Addition Of Nitrate Research Articles

Nitrate removal during Fe(III) bio-reduction in microbial-mediated iron redox cycling systems

Abstract Fe(III) bio-reduction provides a prospect of applying the iron redox cycle to nitrate remediation in the aquatic environment. The objective of this study was to realize multiple nitrate removals in the system containing Shewanella oneidensis MR-1 (S. oneidensis MR-1) and ferrihydrite or magnetite. The results showed that with three periods of 30 mg·L−1 NO3−-N addition, all nitrate reduction was completed within 170 h. In the first period (0–30 h) of nitrate addition, the main contribution of nitrate removal was due to the biological reduction process by S. oneidensis MR-1, accompanied by the reduction of Fe(III). During the second (45–90 h) and third periods (100–170 h) of nitrate addition, oxidation of biogenic Fe(II) coupled with the reduction of nitrate took place. This redox reaction resulted in the production of gaseous nitrogen of 47.33% and 16.8% for ferrihydrite/S. oneidensis MR-1 and magnetite/S. oneidensis MR-1 systems, respectively. In addition, nitrite, as an intermediate product, accumulated and negatively affected nitrate removal after the third addition of nitrate. By comparing the patterns of X-ray diffraction of the iron minerals before and after the bio-reduction, it was found that ferrihydrite was transformed into magnetite, while magnetite kept its original crystal form.

Simultaneous sulfide oxidation and gold dissolution by cyanide-free leaching from refractory and double refractory gold concentrates

Pyrite and arsenopyrite are known to be the most common gold-bearing sulfide minerals in refractory gold ores. Traditionally, these minerals have been first oxidized by roasting, acidic pressure oxidation or bio-oxidation to release gold, after which the gold is dissolved in the subsequent cyanide leaching step. The chloride (chloride-bromide) solution presents an alternative cyanide-free media, which is able not only to leach gold-bearing sulfide minerals, but also gold, in a single unit process. Therefore, the current study presents an investigation of simultaneous sulfide oxidation and gold leaching from refractory (sulfidic) and double refractory (sulfidic and preg-robbing) gold concentrates. The results show that gold extraction from the investigated refractory concentrate was linearly dependent on the sulfide oxidation: 97% sulfide oxidation resulting in 99% gold extraction, 67% sulfide oxidation resulting in 81% gold extraction, and 46% sulfide oxidation resulting in 67% gold extraction. However, with double refractory concentrate, gold extraction was as low as 18% despite 97% sulfide oxidation ([Cl-]aq,0 = 6.3 mol/L, [Br-]aq,0 = 1.0 mol/L, and [Cu2+]aq,0 = 1.6 mol/L). In order to mitigate the challenges related to gold losses due to preg-robbing, active carbon in chloride leach (CICl) as well as the addition of lead nitrate were investigated. With CICl, the gold recovery could be increased significantly (67%). Further, addition of lead nitrate to CICl was shown to improve gold recovery substantially (88%). The investigation shows that the presented cyanide-free leaching approach can address the refractory nature of gold concentrates in atmospheric pressure - the simultaneous oxidation of sulfide minerals and gold in a single unit process providing new horizons for the future of the utilization of refractory gold ores.

Sodium nitrate as a methanogenesis suppressor in earthen separator microbial fuel cell treating rice mill wastewater.

The microbial fuel cell (MFC) is one of the sustainable technologies, which alongside treating wastewater, can generate electricity. However, its performance is limited by factors like methanogenesis where methanogens compete with the anode respiring bacteria for substrate, reducing the power output. Thus, sodium nitrate, which has been previously reported to target the hydrogenotrophic methanogens, was used as a methanogenic suppressor in this study. The performance of MFC with and without sodium nitrate was studied during the treatment of rice mill wastewater. A significantly higher power density and coulombic efficiency (CE) were noted in the MFC with sodium nitrate (MFCT) (271.26 mW/m3) as compared to the control MFC (MFCC) (107.95 mW/m3). Polarization studies showed lower internal resistance for the MFCT (330 Ω) as compared to MFCC (390 Ω). Linear sweep voltammetry and cyclic voltammetry indicated a higher electron discharge on the anode surface due to enhancement of electrogenic activity. Considerable reduction (76.8%) in specific methanogenic activity was also observed in anaerobic sewage sludge mixed with sodium nitrate compared to the activity of anaerobic sewage sludge without any treatment. Due to the inhibition of methanogens, a lower chemical oxygen demand (COD) and phenol removal efficiency were observed in MFCT as compared to MFCC. The COD balance study showed an increase in substrate conversion to electricity despite the increase in nitrate concentration. Therefore, selective inhibition of methanogenesis had been achieved with the addition of sodium nitrate, thus enhancing the power generation by MFCs.

