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Simple Summary: The feeding and nutrition of Hermetia illucens becomes an important issue due to its ability to convert organic by-products obtained from agri-food chains into extremely valuable biomass. In this context, coffee silverskin, a by-product of coffee roasting, enriched with 5%, 10%, 20%, and 25% of microalgae (Schizochytrium limacinum and Isochrysis galbana), was investigated as a basal rearing substrate for H. illucens. The study also analyzed the evaluation of the environmental sustainability of diets. The results showed that the inclusion of microalgae in the diets led to an increase in larval growth performance, especially in larvae fed with S. limacinum. Conversely, the higher the proportion of microalgae, the greater the environmental impact of larval production. Therefore, considering that the 10% S. limacinum inclusion achieved the best waste reduction index and showed only minor differences compared to the higher inclusions of this microalgae, it can be considered a compromise between the nutritional properties of the insects and sustainability. Moreover, considering that the rearing substrate enriched with 10% S. limacinum achieved the best waste reduction index and showed only minor differences in terms of nutritional value of H. illucens prepupae compared to the higher inclusions of this microalgae, it can be considered a compromise for sustainable insect production. Hermetia illucens is a promising insect due to its ability to convert low-value substrates as food chain by-products into highly nutritious feed. Its feeding and nutrition are important issues. The aim of this work was to investigate the effect of different substrates consisting of coffee silverskin, a by-product of the roasting process, enriched with different inclusions of microalgae (5%, 10%, 20%, and 25%), Schizochytrium limacinum, and Isochrysis galbana, combined with the assessment of environmental sustainability by LCA. In general, the addition of microalgae led to an increase in larval growth performance due to the higher content of protein and lipids, although S. limacinum showed the best results with respect to larvae fed with coffee silverskin enriched with I. galbana. A higher prepupal weight was observed in larvae fed with 10%, 20%, and 25% S. limacinum; shorter development times in larvae fed with 25% of both S. limacinum and I. galbana; and a higher growth rate in larvae fed with 25% S. limacinum. The 10% S. limacinum inclusion was only slightly different from the higher inclusions. Furthermore, 10% of S. limacinum achieved the best waste reduction index. The greater the inclusion of microalgae, the greater the environmental impact of larval production. Therefore, the addition of 10% S. limacinum appears to be the best compromise for larval rearing, especially considering that a higher inclusion of microalgae did not yield additional benefits in terms of the nutritional value of H. illucens prepupae. [ABSTRACT FROM AUTHOR]

In the latex production chain, rubber tree seeds (Hevea brasiliensis) represent an underutilized fraction with high potentialities, which can increase the sustainability of the whole process if rightly valorized. In the present study, the quality of all the fractions obtained from the rubber fruit were evaluated, with the aim to identify possible applications for their valorization with a circular economy perspective. Seeds from five different varieties of rubber tree were analyzed. Furthermore, a whole mass and energy balance was defined, which has allowed us to define hypothetical production scenarios. The obtained results show negligible differences among varieties. Shells and capsules have shown a composition similar to woody biomass, with high heating values (more than 16.5 MJ kg−1), low nitrogen content (below 0.5% on weight basis (w/w)) and reduced ash content (0.51% w/w and 1.90% w/w, respectively). Kernels were chemically extracted comparing two different solvents: n-hexane and ethanol. Both solvents showed similar extraction yields, i.e., 49% w/w and 46% w/w for n-hexane and ethanol, respectively. The resulting extraction flour was characterized by a high protein content (around 40% w/w) making it suitable for animal feeding. The rubber seed oil could be used in blends of different vegetable oils for biodiesel production. All this information is useful for improving the sustainability of the latex production chain and to assess the sustainability of possible bioenergy value chains. [ABSTRACT FROM AUTHOR]