https://hal.inria.fr/hal-00854465/file/2009_Sialve_Anaerobic_Digestion_Microalgae_SIALVE_Biotech_Adv.pdf

Anaerobic digestion of microalgae as a necessary step to make microalgal biodiesel sustainable.

Microalgae have recently attracted considerable interest worldwide, due to their extensive application potential in the renewable energy, biopharmaceutical, and nutraceutical industries. Microalgae are renewable, sustainable, and economical sources of biofuels, bioactive medicinal products, and food ingredients. Several microalgae species have been investigated for their potential as value-added products with remarkable pharmacological and biological qualities. As biofuels, they are a perfect substitute to liquid fossil fuels with respect to cost, renewability, and environmental concerns. Microalgae have a significant ability to convert atmospheric CO2 to useful products such as carbohydrates, lipids, and other bioactive metabolites. Although microalgae are feasible sources for bioenergy and biopharmaceuticals in general, some limitations and challenges remain, which must be overcome to upgrade the technology from pilot-phase to industrial level. The most challenging and crucial issues are enhancing microalgae growth rate and product synthesis, dewatering algae culture for biomass production, pretreating biomass, and optimizing the fermentation process in case of algal bioethanol production. The present review describes the advantages of microalgae for the production of biofuels and various bioactive compounds and discusses culturing parameters.

https://link.springer.com/content/pdf/10.1186/s12934-018-0879-x.pdf

The promising future of microalgae: current status, challenges, and optimization of a sustainable and renewable industry for biofuels, feed, and other products

Algae are an attractive source of biomass energy since they do not compete with food crops and have higher energy yields per area than terrestrial crops. In spite of these advantages, algae cultivation has not yet been compared with conventional crops from a life cycle perspective. In this work, the impacts associated with algae production were determined using a stochastic life cycle model and compared with switchgrass, canola, and corn farming. The results indicate that these conventional crops have lower environmental impacts than algae in energy use, greenhouse gas emissions, and water regardless of cultivation location. Only in total land use and eutrophication potential do algae perform favorably. The large environmental footprint of algae cultivation is driven predominantly by upstream impacts, such as the demand for CO2 and fertilizer. To reduce these impacts, flue gas and, to a greater extent, wastewater could be used to offset most of the environmental burdens associated with algae. To demonstra...

Environmental Life Cycle Comparison of Algae to Other Bioenergy Feedstocks

Wastewater treatment high rate algal ponds for biofuel production.

Dual role of microalgae: Phycoremediation of domestic wastewater and biomass production for sustainable biofuels production

Determining variables that influence the phosphorus content of waste stabilization pond algae.

Ammonia volatilization from a piggery pond

Microalgal luxury uptake of phosphorus in waste stabilization ponds – frequency of occurrence and high performing genera

The ability to predict water evaporation from shallow ponds is needed to accurately assess the water demand and costs of microalgae farming This study assessed the accuracy of seven evaporation models available in the literature against experimental data collected in a raceway algal pond located in Narbonne, France A theoretical ‘flat-plate’ evaporation model and the “Sartori model” were identified as the most accurate models (errors of 142% and 92%, respectively, over a period of 274 days) As these two models require the mathematical determination of pond temperature, simulations were performed to determine if pond temperature could be substituted for air temperature to compute yearly evaporation estimates Unfortunately, assuming that pond temperature was equal to air temperature caused significant inaccuracies on the yearly evaporation (eg up to 68% in an arid climate with the Sartori model) High-resolution co-modeling of evaporation and temperature is therefore required for accurate evaporation predictions

Comparative assessment of evaporation models in algal ponds

Increasing biogas production from municipal anaerobic digesters via additional loading with industrial/agricultural wastes offers a low-cost, sustainable energy generation option of significant untapped potential. In this work, bench-top reactors were used to mimic a full-scale primary sludge digester operating at an organic loading rate (OLR) of 2.4 kg COD/m3 d and a 20 d hydraulic retention time (HRT). Co-digestion of whey with primary sludge was sustained at a loading rate of 3.2 kg COD/m3 d (17 d HRT) and boosted gas production to 151% compared to primary sludge digestion alone. Addition of chemical alkalinity enabled co-digestion of whey with primary sludge to be maintained at an elevated OLR of 6.4 kg COD/m3 d (11 d HRT) with gas production increased to 208%. However, when the chemical addition was simply replaced by cow manure, stable operation was maintained at OLRs of 5.2–6.9 kg COD/m3 d (11–14 d HRT) with gas production boosted up to 268%.

Andy Shilton

Papers

Determining variables that influence the phosphorus content of waste stabilization pond algae.

Ammonia volatilization from a piggery pond

Microalgal luxury uptake of phosphorus in waste stabilization ponds – frequency of occurrence and high performing genera

Comparative assessment of evaporation models in algal ponds

Enhanced biogas production using cow manure to stabilize co-digestion of whey and primary sludge