Haloalkaliphilic denitrifiers-dependent sulfate-reducing bacteria thrive in nitrate-enriched environments

As bridge in global cycles of carbon, nitrogen, and sulfur, sulfate-reducing bacteria (SRB) play more and more important role under various environments, especially the saline-alkali environments with significant increase in area caused by human activities. Sulfate reduction can be inhibited by environmental nitrate. However, how SRB cope with environmental nitrate stress in these extreme environments still remain unclear. Here, after a long-term enrichment of sediment from saline-alkali Qinghai Lake of China using anaerobic filter reactors, nitrate was added to evaluate the response of SRB. With the increase in nitrate concentrations, the inhibition on sulfate reduction was gradually observed. Interestingly, extension of hydraulic retention time can relieve the inhibition caused by high nitrate concentration. Mass balance analysis showed that nitrate reduction is prior to sulfate reduction. Further metatranscriptomic analysis shows that, genes of nitrite reductase (periplasmic cytochrome c nitrite reductase gene) and energy metabolisms (lactate dehydrogenase, formate dehydrogenase, pyruvate:ferredoxin-oxidoreductase, and fumarate reductase genes) in SRB was down-regulated, challenging the long-held opinion that up-regulation of these genes can relieve the nitrate inhibition. Most importantly, the nitrate addition activated the denitrification pathway in denitrifying bacteria (DB) via significantly up-regulating the expression of the corresponding genes (nitrite reductase, nitric oxide reductase c subunit, nitric oxide reductase activation protein and nitrous oxide reductase genes), quickly reducing the environmental nitrate and relieving the nitrate inhibition on SRB. Our findings unravel that in response to environmental nitrate stress, haloalkaliphilic SRB show dependency on DB, and expand our knowledge of microbial relationship during sulfur and nitrogen cycles.

Morphological Conversion to Aligned Electrospun Fibers through the Enhancement of Electric Field Caused by Addition of Silver Nitrate

Morphological Conversion to Aligned Electrospun Fibers through the Enhancement of Electric Field Caused by Addition of Silver Nitrate

Synthesis and characterization of stable aqueous dispersion of silver nanoparticle from citrullus vulgaris seed oil via lecithin

Nanoparticles are known to be of wide applications in various fields of human endeavours. Many methods of syntheses such as physical, chemical are harmful to the environment, thus, this study utilised green production of nanoparticles via waste product such as Citrulus vulgaris seed. Oil was extracted using soxhlet extractor from the prepared Citrulus vulgaris seed. Physico-chemical properties such as percentage yield, acid value, peroxide value were carried out on the Citrulus vulgaris seed oil. Citrulus vulgaris was further processed to form lecithin. The lecithin extracted was characterized for colour, Peroxide Value, Acetone Insoluble (AI), Acid Value, solubility in water and organic solvents. The result of the physico-chemical parameters was in conformity with the standard and various literatures. Therefore, lecithin is processed into dispersed aqueous silver nanoparticles by the addition of silver nitrate. The chemical reaction was monitored progressively using visual assessment, UV-visible and FTIR Spectroscopy. The size and surface of the dispersed silver nanoparticles produced was analysed using Atomic Force Microscopy. Therefore, a dispersed aqueous silver nanoparticle was produced from lecithin made from Citrulus vulgaris seed oil.

The direct and interactive effects of elevated CO2 and additional nitrate on relative costs and benefits of legume-rhizobia symbiosis

Rising concentrations of carbon dioxide (CO2) is likely to have important effects on growth and development of plants and on their relationship with symbiotic microbes. A rise in CO2 could increase demand by plant hosts for nutrient resources, which may increase host investments in beneficial symbionts. In the legume-rhizobia mutualism, while elevated CO2 is often associated with increased nodule growth and investment in N2-fixing rhizobia, it is yet unclear if this response depends on the mutualistic quality of the rhizobia. To test if host carbon allocation towards more-beneficial nodules are similar to less-beneficial (but still effective) nodules when plant N demand changes, we manipulated plant C and N status with elevated CO2 and additional nitrate. We used two isogenic Rhizobium etli strains that differ in their ability to synthesize an energy reserve compound, poly-beta-hydroxybutyrate (PHB), as well as their efficiencies for nitrogen fixation and nodulation rates, resulting in two Phaseolus vulgaris host groups with either large number of small nodules or small number of large nodules. The addition of nitrate negatively affected carbon allocation towards nodules, and elevated CO2 reversed this effect, as expected. However, this alleviation of nodule inhibition was greater on plants that started with greater numbers of smaller nodules. If smaller nodules indicate less-efficient or low-fixing rhizobia, this study suggests that increased demand for nitrogen in the face of elevated CO2 has the potential to disproportionately favor less-beneficial strains and increase variation of nitrogen fixation quality among rhizobia.

