Tania V. Fernandes

Dr. ir. Tania V. Fernandes


Droevendaalsesteeg 10
6708 PB Wageningen

+31 (0) 317 47 34 00

The Netherlands


Applying ecological knowledge on nature-based solutions for improved water quality and valorization of resources


Tânia is an Environmental Engineer with a PhD degree in Environmental Technology from Wageningen University (2010). She is a researcher at NIOO from 2011, and since 2017 she founded the Microalgae Eco-Technologies Solutions unit (METS) within the Aquatic Ecology Department. Within her unit, she explores the potential of microalgae - bacteria biodiversity and interactions for ecological and sustainable nature- based technologies, providing clean water, valorisation of resources and safe solutions. She applies modern ecological principles and theories in designing biodiverse engineered ecosystems for closing carbon and nutrients cycles and removing anthropogenic pollutants, such as pharmaceuticals and pesticides.


Peer-reviewed publicaties

  • Environmental Pollution

    Effect of an antidepressant on aquatic ecosystems in the presence of microplastics

    Nandini Raman, Berte Mekonen Belay, Josie South, Tarryn L. Botha, Josephine Pegg, Dumisani Khosa, Lubabalo Mofu, Gina Walsh, Martine S. Jordaan, Albert A Koelmans, Sven Teurlincx, Nico Helmsing, Nina de Jong, Ellen Van Donk, Miquel Lürling, Victor Wepener, Tania Vasconcelos Fernandes, Lisette de Senerpont Domis
    Emerging pollutants, such as pharmaceuticals and microplastics have become a pressing concern due to their widespread presence and potential impacts on ecological systems. To assess the ecosystem-level effects of these pollutants within a multi-stressor context, we simulated real-world conditions by exposing a near-natural multi-trophic aquatic food web to a gradient of environmentally relevant concentrations of fluoxetine and microplastics in large mesocosms over a period of more than three months. We measured the biomass and abundance of different trophic groups, as well as ecological functions such as nutrient availability and decomposition rate. To explore the mechanisms underlying potential community and ecosystem-level effects, we also performed behavioral assays focusing on locomotion parameters as a response variable in three species: Daphnia magna (zooplankton prey), Chaoborus flavicans larvae (invertebrate pelagic predator of zooplankton) and Asellus aquaticus (benthic macroinvertebrate), using water from the mesocosms. Our mesocosm results demonstrate that presence of microplastics governs the response in phytoplankton biomass, with a weak non-monotonic dose-response relationship due to the interaction between microplastics and fluoxetine. However, exposure to fluoxetine evoked a strong non-monotonic dose-response in zooplankton abundance and microbial decomposition rate of plant material. In the behavioral assays, the locomotion of zooplankton prey D. magna showed a similar non-monotonic response primarily induced by fluoxetine. Its predator C. flavicans, however, showed a significant non-monotonic response governed by both microplastics and fluoxetine. The behavior of the decomposer A. aquaticus significantly decreased at higher fluoxetine concentrations, potentially leading to reduced decomposition rates near the sediment. Our study demonstrates that effects observed upon short-term exposure result in more pronounced ecosystem-level effects following chronic exposure.
  • Water Research

    Making waves

    Lukas M. Trebuch, Jolieke Timmer, Jan van de Graaf, Marcel Janssen, Tania Vasconcelos Fernandes

