


































Energy and Earth Science 
Vol. 4, No. 3, 2021 

www.scholink.org/ojs/index.php/ees 

ISSN 2578-1359 (Print)   ISSN 2578-1367 (Online) 

1 

Original Paper 

Comparison of Biogas Concentrations in Various Environmental 

Conditions and Determination of the Optimal Period of Its 

Production at Environment Temperature 

Edmond Demollari
1*

, Etleva Jojic
1
, Enkeleda Sallaku

2
, Valdete Vorpsi

1
, Erta Dodona

1
 & Olsid Mema

1
 

1
 Department of Agronomic Sciences, Agricultural University of Tirana, Tirana, Albania 

2
 Department of Animal Sciences, Agricultural University of Tirana, Tirana, Albania 

*
 Edmond Demollari, Department of Agronomic Sciences, Agricultural University of Tirana, Tirana, 

Albania  

 

Received: February 23, 2021      Accepted: March 8, 2021     Online Published: August 23, 2021 

doi:10.22158/ees.v4n3p1                     URL: http://dx.doi.org/10.22158/ees.v4n3p1 

 

Abstract 

Albania, as a part of Western Balkan, has a variety of climate systems. This type of climate has a closed 

connection with waste treatment process. The biogas volume produced by the experimental 

environmental was 0.6 m
3
. The maximum methane concentration in biogas was reached at 

55.8%/volume. The enclosed area (in oval circle) is another indicator of this system. This area extends 

over the period from 14.08.2018 until 26.08.2018 (12 days). The biomethane maximum biogas 

concentration reached 53.5 %/vol. up to 55.8% vol. The concentration drop was 4.2 %/vol. The main 

factor was the temperature. In the period of maximum durability the temperatures were minimum 30°C 

and maximum 42°C. Another contributing factor was the inoculum. Since inoculum was made from the 

treatment of four types of waste of different nature, then the concentration of microorganisms was 

higher. The purpose of the comparison between the two experiments is the sustainability of biogas 

production as well as the biomethane concentration biogas concentration on waste treatment. 

Environmental temperature was studied in three different regions of Albania: Shkodra, Tirana and 

Vlora. The observations showed that the region of Vlora has the longest period of average daily 

temperature (June 14
th

 to October 1
st
).  

Keywords  

thermal equilibrium, performance of biogas, analytical relation 

 

 



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1. Introduction 

Albania is a country that lies in Balkan Peninsula, in South-Eastern Europe. Albania has two different 

climate zones. The coast of Albania has a Mediterranean climate. This area has long hot summers and 

wet but mild winters. Inland is a continental climate 

(https://weather-and-climate.com/average-monthly-Rainfall-Temperature-Sunshine-in-Albania). 

However, winters here are severe with a high chance of snow. Albania’s climate is strongly influenced 

by the country’s location. Temperatures are affected from both the Adriatic and the Albanian Alps. Heat 

waves can disappear quickly by sometimes very heavy rain and thunderstorms, with the daily 

temperature falling by more than ten degrees within a day 

(https://weather-and-climate.com/average-monthly-Rainfall-Temperature-Sunshine-in-Albania). 

Biodegradation rates in the bio-toilet system are affected, among several factors, by environmental 

conditions such as temperature, moisture content, oxygen availability and pH. Temperature is one of 

the most important factors affecting microbial growth and biological reactions. Temperature can exert 

an effect on biological reactions in two ways: by influencing the rates of enzymatically catalyzed 

reactions and by affecting the rate of diffusion of substrate to the cells (Grady, Daigger & Lim, 1999). 

Of all the factors affecting the yield of biogas temperature of the digester environment is the most 

important. The temperature of the region decides the group of methanogenic bacteria that shall be 

stimulated for production of methane (Ahuja et al., 2016). Temperature control therefore becomes an 

important design criterion while designing anaerobic biogas digesters. Use of digester insulation, 

maintaining temperature in the digester via heat exchangers, heating elements, placing digesters inside 

a water bath, and injecting steam in the digester are some of the means of maintaining temperature of 

the digester in its operating range (Energypedia, “DigesterHeating” [Online]; Waste Digester Design 

Instructor Materials). In practice, sudden environmental changes, e.g., dramatic increases or drops in 

temperature, may cause severe disturbances in all parameters of the process, and the system requires a 

long period of time to adapt to a stable state. Furthermore, the temperature has a significant impact on 

the growth and metabolism of microorganisms and the interactions between the microbial groups 

(Alvarez & Lidén, 2008; El-Mashad, Zeeman, van Loon, Bot & Lettinga, 2004; Xiong, Chen, Wang & 

Shi, 2012; Rademacher, Nolte, Schonberg & Klocke, 2012).  