The effect of isosorbide-mononitrate on proteinuria in patients with diabetic nephropathy

Background/Aim: Diabetic nephropathy (DN) occurs in approximately 40% of patients with Type 1 and Type 2 diabetes mellitus (DM) and is one of the most common causes of end-stage renal disease (ESRD). New treatment strategies are needed to prevent DN. This study aims to investigate the effect of the use of isosorbide-mononitrate (IMN) on diabetic nephropathy. Methods: In this study, patients with type 2 diabetes mellitus were divided into two groups, as those using and not using IMN to evaluate whether IMN reduces proteinuria. Biochemical parameters and proteinuria values were recorded and comparatively analyzed. Results: The urea and creatinine values of patients with type 2 DM who were using IMN were significantly higher and e-GFR values were significantly lower than those of the control group (P=0.049, P=0.001, P=0.013, respectively). However, the proteinuria amounts of Type 2 DM patients using IMN (0.98 g/day [0.52-1.43]) were significantly lower than those who were not (1.61 g/day [1.02-2.69] (P=0.001)). Conclusion: The addition of nitrate to angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II receptor blocker (ARB) in the treatment of patients with DN may be a new alternative for reducing proteinuria.

Coupling oxidation of acid volatile sulfide, ferrous iron, and ammonia nitrogen from black-odorous sediment via autotrophic denitrification-anammox by nitrate addition

The coupling removal of acid volatile sulfide (AVS), ferrous iron, and ammonia nitrogen has been applied for black-odorous sediment remediation. In this study, calcium nitrate with different N/(S + Fe) ratios (0.45, 0.90, 1.20 and 1.80) was added into black-odorous sediment in four systems named R1, R2, R3, and R4. Results showed that the removal rate of AVS was 76.40% in the R1, which was lower compared with rates in R2–R4 around 96.70%. The ferrous oxidation rate was approximately 87.00% in R2–R4, which was considerably higher than that in the R1 (24.62%). And the ammonia was reduced by 81.02%, 88.00%, 100%, and 57.18% in R1, R2, R3 and R4, respectively. During the reaction, nitrite accumulation was observed, indicating partial denitrification. Moreover, microbes related to autotrophic denitrification (e.g., genus Thiobacillus, Dok59, GOUTA19, Gallionella, with the highest abundance of 15.40%, 13.21%, 8.79%, 9.44%, respectively) were detected in all systems. Furthermore, the anammox bacteria Candidatus_Brocadia with the highest abundance of 3.44% and 4.00% in R2 and R3, respectively was also found. These findings confirmed that AVS, ferrous iron, and ammonia nitrogen could be simultaneously removed via autotrophic denitrification coupled with anammox in black-odorous sediment by nitrate addition.

Substrate competition and microbial function in sulfate-reducing internal circulation anaerobic reactor in the presence of nitrate

Nitrate and sulfate often coexist in organic wastewater. In this study, an internal circulation anaerobic reactor was conducted to investigate the impact of nitrate on sulfate reduction. The results showed that sulfate reduction rate dropped from 78.4% to 41.4% at NO3- /SO42- ratios ranging from 0 to 1.03, largely attributed to the inactivity of acetate-utilizing sulfate-reducing bacteria (SRB) and preferential usage of nitrate of propionate-utilizing SRB. Meanwhile, high nitrate removal efficiency was maintained and COD removal efficiency increased with nitrate addition. Enhancement of propionate and butyrate degradation based on Modified Gompertz model and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt2) analysis. Moreover, nitrate triggered the shift of microbial community and function. Twelve genera affiliated to Firmicutes, Bacteroidetes and Proteobacteria were identified as keystone genera via network analysis, which kept functional stability of the bacterial community responding to nitrate stress. Increased nitrate inhibited Desulfovibrio, but promoted the growth of Desulforhabdus. Both the predicted functional genes associated with assimilatory sulfate reduction pathway (cysC and cysNC) and dissimilatory sulfate reduction pathway (aprA, aprB, dsrA and dsrB) exhibited negative relationship with nitrate addition.

