The anaerobic digestion process is applied worldwide in the treatment of various organic wastes, allowing energy production from biogas and organic recovery from digested sludge. In the evaluation of suitable substrates for anaerobic digestion, Biochemical Methane Potential assays are the most applied, and, despite several efforts to standardize this method, it is observed that there are still several studies that do not apply all the criteria. This current paper’s main goal is to present a review of anaerobic feedstocks, BMP methodologies, experimental conditions, and results of specific methane production from 2008 to 2023. A wide range of anaerobic feedstocks was found, which was divided into five groups: animal manure, sludge, food wastes, energy crops, and other organic wastes. Several parameters were used to characterize the anaerobic feedstocks, like TS, VS, COD, and pH, displaying different value ranges. The number of publications concerning BMP assays increased significantly over the years until 2021, having stabilized in the last two years. This evolution allowed for several attempts to standardize the BMP method with positive developments, but there are still some gaps in the experimental conditions and the determination of specific methane production. All of this makes the comparison of some studies a challenge.

In this experimental work, calcium from natural seafood wastes was used as a heterogeneous catalyst separately or in a blend of “shell mix” for producing biodiesel. Several chemical reaction runs were conducted at varied reaction times ranging from 30 min to 8 h, at 60 °C, with a mass content of 5% (Wcat./Woil) and a methanol/oil molar ratio of 12. After the purification process, the biodiesel with fatty acid methyl ester (FAME) weight content measured was higher than 99%, which indicated that it was a pure biodiesel. This work also showed that the inorganic solid waste shell mixture used as the heterogeneous catalyst can be reused three times and the reused mixture still resulted in a FAME content higher than 99%. After 40 different transesterification reactions were performed using liquid (waste cooking oils) and solid (calcium seafood shells) wastes for producing biodiesel, under the specific conditions stated above, we found a successful, innovative, and promising way to produce biodiesel. In addition, blends prepared with jet fuel A1 and biodiesel were recorded with no invalid results after certain tests, at 25 °C. In this case, except for the 10% blend, the added biodiesel had no significant effect on the viscosity (fluidity) of the biojet fuel.