Significant Biomass Production Research Articles

Utilizing Mixed Cultures of Microalgae to Up-Cycle and Remove Nutrients from Dairy Wastewater.

This study explores the novel use of mixed cultures of microalgae-Spirulina platensis, Micractinium, and Chlorella-for nutrient removal from dairy wastewater (DW). Microalgae were isolated from a local wastewater treatment plant and cultivated under various light conditions. The results showed significant biomass production, with mixed cultures achieving the highest biomass (2.51 g/L), followed by Spirulina (1.98 g/L) and Chlorella (1.92 g/L). Supplementing DW (75%) with BG medium (25%) significantly enhanced biomass and pH levels, improving pathogenic bacteria removal. Spirulina and mixed cultures exhibited high nitrogen removal efficiencies of 92.56% and 93.34%, respectively, while Chlorella achieved 86.85% nitrogen and 83.45% phosphorus removal. Although growth rates were lower under phosphorus-limited conditions, the microalgae adapted well to real DW, which is essential for effective algal harvesting. Phosphorus removal efficiencies ranged from 69.56% to 86.67%, with mixed cultures achieving the highest removal. Microbial and coliform removal efficiencies reached 97.81%, with elevated pH levels contributing to significant reductions in fecal E. coli and coliform levels. These findings suggest that integrating microalgae cultivation into DW treatment systems can significantly enhance nutrient and pathogen removal, providing a sustainable solution for wastewater management.

From kitchen to crop: The efficacy and safety of the microbial consortium treated dishwasher wastewater for the Zero Mile system

A microbial consortium, based on the functional integration of photosynthetic and heterotrophic microorganisms, is the core of the Zero Mile System. This system is designed for reusing and upcycling household greywaters, a still untapped water resource. The previous challenges of dishwasher wastewater bioremediation demonstrated the capability of an ad hoc consortium (including a photosynthetic cyanobacterium and three heterotrophic bacterial isolates from dishwasher wastewater) to reclaim the wastewater at small/medium scale. In this study the wastewater treatment demonstrated to be effective in nutrient recycling and upcycling at a larger scale, i.e. 4 L (in three replicates to treat the total amount of wastewater discharged by the dishwasher), by removing high percentage of N and P from the wastewater (70% nitrogen, 50% phosphorous, respectively). Again, the reclaimed wastewater successfully fertilized lettuce plants both indoor (in the Zero Mile System demonstrator) and outdoor (in open field). Plants showed a significant higher biomass productivity in fresh weight compared to control plants and comparable or better values of the pigments and quality indices (e.g., soluble solids, total phenols, total flavonoids). Furthermore, the safety of the reclaimed wastewater is demonstrated by the analysis of the metabolic/ecologically relevant functions of the microbial communities in both untreated and treated wastewater. Colonizers were mainly organic matter degraders and bacteria involved in nitrogen cycling. The human related genera are quite few and no pathogens or potential microbiological contaminants of water bodies (as E. coli), were found. Hence, the utilization of treated dishwasher wastewater does not imply biological risks to agricultural products, soil, or groundwater.

Crude Oil Biodegradation Performance in Natural Seawater of a Trichoderma species from Decaying Mangrove Wood in East Kalimantan

Large-scale petroleum production poses environmental and human health risks, particularly due to petroleum contamination in marine environments. The aim of this study was to isolate and screen fungi inhabiting decaying mangrove wood in East Kalimantan with their ability to degrade crude oil in seawater. In the initial step, fungi were isolated using standard methods and screened for crude oil degradation and biomass production. Selected fungi were based on their significant biomass production. Subsequently, the selected fungus was cultured in three types of media based on natural seawater and crude oil at initial concentrations ranging from 1% to 5% (v/v). The biodegradation of crude oil was assessed spectrophotometrically at 420 nm. Out of the 17 decaying wood fungi, MG-07 exhibited significantly higher biomass production compared to the control medium (without crude oil). Gas chromatography-mass spectrometry analysis indicated that MG-07 degraded 20%–80% of the normal aliphatic compounds in the tested crude oils within 2 weeks. Furthermore, the growth and degradation efficiency of MG-07 was significantly enhanced when cultured in a natural seawater medium containing crude oil, supplemented with glucose (20 g/L) and Tween 80 (1% v/v). The highest observed biomass gains were 867%, with a biodegradation efficiency of 31.6% at a crude oil concentration of 1%. MG-07 was identified as Trichoderma sp. based on the internal transcribed spacer region. The results obtained from this study demonstrate that MG-07 has significant potential for degrading crude oil in saline environments. These findings provide valuable insights for the application of fungi in marine oil spill remediation.

