Valorisation des déchets ménagers et des grignons d’olive par dégradation anaérobie et production de compost et de biogaz .

Abstract

The management of household waste is one of the major environmental problem and topicality. In Algeria, the olive oil industry produces mainly olive oil and therefore large quantities of waste(olive pomace, margins) harmful to the environment.Although their chemical composition is very rich in organic matter, This waste is untapped and not recovered. As a result, their valuation is necessary. The present work consists on the one hand to valorize the household waste and the olive residue and on the other hand to study the influence of the addition of this latter on the gas production and the properties of the composts obtained by anaerobic fermentation. The results obtained have shown that: 1 / The gaseous productivity of the anaerobic degradation of organic waste depends essentially on the nature of the substrate to be fermented; thus, the addition of the olive pomace to the substrate makes it possible to increase the gaseous productivity. In addition, we previously noted a weekly average of biogas (cm3) produced in HWD (Household Waste Digester) and HWOD (Household Waste Digester and Olive Oil) respectively of [523,8±33,7] et [939,1±59,4] cm 3the difference is very significant. In addition, in the cold period and for the same substrate, the gas production decreases and beco mes slower than in the hot period. Indeed, our study revealed a weekly average of biogas recovered from [177,7±15,6] et [385,4±33] cm 3 respectively in HWD and HWOD in cold period. 2 / The HWD and HWOD composts obtained from the anaerobic degradation are considered as mature, Indeed, the pH (7,9), the %H (56,5 and 40,0 %H), the %MS (43,53 and 60.19 %MS), %Nt (1.8 and 1.4 %Nt) respectively for HWD HWOD, have physicochemical characteristics similar to compost obtained by composting, so the addition of olive grignions does not seem to influence these characteristics. On the other hand, they have relatively high contents in TOC% (11.4 and 33.3%), MO% (19.68 and 57.42%) and HWOD has a C / N ratio 3 times higher than HWD (23.30 and 6.80). thus, the olive pomace contributes to increase the organic carbon content and the organic matter and thus promotes a better maturation (C / N) and produces a compost of quality. 3 / The study of the physicochemical parameters of HWD and HWOD leachates obtained pH (6.05, 6.25), Ce (639 and 715μS / cm) and P (1.65 and 5.3 mg P / L) for respectively HWD and HWOD, are in the norms of the minimum criteria of quality of the leachates. Thus, the addition of olive pomace to domestic waste to ferment, would promote the increase of the mineral content in HWOD leachate. However, a reduction treatment of total nitrogen concentration (180.8 and 207.0 mgN / L) is necessary before their release into the wild.