Répercussions agronomiques de l'épandage d'effluents et déchets de moulins à huile d'olive

Abstract

Les répercussions agronomiques de l'épandage d'effluents (ou margines) de moulins à huile d'olive sont étudiées au moyen de cultures de ray-grass en pots sous serre et de tests d'incubation sur l'azote minéral. L'épandage de 40 mm (40 I/m 2) de margines sur une plantation de ray-grass diminue le rendement moyen de 45 p. 100 par rapport à celui de la culture de référence. La production de matière sèche des ray-grass semés immédiatement après l'épandage (doses de 40 et 80 mm) est égale au tiers de la production de référence. La salinité extrêmement élevée des margines, leur acidité, la présence possible de polyphénols ou d'autres substances toxiques biodégradables et l'absence de fourniture d'azote minéral, peuvent expliquer ces répercussions négatives. Les semis réalisés 45 j après l'épandage montrent que, lorsque les margines ont eu un effet sur la croissance des végétaux, il a toujours été favorable : si dans 5 traitements (doses de 40 à 80 mm), l'apport des margines n'a pas significativement augmenté les rendements, dans 5 autres cas (doses de 20 à 80 mm), il les a améliorés. Les analyses de sols permettent d'attribuer une partie de cet effet fertilisant à l'enrichissement en potassium échangeable. Les tests d'incubation révèlent que les margines peuvent provoquer une légère disparition d'azote nitrique, limitée dans ces essais à 0,2 p. 1 000 du poids de margines. L'ensemble de ces tests montre que, dans ces conditions expérimentales et aux doses indiquées, on ne peut pas imputer aux margines une inhibition des microflores ammonifiantes et nitrifiantes du sol. La disparition d'azote nitrique serait provoquée soit par dénitrification, soit par réorganisation. Mots clés additionnels : Margines, azote, azote nitrique, potassium, phytotoxicité. SUMMARY Agronomic effects of land disposal of waste from olive oil crushers. The agronomic effects of land disposal of waste from olive oil crushers were studied. Experimental crops of rye-grass were grown in pots in the greenhouse, and nitrogen mineralization trials were carried out. The input of the equivalent of 40 mm (40 I/ M 2) of waste on an established rye-grass crop, resulted in a 45 0 7o decrease in yield. When the rye-grass was sown immediately after the input of waste (amounts equivalent to 40 and 80 mm) the dry matter yield equaled one third of the reference yield. These negative effects could be explained by the very high salinity of these effluents, their acidity, the possible presence of polyphenols or other toxic biodegradable substances and a lack of nitrate nitrogen. Rye-grass sown 45 days after the input of waste showed positive effects (significant for 5 out of 10 crops). Soil analyses revealed an increase in the amount of exchangeable potassium. Nitrogen mineralization trials revealed a slight decrease of soil nitrate nitrogen, limited to 0,2 mg N/g waste. Neither ammonification, nor nitrification inhibition could be ascribed to the waste from the olive oil crusher, within the conditions and amounts studied. So, the disappearance of nitrate nitrogen coul...

A review on thermochemical treatment of biomass: Pyrolysis of olive mill wastes in comparison with other types of biomass

“…Cellulose is insoluble in water, forms the skeletal structure of most terrestrial biomass, while lignins are highly branched, substituted, mononuclear aromatic polymers in the cell walls of certain biomass [39,43]. At pyrolysis process, the main biomasses such as olive mill solid waste, olive mill wastewater, nut shell, sugar cane bagasse and other types of biomass, components contribute to product yields mainly as follows: hemicelluloses and cellulose components provide the volatile pyrolysis products, while the lignin predominantly forms a charred residue [24,26] [44][45][46][47][48][49][50][51][52][53][54] were working on the pyrolysis of several agricultural types of biomass (Fig. 7), these researches showed that condensable and non-condensable gas yields and char differ from one kind of biomass to another.…”

“…They used different particle size (0.5-0.8 mm for olive waste and 0.5-1.0 mm for straw) and they noticed that this parameter had an influence on char, bio-oil and gas yields and on surface area and the composition of bio-char. A. Morisot, M. Mebirouk, I. Fki, I. Kappellakis and Y. Yacoub [50][51][52][53][54] recommended and reported that medium particle size yielded maximum liquid compared to smaller and larger feed sizes. A. Pûtun et al [69] have established the effect of particle size on the pyrolysis yields, they showed that particle size (Dp) ranges between 0.425 and 0.85 mm give better yields than particle size between 0.85 and 1.8 mm, Dp<0.425 mm and Dp>1.8 mm.…”

“…However, lignin decompos-es over a wide temperature range unlike hemicellulose and cellulose. Several authors noted that biomass conversion is sequentially dependent upon temperature increase [50,86]. Fig.…”