Production of Nutrient-Rich Biofertilizer Through Membrane Filtration of Digestate: Application for Tomato (Lycopersicon esculentum L.) Cultivation

Anaerobic digestion (AD) of organic wastes is an alternative approach for a sustainable waste management. This biotechnology produces biogas and a nutrient-rich residue, digestate, which can be returned to land as a biofertilizer for crops. In the present study, membrane filtration was suggested to obtain a concentrated organic-mineral fertilizer from a liquid digestate obtained from the co-digestion of olive mill wastewater and poultry manure. The comparison of the nutrient profiles of raw and post-treated digestate showed that the retentate of microfiltration was the best nutrient-rich solution (N, P, K, Mg, Ca, Fe; Humic and fulvic acids) in comparison to the raw digestate and the filtrate. Moreover, digestates were suitable for use in agriculture because they were poorly contaminated by heavy metals. The results of the fertigation study have shown that the retentate of microfiltration increased the growth and the mean fruit weight of tomato plants up to 49.63% and 57.96%, respectively. Membrane filtration demonstrated efficient segregation of nutrients and provided a suitable biofertilizer for successful tomato plants cultivation.