Exploring microalgal nutrient-light synergy to enhance CO2 utilization and lipid productivity in sustainable long-term water recycling cultivation

In this work the effects of nutrient availability and light conditions on CO2 utilization and lipid production in Micractinium pusillum KMC8 is reported. The study investigated the ideal nitrogen concentrations for growth and nitrogen utilization in a 15% CO2 environment. Logistic and Gompertz models were employed to analyze the kinetics of KMC8 cell growth. Compared to 17.6 mmol L−1 control nitrogen, which generated 1.6 g L−1 growth, doubling and quadrupling nitrogen concentrations boosted biomass growth by 12.5% and 28.78%. At 8.6 mmol L−1 nitrogen, the growth decreased but lipid productivity increased to 18.62 mg L−1 day−1. At 70.6 mmol L−1 nitrogen, elevated nitrogen levels maintained an alkaline pH above 7 and enhanced CO2 mitigation, achieving 2.27% CO2 utilization efficiency. Nitrogen shows a positive correlation with higher rates of carbon and nitrogen fixation. The investigation extends to find out the influence of phosphorus and light conditions on microalgae. Increasing light intensity incrementally from 150 to 1200 μmol m−2 s−1 with more phosphorus increased biomass productivity by 85% (255 mg L-1 day−1) and lipid productivity by 2.5-fold (84.76 mg L-1 day−1), with 3.3% CO2 utilization efficiency compared to directly using 1200 μmol m−2 s−1. This study suggests a water recycling-fed batch cycle with gradual light feeding, which results in high CO2 fixation (1.1 g L−1 day−1), 7% CO2 utilization, and significant biomass and lipid productivity (577.23 and 150 mg L−1 day−1). This approach promotes lipid synthesis, maintains carbon fixation, and minimizes biomass loss, thus supporting sustainable bioenergy development in a circular bio-economy framework.

Nutrient uptake efficiency and stoichiometry for different plant functional groups on spoil heap after hard coal mining in Upper Silesia, Poland

Various plant functional groups (PFGs) used in the reclamation of post-mining heaps may differ in their nutrient uptake efficiency and thus in their effect on the ecosystem development. The effect of PFGs may be additionally modified by the applied reclamation measures such as e.g. topsoiling. In this study we compared the nutrient uptake efficiencies and plant stoichiometry for two PFGs (grasses and forbs) growing on the sites reclaimed by applying topsoil (TS) and unreclaimed sites on carboniferous bare rock (BR) in hard coal spoil heap in Upper Silesia (southern Poland). Basic soil parameters, including pH, texture, soil organic carbon, and nutrients (N, P, K, Ca, and Mg), were measured, and the aboveground plant biomass and nutrient content in plant tissue were determined. Forbs were characterized by a larger biomass and higher nutrient concentrations (except for P) than grasses. The TS treatment supported higher concentrations of N and P in plant tissues but not to the level ensuring more significant primary biomass production. The nutrient concentration and elemental stoichiometry in plant tissue indicated that N was the primary limiting element. However, the major growth limitation for N-fixing forbs was from P. Forbs were much more efficient in nutrient uptake than grasses, independent of the reclamation treatment. Therefore, they stimulate nutrient cycling in the restored ecosystems more than grasses.

