INNOVATIVE APPROACH TO HOUSEHOLD BIOLOGICAL WASTE TREATMENT: DESIGN AND TECHNICAL SOLUTION OF A BIOGAS PLANT

ABSTRACT

This paper showcases a novel bioreactor design, created to efficiently process biological waste from humans and cattle, converting it into biological gas. The resulting gas, which can contain up to 85% methane, is intended for use as fuel in both household and industrial settings. The bioreactor is designed with a conical shape and diagonally arranged blades on the shaft and walls. This feature ensures optimal cofermentation of raw materials while preventing adhesion of biomass particles to the walls and bottom of the apparatus. It is worth noting that this design solution significantly reduces the size of the unit, making it suitable for domestic purposes.

АННОТАЦИЯ

Настоящая статья представляет конструктивное решение биореактора, разработанного для эффективной переработки биологических отходов животного, растительного и человеческого происхождения. Полученный газ, содержащий в себе до 85% метана, предназначен для использования в быту и на производстве в качестве топлива. Конструкция биореактора включает в себя коническую форму, а также диагонально расположенные лопасти на вале и стенках, обеспечивающие оптимальную коферментацию сырья и предотвращающие прилипание частиц биомассы к стенкам и днищу установки. Примечательно, что данное конструктивное решение значительно уменьшает габариты аппарата, делая его пригодным для бытового использования.

Keywords: biogas plant, bioreactor, biological waste processing, methane, energy efficiency, domestic use, innovative design.

Ключевые слова: биогазовая установка, биореактор, переработка биологических отходов, метан, энергетическая эффективность, бытовое использование, инновационная конструкция.

Introduction. In the context of increasing energy consumption and biowaste utilisation problems, this paper presents a novel method for efficient conversion of domestic biowaste into biogas with high methane content. The innovative bioreactor design not only leads to a significant reduction in the size of the plant, but also facilitates its utilisation on a domestic scale. The transition to compact and efficient plants from traditional bulky systems promises to revolutionise biogas production. This transition can help to increase the availability of biogas for domestic use. This article provides a complete technical description of the bioreactor design and assesses the potential for its application at different scales ranging from large agricultural complexes to households[1,2].

According to the definition, technical potential is the total estimated national potential that is technically possible. Economic potential is based on technical potential subject to constraints that are determined through economic efficiency analysis (profitability requirements). This has been studied by a number of authors; the results are summarised in this report. Table 1 summarises a comparative assessment of the potential for biogas production from EU animal waste.

Another study was conducted within the TACIS programme to determine the technical and economic potential for biogas production (using municipal solid waste). It was found that the technical potential for biogas production is 200 GWh and the economic potential is 50 Mg, which is significant. [3]

Table 1.

Potential for biogas production using livestock waste

Source: TACIS, 1997.

Table 2.

Data for 2010-2023 are given taking into account updated (revised) data Agency of Statistics under the President of the Republic of Uzbekistan

Figure 1. Data on the number of legal entities for 2020-2023 are given

Research methodology. As shown in Table 2 and Figure 1, there is stability in the structure of agricultural production and the number of legal organisations, which is proportional to the amount of waste produced and its further use as a raw material base for biogas plants. Data provided by the Statistical Agency under the President of the Republic of Uzbekistan.

The use of renewable energy sources as an alternative to energy from combustible minerals is an important contribution to reducing greenhouse gas emissions.

International experience in biogas plant design. In Georgia, various engineering companies, research/engineering institutes and individuals have expertise in biogas production. Among them the best known are: Bioenergia LLC, Constructors LLC and the Georgian National Centre of High Technologies.

In the 1990s, Bioenergia Ltd. developed small-sized mesophilic biogas reactors of two types - with fixed and floating lids (Figure 2). Such systems are convenient in operation, but less efficient in terms of biogas production. Given the local conditions, these systems are the most attractive for most households with one or two livestock units. Subsequently, Bioenergy has also developed more efficient mesophilic biogas digesters with a volume of 6 m3, but requiring waste from at least four livestock units.[4]

Figure 2: Small biogas digesters with fixed lid (A) and with floating lid (B)

Source: TACIS, 1997.

