Tampere University of Technology

Optimization of microalgae cultivation in liquid digestate from pulp and paper mill

CitationTao, R., Lakaniemi, A-M., & Rintala, J. (2017). Optimization of microalgae cultivation in liquid digestate from pulpand paper mill. Paper presented at 1st International ABWET conference: Waste-to-Bioenergy: Applications toUrban Areas, Paris, France.Year2017

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Optimization of microalgae cultivation in liquid digestate from

pulp and paper millR. Tao, A.-M. Lakaniemi, J.A. Rintala

Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, 33101 Tampere, Finland

IntroductionMicroalgae can efficiently remove nutrients from liquid digestates while

producing biomass that can be converted into bioenergy and biofuels (Xia

and Murphy, 2016). However, high ammonia levels in liquid digestates may

inhibit the microalgal growth, and therefore wastewater dilution plays an

important role in the optimization of the biomass production and nutrient

removal efficiency. Recently, a microalgae-utilizing biorefinery concept

integrated into a traditional pulp and paper mill has been suggested. In this

concept, liquid digestate of pulp and paper wastewater treatment biosludge

is used for microalgal cultivation (Kouhia et al., 2015; Kinnunen and Rintala,

2016).

ConclusionsS. acuminatus enabled higher biomass production and nutrient removal

efficiency than C. vulgaris when cultivated in the liquid digestate from pulp

and paper mill wastewater treatment. Compared to previous studies

reporting microalgal cultivation in real wastewaters, S. acuminatus growing

in the liquid digestate from the pulp and paper mill resulted in one of the

highest microalgal biomass concentrations. This finding promotes the

development of the microalgae-utilizing biorefinery concept integrated into

pulp and paper mills.

ReferencesKinnunen, V.; Rintala, J.A. (2016). Bioresource Technology, 221, 78–84.

Kouhia, M.; Holmberg, H.; Ahtila, P. (2015). Algal Research, 10, 41–47.

Xia, A.; Murphy, J.D. (2016). Trends in Biotechnology, 34, 264-275.

Singh, M.; Reynolds, D.L.; Das, K.C. (2011). Bioresource Technology, 102, 10841-10848.

Tuantet, K.; Temmink, H.; Zeeman, G.; Janssen, M.; Wijffels, R.H.; Buisman, C.J. (2014). Water Research, 55, 162-174.

Tan, X.B.; Yang, L.B.; Zhang, Y.L.; Zhao, F.C.; Chu, H.Q.; Guo, J. (2015). Bioresource Technology, 198, 340-350.

Marjakangas, J.M.; Chen, C.Y.; Lakaniemi, A.M.; Puhakka, J.A.; Whang, L.M.; Chang, J.S. (2015). Biochemical Engineering

Journal, 103, 177-184.

Ho, S.H.; Huang, S.W.; Chen, C.Y.; Hasunuma, T.; Kondo, A.; Chang, J.S. (2013). Bioresource Technology, 135, 157-165.

Materials and MethodsC. vulgaris and S. acuminatus were cultivated in ADPP from anaerobic

reactors operated at mesophilic conditions treating activated sludge from

pulp and paper industry wastewater treatment plant. The initial ammonium

and phosphate-P concentration of the liquid digestate were 350±40 mg/L

and 25±1 mg/L, respectively. The liquid digestate was diluted with deionized

water, using dilution factors of 5x, 3x and 1.5x. Cultivations with each

dilution were performed under 150 µmol photos/(m2·s) and 240 µmol

photos/(m2·s) for C. vulgaris and S. acuminatus, respectively, with 5% CO2

in the air (v/v) for 12 days.

Fig. 1 Photographs of the photobioreactors used in the experiments and the two

microalgae observed under microscope.

AcknowledgmentsThis project has received funding from the European Union’s Horizon

2020 research and innovation programme under the Marie Sklodowska-

Curie grant agreement No 643071.

ObjectivesThe aim of the present study was to study the cultivation of two freshwater

microalgae, Chlorella vulgaris and Scenedesmus acuminatus in a diluted

liquid fraction of the pulp and paper mill biosludge after anaerobic digestion

(ADPP). Simultaneous nutrient removal from the liquid digestate was also

investigated.

C. vulgaris S. acuminatus

Results

Fig. 2 Microalgal biomass concentration (as g VSS/L) during the cultivation of

Chlorella vulgaris and Scenedesmus acuminatus in differently diluted ADPP.

Medium Microalgae Maximum biomass concentration (g/L)

Reference

ADPP Chlorella vulgaris 5.1 This study

ADPP Scenedesmus acuminatus

9.4 This study

Anaerobically digested poultry litter

Scenedesmus bijuga 0.4 Singh et al., 2011

Human urine Chlorella sorokiniana

9.3 Tuantet et al., 2014

Anaerobically digested municipal wastewater

Chlorella pyrenoidosa

2.0 Tan et al., 2015

Anaerobically digested Piggery wastewater

Chlorella vulgaris 3.2 Marjakangas et al., 2015

Modified Basal Medium

Chlorella vulgarisFSP-E

7.2 Ho et al., 2013

Funded by

the European Union

Fig. 3 The soluble ammonium and phosphate removal efficiencies during the

cultivation of Chlorella vulgaris and Scenedesmus acuminatus in differently diluted

ADPP.

Table 1: Maximum biomass levels from selected studies in which microalgae were

cultivated in real wastewaters and synthetic medium.