DOI: 10.3303/CET2292061

Paper Received: 8 February 2022; Revised: 19 March 2022; Accepted: 26 April 2022
Please cite this article as: Cadillo Garay L.Y., Ramos Rico N.R., Castaneda-Olivera C.A., Cabrera Carranza C., Benites Alfaro E., Tello Mendivil
V., 2022, Biogas as Clean Energy from Bovine, Porcine and Ovine Rumen Contents: Obtaining and Characterization, Chemical Engineering
Transactions, 92, 361-366 DOI:10.3303/CET2292061

CHEMICAL ENGINEERING TRANSACTIONS

VOL. 92, 2022

A publication of

The Italian Association
of Chemical Engineering
Online at www.cetjournal.it

Guest Editors: Rubens Maciel Filho, Eliseo Ranzi, Leonardo Tognotti

ISBN 978-88-95608-90-7; ISSN 2283-9216

Biogas as Clean Energy from Bovine, Porcine and Ovine

Rumen Contents: Obtaining and Characterization

Luz Y. Cadillo Garay, Noemi R. Ramos Rico, Carlos A. Castañeda-Olivera*, Carlos

Cabrera Carranza, Elmer Benites-Alfaro, Veronica Tello Mendivil

Universidad César Vallejo, Campus Los Olivos, Lima, Perú

caralcaso@gmail.com

Fossil energy sources and the pollution they cause is an environmental problem that urgently requires

alternative solutions, one of which is biogas. Thus, the present research was carried out with the objective of

evaluating the quality of biogas obtained from bovine, percine and ovine rumen content in a municipal

slaughterhouse in the district of Huallanca - Ancash, Peru. A tubular biodigester with dimensions of 6 m long x

0.40 m in diameter was designed for the process. An iron chip filter treated with 5% HCL and 5% NaOH was

also installed to reduce H2S (the cause of unpleasant odors), and consequently improve the quality of the biogas.

The ratio of organic load and water in the biodigester reactor was 1:2, resulting in a total load volume of 1.5625

m3, and the hydraulic retention time was 85 days. It was observed that the temperature in the process ranged

between 14.3 and 25.3 °C and the pH was maintained between 5.5 and 7.6. The biogas characterization showed

16.6 % CH4, 37 % CO2, 11.8 % O2, 550 ppm H2S and 19 ppm CO. From the results obtained, the viable

alternative of using biomass composed of organic waste from slaughterhouses to generate biogas as a source

of clean energy is clear.

1. Introduction

The need for energy in many rural areas, given the scarcity of non-renewable fossil fuels, has led to the use of

vegetable and animal biomass as an alternative for obtaining biogas as a source of energy, with the advantage

of being environmentally friendly. The meat industry generates a large amount of waste that often causes

problems due to inadequate disposal (Guerrero and Ramírez, 2004), including rumen waste, which in some

cases is discharged into rivers and pollutes them, but in others is used as compost (Uicab and Sandoval, 2018).

Various raw materials have been used to obtain biogas, such as organic vegetable waste, sludge from treatment

plants (Gamba et al., 2014), sludge and organic waste (Zirngast et al., 2021), animal manure, among others. In

the literature, it has been verified that it is possible to obtain biogas from cow manure, banana and mango peels

(Tewelde, 2018), fruit and vegetable waste (Deressa et al., 2015), corn straw and cow manure (Chukwuka et

al., 2021) and pig manure (Sanchez, 2017; Venegas Venegas et al., 2019). Other authors such as Mejia and

Peralta (2019) achieved the same objective using the mixture of semi-solid residues of manure (bovine and

swine) and rumen. Also, Yusuf et al. (2021) obtained biogas from cattle manure digestion and co-digestion with

Typha Latifolia.

The process of obtaining biogas from plant and animal biomass has allowed its transformation into an energy

source with very good results that can be used in places where these residues are abundant (Palacios et al.,

2020). The generation of this fuel is very important because of its nature as a non-polluting renewable energy

that benefits the population due to its relatively low cost and easy production.

