RU2588655C1 - Raw material for obtaining bioethanol - Google Patents

Abstract

FIELD: biotechnology.

SUBSTANCE: invention relates to use of excessive active sludge in secondary settling tanks of biological treatment plants in cities and settlements in order to obtain bioethanol. Bioethanol is obtained by introduction sugar-rectificate and yeast into sludge with subsequent fermentation, distillation of obtained alcohol and its rectification. Products remaining after distillation of alcohol can be used as organic fertilizers.

EFFECT: suggested invention allows to save natural resources and improve environment due to waste processing.

1 cl, 1 tbl

Description

The invention relates to the field of ecology and biotechnology, in particular to the production of bioethanol from excess activated sludge of secondary sedimentation tanks, which are formed in large quantities during the treatment of municipal and industrial wastewater at biological treatment plants in cities and towns.

A known method of producing sugar-containing hydrolysates for the production of bioethanol, including washing, grinding tubers of Jerusalem artichoke, hydrolysis of crushed mass, cooling and aseptic hydrolyzate (RU 2012128098 A) is a prototype. The disadvantage of this method is the high energy consumption associated with washing, grinding tubers of Jerusalem artichoke.

A known method of producing ethanol from algae, including the formation of biomass from dried seaweed, initiating the decay of biomass, introducing yeast into the decaying biomass that can cause fermentation in it to form a fermenting solution, separating the resulting ethanol from the fermenting solution, characterized in that the formation of dried biomass algae are carried out by grinding them mechanically and then soaking in water in a ratio of 1: 5, the decomposition of the resulting biomass is carried out after series with a chemical, followed by enzymatic hydrolysis followed by sterilizing the biomass disintegrates (Patent RU 2421521 C2) - analogue.

The disadvantage of this invention is also the high energy consumption associated with the extraction and grinding of biomass of dried algae, the preparation of a nutrient medium and seed, as well as the violation of the ecological environment of the seas.

The raw materials we offer for bioethanol production not only eliminate the above disadvantages, but also contribute to the improvement of the natural environment.

The technical result is achieved by the fact that an unconventional, non-deficient cheap product, activated sludge of secondary sumps, which have passed the main stages of wastewater treatment, is recommended as a raw material for the production of technical bioethanol: coarse garbage is extracted on the gratings - large waste that residents throw into the toilet - cleaning from vegetables, fruits, plastic containers, etc .; gross waste after disinfection is disposed of in a landfill. In sand traps, sand coming from roads, from washing vegetables, etc .; after natural drying, they are used for planning the territory of the enterprise. In primary sedimentation tanks, raw sediments are mainly fecal matter; currently aged on silt maps and slag collectors. In secondary sedimentation tanks, there is excess activated sludge, this is an increase in activated sludge, which is removed from the production cycle, mixed with raw sludge, aged and dehydrated on sludge maps and slag collectors. Wastewater sludge treatment includes: compaction of excess activated sludge in sludge compactors in order to reduce its moisture content to 97.0%, dehydration of the formed sludge, which is carried out by two methods: natural dewatering is carried out in sludge charts due to settling, evaporation and freezing of moisture, humidity sediment on silt maps during the year decreases from 98-96% to 77-78%; mechanical dewatering of sediments is carried out in a centrifuge (HILLER, Germany) with the use of cationic flocculants, the humidity is reduced to 73-75%.

To date, the achieved daily capacity of structures located on approximately 135 hectares is 322 thousand m ³ , the precipitation generated (≈30 thousand tons per year) occupy large areas, the smell from accumulated precipitation reaches the city.

Such an amount (daily intake - 322 thousand m ³ ) for the treatment of domestic and industrial wastewater affects only two cities - Cheboksary and Novocheboksarsk.

Our scientific studies indicate the possibility of using urban wastewater sludge (OHSW) as a fertilizer. In various scientific journals we published (from 1981 to 2014) numerous scientific articles confirming this point of view. The great chemist D.I. Mendeleev once argued: "there are no harmful substances in the world, but harmful concentrations." In view of the foregoing, the most important task facing mankind is to return to the biological cycle various kinds of waste generated in large quantities in the process of human life, economic and industrial activity. Moreover, return strictly on a scientific basis, so as not to pollute the natural environment.

Along with the use of OGSV as an organo-mineral fertilizer, the raw materials we offer are excess activated sludge from secondary clarifiers of biological treatment facilities, which contain a large amount (up to 80%) of organic substances (see table) for bioethanol production and its subsequent use for technical needs and it’s even possible to use gasoline as a substitute or add a certain amount of bioethanol to gasoline to improve its environmental effect - a completely new direction in business tilizatsii OGSV having no analogue in the world.

