Cow dung, coming from a rumen animal is known to contain the native microbial flora that aids
in faster biogas production. It has also been reported severally that cow dung is a very good
starter for poor producing feedstocks [29, 30&31]. The Energy content of the waste was
increased as well as the volatile solids and the nutrients (crude fat and protein). The C/N ratio
was also reduced to the optimum range This is as a result of the synergy in operation between
the two wastes. The cumulative biogas yield of the blend under a retention period of 45 days was
still higher than the cumulative biogas yield of the single waste under a 77 days retention period
which was 8dm3/kg of slurry [15]. Blending or co-digestion of wastes is one of the optimization techniques known to improve biogas production [32 & 33]. All these factors may have been responsible for the better performance of the PW: CD. The result of the microbial total viable count (TVC) revealed the progression of the
microbes that converted the wastes to biogas (Table 3). The microbial load started lower, increased towards the peak of production and reduced towards the end of the retention period. For the PW alone, peak of production and towards the end of the retention period had very close TVC’s because at that period, the peak of
gas production lingered since the paper waste continued biogas production long after the combined system had stopped. This indicates that the paper waste is a very good feedstock for biogas production since its retention period is long.