2020, Klang, Johanna, Szewzyk, Ulrich, Bock, Daniel, Theuerl, Susanne

In this study the response of biogas-producing microbiomes to a profound feedstock change was investigated. The microbiomes were adapted to the digestion of either 100% sugar beet, maize silage, or of the silages with elevated amounts of total ammonium nitrogen (TAN) by adding ammonium carbonate or animal manure. The feedstock exchange resulted in a short-range decrease or increase in the biogas yields according to the level of chemical feedstock complexity. Fifteen taxa were found in all reactors and can be considered as generalists. Thirteen taxa were detected in the reactors operated with low TAN and six in the reactors with high TAN concentration. Taxa assigned to the phylum Bacteroidetes and to the order Spirochaetales increased with the exchange to sugar beet silage, indicating an affinity to easily degradable compounds. The recorded TAN-sensitive taxa (phylum Cloacimonetes) showed no specific affinity to maize or sugar beet silage. The archaeal community remained unchanged. The reported findings showed a smooth adaptation of the microbial communities, without a profound negative impact on the overall biogas production indicating that the two feedstocks, sugar beet and maize silage, potentially do not contain chemical compounds that are difficult to handle during anaerobic digestion.

2020, Olatayo Jekayinfa, Simeon, Ifeolu Orisaleye, Joseph, Pecenka, Ralf

Nigeria is a developing country with an insufficient supply of energy to meet the continuously growing demand. However, there are several biomass resources available within the country. This paper presents a desk review, which investigates the potential resources for biomass energy generation within the country. Energy policies to aid biomass use as an energy source within the country were also reviewed. Biomass resources identified within Nigeria include forest residues, agricultural residues, human and animal wastes, aquatic biomass, and energy crops. However, several of the resources, particularly agricultural residues, have competing uses, such as livestock feed and soil rejuvenation. An estimation of the technical energy potential of the biomass resources revealed that about 2.33 EJ could be generated from the available resources in Nigeria. Agricultural residues have an energy potential of about 1.09 EJ, with cassava, maize, oil palm, plantain, rice, and sorghum being the major contributors. Animal wastes, municipal solid waste, and forest residues have energy potentials of 0.65, 0.11, and 0.05 EJ, respectively. The potentials of wood fuel and charcoal are 0.38 and 0.05 EJ, respectively. The study found that despite the available potential and existing policies, not much has been done in the implementation of large-scale bioenergy within the country. However, there has been laboratory and research-scale investigations. The review suggests that more policies and stronger enforcement will aid bioenergy development within the country. From the review, it has been suggested that the agricultural sector needs to be developed to generate more biomass resources. More research, development, and implementation have to be carried out on biomass resources and bioenergy generation processes. The production of non-edible energy crops in marginal lands should also be considered prime to the development of bioenergy within the country.