Quality Stock Production of Aquilaria malaccensis Lamk. Using Arbuscular Mycorrhizal Inoculation: Restoration of Agarwood Source

Aquilaria malaccensis Lamk. is a critically endangered and economically important forest tree species of North-east India. In the current study, a biotization experiment was performed to show the effect of arbuscular mycorrhizae on obtaining high-quality agarwood-producing plants. One-month-old seedlings were inoculated in a designed experiment with single and combined endomycorrhizal treatments. All inoculated seedlings showed significant biomass production than control seedlings. The Biovolume index (Bi) was higher in all inoculated plant seedlings than in non-inoculated control seedlings but Acaulospora spp. (EM2) treatment had a higher Bi (78.17±0.024) than the rest of the inoculation treatments. The Quality index (Qi) value was also high (1.22±0.024) in EM2 treatment followed by the Glomus spp. + Acaulospora spp. (EM1+EM2) treatment (1.10±0.031) and Glomus spp. (EM1) (0.83±0.014) treatment. Control seedlings had a lower value (0.14±0.021) of Qi than the rest of the treatments. The plastochrone interval index (Pi) of A. malaccensis after 60 days of inoculation was low in EM1+EM2 treatment as the time interval for initiation of 2nd leaf was 1 day than rest of the treatments in which the time interval was 4 days for initiation of the 2nd leaf primordia. Substantially, the leaf primordia appearance in the EM1+EM2 treatment was impetuous than rest of the treatments. In the control treatment, the 8th leaf primordia appeared on the 36th day and after that, there was no appearance of leaf primordia. Therefore, the EM2 treatment was the best single/alone treatment of mycorrhizal inoculation followed by EM1+EM2 synergistic treatment for quality stock production of A. malaccensis seedlings.

Studies of polyol production by the yeast Yarrowia lipolytica growing on crude glycerol under stressful conditions

Crude glycerol, the principal by-product of biodiesel production process, was employed as substrate by three wild-type Yarrowia lipolytica strains (ACA-YC 5030, LMBF 20 and NRRL Y-323). Stressful conditions (low pH value = 2.0 ± 0.3, low incubation temperature T = 20 ± 1 °C, non-aseptic conditions) were employed. Interesting production of yeast biomass and polyols (viz. erythritol, mannitol and arabitol) was noted at pH = 2.0 ± 0.3 and T = 20 ± 1 °C. Strains failed to produce significant quantities of cellular lipid, while variable quantities of intra-cellular polysaccharides were produced. Fermentations under previously pasteurized media supported significant biomass and polyols production for most of the tested strains, while only one strain (NRRL Y-323), managed to produce polyols at media that were not previously thermally treated at all. The production of mannitol was favored at low initial glycerol (Glol0) concentrations, whereas higher Glol0 quantities favored the biosynthesis of erythritol. For the strain NRRL Y-323, highly aerated / agitated bioreactor trials showed different physiological profiles as compared to the respective flask experiments. Finally, in flask experiments with the strain NRRL Y-323 at high Glol0 amounts (≈140 g/L) at low medium pH (=2.0 ± 0.3), a significant production of polyols (=84.2 g/L) with the corresponding remarkable conversion yield on glycerol consumed = 62 % w/w was achieved. Practical applicationRenewable and biodegradable fuels, such as biodiesel, are safer and environmentally friendlier than the conventional petroleum diesel. Glycerol is a cost-effective substrate obtained as the main side-product from biodiesel production process and is currently being employed in the realm of Industrial Microbiology and Biotechnology to produce metabolic products with added value. Current research focuses on using glycerol as a starting substrate for biotechnological conversions aiming at producing, amongst other compounds, polyols, microbial biomass, citric acid, etc. from selected strains of the Generally Recognized Αs Safe (GRAS) yeast Yarrowia lipolytica. In the current investigation therefore, we examined the capacity of new wild-type non-extensively studied strains of this yeast to grow and assimilate this inexpensive substrate. Specifically, we have performed the acclimatization of the mentioned strains to stressful environments (i.e., low pH, low incubation temperature, non-aseptic conditions, etc.) and remarkable quantities of the added-value compounds (polyols, yeast mass, citric acid) were produced.