Therefore, the objective of the research was to obtain biogas from bovine, percine and ovine rumen content in

a municipal slaughterhouse in the district of Huallanca - Ancash, Peru. The quality of the biogas obtained was

also evaluated, determining the components such as CH4, CO2, O2, H2S and CO.

361

2. Methodology

The research was developed through the following stages:

2.1 Stage 1: Obtaining ruminal content of cattle, pigs and sheep

First, samples of organic residues generated in the slaughterhouse of Huallanca - Ancash, Peru were collected.

Then the viscera of cattle, pigs and sheep were washed, selecting all the material from the animal stomach that

was not digested until the time of slaughter. The rumen content obtained is shown in Figure 1.

Figure 1: Rumen content of sheep, pigs and cattle

2.2 Stage 2: Construction of the biodigester

A tubular or Taiwanese biodigester (Figure 2-a) was designed with dimensions of 6 m long x 0.40 m diameter

(García et al., 2017), taking into account the daily load and volume of biogas to be generated (Martí, 2008). The

biodigester was designed for a capacity of 1.5625 m3, and was installed at the "Ogopampa" municipal organic

waste center in the district of Huallanca - Ancash, Peru. The biodigester was placed and conditioned in a

greenhouse (Figure 2-b) due to the low temperatures of the site.

Figure 2: a) Tubular biodigester and b) Greenhouse

2.3 Stage 3: Characterization of rumen content

The homogenized rumen content was characterized by taking a sample to the Soil and Materials Laboratory of

the Universidad César Vallejo. In the laboratory, pH and temperature (ºC) were measured, and the content of

carbon (C), nitrogen (N), total solids (TS), volatile solids (VS), moisture (% H), electrical conductivity (EC) and

organic matter (OM) were determined. For this purpose, a Hanna EDGE Multiparameter and Kjeldahl equipment

were used.

2.4 Stage 4: Preparation and loading of raw material

First, the rumen contents (bovine, porcine and ovine) were mixed with water in a 1:2 ratio in a container (see

Figure 3-a). Then the feedstock was loaded into the biodigester for biogas production (Figure 3-b).

362

Figure 3: a) Preparation of the raw material and b) Loading of raw material

2.5 Stage 5: Iron filter installation

A filter column (1m long x 0.5m in diameter) was installed with iron chips treated with HCL and 5% NaOH, in

order to remove the hydrogen sulfide (H2S) that caused the bad odor.

2.6 Stage 6: Process monitoring and control

In this stage, the ambient temperature (external temperature) and the temperature and pH of the biodigester

load were measured. This control was carried out three times a week for 85 days.

3. Results and discussion

3.1 Characteristics of bovine, porcine and ovine rumen contents

Table 1 shows that the rumen residues obtained presented acid pH values, which can affect the biogas

generation process. Organic matter is present in high levels that favor anaerobic digestion with the presence of

microorganisms involved in biogas generation. This variable is important in biodigester operation and

management due to the fact that in many cases it is evaluated as the chemical oxygen demand (COD) (Garcia

et al., 2017).

The percentage of nitrogen and carbon are important to evaluate in the biogas production process since from

the biochemical reactions with a nutrient-rich substrate they allow the activity of microorganisms. Macronutrients

are in the rumen residues as a source of carbon for the microorganisms to have energy and nitrogen is

necessary for the formation of new cells (García-Caro Andreu, 2013).

Table 1: Physicochemical parameters of rumen residues

Parameters
Type of rumen residue

Ovine Porcine Bovine Mixture (ovine, porcine and bovine)

pH 4.75 6.62 5.62 5.26

Temperature (°C) 19.20 18.50 18.40 18.50

Electrical conductivity (µS/cm) 2523 2670 2594 2630

Moisture (%) 58.25 60.34 62.15 59.45

Organic matter (%) 86.96 62.15 89.21 87.35

Nitrogen (mg/L) 25.36 28.15 29.75 27.80

Total organic carbon (mg/L) 60.20 62.15 62.15 55.14

Total solids (mg/L) 15.62 15.78 15.69 15.50

Volatile solids (mg/L) 78.14 76.72 76.92 75.19

3.2 Factors in the generation of biogas from rumen waste

a) Carbon/nitrogen ratio

The carbon/nitrogen ratio is important because they are food sources for methanogenic bacteria. This ratio was

calculated using Equation 1 (FAO - UN, 2011).

