Harvesting of Chlorella sorokiniana BR001 cultivated in a low-nitrogen medium using different techniques

ABSTRACT: The harvesting process is a current challenge for the commercial production of microalgae because the biomass is diluted in the culture medium. Several methods have been proposed to harvest microalgae cells, but there is not a consensus about the optimum method for such application. Herein, the methods based on sedimentation, flocculation, and centrifugation were evaluated on the recovery of Chlorella sorokiniana BR001 cultivated in a low-nitrogen medium. C. sorokiniana BR001 was cultivated using a low-nitrogen medium to trigger the accumulation of neutral lipids and neutral carbohydrates. The biomass of C. sorokiniana BR001 cultivated in a low-nitrogen medium showed a total lipid content of 1.9 times higher (23.8 ± 4.5%) when compared to the biomass produced in a high-nitrogen medium (12.3 ± 1.2%). In addition, the biomass of the BR001 strain cultivated in a low-nitrogen medium showed a high content of neutral carbohydrates (52.1 ± 1.5%). The natural sedimentation-based process was evaluated using a sedimentation column, and it was concluded that C. sorokiniana BR001 is a non-flocculent strain. Therefore, it was evaluated the effect of different concentrations of ferric sulfate (0.005 to 1 g L-1) or aluminum sulfate (0.025 to 0.83 g L-1) on the flocculation process of C. sorokiniana BR001, but high doses of flocculant agents were required for an efficient harvest of biomass. It was evaluated the centrifugation at low speed (300 to 3,000 g) as well, and it was possible to conclude that this process was the most adequate to harvest the non-flocculent strain C. sorokiniana BR001.

Combination of Coagulation, Adsorption, and Ultrafiltration Processes for Organic Matter Removal from Peat Water

The high content of natural organic matter (NOM) is one of the challenging characteristics of peat water. It is also highly contaminated and contributes to some water-borne diseases. Before being used for potable purposes, peat water must undergo a series of treatments, particularly for NOM removal. This study investigated the effect of coagulation using aluminum sulfate coagulant and adsorption using powdered activated carbon (PAC) as a pretreatment of ultrafiltration (UF) for removal of NOM from actual peat water. After preparation and characterization of polysulfone (Psf)-based membrane, the system’s performance was evaluated using actual peat water, particularly on NOM removal and the UF performances. The coagulation and adsorption tests were done under variable dosings. Results show that pretreatment through coagulation–adsorption successfully removed most of the NOM. As such, the UF fouling propensity of the pretreated peat water was substantially lowered. The optimum aluminum sulfate dosing of 175 mg/L as the first pretreatment stage removed up to 75–78% NOM. Further treatment using the PAC-based adsorption process further increased 92–96% NOM removals at an optimum PAC dosing of 120 mg/L. The final UF-PSf treatment reached NOM removals of 95% with high filtration fluxes of up to 92.4 L/(m2.h). The combination of three treatment stages showed enhanced UF performance thanks to partial pre-removal of NOM that otherwise might cause severe membrane fouling.

Efeito do sulfato de alumínio e da taxa de lotação sobre o desempenho e características de carcaça de frangos de corte / Aluminum sulfate and stocking density effects on live performance and carcass characteristics of broiler chicks

O objetivo deste estudo foi avaliar os efeitos de diferentes doses do aditivo acidificante (sulfato de alumínio) - [0, 200, 400 e 600 g/m2] no tratamento da cama aviária e da densidade de alojamento (8 e 9 aves/m2) sobre o desempenho zootécnico e características de carcaça de frangos de corte. Foram utilizados 532 pintos machos de um dia de idade, com peso inicial médio de 46 g ± 2,3. As aves foramdistribuídas em delineamento inteiramente casualizado e arranjo de tratamento em fatorial 4x2, com sete repetições. Além do desempenho também foram avaliadoso rendimento de carcaça edos cortes (peito, coxa e sobrecoxa), bem como a prevalência de lesão nos pés das aves. A análise dos dados foi realizada utilizando o procedimento MIXED do programa estatístico SAS® (versão 9.2). O uso doaditivo e a densidade de alojamento não interagiram sobre desempenho de frangos de corte. Em geral, o aumento da densidade afetou negativamente o ganho de peso e a conversão alimentar. A dose do aditivo e a densidade de alojamento interagiram para o rendimento de carcaça. O aumento da dose do aditivo diminuiu o rendimento de carcaça, quando a densidade foi de 9 aves/m2. Em conclusão com base na densidade de alojamento e usando derivações da equação de superfície, foi possível recomendar a adição de 193,22 g do aditivo acidificante por m2. Portanto, a dose ótima de inclusão de sulfato de alumínio que favoreceu aumento do rendimento de carcaça é igual a (Y = 78,013 + 0,0114x - 0,00002952x2).