CO2 to green fuel converter: Photoautotrophic-cultivation of microalgae and its lipids conversion to biodiesel

This research focused on utilizing photoautotrophically-cultivated microalgae as efficient converters of CO2 into high-quality renewable biodiesel. This study investigated the feasibility of capturing CO2 from the atmosphere (0.04 % CO2) and simulating industrial sources (20–40 % CO2) for utilization as a simulated waste carbon source for the growth and biodiesel feedstock accumulation of three photoautotrophically-cultivated microalgae species, including Chlorella sp. AARL G049, Tetradesmus obliquus AARL G090, and Desmodesmus opoliensis AARL G085. The results demonstrated that all the tested microalgae are promising CO2-to-fuel converters due to their ability to efficiently convert CO2 into lipid-rich biomass, which can subsequently be processed into biodiesel. All three strains of microalgae displayed remarkable CO2 capture capabilities as well as significant biomass production and lipid accumulation, with the highest performance observed under a 20 % CO2 concentration. The microalgae demonstrated CO2 fixation rates ranging from 0.020 to 0.072 g-CO2/L/day, leading to significant improvements in both biomass productivity, which ranged from 0.011 to 0.040 g/L/day, and lipid accumulation, which ranged from 0.22 to 3.39 mg/L/day. Additionally, the lipid content varied between 5.04 % and 14.75 %. Interestingly, changes in CO2 concentration, ranging from 0.04 % to 40 %, significantly influenced the composition of fatty acids, leading to elevated levels of C16–C18 fatty acids. Nevertheless, these alterations had a minimal impact on the overall quality of biodiesel. The estimated fuel characteristics of the produced biodiesel complied with global specifications for biodiesel, providing better oxidative stability (≥6 h), high heating value (≥39 MJ/kg), and cetane number (≥47). Therefore, this study emphasizes sustainable CO2 capture and the potential of microalgae as a renewable source of economically viable biodiesel.

Sustainable Use of CO2 and Wastewater from Mushroom Farm for Chlorella vulgaris Cultivation: Experimental and Kinetic Studies on Algal Growth and Pollutant Removal

The potential use of carbon dioxide (CO2) and wastewater released from a mushroom farm for the cultivation of Chlorella vulgaris microalga was investigated in this study. For this purpose, a microcontroller-based aided CO2 capture and mixing prototype was constructed for the cultivation of C. vulgaris under varying concentrations of mushroom farm wastewater (0 as control, 50 and 100%). The results showed that the constructed prototype was helpful to maintain desirable CO2 levels (6000 ppm) in the mushroom cultivation chamber with constant CO2 supply to algal culture, i.e., 0.6% at an airflow rate of 50 mL/min. After 16 days of algal cultivation, it was observed that the maximum significant (p < 0.05) algal biomass production of 2.550 ± 0.073 mg/L was recorded in 50% wastewater concentration followed by 100% and control. Also, the maximum removal of selected mushroom farm wastewater pollutants, such as total dissolved solids (84.00 ± 1.37%), biochemical oxygen demand (90.17 ± 2.42%), chemical oxygen demand (91.53 ± 0.97%), total nitrogen (86.27 ± 1.60%) and total phosphorus (94.19 ± 2.33%), was achieved in 50% concentration of wastewater treatment with maximum first-order rate constant (k) values. In addition, the algal growth kinetics results showed that the logistic model fit best compared to the modified Gompertz model, based on selected validation tools, such as experimental vs. predicted values, coefficient of determination (R2 > 0.9938), model efficiency (ME > 0.98) and root mean square error (RMSE < 0.03). The post-harvest characterization of algal biomass revealed that the proximate, biochemical, ultimate elements (carbon, oxygen and nitrogen) and structural properties were significantly higher in 50% treatment than those in 100% and control treatments. Therefore, the findings of this study are novel and provide significant insight into the synergistic use of CO2 and wastewater produced by mushroom farms for algal cultivation and biological wastewater treatment.