    Global surface waters are in a bad ecological and chemical state, which has detrimental effects on entire ecosystems. To prevent further deterioration of ecosystems and ecosystem services, it is vital to minimize environmental pollution and come up with ways to keep surface water healthy and clean. Recently, photogranules have emerged as a promising platform for wastewater treatment to remove organic matter and nutrients with reduced or eliminated mechanical aeration, while also facilitating CO2 capture and production of various bioproducts. Photogranules are microbial aggregates of microalgae, cyanobacteria, and other non-phototrophic organisms that form dense spheroidic granules. Photogranules settle fast and can be easily retained in the treatment system, which allows increased amounts of water and wastewater to be treated. So far, photogranules have only been tested on various “high-strength” wastewaters but they might be an excellent choice for treatment of large volumes of polluted surface water as well. Here, we propose and tested for the first time photogranules on their effectiveness to remove nutrients from polluted surface water at unprecedented low concentrations (3.2 mg/L of nitrogen and 0.12 mg/L of phosphorous) and low hydraulic retention time (HRT = 1.5 h). Photogranules can successfully remove nitrogen (<0.6 mg/L, ∼80 % removal) and phosphorous (<0.01 mg/L, 90–95 % removal) to low levels in sequencing batch operation even without the need for pH control. Subjecting photogranules to surface water treatment conditions drastically changed their morphology. While, under “high-strength” conditions the photogranules were spherical, dense and defined, under polluted surface water conditions photogranules increased their surface area by forming fingers. However, this did not compromise their excellent settling properties. Finally, we discuss the future perspectives of photogranular technology for surface water treatment.

  • Bioresource Technology

    Impact of mixed microalgal and bacterial species on organic micropollutants removal in photobioreactors under natural light

    Kaiyi Wu, Hans Zweers, Huub Rijnaarts, Alette Langenhoff, Tania Vasconcelos Fernandes
    Single microalgae species are effective at the removal of various organic micropollutants (OMPs), however increased species diversity might enhance this removal. Sixteen OMPs were added to 2 continuous photobioreactors, one inoculated with Chlorella sorokiniana and the other with a microalgal-bacterial community, for 112 d under natural light. Three media were sequentially used in 3 Periods: I) synthetic sewage (d 0–28), II) 10x diluted anaerobically digested black water (AnBW) (d 28–94) and III) 5x diluted AnBW (d 94–112). Twelve OMPs were removed > 30 %, while 4 were < 10 % removed. Removal efficiencies were similar for 9 OMPs, yet the mixed community showed a 2–3 times higher removal capacity (µg OMP/g dry weight) than C. sorokiniana during Period II pseudo steady state. The removal decreased drastically in Period III due to overgrowth of filamentous green algae. This study shows for the first time how microbial community composition and abundance are key for OMPs removal.
  • Environmental Science and Pollution Research

    Understanding the differential impacts of two antidepressants on locomotion of freshwater snails (Lymnaea stagnalis)

    Nandini Raman, Asmita Dubey, Ellen Van Donk, Eric von Elert, Miquel Lürling, Tania Vasconcelos Fernandes, Lisette de Senerpont Domis
    There is growing evidence of negative impacts of antidepressants on behavior of aquatic non-target organisms. Accurate environmental risk assessment requires an understanding of whether antidepressants with similar modes of action have consistent negative impacts. Here, we tested the effect of acute exposure to two antidepressants, fluoxetine and venlafaxine (0–50 µg/L), on the behavior of non-target organism, i.e., freshwater pond snail, Lymnaea stagnalis. As compounds interact with chemical cues in the aquatic ecosystems, we also tested whether the effects altered in the presence of bile extract containing 5α-cyprinol sulfate (5α-CPS), a characterized kairomone of a natural predator, common carp (Cyprinus carpio). Behavior was studied using automated tracking and analysis of various locomotion parameters of L. stagnalis. Our results suggest that there are differences in the effects on locomotion upon exposure to venlafaxine and fluoxetine. We found strong evidence for a non-monotonic dose response on venlafaxine exposure, whereas fluoxetine only showed weak evidence of altered locomotion for a specific concentration. Combined exposure to compounds and 5α-CPS reduced the intensity of effects observed in the absence of 5α-CPS, possibly due to reduced bioavailability of the compounds. The results highlight the need for acknowledging different mechanisms of action among antidepressants while investigating their environmental risks. In addition, our results underline the importance of reporting non-significant effects and acknowledging individual variation in behavior for environmental risk assessment.
  • Journal of Hazardous Materials

    Impact of wastewater characteristics on the removal of organic micropollutants by Chlorella sorokiniana