High plasticity of nitrogen fixation and denitrification of common coral reef substrates in response to nitrate availability

Nitrogen cycling in coral reefs may be affected by nutrient availability, but knowledge about concentration-dependent thresholds that modulate dinitrogen fixation and denitrification is missing. We determined the effects of different nitrate concentrations (ambient, 1, 5, 10 μM nitrate addition) on both processes under two light scenarios (i.e., light and dark) using a combined acetylene assay for two common benthic reef substrates, i.e., turf algae and coral rubble. For both substrates, dinitrogen fixation rates peaked at 5 μM nitrate addition in light, whereas denitrification was highest at 10 μM nitrate addition in the dark. At 10 μm nitrate addition in the dark, a near-complete collapse of dinitrogen fixation concurrent with a 76-fold increase in denitrification observed for coral rubble, suggesting potential threshold responses linked to the nutritional state of the community. We conclude that dynamic nitrogen cycling activity may help stabilise nitrogen availability in microbial communities associated with coral reef substrates.

Facile synthesis of N doped ZnO Coral bundles for enhanced photocatalytic and antimicrobial activity

AbstractAn efficient single‐step facile synthesis of coral bundle‐like nanocrystalline N‐doped ZnO was developed using (NH4)2CO3 as a source of nitrogen. The method of zinc nitrate addition and concentration of ammonium carbonate (3.5 mol/L) played a pivotal role in the formation of coral bundle‐like morphology along with nitrogen doping and change in color of the prepared nanomaterial. XPS, Raman, and the peak broadening in XRD confirmed the presence of nitrogen in the crystal lattice. An enhanced absorbance in the UV‐visible DRS spectrum predicts the visible light‐ and UV light‐induced photocatalytic activities for the degradation of organics via a radical mediated mechanism as evidenced by EPR analysis. The results evidence the particle size (9‐12 nm), morphology (coral bundle like), surface roughness (33.87 nm), and surface area (44.028 m2/g) of the prepared coral bundle‐shaped nitrogen‐doped zinc oxide (CBSNZ) photocatalyst. CBSNZ showed a twofold increase in visible light photocatalytic activity when compared to ZnO and excellent antimicrobial properties when compared to the standard streptomycin and ketoconazole. The MIC for CBSNZ was very less when compared to the standards for “Salmonella typhimurium, Pseudomonas aeruginosa and Enterobacter aerogenes.” This provides a wider application of CBSNZ as an environmentally benign nanomaterial.

The kinetics of tempeh wastewater treatment using Arthrospira platensis.

The microalga Arthrospira platensis (Spirulina) was used for tempeh wastewater treatment. Microalga growth and the kinetics of chemical oxygen demand (COD) degradation under different light intensities (2,100 and 4,300 lux), tempeh wastewater concentrations (0, 0.5, 1, 1.5% v/v), and sodium nitrate concentrations (0, 0.75, 1, 2, 2.5 g/L) were studied. Improved cell growth in wastewater indicated that mixotrophic growth was preferred. The addition of sodium nitrate up to 2 g/L increased COD removal. The highest COD removal was 92.2%, which was obtained from cultivation with 1% v/v tempeh wastewater, 2 g/L sodium nitrate, 2,100 lux, and the specific growth rate of 0.33 ± 0.01 day-1. The COD removal followed a pseudo-first-order kinetic model with the kinetic constant of 0.3748 day-1 and the nitrate uptake rate of 0.122 g/L-day. The results can be used to design a pilot-scale tempeh wastewater treatment facility using A. platensis for tertiary treatment. Based on the kinetic model, a 20 m3 reactor can treat tempeh wastewater to reduce the COD from 400 to 100 ppm in 4 days and produces approximately 32.8 kg of dried microalgae.

