Microalgae harvesting from wastewater by pH modulation and flotation: Assessing and optimizing operational parameters

Leite, Luan de Souza; Santos, Priscila Ribeiro dos; Daniel, Luiz Antônio

doi:10.1016/j.jenvman.2019.109825

Cited by 27 publications

(7 citation statements)

References 55 publications

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“…Furthermore, one of the most important challenges in microalgal biomass production is finding an adequate technique to separate suspended algae from wastewater due to the high environmental and economic costs associated with this process (Kohlheb et al, 2020). Harvesting turns out to be the main bottleneck for large-scale microalgae cultivation, due to the small size of the microalgal cells (Ho and Goethals, 2020;Leite et al, 2020). There are mechanical (centrifugation, filtration, etc.)…”

Section: Discussionmentioning

confidence: 99%

Bio-products from algae-based biorefinery on wastewater: A review

Catone

Ripa

Geremia

et al. 2021

Journal of Environmental Management

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Section: Discussionmentioning

confidence: 99%

Bio-products from algae-based biorefinery on wastewater: A review

Catone

Ripa

Geremia

et al. 2021

Journal of Environmental Management

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“…Dissolved air flotation is a method commonly used in wastewater treatment sludge removal, i.e., for large scale setups but flocculants can cause a problem during downstream processing of algae (Greenwell et al, 2009). It was studied that pH-modulated dissolved air floatation harvesting method having optimized parameters such as pH, velocity gradient, mixing time, and floatation to harvest Chlorella sorokiniana from wastewater (de Leite et al, 2020). The major limitation of the mechanical method is the increased operational costs for algal production and is economically feasible only when a higher number of value-added products are produced (Park et al, 2011).…”

Section: Mechanical Methodsmentioning

confidence: 99%

Valorization of Wastewater Resources Into Biofuel and Value-Added Products Using Microalgal System

et al. 2021

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Wastewater is not a liability, instead considered as a resource for microbial fermentation and value-added products. Most of the wastewater contains various nutrients like nitrates and phosphates apart from the organic constituents that favor microbial growth. Microalgae are unicellular aquatic organisms and are widely used for wastewater treatment. Various cultivation methods such as open, closed, and integrated have been reported for microalgal cultivation to treat wastewater and resource recovery simultaneously. Microalgal growth is affected by various factors such as sunlight, temperature, pH, and nutrients that affect the growth rate of microalgae. Microalgae can consume urea, phosphates, and metals such as magnesium, zinc, lead, cadmium, arsenic, etc. for their growth and reduces the biochemical oxygen demand (BOD). The microalgal biomass produced during the wastewater treatment can be further used to produce carbon-neutral products such as biofuel, feed, bio-fertilizer, bioplastic, and exopolysaccharides. Integration of wastewater treatment with microalgal bio-refinery not only solves the wastewater treatment problem but also generates revenue and supports a sustainable and circular bio-economy. The present review will highlight the current and advanced methods used to integrate microalgae for the complete reclamation of nutrients from industrial wastewater sources and their utilization for value-added compound production. Furthermore, pertaining challenges are briefly discussed along with the techno-economic analysis of current pilot-scale projects worldwide.

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“…Previously, Besson and Guiraud (2013) carried out a pH-induced flocculation followed by flotation with the addition of sodium hydroxide in harvesting hypersaline microalga Dunaliella salina. This method proved that microalgae were able to form flocs spontaneously at higher pH and simulate auto-flocculation (Barros et al 2015;Gerardo et al 2015;Kim & Kwak 2020;Leite et al 2019). Microalgal biomass harvest using magnesium coagulation with dissolved air flotation has also been reported in harvesting freshwater microalgae such as Chlorella zofingiensis and Scenedesmus dimorphus, and marine microalgae such as Nannochloropsis sp.…”

Section: Introductionmentioning

confidence: 91%

“…Saturator pressure is important for dissolved air flotation technique as it affects the bubble size or the quantity of air bubbles (Edzwald 2010;Leite et al 2019). Highest pressure at 2.2 bar generated a concentrated cloud of milky bubble solution compared to 1.8 bar and 2 bar.…”

Section: Effect Of Different Saturator Pressurementioning

confidence: 99%

Harvesting Marine Microalgae Nannochloropsis sp. using Dissolved Air Flotation (DAF) Technique

Fuad¹,

Omar²,

Kamarudin³

et al. 2021

JSM

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The production of high-value bioproducts from microalgae biomass has been widely investigated. However, their production is hindered by the expensive harvesting process. To date, flocculation followed by DAF process has been accepted as one of the affordable harvesting approaches. In this study, the use of DAF technique was attempted to harvest marine microalgae Nannochloropsis sp. Batch DAF harvesting was carried out using fabricated DAF unit equipped with several compartments including separation column, product collecting vessel and rotary skimmer. Tannin-based biopolymer flocculant, AFlok-BP1 at pH 5 with a concentration of 160 mg/L was used to facilitate the flocculation of particles. The effects of different saturator pressure at 1.8, 2, and 2.2 bar were then evaluated at a constant volume of 6 L microalgae culture. The effects of different microalgae culture volumes (6, 8 and 10 L) were also evaluated at a fixed saturator pressure of 2.2 bar. The highest pressure at 2.2 bar yielded the best result with the highest total solid of 3.19 ± 0.01% and a maximum yield of 1.70 ± 0.05 g/g (wet basis). The microalgae concentration was the lowest (0.027 g/L) when 6 L of culture volume was used. However, the values were significantly higher when the culture volume was increased to 8 and 10 L to approximately 0.035 and 0.050 g/L, respectively. As a conclusion, the study provided evidence for the feasibility of DAF technique in harvesting marine microalgae Nannochloropsis sp.

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Microalgae harvesting from wastewater by pH modulation and flotation: Assessing and optimizing operational parameters

Cited by 27 publications

References 55 publications

Bio-products from algae-based biorefinery on wastewater: A review

Bio-products from algae-based biorefinery on wastewater: A review

Valorization of Wastewater Resources Into Biofuel and Value-Added Products Using Microalgal System

Harvesting Marine Microalgae Nannochloropsis sp. using Dissolved Air Flotation (DAF) Technique

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