    Kaiyi Wu, Merve Atasoy, Hans Zweers, Huub Rijnaarts, Alette Langenhoff, Tania Vasconcelos Fernandes
    Microalgae-based technologies can be used for the removal of organic micropollutants (OMPs) from different types of wastewater. However, the effect of wastewater characteristics on the removal is still poorly understood. In this study, the removal of sixteen OMPs by Chlorella sorokiniana, cultivated in three types of wastewater (anaerobically digested black water (AnBW), municipal wastewater (MW), and secondary clarified effluent (SCE)), were assessed. During batch operational mode, eleven OMPs were removed from AnBW and MW. When switching from batch to continuous mode (0.8 d HRT), the removal of most OMPs from AnBW and MW decreased, suggesting that a longer retention time enhances the removal of some OMPs. Most OMPs were not removed from SCE since poor nutrient availability limited C. sorokiniana growth. Further correlation analyses between wastewater characteristics, biomass and OMPs removal indicated that the wastewater soluble COD and biomass concentration predominantly affected the removal of OMPs. Lastly, carbon uptake rate had a higher effect on the removal of OMPs than nitrogen and phosphate uptake rate. These data will give an insight on the implementation of microalgae-based technologies for the removal of OMPs in wastewater with varying strengths and nutrient availability.
  • Water Research

    Enhancing phosphorus removal of photogranules by incorporating polyphosphate accumulating organisms

    Lukas M. Trebuch, Jasper Sohier, Sido Altenburg, Ben Oyserman, Mario Pronk, Marcel Janssen, Louise E.M. Vet, René H. Wijffels, Tania Vasconcelos Fernandes

    Photogranules are a novel wastewater treatment technology that can utilize the sun's energy to treat water with lower energy input and have great potential for nutrient recovery applications. They have been proven to efficiently remove nitrogen and carbon but show lower conversion rates for phosphorus compared to established treatment systems, such as aerobic granular sludge. In this study, we successfully introduced polyphosphate accumulating organisms (PAOs) to an established photogranular culture. We operated photobioreactors in sequencing batch mode with six cycles per day and alternating anaerobic (dark) and aerobic (light) phases. We were able to increase phosphorus removal/recovery by 6 times from 5.4 to 30 mg/L/d while maintaining similar nitrogen and carbon removal compared to photogranules without PAOs. To maintain PAOs activity, alternating anaerobic feast and aerobic famine conditions were required. In future applications, where aerobic conditions are dependent on in-situ oxygenation via photosynthesis, the process will rely on sunlight availability. Therefore, we investigated the feasibility of the process under diurnal cycles with a 12-h anaerobic phase during nighttime and six short cycles during the 12 h daytime. The 12-h anaerobic phase had no adverse effect on the PAOs and phototrophs. Due to the extension of one anaerobic phase to 12 h the six aerobic phases were shortened by 47% and consequently decreased the light hours per day. This resulted in a decrease of phototrophs, which reduced nitrogen removal and biomass productivity up to 30%. Finally, we discuss and suggest strategies to apply PAO-enriched photogranules at large-scale.

  • ISME Journal

    High resolution functional analysis and community structure of photogranules

    Lukas M. Trebuch, Olivia M. Bourceau, Stijn M. F. Vaessen, Thomas R. Neu, Marcel Janssen, Dirk de Beer, Louise E.M. Vet, René H. Wijffels, Tania Vasconcelos Fernandes
    Photogranules are spherical aggregates formed of complex phototrophic ecosystems with potential for “aeration-free” wastewater treatment. Photogranules from a sequencing batch reactor were investigated by fluorescence microscopy, 16S/18S rRNA gene amplicon sequencing, microsensors, and stable- and radioisotope incubations to determine the granules’ composition, nutrient distribution, and light, carbon, and nitrogen budgets. The photogranules were biologically and chemically stratified, with filamentous cyanobacteria arranged in discrete layers and forming a scaffold to which other organisms were attached. Oxygen, nitrate, and light gradients were also detectable. Photosynthetic activity and nitrification were both predominantly restricted to the outer 500 µm, but while photosynthesis was relatively insensitive to the oxygen and nutrient (ammonium, phosphate, acetate) concentrations tested, nitrification was highly sensitive. Oxygen was cycled internally, with oxygen produced through photosynthesis rapidly consumed by aerobic respiration and nitrification. Oxygen production and consumption were well balanced. Similarly, nitrogen was cycled through paired nitrification and denitrification, and carbon was exchanged through photosynthesis and respiration. Our findings highlight that photogranules are complete, complex ecosystems with multiple linked nutrient cycles and will aid engineering decisions in photogranular wastewater treatment.
  • Biotechnology and Bioengineering

