Impact of microalgae characteristics on their conversion to biofuel. Part II: Focus on biomethane production

Abstract

Among biofuel production processes using microalgal biomass, biogas generation seems to be the least complex. This review summarizes information regarding anaerobic digestion of different microalgae species. Various operational parameters and microalgae characteristics (macromolecular distribution and cell wall) are reviewed in the light of their effects on methane production. Additionally, the enhancement of methane production rates achievable by applying biomass pre-treatments and codigestion of substrates is also reported. The review finally covers the so-claimed similarities of microalgal biomass and activated sludge as a substrate for anaerobic digestion

Comparative testing of energy yields from micro-algal biomass cultures processed via anaerobic digestion

“…To date most micro-algae that have been tested for digestion have low carbon/nitrogen ratios that may contribute to high digester ammonia concentrations and toxicity [26]. Many micro-algal species have also shown low biodegradability, possibly due to the nature of the cell walls [27], although pre-treatments can improve methane yield [28]. When considering the potential for micro-algal digestion, it is therefore important that the origin and type of the micro-algal material is taken into consideration.…”

Anaerobic Co-digestion of the Energy Crop Sida hermaphrodita and Microalgae Biomass for Enhanced Biogas Production

“…Algal biomass characteristics depend on the species, growth phase, environmental conditions, nutrient supply, culture conditions, and harvesting/processing techniques (Gonzalez Fernandez et al 2012;Wang and Park 2015). In our study, the MB characteristics were set in the typical range reported in the literature, where microalgae contained 18-46% carbohydrate, 12-48% lipids, and 18-60% proteins (Tibbetts et al 2015).…”

Methods of energy extraction from microalgal biomass: a review

“…Considerable research has been carried out on the anaerobic digestion of a variety of organic materials and some of the earliest studies on extracting bioenergy from microalgae examined anaerobic digestion (Golueke et al 1957). Relatively few studies have been carried on the anaerobic digestion of freshwater microalgae, however, and almost none on marine microalgae (Zamalloa et al 2011;Gonzalez-Fernandez et al 2012a). …”

“…The destruction of organic volatile solids from microalgae was found to be only 60-70 % of that found in raw sewage (Golueke et al 1957). Methane yields from the anaerobic production of microalgae have been reported in the range of 0.09-0.34 l g -1 of volatile solids (Zamalloa et al 2011;Gonzalez-Fernandez et al 2012a). There is considerable conjecture about the reason for the relatively low practical methane yields compared to the theoretical values.…”

“…The low methane yield of microalgal biomass has been attributed to ammonia toxicity derived from the high concentrations of protein found in many microalgae (Park and Li 2012;Golueke and Oswald 1959;Samson and LeDuy 1983). The codigestion of organic nitrogen rich microalgae with low nitrogen/ high carbon substrates, such as sewage sludge or glycerol, has been found to produce a synergistic effect with methane yields higher than from either substrate (Samson and LeDuy 1983;Gonzalez-Fernandez et al 2012a). Methane yields double that of microalgal biomass alone have been achieved by co-digestion with low nitrogen wastes (Samson and LeDuy 1983;Bohutskyi and Bouwer 2013;Ward et al 2014).…”