## 3 Results and Discussion
### Two-Stage Anaerobic Co-Digestion of CSL  
The potential approach of applying the two-stage anaerobic co-digestion process to utilize waste substrates along with the production of valuable bioenergy carriers was demonstrated. A continuous AD process was accomplished with the substrate that led to the highest hydrogen and methane yields: CSL:cattle manure = 1:1. CSL is rich in soluble carbon and nitrogen nutrients that are readily available for the participating microorganisms' growth and development. Cattle manure, on its side consists of lignocellulosic material, together with a variety of minerals, including trace quantities of iron, copper, manganese, magnesium, cobalt, and sulphur. Minerals like potassium, nitrogen, calcium, phosphorus, and zinc may be present in higher amounts [29]. It is known for being a suitable substrate for biogas production [30]. The different constituents present in cattle manure help for the proliferation of complex microbial communities [31]. Their combination was proven to be appropriate in the two-stage process for agricultural waste vaporization. The results indicated that the organic matter CSL and cattle manure were digested and the energy carriers hydrogen and methane were obtained at the expense of cellulose and the decrease in reducing sugar content. Tables 5 and 6 contain the measured values for the hydrogen or methane yield, total solids and volatile solids, glucose, cellulose, and protein and their changes during the continuous processes in the hydrogen and in the methane bioreactors. The values presented vary as, every day, the process is being fed. Figure 2: Cumulative hydrogen yield. The graphics in Figure 3 show the daily hydrogen (a) and methane (b) yields from the co-digestion, in comparison with a single digestion of corn steep liquor. The overall hydrogen yield from co-digestion in 2.29 dm\({}^{3}\) biogas/L working volume versus 1.55 from the single digestion performed. The overall methane yielded from co-digestion is 10.68 dm\({}^{3}\) biogas/L working volume versus 1.45 from the single digestion. It can be seen that the yields from co-digestion are greater than those from the single digestion. In addition, the overall hydrogen and methane yields are greater for the whole process with the mixture of two substrates. In the report of [PERSON] et al. (2025), they also established that the biogas production with only cattle dung as a substrate had an almost linear increase, while accomplishing a co-digestion by the addition of cabbage waste made the production of biogas higher [32]. According to [PERSON] et al. (2000), the digestion of more than one substrate in the same digester can establish positive synergism and the additional nutrients introduced could support microbial growth [33]. Comparative Analysis of the Taxonomic Composition at a Phylum Level in the Two bioreactors for Anaerobic Waste Degradation with Hydrogen and Methane Production  
The microbial composition of bioreactors plays a critical role for the process efficiency. The microbial community in the two bioreactors was analyzed and their structure at the phylum, genus, and species levels was compared. The microbial composition analysis was performed using 16S rRNA sequencing on the MiSeq Illumina platform--300 PE. The data were processed using bioinformatics methods for the identification and quantitative analysis of the predominant taxonomic groups.