    N 2 ‐fixation can sustain wastewater treatment performance of photogranules under nitrogen limiting conditions

    Lukas M. Trebuch, Kobe Schoofs, Stijn M. F. Vaessen, Thomas R. Neu, Marcel Janssen, René H. Wijffels, Louise E.M. Vet, Tania Vasconcelos Fernandes
    Wastewater characteristics can vary significantly, and in some municipal wastewaters the N:P ratio is as low as 5 resulting in nitrogen-limiting conditions. In this study, the microbial community, function, and morphology of photogranules under nitrogen-replete (N+) and limiting (N−) conditions was assessed in sequencing batch reactors. Photogranules under N− condition were nitrogen deprived 2/3 of a batch cycle duration. Surprisingly, this nitrogen limitation had no adverse effect on biomass productivity. Moreover, phosphorus and chemical oxygen demand removal were similar to their removal under N+ conditions. Although performance was similar, the difference in granule morphology was obvious. While N+ photogranules were dense and structurally confined, N− photogranules showed loose structures with occasional voids. Microbial community analysis revealed high abundance of cyanobacteria capable of N2-fixation. These were higher at N− (38%) than N+ (29%) treatments, showing that photogranules could adjust and maintain treatment performance and high biomass productivity by means of N2-fixation.
  • Science of the Total Environment

    Removal processes of individual and a mixture of organic micropollutants in the presence of Scenedesmus obliquus

    Kaiyi Wu, Rosaria Tizzani, Hans Zweers, Huub Rijnaarts, Alette Langenhoff, Tania Vasconcelos Fernandes

    Organic micropollutants (OMPs) need to be removed from wastewater as they can negatively affect aquatic organisms. It has been demonstrated that microalgae-based technologies are efficient in removing OMPs from wastewater. In this study, the removal processes and kinetics of six persistent OMPs (diclofenac, clarithromycin, benzotriazole, metoprolol, carbamazepine and mecoprop) were studied during cultivation of Scenedesmus obliquus in batch mode. These OMPs were added as individual compounds and in a mixture. Short experiments (8 days) were performed to avoid masking of OMP removal processes by light and nutrient limitation. The results show that diclofenac, clarithromycin, and benzotriazole were mainly removed by photodegradation (diclofenac), biodegradation (benzotriazole), or a combination of these two processes (clarithromycin). Peroxidase was involved in intracellular and extracellular biodegradation when benzotriazole was present as individual compound. Carbamazepine, metoprolol and mecoprop showed no biodegradation or photodegradation, and neglectable removal (<5%) by bioadsorption and bioaccumulation. Using an OMP mixture had an adverse effect on the photodegradation of clarithromycin and diclofenac, with reduced first-order kinetic constants compared to the individual compounds. Benzotriazole biodegradation was inhibited by the presence of the OMP mixture. This indicates that the presence of OMPs inhibits the photodegradation and biodegradation of some individual OMPs. These results will improve our understanding of removal processes of individual and mixtures of OMPs by microalgae-based technologies for wastewater treatment.