Water flux and biomass production of native plants at different substrate compactions for landfill phytocaps in Southeast Queensland, Australia

Phytocaps for landfills and degraded sites have multiple benefits provided by the established vegetation, including reducing substrate moisture content and drainage through evapotranspiration. One of the factors affecting plant development measured by biomass production is substrate compaction. However, the relationship between drainage and biomass production related to substrate compaction is largely unknown. In an outdoor pot experiment, four native plant species: Eucalyptus terreticornis, Acacia concurrens, Allocasuarina littoralis, and Themeda triandra, grown in coal overburden at three different relative compactions (RC) levels (64%, 77% and 87% of the maximum compaction) in Southeast Queensland, Australia, over seven months. Evapotranspiration rate was measured by change in pot weight. Drainage for each pot was collected in a container after every irrigation and rainfall. Biomass of plants were harvested for dry shoot and root weight measurement. Additionally, root length density was obtained by a root scanner. Our statistical model predicted that 69.8% RC for maximum weekly ET. Overall, 77% RC treatment resulted in higher total evapotranspiration (1.5%), more significant shoot and root biomass production (17.2% and 11.8%, respectively), higher root length density (33.4%) and lower total drainage (20%) compared to 64% and 87% RC treatments. Native woody species had a higher rate of evapotranspiration and a lower rate of drainage than the native grass. Reduction in drainage was correlated with increase in evapotranspiration rate for all plant species, as the soil moisture content decreases through evapotranspiration. These findings support the notion of maximising evapotranspiration to minimise drainage, a key objective for phytocap design. From biomass production, root biomass closely correlates to a reduction in drainage. Multiple lines of evidence from this study indicate that 77% RC treatment maximises evapotranspiration and plant development and minimises deep drainage for phytocap applications, even though harsh microclimate in this experiment may have constrained plant development and affected the water flux.

Dynamical Darwinian selection of a more productive strain of Tisochrysis lutea

Species domestication and improvement were decisive in increasing agricultural production yields. The microalgae industry must now realize the same accomplishment to boost its development instead of only using wild strains. Although genetically engineering microalgae is a promising path to explore, the artificial modification of the microalgae genome can have adverse side-effects on biomass productivity. Here, we propose a Darwinian method to select and improve microalgal strains, exploiting the competitive exclusion principle in a dynamical environment to drive evolution. Choosing an appropriate selection pressure allows a new adapted population having enhanced properties to emerge. In a natural growing environment, light intensity is consistently changing due to meteorological events, differing microalgae concentration and other exogenous factors. Consequently, the pigmentary profile regulation and the associated genetic mechanism is highly modulable in most microalgae. On top of this, high light intensities are known to elicit strong cellular stresses. For these reasons, a dynamical light regime with high light intensities was deemed a potentially efficient selection factor for the emergence of a new strain adapted to higher irradiance levels. Following 160 days of selection under variable light intensity the biomass productivity of Tisochrysis lutea increased by 77%. Genetic analyses further confirmed the selection protocol's success, with the apparition of 2716 new alleles. To our knowledge, this is the first selection approach allowing a significant biomass productivity increase resulting from an enhanced capacity of microalgae pigment photoadaptation.

Response of sea surface temperature, chlorophyll and particulate organic carbon to a tropical cyclonic storm over the Arabian Sea, Southwest India

