Contents lists available at ScienceDirect Algal Research journal homepage: www.elsevier.com/locate/algal Life cycle assessment of microalgae production in a raceway pond with alternative culture media Rosana de Cassia de Souza Schneider a,b, ⁎ , Marcelo de Moura Lima a , Michele Hoeltz a,c , Fábio de Farias Neves d , Danielle Kochenborger John b , Amaro de Azevedo a a Environmental Technology Postgraduation Program, Santa Cruz do Sul University, Santa Cruz do Sul CEP 96815-900, Rio Grande do Sul, Brazil b Department of Chemistry and Physics, Santa Cruz do Sul University, Santa Cruz do Sul CEP 96815-900, Rio Grande do Sul, Brazil c Department of Biology and Pharmacy, University of Santa Cruz do Sul, Santa Cruz do Sul University, Santa Cruz do Sul CEP 96815-900; Rio Grande do Sul, Brazil d Department of Fisheries Engineering, Santa Catarina State University, Laguna CEP: 88790-000, Santa Catarina, Brazil ARTICLE INFO Keywords: Life cycle assessment Microalgae Wastewater NPK Environmental impacts Raceway ponds ABSTRACT Microalgae production is responsible for phycoremediation and the development of green products synthesis and for cleaning processes. Studies on the environmental impacts of this process are fundamental to make these systems feasible. In these studies, a life cycle assessment of the production of microalgae biomass is important. We performed this study considering the production in wastewater or NPK medium and different methods of biomass separation. The LCA model was developed for the production of 9 and 12 kg of Desmodesmus subspicatus microalgae biomass in 10 days, which represents the production in 8000 L of wastewater and NPK solution, respectively. The total volume corresponded to 4 tanks of 2000 L each. The growth system used was an open raceway pond with culture movement caused by an air-lift system or by paddle wheels. Flocculation with NaOH and electroflotation with Al and Fe were chosen as the methods of biomass separation. These methods were chosen because they facilitate the separation using filtration or centrifugation. The final step was drying, which can be conducted with the biomass after filtration (80% water) or centrifugation (40% water). Several scenarios were examined to identify a more environmentally friendly method for microalgae biomass production. There were no differences using air lift or paddle wheels, however it was identified impacts in all stages. Also, there were fewer impacts using wastewater than using NPK. Regarding the separation of the biomass, electroflotation caused fewer impacts when compared to flocculation with NaOH. Overall, the scenario with fewest impacts was the one configured using wastewater for microalgae cultivation, followed by centrifugation and drying. 1. Introduction There is a wide range of potential technologies for capturing CO 2 from the atmosphere, and their cost and performance should be as- sessed. With the capture of this gas by microalgae, other benefits are also achieved, and this has the potential to be an economically inter- esting system. Thus, microalgae have been suggested as excellent candidates for carbon sequestration and biofuel production. Among its advantages are high photosynthetic efficiency, high biomass production and rapid growth compared to other crops used for energy purposes. The growth of microalgae requires sunlight, water, CO 2 , and nutrients for photo- synthesis [1]. In addition, the use of microalgae for carbon mitigation includes the ability to capture nutrients from wastewater and other gaseous emis- sions [2]. According to Kumar et al. [3], Ahmad et al. [4], Khan et al. [5], 1 kg dry biomass requires approximately 1.8 kg of CO 2 , and this fixation efficiency is 10–50 times greater than that of terrestrial plants. The possibility of using wastewater to reach the nutrient amounts necessary for biomass growth should also be highlighted. This would mean lowering costs and the volume of treated water, providing a method of water reuse as well as nutrients for the algae [6]. Microalgae species can grow efficiently in wastewater due to their ability to utilize the inorganic and organic carbon, nitrogen and phos- phorus present in these waters [7]. A wide variety of urban wastewaters have been tested as culture media for microalgae, from raw sewage to previously treated effluent at different levels (primary, secondary, ac- tivated sludge, clarified effluents), and even effluents from activated sludge thickening processes have produced satisfactory biomass pro- ductivity results [8]. Municipal wastewater typically contains ap- proximately 350 mg L -1 of COD (chemical oxygen demand), 50 mg L -1 https://doi.org/10.1016/j.algal.2018.04.012 Received 31 October 2017; Received in revised form 14 April 2018; Accepted 15 April 2018 ⁎ Corresponding author at: Environmental Technology Postgraduation Program, Santa Cruz do Sul University, Santa Cruz do Sul CEP 96815-900, Rio Grande do Sul, Brazil. E-mail address: rosana@unisc.br (R.d.C.d.S. Schneider). Algal Research 32 (2018) 280–292 2211-9264/ © 2018 Elsevier B.V. All rights reserved. T