  • Microorganisms

    On-site blackwater treatment fosters microbial groups and functions to efficiently and robustly recover carbon and nutrients

    Eiko Kuramae, Mauricio Rocha Dimitrov, Gustavo Ribeiro da Silva, Adriano Reis Lucheta, L.W. Mendes, Ronildson Lima Luz, Louise E.M. Vet, Tania Vasconcelos Fernandes
    Background: Wastewater is considered as a renewable resource water and energy. An advantage of decentralized sanitation systems is the separation of the blackwater (BW) stream, which is highly contaminated with human pathogens, from the remaining household water. However, the composition and functions of the microbial community in BW are not known. In this study, we used shotgun metagenomics to assess the dynamics of microbial community structure and function throughout a new BW anaerobic digestion system installed at The Netherlands Institute of Ecology. Samples from the influent (BW), primary effluent (anaerobic digested BW), sludge and final effluent of the pilot upflow anaerobic sludge blanket (UASB) reactor and microalgae pilot tubular photobioreactor (PBR) were analyzed.

    Results: Our results showed a decrease in microbial richness and diversity followed by a decrease in functional complexity and co-occurrence along the different modules of the bioreactor. The microbial diversity and function decrease were reflected both changes in substrate composition and wash conditions. The most prevalent core functions in influent (BW) were related to metabolism of carbohydrates, response to chemicals and drugs, and nitrogen. The core functions in anaerobic digested BW and upflow anaerobic sludge blanket reactor were related to response to stress, viral processes and iron-sulfur metabolism. Methanogenesis-related functions were most abundant in upflow anaerobic sludge blanket reactor. Effluent from tubular photobioreactor presented high abundances of functions related to nitrogen utilization, metal ion binding and antibiotic biosynthetic processes. Interestingly, the abundance of sequences related to ‘pathogenesis’ decreased from influent BW to SP1 to effluent from tubular photobioreactor. Our wastewater treatment system also decreased potential microbial functions related to pathogenesis.

    Conclusions: The new sanitation system studied here fosters microbial groups and functions that allow the system to efficiently and robustly recover carbon and nutrients while reducing pathogenic groups, ultimately generating a final effluent safe for discharge and reuse.
  • Water Research

    Impact of hydraulic retention time on community assembly and function of photogranules for wastewater treatment

    Lukas M. Trebuch, Ben Oyserman, Marcel Janssen, René H. Wijffels, Louise E.M. Vet, Tania Vasconcelos Fernandes
    Photogranules are dense, spherical agglomerates of cyanobacteria, microalgae and non-phototrophic microorganisms that have considerable advantages in terms of harvesting and nutrient removal rates for light driven wastewater treatment processes. This ecosystem is poorly understood in terms of the microbial community structure and the response of the community to changing abiotic conditions. To get a better understanding, we investigated the effect of hydraulic retention time (HRT) on photogranule formation and community assembly over a period of 148 days. Three laboratory bioreactors were inoculated with field samples from various locations in the Netherlands and operated in sequencing batch mode. The bioreactors were operated at four different HRTs (2.00, 1.00, 0.67, 0.33 days), while retaining the same solid retention time of 7 days. A microbial community with excellent settling characteristics (95–99% separation efficiency) was established within 2–5 weeks. The observed nutrient uptake rates ranged from 24 to 90 mgN L−1 day−1 and from 3.1 to 5.4 mgP L−1 day−1 depending on the applied HRT. The transition from single-cell suspension culture to floccular agglomeration to granular sludge was monitored by microscopy and 16S/18S sequencing. In particular, two important variables for driving aggregation and granulation, and for the structural integrity of photogranules were identified: 1. Extracellular polymeric substances (EPS) with high protein to polysaccharide ratio and 2. specific microorganisms. The key players were found to be the cyanobacteria Limnothrix and Cephalothrix, the colony forming photosynthetic eukaryotes within Chlamydomonadaceae, and the biofilm producing bacteria Zoogloea and Thauera. Knowing the makeup of the microbial community and the operational conditions influencing granulation and bioreactor function is crucial for successful operation of photogranular systems.
  • Resources, Conservation and Recycling