Effect of electrolytes with multicharged cations on the strength of stone made of a modified mixed air binder

The possibility of obtaining mixed air binder of high strength and water resistance by using active mineral additives has been considered. In this work, the gypsum binder has been replaced by a combination of hydrated lime with active additives - metakaolin and granulated slag. The ratio effect of the silica component to the binder on the compressive strength of the stone was studied. According to the results of X-ray phase analysis, the presence of tobermorite-like calcium hydrosilicates and the absence of hydrate lime phase were diagnosed in the stone. The influence of electrolyte additives - salts with three-charged cations - on stone hardening kinetics is shown. Increase in the compressive strength of 28-day-old stone from the modified mixed air binder by 5% with the introduction of 1% of the binder mass aluminum sulfate in the mixing water was established. The use of FeCl3 solution for mixing the modified mixed air binder leads to a decrease in the compressive strength of the 28-day-old stone. The mixing of the modified mixed air binder with Al2(SO4)3 solution reduces the time of setting.

A bioassay of the toxic effects of aluminum chloride and aluminum sulfate using Auloforus (Dero furcata)

The analysis of the toxicity of aluminum salts is determined by the fact that aluminum cation is contained in drinking water, artificial dyes and additives, medicines, vaccines, aerosols, and there is also a correlation between the concentration of aluminum ion in brain tissues and clinical manifestations of Alzheimer’s disease. The article presents the results of biotesting the toxic effects of aluminum chloride and sulfate using Aulophorus (Dero furcata). Currently, the methods of bioassay do not have a generally recognized and standardized system of biological analysis, there are no unambiguous requirements that an indicator system should meet. These worms are a biotest object, because its reaction to the environment can be traced by its creation of conglomerates. The behavior of Auloforus in the experiment depends on the concentration, the time spent in aluminum solutions, as well as on the specific salt. When comparing the dynamics of the behavior of Auloforus in experimental samples of aluminum solutions, we established toxic concentrations. It was found that aluminum chloride salts have a less toxic effect than aluminum sulfate.

USE OF MODIFIED REAGENTS SOLUTIONS WHEN PREPARING DRINKING WATER

Currently, attention is paid to the intensification of the process of natural and wastewater treatment, improvement of technology, development of new effective methods of intensification of water treatment. This will simplify the existing technology of water treatment, reduce labor-intensive processes of preparation and dosing of reagents, reduce the cost of operating treatment plants, increase their productivity, improve quality and reduce the cost of treated water. Treatment of water with a modified coagulant solution allows to increase the hydraulic size of the coagulated suspension. The strongest effect of the modified coagulant solution has on the hydraulic suspension size of 0.2 mm/s and less, i.e. the smallest and the suspension, which is difficult to remove, which creates conditions for more intensive sedimentation in settling tanks and improve the quality of water clarification and fed to fast filters. It has been experimentally determined that the treatment of water with a modified solution of aluminum sulfate coagulant should be performed when the content of suspended solids in the clarified water is up to 100–150 mg / dm3. The color of the clarified water during treatment with a modified solution of aluminum sulfate coagulant does not depend on the content of suspended solids and is 1.5-1.6 times lower than the color than when using a conventional coagulant solution. It is established that the use of a modified solution of aluminum sulfate coagulant in water purification can reduce the residual aluminum content in clarified water by an average of 50-60%. The results of researches of the modified solutions of reagents which are used at preparation of drinking water are presented. It is established that water treatment with a modified solution of aluminum sulfate coagulant allows to improve the quality of drinking water preparation by suspended solids, color, reduce the content of aluminum salts in the clarified water, thereby increasing the environmental safety of drinking water.

Decay Resistance and Color Change of Pine and Beech Wood Impregnated with R. Luteum and R. Ponticum Plant Extracts

In this study, the effect of impregnation with natural extracts on decay resistance and color change of pine and beech wood was analyzed. Flowers of Rhododendron luteum and Rhododendron ponticum plants were extracted according to the decoction method and aqueous solutions were prepared at different concentration levels (2 %, 4 % and 7 %). In addition, ferrous sulfate, copper sulfate and aluminum sulfate mordants were added to the solution to improve the properties of the extracts. Then the wood specimens were impregnated with the prepared solutions. The results indicated that the effect of plant species on the mass loss of specimens exposed to T. versicolor (white-rot fungus) was insignificant. Non-mordant extracts had a slight effect on the mass loss of the specimens. However, in pine and beech specimens impregnated with mordant-added (especially ferrous sulfate-added) extracts, mass loss was significantly reduced and resistance to fungal rot was almost completely achieved. The concentration level did not have a significant effect on the mass loss of specimens treated with mordant-added extracts. After impregnation, the L* value of all specimens (especially those treated with ferrous sulfate-added extracts) decreased and the specimens darkened. The a* and b* values increased in specimens treated with non-mordant and aluminum sulfate-added extracts and these specimens tend to have a red-yellow color. The a* value decreased and the b* value increased in wood specimens treated with copper sulfate-added extracts. The green-yellow color trend of these specimens increased. Both the a* and b* values of the specimens treated with ferrous sulfate-added extracts decreased and the green-blue color tendency increased in these specimens. The increase in the concentration level positively affected the determined color changes. The total color change (ΔE*) was higher in wood specimens (especially pine) treated with ferrous sulfate-added R. ponticum extracts.