Effects of low temperature and nitrogen addition during cold stratification on seed germination of Korean pine (Pinus koraiensis)

Pinus koraiensis Siebold & Zucc. seeds are primarily dormant following dispersal, restricting the natural regeneration of populations. The aim of this study was to determine the combined effects of increasing low temperature and nitrogen addition during cold stratification on seed germination. We stratified the seeds at 0 °C, 5 °C, and 10 °C for 3.5 months. At each cold stratification temperature, seeds were subjected to 0 (0 nitrogen), 0.08 (low nitrogen), 0.16 (medium nitrogen), and 0.25 mol·L–1 (high nitrogen) nitrate additions. Seed germination response was tested at 25/15 °C and 10/5 °C. Under 0 nitrogen and high nitrogen levels, increasing cold stratification temperature did not markedly affect seed germination at 25/15 °C, but significantly inhibited seed germination at 10/5 °C. At medium nitrogen levels, seed germination at both 25/15 °C and 10/5 °C significantly decreased. At low nitrogen levels, increasing cold stratification temperature significantly decreased germination percentage at 25/15 °C from 86.7% (0 °C) to 50.2% (10 °C) but did not markedly change seed germination percentage at 10/5 °C. We suggest that the effect of increasing cold stratification temperature on seed germination of P. koraiensis depends on both the level of nitrogen addition during cold stratification and subsequent incubation temperature after cold stratification.

Organic and inorganic elicitors enhance in vitro regeneration of Rosa canina

BackgroundRosa canina is one of the most popular rose species which is widely used as the rootstock for the propagation of rose cultivars. The purpose of the present study is to improve the in vitro propagation efficiency of this valuable plant species using various growth stimulants in a proliferation medium. In this study, in vitro-derived axillary buds of R. canina were inoculated in Vander Salm (VS) medium supplemented with varying levels of organic or inorganic elicitors including casein hydrolysate (200, 400, and 600 mg/l), glutamic acid (2, 4, 8, and 12 mg/l), proline (500, 1000, 1500, and 2000 mg/l), and silver nitrate (25, 50, 75, and 100 mg/l), separately. Benzyl amino purine (BAP) as well as naphthalin acetic acid (NAA) were added to all media at a constant rate to promote shoot proliferation. ResultsThe results indicated that the supplementation of casein hydrolysate to the VS medium markedly stimulated shoot regeneration by 173% in comparison to control. Shoot proliferation was also positively influenced by glutamic acid at all levels, however, at a lesser extent compared to casein hydrolysate. Silver nitrate at 100 mg/l induced the longest shoots (2.52 ± 0.248 cm) and maximum leaf number (8.90 ± 0.276) among all treatments. Although it did not encourage efficient shoot regeneration, the highest quality shoots with maximum growth vigor were observed in this treatment. ConclusionIn this study, the promising role of casein hydrolysate in combination with plant growth regulators has been emphasized for the improved efficiency of R. canina regeneration protocol. Moreover, the addition of silver nitrate to the culture medium seems vital for enhancing the quality of regenerated shoots. The results of this study could be beneficial either for the further pharmaceutical or biochemical investigations of R. canina or commercial purposes for mass propagation of this specimen.

Nitrate Additives Coordinated with Crown Ether Stabilize Lithium Metal Anodes in Carbonate Electrolyte

AbstractLithium metal anodes (LMAs) are promising for next‐generation batteries but have poor compatibility with the widely used carbonate‐based electrolytes, which is a major reason for their severe dendrite growth and low Coulombic efficiency (CE). A nitrate additive to the electrolyte is an effective solution, but its low solubility in carbonates is a problem that can be solved using a crown ether, as reported. A rubidium nitrate additive coordinated with 18‐crown‐6 crown ether stabilizes the LMA in a carbonate electrolyte. The coordination promotes the dissolution of NO3− ions and helps form a dense solid electrolyte interface that is Li3N‐rich which guides uniform Li deposition. In addition, the Rb (18‐crown‐6)+ complexes are adsorbed on the dendrite tips, shielding them from Li deposition on the dendrite tips. A high CE of 97.1% is achieved with a capacity of 1 mAh cm−2 in a half cell, much higher than when using the additive‐free electrolyte (92.2%). Such an additive is very compatible with a nickel‐rich ternary cathode at a high voltage, and the assembled full battery with a cathode material loading up to 10 mg cm−2 shows an average CE of 99.8% over 200 cycles, indicating a potential for practical use.

Studies on Syngas Fermentation With Clostridium carboxidivorans in Stirred-Tank Reactors With Defined Gas Impurities.

