Abstract

Content

• Introduction
• 1. Relevance of the topic
• 2. Purpose of the master's thesis and research objectives
• 3. Object and research methods
• Conclusion
• References

Introduction

Biofuel is a fuel made from plant or animal raw materials, from waste products of organisms or organic industrial waste. A distinction is made between liquid biofuels (for internal combustion engines, for example, ethanol, methanol, biodiesel), solid biofuels (firewood, briquettes, fuel pellets, wood chips, straw, husks) and gaseous (synthesis gas, biogas, hydrogen). 54–60% of biofuels are its traditional forms: firewood, plant residues and dried manure for heating houses and cooking. They are used by 38% of the world's population [2].

The expansion of the use of biofuels is facilitated by mandatory regulations requiring a certain percentage of biofuels in energy consumption. Human life is impossible without the use of fuels. There are two groups of fuels:

• fuels extracted from the earth's interior (fossil fuels);
• fuels obtained from land–based raw materials (they are usually called biofuels).

The main difference between these groups of fuels is that the combustion of fossil fuels leads to an increase in the content of carbon dioxide (the so–called greenhouse) gas in the Earth's atmosphere (carbon in the Earth becomes less, and more in the atmosphere); burning of fuels of the second group does not increase the content of carbon dioxide in the atmosphere (for example, when burning wood, exactly carbon dioxide is introduced into the atmosphere, as much was removed from the atmosphere during the growth of wood due to photosynthesis) [1].

It is obvious that algae are the most promising raw material for biofuel production. Algae are the fastest growing plants on earth (their weight doubles per day), and their growth requires readily available raw materials: sunlight, water and carbon dioxide.

Microalgae can be grown in both fresh water and salt water. Also, the production of microalgae does not require the use of harmful pesticides and herbicides. One of the main benefits of microalgae is that they efficiently convert energy from sunlight into biomass

The prefix "bio" in the name says that we used carbon dioxide in the process of producing biofuel. It should be noted that biofuel is a CO₂-neutral fuel: when biofuels are burned, carbon dioxide is produced, but when it is obtained, the same amount of carbon dioxide is again converted into biomass.

Over the past 20 years, carbon dioxide emissions into the atmosphere have increased by one and a half times, and the concentration of gas in the atmosphere is increasing every year. It can be assumed that the photosynthesizing potential located on the Earth can no longer cope with the carbon dioxide emissions that humanity produces. Carbon dioxide, water and the energy of sunlight are converted in the process of photosynthesis into the energy of bonds of chemical compounds of organic matter and oxygen.

The process of photosynthesis is a reaction that determines the cycle of carbon and oxygen in nature. According to experts, up to 80% of all oxygen on our planet is produced in the seas and oceans by phytoplankton, that is, algae and cyanobacteria, and the remaining 20% ??- by terrestrial plants. Today in the scientific community there is great interest in microalgae as a means of capturing carbon dioxide and a renewable source of biofuels.

The most common algae is Chlorella vulgaris.

Chlorella vulgaris is a unicellular algae that lives in fresh and salt water bodies, on moist soil, rocks. The cells look like green balls up to 15 microns in diameter. It has no flagella, ocelli and contractile vacuoles. The cells have a cup-shaped chromatophore with or without a pyrenoid and a small nucleus. The sexual process for this alga is not known. Asexual reproduction occurs by mitotic division of the contents of the mother cell twice or three times.

As a result of division, four or eight daughter cells are formed. After the rupture of the maternal membrane, the cells come out, increase in size and divide again.

Chlorella is interesting in that its cells contain a large amount of nutrients - 50 complete proteins, fatty oils, carbohydrates, vitamins B, C and K and even antibiotics. It multiplies so intensively that a thousandfold increase in the number of its cells occurs per day. Chlorella became the first algae that humans began to grow in culture. It was used as an experimental object to study some of the stages of photosynthesis.

1. Relevance of the topic

One of the urgent problems of our time is the search for alternative types of energy sources. One of them is liquid fuel, among them different types of biofuels can be distinguished, including the most relevant biofuel obtained from microalgae. The positive point is that microalgae can be intensively grown in a large volume, and the technology of this process is quite simple [3].

2. Purpose of the master's thesis and research objectives

The purpose of this work is: to study the process of genesis of microalgae with the determination of its qualitative indicators on an experimental setup.

Tasks:

1. Determination of quality indicators of microalgae growth by various instrumental methods.
2. Comparison and selection of the best instrumental method.

3. Object and research methods

The object of research was the culture medium of microalgae at various stages. The main difference between the suspension was the intensity of its color, and therefore, at the first stage, it is necessary to determine the real number of cells per unit volume (mln/ml).

Evaluation of the productivity of microalgae is carried out according to the standard method, which uses the traditional method of counting culture cells using counting chambers (Goryaeva, Toma – Zeiss), which is traditional for light microscopy [5].

1 – plates with engraved grids; 2 – longitudinal grooves; the middle part of the plate is 0.1 mm lower than the lateral ones (chamber depth) and is divided by a transverse groove (3); 4 – cover glass.

After thorough mixing of the test liquid, take its sample and put it on the grid of the counting chamber, cover with a cover glass measuring 18 x 18 mm with a thickness of 0.25–0.35 mm and rub the cover glass to the side plates of the chamber until Newton rings are formed. The cover glass is rubbed so that the height of the test liquid layer in the chamber is 0.1 mm.

After filling the chamber with the sample under study, it is placed on the stage of the microscope and a grid is found in its field of view. All cells of microorganisms are counted inside the large square, as well as on the border lines, if the cells are mostly located in this square. If the cells intersect with a border line in half, then the cells are considered only on two adjacent sides as a square. In each preparation, cells are counted in five large squares, for example, at the corners and in the center of the grid.

