Preventing and treating odors from wine effluents

Like most agri-food sectors, the wine industry generates wastewater with a high biodegradable organic load. Thanks to the wastewater treatment systems in place, organic pollution is now well under control. On the other hand, the olfactory nuisance generated by effluents is one of the current environmental problems facing the wine industry, as well as many other food processing industries.

According to the French Environment Code, olfactory nuisance is defined as atmospheric pollution (pollution olfactive). The impact of olfactory pollution can be felt at many different levels, and is of major economic and societal importance: annoyance for local residents, leading to complaints and conflicts; hindrance to urban development and land depreciation; hindrance to the development of tourist activities; devaluation of the "quality" approach adopted by companies; and, in some cases, a threat to the long-term viability of industrial activity.

French wine production [1] , the world's largest, comprises two sectors that differ in terms of their activities and the nature of the residues:

• wineries and wine merchants generate wine effluents (around 6 million m ³ /year) and by-products (marc and lees);

• wine distilleries transform these by-products into alcohol, brandy, calcium tartrate, colorants, composts... and produce wastewater: distillery vinasse.

Although most treatment methods have been applied to wine effluent: land application, aerobic biological purification (activated sludge, aerated lagooning, aerated storage), anaerobic digestion, thermal concentration, distillation-evapo-concentration, natural evaporation, some are better suited to the nature of the effluent, the pace and context of the activity.

Treatment by natural evaporation is widespread, particularly in Mediterranean regions. For other treatments, prior storage of effluent is necessary to balance out overloads and ensure the ramp-up of biological treatments; in the case of land application, it is compulsory to compensate for unfavorable periods (rain, frost).

The storage of effluent rich in organic matter inevitably leads to the development of anaerobic micro-organisms which, through fermentation, form malodorous compounds. Volatile fatty acids (propionic, butyric, valeric, caproic acids, etc.) are the main family of malodorous compounds found in wine effluents. Other malodorous compounds, such as amines, ammonia, mercaptans and sulfides, can also be produced from the organic (nitrogen compounds, sulfur compounds, etc.) and mineral (sulfate)...