Syngas fermentation processes with acetogenic bacteria like Clostridium carboxidivorans have been proven to be a promising approach for the conversion of CO-rich waste gases into short- and medium-chain alcohols. The challenge of synthesis gas impurities, on the other hand, has always been a major concern for establishing an industrial-scale process, since some of the trace components in waste gases, such as NH3, H2S, and NOx, can have inhibiting or even toxic effects on microbial growth and product formation. Thus, this study aims to identify the effects of the main trace impurities in syngas from gasification of biogenic residues by the supply of defined concentrations of trace impurities to the cultivation medium. Autotrophic gas fermentation studies were performed with C. carboxidivorans in batch-operated fully-controlled stirred-tank bioreactors with continuous gas supply (80% CO and 20% CO2). The syngas components NH3 and H2S had a positive effect on both growth and alcohol formation (ethanol, 1-butanol, and 1-hexanol). The maximum biomass concentration was increased by more than 50%, and the maximum ethanol concentration was more than doubled with 5.0 g L−1 NH4Cl or 1.0 g L−1 H2S provided by the addition of 2.2 g L−1 thioacetamide. The addition of the nitrogen oxide species nitrate and nitrite, on the other hand, reduced biomass growth as well as alcohol concentrations. Already, the supply of 0.1 g L−1 NaNO3 resulted in reduced growth and 25% reduction of the maximum ethanol concentration. The production of the longer chain alcohols 1-butanol and 1-hexanol was reduced as well. All NaNO2 concentrations tested showed a strong toxic effect on the metabolism of C. carboxidivorans, and neither CO consumption nor product formation was observed after addition. As a consequence, NOx components in syngas from the gasification of biogenic residues should be reduced by the gasification process and/or selectively removed from the syngas after gasification.

Denitrifying bio-cathodes developed from constructed wetland sediments exhibit electroactive nitrate reducing biofilms dominated by the genera Azoarcus and Pontibacter

To limit the nitrate contamination of ground and surface water, stimulation of denitrification by electrochemical approach is an innovative way to be explored. Two nitrate reducing bio-cathodes were developed under constant polarization (-0.5 V vs SCE) using sediments and water from a constructed wetland (Rampillon, Seine-et-Marne, France). The bio-cathodes responded to nitrate addition on chronoamperometry through an increase of the reductive current. The denitrification efficiency of the pilots increased by 47% compared to the negative controls without electrodes after polarization. 16S rRNA gene sequencing of the biofilms and sediments evidenced the significant and discriminating presence of the Azoarcus and Pontibacter genera in the biofilms from biocathodes active for nitrate reduction. Our study shows the possibility to promote the development of efficient Azoarcus-dominated biocathodes from freshwater sediment to enhance nitrate removal from surface waters.

Effects of glycerol addition on the slurry dispersion and mechanical properties of alumina ceramics prepared by gel-casting process

The addition of glycerin reduced the dielectric constant of the aqueous alumina suspension, increased the zeta potential of the alumina powder, thickened the electric double layer, and improved the dispersibility of an alumina suspension for aqueous gel-casting. The glycerin-added suspension can effectively avoid the agglomeration, so that the green body had a more uniform microstructure and a higher relative density. The simultaneous addition of magnesium nitrate, EDTA and glycerol in aqueous-based alumina slurry can effectively promote the homogeneity of green microstructure and hence obtaining the sintered sample with relative sintered density of 99.7% and the mean grain size and distribution of 1.20 ± 0.44 μm. The (pressure-less sintered) sample Mg + EDTA + Gly exhibited superior Vickers hardness comparable to the samples prepared using HP, HIP, and SPS due to the small grain size (1.2 μm) and high sintered density (99.7%).

EFFECT OF NITRATE AND PHOSPATE CONCENTRATION ON Spirulina platensis WITH INDOOR SCALE

One of the microalgae that are widely used in the industrial world is Spirulina platensis which has high nutritional content of protein, fatty acids, vitamins and antioxidants. In its growth, this microalgae requires media and the addition of macronutrients nitrate and phosphate which greatly affect the growth and productivity of S. platensis biomass. This study aims to determine the effect of nitrate and phosphate concentrations on S. platensis biomass on an indoor scale and to determine the optimal nitrate and phosphate concentrations to achieve maximum biomass. This research was conducted in August 2020 as an experimental method, with culturing S. platensis with the addition of different concentrations of nitrate and phosphate. The design used in this study was a Completely Randomized Design consisting of 5 treatments that are 0 ppm, 10 ppm, 20 ppm, 30 ppm, and 40 ppm, each treatment with 3 repetitions. The source of nitrate and phosphate used is NPK. Water quality parameters during culture with temperatures ranging from 29-30oC, salinity 25-26 ppt, and pH 8. The optimal concentrations of nitrate and phosphate to achieve the maximum biomass is in treatment C (30 ppm) with a total of biomass 0,43 g. Whereas in treatment D (40 ppm) the biomass did not show a significant increase because the dose was too high with a total of biomass only 0,299 g