The response of sea surface temperature (SST), chlorophyll (Chl) and particulate organic carbon (POC) to the tropical cyclonic storm Ockhi between 29th November and 6th December 2017 over the Arabian Sea, Southwest coast of India was studied. The unique observation is that the cyclone overturned northeastwards (clockwise), the wind speed in north-northwestwards (8–12 m s−1) which caused cold patches (< 28.5 °C) in the northwestern Arabian Sea compared to the southwest coast of India. Sea surface cooling (3–4 °C) was observed in concurrence with significant Chl response (0.5–7.5 mg m−3) along the Ockhi cyclone path. The post cyclonic low SST and high Chl from cyclone centre to farther areas suggested the extent of upwelled nutrient rich cold waters for plankton proliferation. POC levels showed a 3-fold increase, affected by significant biomass production due to subsurface phytoplankton and nutrient sources evidenced by deepening of mixed layer depth. The cyclone induced contrasting surface Chl (< 1 mg m−3) and POC (80–160 mg m−3) concentration substantiated the dominance of less labile refractory organic particulates in the offshore waters. The sub surface cooling and Chl bloom was noticed up to 50 m indicating the strong relation of vertical bio-physical structure during tropical cyclones. This study revealed that the tropical cyclones can act in such a way that it improves the positive magnitude of Chl and POC whereas reverses the SST behavior, on either side of the cyclone path within a short period in the oligotrophic waters of Arabian Sea.

Low Crystallinity of Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate) Bioproduction by Hot Spring Cyanobacterium Cyanosarcina sp. AARL T020.

The poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) derived from cyanobacteria is an environmentally friendly biodegradable polymer. The low yield of PHBV’s production is the main hindrance to its sustainable production, and the manipulation of PHBV production processes could potentially overcome this obstacle. The present research investigated evolutionarily divergent cyanobacteria obtained from local environments of Thailand. Among the strains tested, Cyanosarcina sp. AARL T020, a hot spring cyanobacterium, showed a high rate of PHBV accumulation with a fascinating 3-hydroxyvalerate mole fraction. A two-stage cultivation strategy with sole organic carbon supplementation was successful in maximizing cyanobacterial PHBV production. The use of an optimized medium in the first stage of cultivation provided a 4.9-fold increase in biomass production. Subsequently, the addition of levulinic acid in the second stage of cultivation can induce significant biomass and PHBV production. With this strategy, the final biomass production and PHBV productivity were increased by 6.5 and 73.2 fold, respectively. The GC-MS, FTIR, and NMR analyses confirmed that the obtained PHBV consisted of two subunits of 3-hydroxyvaryrate and 3-hydroxybutyrate. Interestingly, the cyanobacterial PHBV contained a very high 3-hydroxyvalerate mole fraction (94%) exhibiting a low degree of crystallinity and expanding in processability window, which could be applied to polymers for desirable advanced applications.

Screening of two freshwater green microalgae in pulp and paper mill wastewater effluents in Nova Scotia, Canada.

In recent years, the use of microalgae as feedstock for many marketable products, such as animal/aqua feeds, bioplastics and fertilizers, has gained renewed interest due to their fast growth potential coupled with relatively high lipid, carbohydrate and nutrient content. An algal biorefinery at an industrial site has the potential to sustainably and profitably convert carbon dioxide emissions into microalgal biomass and concomitantly reduce nitrogen and phosphorus from wastewaters. Industrial wastewaters are a potential alternative to traditional media used for large-scale microalgal cultivation. Pulp and paper mills are major consumers of water resources and discharge a huge amount of water to nearby lakes or rivers. This study investigated whether pulp and paper mill waste water is suitable for microalgal cultivation with the aim of achieving significant biomass production. Six different process waters from one Canadian pulp and paper mill were tested with two freshwater green microalgae. All of these waters were unable to support growth of microalgae due to inadequate nutrient concentrations, colour, turbidity and possible toxicity issues.

