Microalgal Cultivation Using Animal Production Exhaust Air: Technical and Economic Feasibility

Abstract

Fixing airborne nutrients from animal feeding operations (AFOs) into microalgal biomass could alleviate AFOs air emissions and reduce microalgal production cost. The aim of this study was to conduct a technical and economic assessment of integrating air emissions mitigation with microalgal cultivation. Experiments were conducted to determine technical feasibility for three air emission scenarios of exhaust gases, dust (particulate matter), and exhaust air. In the first scenario, microalgal Scenedesmus and Desmodesmus growing on the nutrients from exhaust gases had 92.7 and 71.0% of NH3 mitigation efficiency with biomass productivities of 11.2 and 21.5 g/m2 per day, respectively. In the second scenario, particulate matter from AFOs provided essential nutrients for Desmodesmus cultivation. The nutrient recoveries were 0.08 mg NH4+‐N/mg biomass, 0.13 mg NO3−‐N/mg biomass, and 0.03 mg PO43−‐P/mg biomass. The biomass productivity was 21.4 g/m2 per day. In the third scenario, exhaust air from AFOs was the nutrient source to culture three microalgae of Scenedesmus, Chlorella, and Chlamydomonas. The corresponding microalgal biomass productivities were 14.5, 9.7, and 8.7 g/m2 per day. Four conceptual cases were applied to assess the economic feasibility of the integrated air emission mitigation and microalgae cultivation. The results demonstrated that using the recovered CO2 and nutrients in exhaust air could significantly reduce the cost of microalgal culture systems, and a net revenue of $0.0005/egg could be achieved by the integrated system with improved microalgal biomass productivity of 20 g/m2 per day.

Pollutant Gases to Algal Animal Feed: Impacts of Poultry House Exhaust Air on Amino Acid Profile of Algae

“…The biomass productivity was the highest in Scenedesmus sp., Ankistrodesmus sp., and Synechococcaceae grown with BBM−N culture (43.0, 41.8, and 46.7 mgL −1 d −1 , respectively, p < 0.0015). It has been indicated that exhaust gases have sufficient nutrients, including carbon, nitrogen, phosphorus, etc., to enhance microalgal growth [ 29 ]. In previous studies performed by Boonma et al [ 39 ] and Packer [ 40 ], it was reported that Scenedesmus spp.…”

“…Today, commercial production of microalgae cannot be cost-competitive because it demands more water, energy, and nutrients [ 27 , 28 ]. Therefore, integrating microalgae cultivation systems and agricultural and industrial processes that release carbon dioxide and nutrients as waste could be potentially advantageous for creating a win–win situation that supports microalgae sustainability and environmental protection [ 29 , 30 ]. This study highlights the environmental impact of poultry production, focusing on reducing greenhouse gas and ammonia production by algae species suitable for animal nutrition, underscoring the need for sustainable feed sources in poultry farming.…”

Multi-Criteria Decision Analysis for Optimizing CO2 and NH3 Removal by Scenedesmus dimorphus Photobioreactors

“…Microalgae have substantially higher cell growth and CO 2 fixation rates (about 10-50 times) than terrestrial plants [7]. They can be further valorised into biofuels, animal feed, nutrition additives, cosmetics, and pharmaceuticals [8].…”

“…For example, CO 2 and NH 3 fixation efficiencies can be affected by many operating parameters, such as gas loading rates, gas concentrations, pH, light intensity, and temperature. Numerous studies have been conducted to examine the effects of these parameters [8,[11][12][13]. In nearly all these studies, different parameters were examined separately.…”