Bioreactor

The production of biofuels from the lipids contained in microalgae is a highly efficient biotechnology and has significant potential.

A bioreactor is an apparatus in which the growth and development of genesis is carried out, as well as mixing of the culture medium in the process of microbiological synthesis.

A chlorella bioreactor at the inlet with a ready–made suspension tank ensures the implementation of the optimal technology for growing microalgae with a high–quality target product.

The installation includes a block for determining quantitative indicators using instruments for determining the color intensity of the culture medium (Chlorella suspension).

The high productivity of microalgae depends on the following cultivation conditions: light regime, nutrient medium composition, CO₂, concentration , photobioreactor design. An optimal combination of all these parameters will allow obtaining the maximum biomass yield. CO₂ is the main power source.

The value of the required concentration of carbon dioxide in the gas–air mixture depends on the strain used, the design of the photobioreactor and the cultivation regime. Carbon dioxide is introduced into photobioreactors with air or in pure form from cylinders.

The concentration of carbon dioxide depends on the density of microalgae cells in suspension. Thus, at a chlorella cell density of 100–150 mln/ml, carbon dioxide saturation of photosynthesis occurs at a CO₂ concentration in the gas mixture of 0.2%, and at 4–5 billion – 4.5–5.5%.

The factor most influencing the growth of microalgae is illumination. It is known that the lack or excess of illumination slows down the process of photosynthesis, which negatively affects the growth of biomass.

One of the most promising areas is the use of closed photobioreactors using artificial light to illuminate the biomass at night.

At present, fluorescent, sodium, LED (phyto or bicolor), halogen lamps, and incandescent lamps are used as artificial light sources [4].

Photographic method

A significant advantage of the photographic method is its documentation, since the photographic plate with the spectrum can be preserved. In addition, the method is characterized by high absolute sensitivity and reproducibility sufficient for determining low concentrations [4].

The photographic method is a method of studying various phenomena occurring in nature, which consists in capturing the phenomenon in a photograph or a series of photographs, which are subsequently analyzed by specialists. Let us simulate the genesis process in order to determine the dependence of the dye, how the amount of dye affects the intensity and color intensity of the suspension under study. Pour 1 ml into one and get 20 million cells; in the second 3ml – 60 million cells, in the third 5ml – 100 million cells. Next, we will work with a graphical editor. You need to fill in the photo with test tubes, point to the center of the photo and get the result of the values of the three color components R (red), G (green), B (blue). The G value is used for plotting.

Photocolorimetric method

The photocolorimetric method is based on determining the content of substances in solutions by the absorption of nonmonochromatic light radiation in the visible region of the spectrum. This method can be used to determine the concentration of the analyte in the solution by the color intensity of the solution [4].

To do this, we need: three test tubes with a substance, a TCS230 color sensor, Arduino UNO, software for Arduino UNO.

We connect the circuit, on top of the sensor you need to bring it in turn, each of the tubes, on the screen in the Arduino program, we will see the RGB values. Next, you need to build a graph and draw a conclusion.

The TCS230 sensor, located in the center of the board, consists of four types of photodiodes: 16 photodiodes with a red filter, 16 photodiodes with a green filter, 16 photodiodes with a blue filter and 16 photodiodes without a light filter. A sample of one of three colors – red, green or blue – is brought to the sensor. The sample is illuminated by LEDs on a circuit board around the sensor. The sensor has a current–to–frequency converter, it converts the readings of the photodiodes into a square wave with a frequency proportional to the light intensity of the selected color. This frequency is then read by the Arduino.

G1 – Photographic method, G2 – Photocolorimetric method.

Conclusion

Thus, biodiesel – fuel based on fats of animal, vegetable and microbial origin, as well as products of their esterification.

Vegetable or animal fats are used to produce biodiesel fuel. Raw materials can be rapeseed, soybean, palm, coconut oil, or any other, as well as food industry waste. Technologies for the production of biodiesel from algae are being developed.

The selection of a suitable medium is essential for successful microalgae cultivation. Therefore, before starting the isolation, the most careful attention should be paid to the choice of the culture medium.

Determination of the intensity of the color component (G1, G2), by various methods, showed that the nature of the dependence is of a similar nature.

For photographic and colorimetric methods, an important task of this study is to determine the amount of microalgae for biofuel production.

References

1. Основные тенденции развития рынка биотоплива в мире и России за период 2000–2012 годов. [Электронный ресурс]. URL: http://portal-energo.ru/files/...
2. Биодизельное топливо. Производство биодизеля. [Электронный ресурс]. URL: http://amastercar.ru/articles/...
3. Кулманаков, С. С. Перспективные смесевые кислородсодержащие топлива / С. С. Кулманаков, Д. Д. Матиевский, А. И. Балашев, С. В. Лебедевас // Ползуновский Вестник. – 2009 г. – №1–2. – С. 17–21.
4. Попова, И. Ю. Методы биотоплива / И. Ю. Попова // Сверхкритические Флюиды: Теория и Практика. – 2007 г. Т. 2. – № 4. – C. 85–95.
5. Иманкулов, Н. Н. Фотокалориметрический метод / Н. Н. Иманкулов, О. С. Балабеков // Материалы научно–практической конференции Нефтехимия и нефтепереработка. Уфа, 2008 г.
6. Виноградова, А. В., Биотехнология топлива: учеб. пособие / А. В. Виноградова, Г. А. Козлова, Л. В. Аникина. – Пермь: Изд–во Перм. гос. техн. ун–та, 2008. – 212 с.
7. Особенности производства биодизеля. [Эдектронный ресурс]. – Режим доступа: http://www.cleandex.ru/articles/...