conditions, less ammonia stripping and larger inocula in Vaudreuil. The quality of biomass obtained was satisfactory : heavy metals were present at acceptable levels and no contamination by organochlorinated compounds occurred. According to our results, it appears that biological tertiary treatment of urban effluent and algal biomass production are technically possible under Québec summer conditions

The languages of peace during the French religious wars

The desirability of peace was a common topos in sixteenth-century political rhetoric, and the duty of the king to uphold the peace for the benefit of his subjects was also a long-established tradition. However, the peculiar circumstances of the French religious wars, and the preferred royal policy of pacification, galvanized impassioned debate among both those who supported and those who opposed confessional coexistence. This article looks at the diverse ways in which peace was viewed during the religious wars through an exploration of language and context. It draws not only on the pronouncements of the crown and its officials, and of poets and jurists, but also on those of local communities and confessional groups. Opinion was not just divided along religious lines; political imperatives, philosophical positions and local conditions all came into play in the arguments deployed. The variegated languages of peace provide a social and cultural dimension for the contested nature of sixteenth-century French politics. However, they could not restore harmony to a war-torn and divided kingdom