Development of a novel nannochloropsis strain with enhanced violaxanthin yield for large\u2010scale production

BackgroundNannochloropsis is a marine microalga that has been extensively studied. The major carotenoid produced by this group of microalgae is violaxanthin, which exhibits anti-inflammatory, anti-photoaging, and antiproliferative activities. Therefore, it has a wide range of potential applications. However, large-scale production of this pigment has not been much studied, thereby limiting its industrial application.ResultsTo develop a novel strain producing high amount of violaxanthin, various Nannochloropsis species were isolated from seawater samples and their violaxanthin production potential were compared. Of the strains tested, N. oceanica WS-1 exhibited the highest violaxanthin productivity; to further enhance the violaxanthin yield of WS-1, we performed gamma-ray-mediated random mutagenesis followed by colorimetric screening. As a result, Mutant M1 was selected because of its significant higher violaxanthin content and biomass productivity than WS-1 (5.21 ± 0.33 mg g− 1 and 0.2101 g L− 1 d− 1, respectively). Subsequently, we employed a 10 L-scale bioreactor to confirm the large-scale production potential of M1, and the results indicated a 43.54 % increase in violaxanthin production compared with WS-1. In addition, comparative transcriptomic analysis performed under normal light condition identified possible mechanisms associated with remediating photo-inhibitory damage and other key responses in M1, which seemed to at least partially explain enhanced violaxanthin content and delayed growth.ConclusionsNannochloropsis oceanica mutant (M1) with enhanced violaxanthin content was developed and its physiological characteristics were investigated. In addition, enhanced production of violaxanthin was demonstrated in the large-scale cultivation. Key transcriptomic responses that are seemingly associated with different physiological responses of M1 were elucidated under normal light condition, the details of which would guide ongoing efforts to further maximize the industrial potential of violaxanthin producing strains.

Efficiency of Salicornia neei to Treat Aquaculture Effluent from a Hypersaline and Artificial Wetland

In this study, we evaluated the potential of Salicornia neei, a halophyte plant native to South America, to treat saline effluents with simulated concentration of ammonium-N (Amm) and nitrate-N (Nit) in a similar manner to land-based marine aquaculture effluents. Plants were cultivated for 74 days in drainage lysimeters under three treatments of seawater fertilized with: (1) Nit + Amm, (2) Nit, or (3) without fertilizer (Control). Over five repetitions, nitrogen removal efficiency (RE) was high in both treatments (Nit + Amm = 89.6% ± 1.0%; Nit 88.8% ± 0.9%), whereas the nitrogen removal rate (RR) was nonlinear and concentration-dependent (RRday1–4: Nit + Amm = 2.9 ± 0.3 mg L−1 d−1, Nit = 2.4 ± 0.5 mg L−1 d−1; RRday5–8: Nit + Amm = 0.8 ± 0.2 mg L−1 d−1, Nit = 1.0 ± 0.2 mg L−1 d−1). Effluent salinity increased from 40.6 to 49.4 g L−1 during the experiment, with no observed detrimental effects on RE or RR. High nitrogen removal efficiency and significant biomass production were observed (Nit + Amm = 11.3 ± 2.0 kg m−2; Nit = 10.0 ± 0.8 kg m−2; Control = 4.6 ± 0.6 kg m−2) demonstrate that artificial wetlands of S. neei can be used for wastewater treatment in saline aquaculture in South America.

Biotreatment of Poultry Waste Coupled with Biodiesel Production Using Suspended and Attached Growth Microalgal-Based Systems

Poultry litter extract (PLE) was treated using a microbial consortium dominated by the filamentous cyanobacterium Leptolyngbya sp. in synergy with heterotrophic microorganisms of the poultry waste. Laboratory- and pilot-scale experiments were conducted under aerobic conditions using suspended and attached growth photobioreactors. Different dilutions of the extract were performed, leading to different initial pollutant (nitrogen, phosphorus, dissolved chemical oxygen demand (d-COD), total sugars) concentrations. Significant nutrient removal rates, biomass productivity, and maximum lipid production were determined for all the systems examined. Higher d-COD, nitrogen, phosphorus, and total sugars removal were recorded in the attached growth reactors in both laboratory- (up to 94.0%, 88.2%, 97.4%, and 79.3%, respectively) and pilot-scale experiments (up to 82.0%, 69.4%, 81.0%, and 83.8%, respectively). High total biomass productivities were also recorded in the pilot-scale attached growth experiments (up to 335.3 mg L−1d−1). The produced biomass contained up to 19.6% lipids (w/w) on a dry weight basis, while the saturated and monounsaturated fatty acids accounted for more than 70% of the total fatty acids, indicating a potential biodiesel production system. We conclude that the processing systems developed in this work can efficiently treat PLE and simultaneously produce lipids suitable as feedstock in the biodiesel manufacture.