    From toilet to agriculture

    Afnan Suleiman, Késia Lourenço, C Clark, Ronildson Lima Luz, Gustavo H.R. Silva, Louise E.M. Vet, Heitor Cantarella, Tania Vasconcelos Fernandes, Eiko Kuramae
    Human activities are pushing earth beyond its natural limits, so recycling nutrients is mandatory. Microalgae are highly effective in nutrient recovery and have strong potential as a sustainable wastewater treatment technology. Here, nutrients from black water (toilet wastewater) were recovered as microalgal biomass, which was dried and assessed as a fertilizer in pot experiments compared with inorganic fertilizer. We deciphered the effects of microalgal biomass as a biofertilizer on plant growth and quality and the biological processes linked to greenhouse gas (GHG) emissions. In addition, we elucidated the assembly of the active microbiome in bulk soil and rhizosphere during barley development. Microalgal biomass application and inorganic fertilizer (NPK) resulted in similar plant productivity (16.6 g pot−1). Cumulative nitrous oxide (N2O) emissions were 4.6-fold higher in the treatment amended with microalgal fertilizer (3.1% of applied N) than that with inorganic fertilizer (0.5% of applied N). Nitrification by bacteria was likely the main pathway responsible for N2O emissions (R2 = 0.7, p ≤ 0.001). The application of nitrogen fertilizers affected the structures of both the active bacterial and protozoan communities, but these effects were less obvious than the strong plant effect, as the recruited microbiota varied among different plant developmental stages. Both treatments enriched similar bacterial and protozoan taxonomic orders but with different distributions through time across the plant developmental stages. Furthermore, the bacterial community showed a clear trend of resilience from the beginning of the experiment until harvest, which was not observed for protozoa. Our results indicate that the use of microalgal biomass as a fertilizer is a viable option for recycling nutrients from wastewater into plant production.
  • Journal of Environmental Management

    Nutrient and pathogen removal from anaerobically treated black water by microalgae

    Nathalie Dyane Miranda Slompo, Larissa Quartaroli, Tania Vasconcelos Fernandes, Gustavo H.R. Silva, Luiz Antonio Daniel
    The demand for systems that efficiently and sustainably recover value-added compounds and materials from waste streams is a major challenge. The use of wastewater as a source for recovery of carbon and nutrients is an attractive and sustainable alternative. In this study, anaerobically treated black water was treated in photobioreactors (PBRs) inoculated with Chlorella sorokiniana, and the process was investigated in terms of phosphorus and nitrogen removal, biomass growth, and the removal of pathogens. The consumption of bicarbonate (alkalinity) and acetate (volatile fatty acids) as carbon sources by microalgae was investigated. The average nutrient removal achieved was 66% for N and 74% for P. A high consumption of alkalinity (83%) and volatile organic acids (76%) was observed, which suggests that these compounds were used as a source of carbon. The biomass production was 73 mg L−1 day−1, with a mean biomass of 0.7 g L−1 at the end of the batch treatment. At the end of the experiments, a log removal/inactivation of 0.51 log for total coliforms and 2.73 log for Escherichia coli (E. coli) was observed. The configuration used, a flat-panel PBR operated in batch mode without CO2 supplementation, is a cost-effective and environmentally sustainable method for recovering of nutrients and production of algal biomass.
  • Algal Research

    Feasibility of closing nutrient cycles from black water by microalgae-based technology