On the basis of the above, it can be considered that they are very cumbersome and not practical in the conditions of Uzbekistan when used by small households.

Based on my international experience with biogas plants, particularly in Georgia, I propose a novel approach to create a local version of a biogas plant that is suitable for limited and nearby use.

My designed plant introduces groundbreaking ideas in utilizing organic materials, encompassing not solely animal and plant origin but also human. Today's environmental standards and the necessity for effective recycling underscore the requirement to extend the range of raw materials, in order to produce the most efficient and sustainable sources of renewable energy.[5]

The bioreactor design I have developed processes biological waste from human and cattle activities into biological gas comprising of 75-85% methane, which is appropriate for fuel purposes in households and industrial production.

Fig. 3 shows the results of qualitative analysis of biogases emitted in the reactor using an Agilent 6890 gas chromatograph. On the basis of the results shown in Fig. 3 it is established that in the first 5 days the main emitted gas is nitrogen (N2), the volume of which is ~ 75-85 %, and the share of oxygen is 10 and 3 %. A similar proportion is practically made up of carbonate[6] anhydride and methane. In these cases, methane is a necessary component that can be used as a fuel. It should be noted that as the fermentation time increases, the proportion of nitrogen decreases significantly. And in the reactor where a certain amount[7] (100 g) of ammonium mineral was available the nitrogen fraction ~ twice as fast decreases in relation to the fraction of nitrogen gas released in the ammonium mineral reactor.[8]

Figure 3. Chromotographic parameters of the obtained biogas.

The technological scheme and principle of operation of my biogas plant is described in Figure 4.

Figure 4. Continuous plant for biogas production from biological waste

1 - Tank for mixing biological wastes and neutralising them (in case of using human waste); 2 - feedstock loading into bioreactor[9]; 3 - bioreactor; 4 - agitator shaft; 5 - frame slow-speed agitator; 6 - agitator for agitating solid layer of sludge; 7 - device for discharging thickened waste feedstock in the form of thick colloidal solution; 8 - connection for continuous sludge discharge; 9 - knives for cutting and mixing of solid crust formed on the solution surface; 10 - coil for heating the solution; 11 - connection for gas output; 12 - compressor; 13 - gas holder for gas settling; 14 - valve; 15 - connection for gas supply to the consumer.

Results and discussion. The conical shape of the reactor and the diagonally arranged blades on the shaft and walls of the reactor allow biomass particles to hover and mix freely during the cofermentation of the feedstock. This prevents the biomass particles from sticking to the walls and bottom of the unit and increases the biogas output.

The new design solution allows to significantly reduce the size of the apparatus and the accompanying in-line equipment for its use not only in large agricultural associations for the production of large quantities of methane, but also for its installation in the household sector (presumably - in two- or one-room flats or private houses), to produce gas in smaller, but still sufficient for this sector. The raw material in the form of biological waste is loaded into storage tank 1, where it is mixed with neutralising agents (in the case of human biological waste) and water to give the solution the required concentration relative to the solid substance. At the loading connection 2 the obtained biomass is fed to the bioreactor 3, equipped with a triple-acting agitator 5, which is a complex of stirring devices mounted on a single shaft 4. The agitator consists[10] of a frame agitator 5, an agitator for agitating solid settling particles 6, and a knife system for discharging the spent feedstock 7. The spent feedstock is discharged by means of the discharging device 7 through a connection 8. The generated gas, consisting mainly of methane (86%) and carbon dioxide, is fed through connection 11 with the help of compressor 12 to the gas holder 13, where it is settled and supplied[11] to the consumer by means of valve 14 through connection 15. Dimensions of the whole complex of equipment can be placed on 2 m³.

Conclusion. In conclusion, this paper introduces a novel bioreactor design with the goal of enhancing the conversion of biological waste from human and cattle activities into high-methane biogas. The inventive design incorporates a conical shape and diagonally positioned blades, which guarantee optimal cofermentation, prevent biomass adhesion and significantly reduce the size of the device. The move from traditional, cumbersome systems to this streamlined and productive bioreactor holds significant potential for transforming biogas production, especially in residential settings.

