Effective harvesting of the microalgae Chlorella protothecoides via bioflocculation with cationic starch

Letelier-Gordo, Carlos Octavio; Holdt, Susan Løvstad; Francisci, Davide De; Karakashev, Dimitar Borisov; Angelidaki, Irini

doi:10.1016/j.biortech.2014.06.014

Cited by 61 publications

(17 citation statements)

References 24 publications

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“…In the 4 days-HRAP the optimal dose of flocculant was mg/L, while in the 8 days-HRAP was 40 mg/L. These results are in accordance with other studies reporting a positive relation between microalgae concentration and dose of flocculant, where the higher the biomass concentration, the higher the flocculant dose needed to obtain the same biomass recovery [18,41,42]. Table 5 shows the results obtained in the four dynamic sedimentation tests, two without flocculant (control) and two with the optimal dose of Tanfloc SG.…”

Section: Settling Velocities Distribution Of Microalgal Biomass With supporting

confidence: 90%

Settling velocity distribution of microalgal biomass from urban wastewater treatment high rate algal ponds

et al. 2016

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The aim of this study was to evaluate the settling velocity distribution of microalgal biomass with and without flocculant (Tanfloc SG). Microalgal biomass was obtained from two experimental wastewater treatment high rate algal ponds (HRAPs) operated with 4 and 8 days of hydraulic retention time. Two sets of dynamic sedimentation tests were carried out using a water elutriation apparatus. In the first set, most of the biomass of the 8 days-HRAP (63%) had settling velocities between 16.5 and 4 m/h, while most of the biomass of the 4 days-HRAP (65%) had settling velocities between 16.5 and 1 m/h. In the second set, most of the biomass from both HRAPs (60% from the 8 days-HRAP and 80% from the 4 days-HRAP) had settling velocities between 6.5 and 0.4 m/h. In this second set, settling velocities of <0.4 m/h were reached by 20% and 40% of the biomass from 4 days-HRAP and 8 days-HRAP, respectively. The addition of flocculant at optimal doses ranging from 20 to 40 mg/L had impressive effects on the settling velocity distribution in this second set. 70% and 84% of biomass reached velocities of >6.5 m/h, compared to 10% and 14% of microalgal biomass without flocculant for the 8 days-and 4 days-HRAPs, respectively. With flocculant, a very small amount of biomass (3% for the 4 days-HRAP and 8% for the 8 days-HRAP) had settling velocities of <0.4 m/h. Microscopic examination of samples from sedimentation tests showed how an important amount of microalgae settled in the system. Indeed, <1500 microalgae individuals/mL were found in all outlet samples from the elutriation apparatus (inlet samples of >10(5) microalgae individuals/mL). According to our results, a settler designed with a critical settling velocity of 1m/h would reach biomass recoveries as high as 90-94% with flocculant compared to 77-88% without flocculant.Peer ReviewedPostprint (author's final draft

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Section: Settling Velocities Distribution Of Microalgal Biomass With supporting

confidence: 90%

Settling velocity distribution of microalgal biomass from urban wastewater treatment high rate algal ponds

et al. 2016

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“…CS is effective flocculants for negatively charged organic and inorganic colloidal particles over a wide range of pHs . It is usually used as wet‐end additives in papermaking industry, flocculants in wastewater treatment, and antimicrobial products formulations .…”

Section: Introductionmentioning

confidence: 99%

Optical and structural properties of hydrophilic CdTe quantum dots in cationic starch polymeric matrix

2015

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In this work, water soluble CdTe quantum dots (QDs) were incorporated into a biopolymeric matrix of polyacrylamide grafted onto cationic starch (CS-g-PAAm) to enhance optical properties of QDs. To this aim, the effect of various factors such as AAm concentration, molar ratio of CS-g-PAAm/CdTe, reaction temperature and time on optical properties of obtained QDs were investigated via UV-visible (UV-vis) and fluorescence spectra. Finally, the optimized QDs were characterized by Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), thermo-gravimetric (TG) analysis, and energy dispersive X-ray analysis (EDX).

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“…Among these flocculants materials such as chitosan and cationic starch are the most promising ones for application due to abundant source, easy availability and biodegradation with less secondary pollution (Hansel et al, 2014;Letelier-Gordo et al, 2014). However, cationic polymers are often toxic to the aquatic organisms (Lee et al, 2014) and direct application of these materials in aquatic environment may pose adverse effects (Bullock et al, 2000;Rizzo et al, 2008).…”

Section: Toxic Effects Of Chitosan and Cationic Starch On Aquatic Orgmentioning

confidence: 99%

“…Recent studies indicate that toxic Al 3þ could be released after alum application at low pH (<6.0), and sediment-capping with alum could inhibit microbial nitrification and denitrification under aerobic conditions (Gibbs and Oezkundakci, 2011). Recently, natural flocculant materials, such as chitosan and cationic starch, were developed as environmental friendly materials to control harmful algal blooms because of their high flocculation efficiency (Anthony and Sims, 2013;Hansel et al, 2014;Letelier-Gordo et al, 2014;Xu et al, 2013). To improve the HABs removal using clays, chitosan is used to modify the local soils and applied to small natural waters to control both cyanobacteria blooms and sediment nutrient release, leading to recovery in submerged macrophytes Pan, 2015, 2013;Pan et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Ecotoxicological assessment of flocculant modified soil for lake restoration using an integrated biotic toxicity index

2016

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a b s t r a c tFlocculant modified soils/clays are being increasingly studied as geo-engineering materials for lake restoration and harmful algal bloom control. However, the potential impacts of adding these materials in aquatic ecological systems remain unclear. This study investigated the potential effects of chitosan, cationic starch, chitosan modified soils (MS-C) and cationic starch modified soils (MS-S) on the aquatic organisms by using a bioassay battery. The toxicity potential of these four flocculants was quantitatively assessed using an integrated biotic toxicity index (BTI). The test system includes four aquatic species, namely Chlorella vulgaris, Daphnia magna, Cyprinus carpio and Limnodrilus hoffmeisteri, which represent four trophic levels in the freshwater ecosystem. Results showed that median effect concentrations (EC 50 ) of the MS-C and MS-S were 31e124 times higher than chitosan and cationic starch, respectively. D. magna was the most sensitive species to the four flocculants. Histological examination of C. carpio showed that significant pathological changes were found in gills. Different from chitosan and cationic starch, MS-C and MS-S significantly alleviated the acute toxicities of chitosan and cationic starch. The toxicity order of the four flocculants based on BTI were cationic starch > chitosan > MS-S > MS-C. The results suggested that BTI can be used as a quantitative and comparable indicator to assess biotic toxicity for aquatic geo-engineering materials. Chitosan or cationic starch modified soil/clay materials can be used at their optimal dosage without causing substantial adverse effects to the bioassay battery in aquatic ecosystem.

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Effective harvesting of the microalgae Chlorella protothecoides via bioflocculation with cationic starch

Cited by 61 publications

References 24 publications

Settling velocity distribution of microalgal biomass from urban wastewater treatment high rate algal ponds

Settling velocity distribution of microalgal biomass from urban wastewater treatment high rate algal ponds

Optical and structural properties of hydrophilic CdTe quantum dots in cationic starch polymeric matrix

Ecotoxicological assessment of flocculant modified soil for lake restoration using an integrated biotic toxicity index

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