    Gustavo H.R. Silva, Ana Paula E. Sueitt, Sarah Haimes, Aikaterini Ioli Tripidaki, Ralph van Zwieten, Tania Vasconcelos Fernandes
    Microalgae can recover macronutrients and trace elements from wastewaters. The microalgae biomass can then be used as fertilizer to enrich impoverished agricultural soils by increasing the soil´s carbon content and providing essential nutrients for soil health. Using microalgae for wastewater treatment will enable the shift from linear sanitation systems to circular ones where the carbon and nutrient cycles can be closed. By using a nutrient-rich wastewater medium for microalgae cultivation, high biomass productivity and, therefore, high nutrient recovery, can be achieved. In this study, we demonstrated that Chlorella sorokiniana and Chlorococcum sp. were able to grow in and remove nitrogen and phosphorus from anaerobically-digested black water (AnBW), in a 211 L tubular photobioreactor (PBR), placed in a temperature-controlled (25 °C) glass greenhouse, under Dutch natural light conditions (5.8 to 23.3 mol photons.m−2.d-1 and 67 to 270 μmol.s-1. m−2). The microalgae productivity varied from 0.13 g DW.L-1.d-1 (autumn) to 0.36 g DW.L-1.d-1 (summer). The nitrogen and phosphorus removal rates were 28 to 62 mg.L-l.d-1 and 2.3 to 5.4 mg.L-l.d-1, respectively. Due to the insufficient light availability for the high nitrogen and phosphorus concentrations of the AnBW cultivation medium (1280 mg.L-l and 68 mg.L-l, respectively), the overall nutrient removal efficiencies remained below 50% even during the summer period when light intensity was at its highest. Partial nitrification was confirmed by the accumulation of nitrite (≥ 1000 mg NO2-N.L-l) in the PBR. These high NO2 concentrations did not, however, hinder microalgae growth. The macronutrient and trace element compositions of the dry microalgal biomass were similar to commercially available organic fertilizers, indicating a potential for soil enrichment.
  • Bioresource Technology

    Enhancement of co-production of nutritional protein and carotenoids in Dunaliella salina using a two-phase cultivation assisted by nitrogen level and light intensity

    Yixing Sui, Maarten Muys, Dedmer Van de Waal, Sarah D'Adamo, Pieter Vermeir, Tania Vasconcelos Fernandes, Siegfried E. Vlaeminck
    Microalga Dunaliella salina is known for its carotenogenesis. At the same time, it can also produce high-quality protein. The optimal conditions for D. salina to co-produce intracellular pools of both compounds, however, are yet unknown. This study investigated a two-phase cultivation strategy to optimize combined high-quality protein and carotenoid production of D. salina. In phase-one, a gradient of nitrogen concentrations was tested. In phase-two, effects of nitrogen pulse and high illumination were tested. Results reveal optimized protein quantity, quality (expressed as essential amino acid index EAAI) and carotenoids content in a two-phase cultivation, where short nitrogen starvation in phase-one was followed by high illumination during phase-two. Adopting this strategy, productivities of protein, EAA and carotenoids reached 22, 7 and 3 mg/L/d, respectively, with an EAAI of 1.1. The quality of this biomass surpasses FAO/WHO standard for human nutrition, and the observed level of β-carotene presents high antioxidant pro-vitamin A activity.
  • Frontiers in Microbiology

    Toward an Ecologically Optimized N:P Recovery from Wastewater by Microalgae

    Tania Vasconcelos Fernandes, María Suárez-Muñoz, Lukas M. Trebuch, Paul J. Verbraak, Dedmer Van de Waal
    Global stores of important resources such as phosphorus (P) are being rapidly depleted, while the excessive use of nutrients has led to the enrichment of surface waters worldwide. Ideally, nutrients would be recovered from wastewater, which will not only prevent eutrophication but also provide access to alternative nutrient stores. Current state-of-the-art wastewater treatment technologies are effective in removing these nutrients from wastewater, yet they can only recover P and often in an insufficient way. Microalgae, however, can effectively assimilate P and nitrogen (N), as well as other macro- and micronutrients, allowing these nutrients to be recovered into valuable products that can be used to close nutrient cycles (e.g. fertilizer, bioplastics, colour dyes, bulk chemicals). Here, we show that the green alga Chlorella sorokiniana is able to remove all inorganic N and P present in concentrated toilet wastewater (i.e. black water) with N:P ratios ranging between 15 and 26. However, the N and P uptake by the algae is imbalanced relative to the wastewater N:P stoichiometry, resulting in a rapid removal of P but relatively slower removal of N. Here, we discuss how ecological principles such as ecological stoichiometry and resource-ratio theory may help optimize N:P removal and allow for more effective recovery of N and P from black water.
  • Journal of Hazardous Materials

    Micropollutant removal in an algal treatment system fed with source separated wastewater streams