 

2. Material and Methods 

For the construction of the plant at environmental temperature for the production of biogas in Albania, 

the average daily temperatures for the areas under study were carefully observed. This was one of the 

main steps in order to continue further. The average daily temperatures for the annual period 2013-2017 

were taken by the Meteorological Center of the Albanian Air Force. Part of the metodology is and 

comparison of biogas production between two experimental proves: mixing with inoculum containing 

and mixing without inoculum containing, under the same temperature-pressure conditions. The period 

in which the environmental experiment was applied, was July-September 2018. The regions included in 



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the study, showed in Figure 1, were: Shkodra, Tirana and Vlora as part of the Western Lowlands of the 

Republic of Albania. The Western Lowlands represent the largest plain province and is one of the 

largest plains of the Balkan Peninsula. The main constituent units of the Western Lowlands are: 

Shkodra lowland, Field between Lezha city and River of Shkumbin, hilly ridge of Rodon-Krrabë, field 

of Elbasan, Dumre-Darsia Plateau, field of Myzeqe and Hills of Mallakastra. 

 

 

Figure 1. Included Areas in the Study in Republic of Albania 

 

3. Results and Discussion 

The predicted experimental time period should be applied up to 35 days but the experiment lasted for 

up to 50 days. The reason was for observing the production capacity of the biogas mix. According to 

Attar, Mhetre, and Shaale (1998) for a population of 28.6 million birds, produces 1575.5 million 

kg/year of waste, biogas produced is ≈116.6 million m
3
/year (Attar, Mhetre & Shawale, 1998). So, 

based on the above data, 1 kg of poultry treated in anaerobic digester produces 2.02 x 10
-4

 m
3
/day of 

biogas. Based on the Regional Statistical Yearbook (2016), the Ministry of Agriculture, Rural 

Development and Water Administration of Albania, 1 head (cattle) produces 37.19 kg of waste per day 

and 1 bird produces 0.06 kg of waste per day (Regional Statistical Yearbook of Albania, 2016).  

 



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Figure 2. Temperature Measurement Frequency in Greenhouse Environment with Datalogger 

Sensor 

 

Figures 2 and 3 give temperature differences in their values (Chart 1: min 20°C and max 38°C; Chart 2: 

min 30°C and max 42°C). These temperature changes are due to the achievement of thermal 

equilibrium (outside the anaerobic environment) and the endothermic processes (heat-absorbing 

processes) of the microorganisms inside the mixture. The experiment gives us the “right” to think that 

we can predict the performance of biogas production from agricultural waste in function of 

environmental temperatures, taking linear equations composed of three variables: 

 

 

Figure 3. Temperature in Anaerob Environmental and Its Average Temperature 

 

M (Methane) 

T1 (greenhouse temperature) 

T2 (temperature in anaerobic environment) 

 



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Figure 4. Relation between Two Applied Temperatures 

 

The relationship between the temperatures: in the greenhouse environment and in the induced 

temperature environment is given by equation 1, showed in Figure 4. 

T2 = 0.888 T1 + 4.9                              (1) 

Equation 1 represents the analytical relation between T1 and T2. The equation 2 generated by the 

graphio-analytical relation, showed in Figure 5, represents the relation between the temperature inside 

the digester in the function of the methane produced. 

M = 0.202 T2 + 31.33                             (2) 

 

 

Figure 5. Performance of Methane Production as a Function of Temperatures in the Anaerobic 

Environment 

 

The combination of equations (1) and (2) enables us to establish the analytical link between produced 

biogas and greenhouse temperature, ie between M and T1 variables. 



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Generating equation 3 from two equations 1 and 2 at the same time allows us to predict how the biogas 

production performance can be in the future (always in “greenhouse” environmental conditions). 

M = 0.179 T1 + 32.319                                (3) 

The biogas volume produced by the experimental environmental was 0.6 m
3
. The maximum methane 

concentration in biogas was reached at 55.8%/volume. Chart 5 shows a steady performance in biogas 

production from the BES system (Batch Environmental System) (inoculum + substrate), and more to 

biomethane biogas concentration. The enclosed area (in oval circle) is another indicator of this system. 