EFFECT OF INCREASING THE FERTILIZER DOSE ON BIOMASS PRODUCTION OF Eucalyptus dunnii Maiden

With the recent expansion of Eucalyptus dunnii Maiden cultivation in central region of Rio Grande do Sul state, recurrent questions arise from both research and operational silviculture, especially in relation to mineral fertilization. The objective of this study was to test the effect of fertilizer dose increase (150, 225 and 450 g plant-1 of N-P2O5-K2O, in 24:00:24 proportion) on the biomass production, carbon stock and nutrients in Eucalyptus dunnii trees cultivated in dystrophic Inceptisol, in central region of Rio Grande do Sul state, Brazil. This study revealed that there is no effect of the fertilizer dose increase on the accumulation of biomass, carbon and nutrients in components of Eucalyptus dunnii trees. The nutrients were more concentrated in leaves; in stemwood there was greater stock of carbon and potassium; in branches and stembark the calcium prevailed. Due to the significant biomass production, regardless of fertilizer dose, aiming at reducing costs and environmental impacts, it is recommended to apply mineral fertilization with 150 g plant-1 of N-P2O5-K2O, in 24:00:24 proportion, in Eucalyptus dunnii stand cultivated in dystrophic Inceptisol, in central region of Rio Grande do Sul state, Brazil.

Using Various Approaches of Design of Experiments for High Cell Density Production of the Functionally Probiotic Lactobacillus plantarum Strain RPR42 in a Cane Molasses-based Medium.

Considering the economic importance of the probiotics, industrial production of their biomass became important. Cane molasses, as an industrial byproduct, was used in this study to design a medium for biomass overproduction of a functionally probiotic strain, designated as Lactobacillus plantarum strain RPR42. The results showed that strain RPR42 can be best grown anaerobically in 22.5% cane molasses solution. Also, the findings of the single variable at a time experiments and either factorial design indicated that the optimal growth of strain RPR42 can be observed when beef extract, casein hydrolysate, and yeast extract were added into the medium. The central composite design experiments suggested a medium which was designated as cane molasses medium (CMM). Eventually, this medium contained 21.9% cane molasses, 30.72 g/L of a combined mixture of nitrogenous compounds: 0.0754% of a 1:1:1 mixture of polysorbates 20, 60, and 80, and 18.53 gr/L of the combined minerals. Such an optimized cane molasses-based medium supported a significant biomass production since a considerably high cell density, 13.8 g/L/24h of dry biomass, of the strain was produced. Hence, cane molasses can be regarded as a promising substrate for industrial production purposes.

Phycoremediation coupled biomethane production employing sewage wastewater: Energy balance and feasibility analysis

In the present work Chlorella pyrenoidosa, Scenedesmus abundans and Anabaena ambigua have been evaluated for their biomass, phycoremediation efficiency and biomethane production potential by cultivating them in the primary treated sewage waste water (PTSWW) under controlled conditions. By the end of 25-day experiment, up to 52–88% reduction was observed in the nutrient concentration from the 3:1 ratio of PTSWW. Co-digestion of microalgal biomass (dry) with cow dung was performed to estimate biomethane potential. Biogas yield of 618–925 ml g−1 VS with 48–65% of methane content was obtained employing the microalgal species cultivated in PTSWW. Microalgae appeared notably competent at nutrient sequestration from PTSWW with significant microalgal biomass productivity for biogas production. Energy balance studies revealed the feasibility of coupling the remediation with energy generation. High photosynthetic rate and biomass generation ability along with nutrient confiscation supports employment of microalgae as a potential next generation biofuel source with waste management.