The investigation analyses the technical and financial aspects of biogas production, scrutinising its potential at a national and local level. Importantly, the article emphasises the consistency in the agricultural production structure as a critical element that impacts waste production and, subsequently, the feasibility of biogas facilities.

Building on international experiences, particularly in Georgia, the author recommends a customized approach to biogas plant technology, emphasizing its compatibility with small households. The design encompasses organic materials, extending beyond customary sources to involve human waste, aligning with current environmental regulations and the necessity for inclusive recycling.

Moreover, the innovative method provides adaptability in its use, not just in large agricultural facilities but also in domestic environments, fulfilling the need for producing methane on a smaller scale. The overall equipment dimensions, roughly 2 cubic metres, enhance its applicability to various usage scenarios.

In conclusion, this study contributes towards advancing biogas technology, providing a sustainable solution for transforming organic waste into a valuable source of energy. The innovative design, utilization of diverse raw materials and adaptability to different scales of the proposed biogas plant position it as a promising advancement within the field of renewable energy.

References:

1. Gemmeke, B., et al. "Biogas-Messprogramm II, 61 Biogasanlagen im Vergleich." Guelzow-Pruezen: Fachagentur Nachwachsende Rohstoffe (2009).
2. Abdullaev, S. S. "RATIONAL SOLUTION OF THE ISSUE OF PROCESSING OFF-BALANCE ORE INTO CONCENTRATED NITROGEN-PHOSPHATE FERTILIZERS USING CYCLIC METHOD." Экономика и социум 5-1 (108) (2023): 4-9.
3. Weiland, P., et al. "Bundesmeßprogramm zur Bewertung neuartiger Biomasse–Biogasanlagen." Abschlussbericht. Institut für Agrartechnologie und Biosystemtechnik. Johann Heinrich von Thünen-Institut (vTI), Braunschweig. Germany (2009).
4. Canton, Helen. "Organisation for Economic Co-Operation and Development—OECD." The Europa Directory of International Organizations 2021. Routledge, 2021. 677-687.
5. Abdullayev, S. S., et al. "Cyclic Technology for Obtaining Double, Triple Superphosphate and Concentrated Nitrogen-Phosphorus Fertilizer from Low-Grade Phosphorites of Central Kyzylkum." Eurasian Journal of Physics, Chemistry and Mathematics 6 (2022): 49-54.
6. Марупова, М. А., Ж. Т. Мамасаидов, and М. М. Ахаджонов. "ВЛИЯНИЕ ИНСЕКТИЦИДОВ И ФУНГИЦИДОВ НА БИОХИМИЧЕСКИЕ ПОКАЗАТЕЛИ УГЛЕВОДНОГО ОБМЕНА." ББК 28.072 я43 (2022): 100.
7. 16.  Марупова, М. А., М. Ахаджонов, and Н. Б. Одилхужазода. "ПРИМЕНЕНИЕ СОВРЕМЕННЫХ ИНТЕРАКТИВНЫХ МЕТОДОВ ОБУЧЕНИЯ ПРИ ВЕДЕНИИ КУРСА БИОХИМИИ." Университетская наука: взгляд в будущее. 2020.
8. Sultanov B.S.. "UTILIZATION OF AGRICULTURAL WASTE IN THE PRODUCTION OF BIOGAS" Экономика и социум, no. 6-1 (109), 2023, pp. 428-429.
9. Abdurazakova I.A.. "IDISH YUVISH VOSITALARI ZARARI HAQIDA" Экономика и социум, no. 1-2 (104), 2023, pp. 11-13.
10. Ahmedov, Muhammadjon, and Fotimakhon Abdullaeva. "APPLICATION OF AUTOMATIC DESIGN SYSTEMS (CAD) IN THE TRAINING OF SPECIALISTS IN ENGINEERING AND TECHNOLOGY." Universum: технические науки 9-5 (114) (2023): 5-8.
11. Нурматова Салимахон Собировна. "НОРМАТИВНЫЕ ПАРАМЕТРЫ ПРОЦЕССА ПОДАЧИ ХЛОПКА-СЫРЦА В ПНЕВМО-ТРУБОПРОВОД" Universum: технические науки, no. 5-2 (110), 2023, pp. 50-52.