This area extends over the period from 14.08.2018 until 26.08.2018 (12 days). The biomethane 

maximum biogas concentration reached 53.5 %/vol. up to 55.8% vol. This showed the maximum 

sustainability achieved in biogas production in “greenhouse” environmental conditions but this period 

did not last long. The decrease in concentration was observed between 26.08.2018 and ongoing. The 

concentration drop was 4.2%/vol. The main factor was the temperature. In the period of maximum 

durability the temperatures were minimum 30°C and maximum 42°C. Another contributing factor was 

the inoculum. Since inoculum was made from the treatment of four types of waste of different nature, 

then the concentration of microorganisms was higher. The purpose of the comparison between the two 

experiments is the sustainability of biogas production as well as the biomethane concentration biogas 

concentration on waste treatment. 

 

 

Figure 6. Concentration of Biomethane in Biogas Produced by Inoculum-substrate Mixture 

Under “Greenhouse” Environmental Conditions (BES System) 



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Figure 7. Concentration of Biomethane in Biogas Produced Under “Greenhouse” Environmental 

Conditions, without Inoculums “Participation” (BES System, Dissertation “Evaluation and 

Optimization of Indicatorial Parameters in Biogas Production from Agricultural Waste, in 

Albanian Conditions”, 2019, Experiment 2, page 80) 

 

Figure 7 shows the higher biomethane concentration on biogas, the higher its calorific point. Despite 

the maximum concentration in the BES system, the second experiment is 58.6%/vol., i.e., 2.8%/vol. 

CH4 more, this does not mean that the system is the best. His persistence in concentration is small. The 

concentration dropped by almost 8%/vol. after six days. The BES system (inoculum-based) showed 

high concentration stability (about 12 days). From this reasoning it appears that the obtained biogas 

based on inoculum has a more consistent consistency in focusing on “greenhouse” environmental 

conditions than biogas that does not include inoculum. We see that the maximum mean temperature 

reached 27.5°C while the minimum average temperature reached 22°C. This showed that this period 

was the optimal biogas production period from the development of our environmental experiment 

(without induced temperature). This was reflected in green zone (Figure 8). In the green zone we 

distinguish three zones (Area 1 above 27.5°C, Area 2 or intermediate area between 22°C and 27.5°C, 

Area 3 below 22°C). The area in which the experiment with environment temperature can operate is 

Area 2. This is the optimal area of our experiment. Area 1 is the surface where we would like the 

experiment to develop because the values are closer to 37°C but this does not depend on us and are 

very favorable for biogas production. Referring to area 3, it is the area in which the experiment can be 

developed but the biomethane concentration in biogas reaches low values, so the environment would be 

inadequate. If we set the average maximum temperature value and the average minimum temperature 

value in the average daily temperature graphs observed over a 5 year period (2013-2017) of Shkodra, 

Tirana and Vlora regions (refer to Figures: 9, 10 and 11), we will note that periods of biogas production 

would change. From this situation it turns out that the geographic position of these regions (as part of 

the Western Lowlands in Albania) and the large number of livestock farms is the reason we considered 



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these three cities as part of our study. Based on regions of Shkodra, Tirana and Vlora, we see that the 

region of Vlora has the longest period of time with the average daily temperature (June 14 to October 

1). From this reasoning emerges that Vlora as part of the Western Lowland is more favorable for the 

erection and erection of digestive plants for the production of biogas at environment temperature 

compared to the other two cities. The boundaries of the periods of time were determined by the small 

differences in the amplitude of the five years taken in the study. 

 

 

Figure 8. Determining the Minimum Average Temperature and the Maximum Average 

Temperature during the Period of Conducting the Environmental Experiment 

 

 

Fugure 9. Determining the Optimal Period for Biogas Production at Environmental 

Temperatures in the City of Shkodra 



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Figure 10. Determining the Optimal Period for Biogas Production at Environmental 

Temperatures in the City of Tirana 

 

 

Figure 11. Determining the Optimal Period for Biogas Production at Environmental 

Temperatures in the City of Vlora 

 

4. Conclusions 

a) Biogas production in terms of environmental temperatures has a direct relationship, which was 

observed in production downturns whenever there was a decrease in external temperatures. 

b) Inoculum-based biogas, in “greenhouse” environmental conditions, showed a more constant 

concentration of CH4 (about 12 days) than biogas obtained from simple mixing. 

c) The most optimal period of time, considering the duration of the weather, was the region of Vlora 

(14 June to 1 October) compared to the regions of Tirana and Shkodra. 



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Based on above points a, b and c, it turns out that: the most constant concentration of CH4 in the 

produced biogas is inoculum base and the most optimal time period for the duration of the temperature 

is the region of Vlora. The region of Vlora (part of Albania Westlowland) offers the suitable area to 

implement biogas power plant as alternative fuel for the future. 

 

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https://doi.org/10.1016/j.biortech.2007.12.055
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