The alcohol industry is highly developed. For the production of ethyl alcohol, as a rule, they take sugar-containing expensive crops, which are urgently needed to feed an increasing number of people on the planet. In science, the facts of the development (by Japanese scientists) of a faecal burger are known. With this in mind, the idea arose of obtaining bioethanol from human waste products, first for technical purposes, and subsequently with the improvement of rectification processes, for food and medical purposes, since this is an almost inexhaustible source of bioethanol from non-deficient cheap raw materials.

To achieve this goal, we conducted laboratory experiments to obtain bioethanol from excess activated sludge.

The laboratory bioethanol production process consisted of the following steps:

- Delivery of activated sludge from biological treatment facilities in Novocheboksarsk (2 containers of 4 liters);

- the acquisition of sugar, fresh and dry yeast;

- components of the 1st fermentation tank: 4 l of activated sludge, 176.6 g of rectified sugar and 22 g of dry yeast;

- components of the 2nd fermentation tank: 4 l of activated sludge, 176.6 g of rectified sugar and 55 g of fresh yeast;

- anaerobic fermentation (temperature - 30-35 ° C; fermentation time: with fresh yeast - 10 hours, with dry yeast - 11 hours);

- purification of alcohol (primary distillation using a laboratory glass refrigerator) from the fermented component (mixture). Yield - 450 ml of 10% alcohol;

- secondary distillation of the obtained alcohol (using a glass laboratory refrigerator). Yield - 200 ml of 20% alcohol.

For conversion to ethanol, we used ordinary yeast, which is represented by microorganisms (Sacchoromyces cerevisiae, Sacchoromyces rosei, apparently there were mesophilic bacteria of the genus Zymomonas), the optimum temperature for the given group of microorganisms was 30-35 ° С. It was this temperature that was maintained indoors. It is possible that activated sludge contains a group of mesophilic or other bacteria of the genus Zymomonas, which have a several times more intense metabolism than yeast, and contributed to the rapid fermentation process, since the fermentation process with fresh yeast stopped after 10 hours, and with dry yeast - after 11 hours. From 4 l of activated sludge, the yield of 10% ethanol was 450 ml, and after secondary distillation of the same product 200 ml of 20% bioethanol were obtained. Bioethanol is completely pure, light without any color, but with a slight specific odor. Similar results were obtained from 4 l of activated sludge using fresh yeast.

After further distillation in large volumes, 96% ethanol can also be obtained. Alcohol samples are stored, if necessary, can be provided to experts. For the production of bioethanol on an industrial scale, it is simply necessary to make the necessary calculation of the use of excess activated sludge from the secondary settling tanks of biological treatment facilities; sugar or it’s best to use a certain amount of sugar industry waste, in particular beet molasses containing up to 75% sucrose (GOST is given below) or other types of agricultural waste and plant materials with a sufficient amount of sugar-containing substances; fresh or dry yeast, using specific numbers of components used for fermentation in a laboratory experiment, respectively increasing their number in relation to the volume of bioethanol production.

It is well known that alcohol fermentation, the oldest branch of biotechnology, has ready-made technological systems and a developed industrial base.

Due to the fact that the reserves of natural resources - oil, coal and gas - are depleted, the search for other energy sources is very relevant. In our case, non-deficient raw materials are used to produce ethanol. For the fermentation process, expensive sugar can be replaced by alternative sources of carbohydrates, for example, waste from the sugar industry, in particular beet molasses according to GOST R 52304-2005. “Beet molasses. Technical conditions. " Molasses is a waste of sugar production with a high dry matter content (mainly sucrose) from 60 to 75%, which is directly processed by yeast without preliminary preparation, sugarcane, other types of agricultural waste and plant materials, which contain a sufficient amount of sugar-containing substances.

It seems to us that at all treatment facilities of cities and large settlements of the Russian Federation, ready-made technological systems should be introduced in production workshops that process activated sludge into technical ethanol, which are of great economic and environmental importance, and the product remaining after distillation should be used as liquid organic fertilizer . The results of the study of product samples (chemical composition of the excess activated sludge of the secondary sumps at the biological treatment facilities of Novocheboksarsk) are given in the table.

From the data given in the table, it can be seen that in the activated sludge before and after distillation there are no soluble or easily hydrolyzable carbohydrates, indicating that the carbohydrates were completely utilized already during fermentation.

A sufficient amount of organic matter, ash, nitrogen, phosphorus, potassium and a wide range of microelements are found that can, with a scientifically sound approach, increase soil fertility, crop productivity with adequate quality and improve the environment.

Claims (1)

The use of excess activated sludge from the secondary settling tanks of biological treatment facilities as a raw material for bioethanol production.