    Arnoud de Wilt, Andrii Butkovskyi, Kanjana Tuantet, Lucia Hernandez Leal, Tania Vasconcelos Fernandes, Alette Langenhoff, Grietje Zeeman
    Micropollutant removal in an algal treatment system fed with source separated wastewater streams was studied. Batch experiments with the microalgae Chlorella sorokiniana grown on urine, anaerobically treated black water and synthetic urine were performed to assess the removal of six spiked pharmaceuticals (diclofenac, ibuprofen, paracetamol, metoprolol, carbamazepine and trimethoprim). Additionally, incorporation of these pharmaceuticals and three estrogens (estrone, 17β-estradiol and ethinylestradiol) into algal biomass was studied. Biodegradation and photolysis led to 60–100% removal of diclofenac, ibuprofen, paracetamol and metoprolol. Removal of carbamazepine and trimethoprim was incomplete and did not exceed 30% and 60%, respectively. Sorption to algal biomass accounted for less than 20% of the micropollutant removal. Furthermore, the presence of micropollutants did not inhibit C. sorokiniana growth at applied concentrations. Algal treatment systems allow simultaneous removal of micropollutants and recovery of nutrients from source separated wastewater. Nutrient rich algal biomass can be harvested and applied as fertilizer in agriculture, as lower input of micropollutants to soil is achieved when algal biomass is applied as fertilizer instead of urine.
  • Bioenergy Research

    Humic Acid-Like and Fulvic Acid-Like Inhibition on the Hydrolysis of Cellulose and Tributyrin

    Tania Vasconcelos Fernandes, Jules B. van Lier, Grietje Zeeman
    Enzymatic hydrolysis of complex wastes is a critical step for efficient biogas production in anaerobic digesters. Inhibition of this hydrolytic step was studied by addition of humic acid-like (HAL) and fulvic acid-like (FAL) substances, extracted from maize silage and fresh cow manure, to batch tests with cellulose and cellulases from Aspergillus niger and tributyrin and lipases from Candida rugosa. To confirm the inhibition results, microbially catalysed hydrolysis trials were performed, where Fibrobacter succinogenes was grown exclusively on cellulose. Hydrolysis products, as glucose, glycerol and butyric acid, were measured to determine the hydrolysis efficiency and its rate. Cellulose hydrolysis was inhibited by 0.5 to 5.0 g l(-1) of HAL and FAL substances extracted from maize and cow manure, which are relevant concentrations for manure and maize digestion. Tributyrin hydrolysis, on the other hand, was only inhibited by 0.5 to 5.0 g l(-1) of HAL substances extracted from maize and cow manure and not by FAL substances.
  • Environmental Science and Technology

    Closing Domestic Nutrient Cycles Using Microalgae

    Tania Vasconcelos Fernandes, R. Shrestha, Yixing Sui, Gustavo Papini, Grietje Zeeman, Louise E.M. Vet, René H. Wijffels, Packo Lamers
    This study demonstrates that microalgae can effectively recover all P and N from anaerobically treated black water (toilet wastewater). Thus, enabling the removal of nutrients from the black water and the generation of a valuable algae product in one step. Screening experiments with green microalgae and cyanobacteria showed that all tested green microalgae species successfully grew on anaerobically treated black water. In a
    subsequent controlled experiment in flat-panel photobioreactors, Chlorella sorokiniana was able to remove 100% of the phosphorus and nitrogen from the medium. Phosphorus was depleted within 4 days while nitrogen took 12 days to reach depletion. The phosphorus and nitrogen removal rates during the initial linear growth phase were 17 and 122 mg·L−1·d−1, respectively. After this initial phase, the phosphorus was depleted. The nitrogen removal rate continued to decrease in the second phase, resulting in an overall removal rate of 80 mg·L−1·d−1. The biomass concentration at the end of the experiment was 11.5 g·L−1, with a P content of approximately 1% and a N content of 7.6%. This high algal biomass concentration, together with a relatively short P recovery time, is a promising finding for future post-treatment of black water while gaining valuable algal biomass for further application.

Projecten & samenwerkingen