363

𝐶/𝑁 (𝑀𝑖𝑥𝑡𝑢𝑟𝑒) = (𝐶1 ∗ 𝑄1 + 𝐶2 ∗ 𝑄2 + ⋯ 𝐶𝑛 ∗ 𝑄𝑛)/(𝑁1 ∗ 𝑄1 + 𝑁2 ∗ 𝑄2 + 𝑁𝑛 ∗ 𝑄𝑛) (1)

Where: C=% of carbon; N= % of nitrogen; Q=Fresh weight of residue (kg)

Table 2: Carbon/nitrogen ratio of rumen residues

Type Weight (kg) C (%)

N (%) C/N ratio

Ovine 1 60.2 25.36

Porcine 1 62.15 28.15

Bovine 1 62.15 29.75

Resulted 2.2440

b) Rumen waste/water ratio

The biodigester was loaded three times per week using a 1:2 ratio for rumen waste/water. The loading was

calculated taking into account the percentage of total solids in the ruminal waste, using Equation 2. The total

waste loading in the process was 1,548 kg.

% 𝑜𝑓 𝑇𝑆 (𝑡𝑜𝑡𝑎𝑙 𝑠𝑜𝑙𝑖𝑑𝑠 𝑑𝑖𝑙𝑢𝑡𝑒𝑑) = (1 𝑘𝑔 𝑟𝑢𝑚𝑒𝑛 ∗ % 𝑇𝑆 𝑟𝑢𝑚𝑒𝑛)/(1𝑘𝑔 𝑟𝑢𝑚𝑒𝑛 + 𝑤𝑎𝑡𝑒𝑟 𝑤𝑒𝑖𝑔ℎ𝑡) (2)

c) pH and temperature in the biogas generation process

The pH of the biodigester mixture (load) was monitored with a PH60S digital pH meter, with values in the range

of 5.5 to 7.6. The internal temperature of the biodigester varied between 14.3 and 25.3 °C, while the ambient

temperature (external temperature) in the greenhouse varied between 15 and 33.2 °C (see Table 3). The

ambient temperature is an indicator for the retention time of the process; at high temperatures the retention time

is shortened. The scientific literature recommends that at 10, 15, 20, 20, 25, 30 and 35 °C, the retention time

should be 90, 60, 45, 37, 32 and 28 days, respectively (Prieto and Fajardo, 2017). However, in the research,

the ambient temperature in the greenhouse was taken as a reference in view of the fact that the location has

drastic values of variation. The retention time of the process was 85 days, with 30 temperature and pH controls,

as shown in Table 3. It shows variable temperatures, generally low despite the installation of a greenhouse to

raise the temperature, which did not favor anaerobic digestion (Rahman et al., 2019).

Table 3: Temperature and pH of the biodigester process

Nº

Internal

temperature

ºC

External

temperature

ºC

pH Nº

Internal

temperature

ºC

External

temperature

ºC

1 16.3 16.5 6.90 16 18.3 21.9 6.90

2 17.0 17.4 5.50 17 19.2 20.8 6.60

3 14.3 15.0 5.69 18 18.5 25.2 7.00

4 17.2 17.4 6.13 19 19.5 20.6 6.50

5 18.0 20.0 6.15 20 21.2 28.5 6.00

6 24.3 24.5 6.18 21 22.6 21.5 6.90

7 23.6 30.0 6.50 22 23.3 30.0 6.00

8 25.3 28.5 6.43 23 17.40 18.30 7.60

9 22.5 24.0 5.90 24 16.90 17.20 5.96

10 16.2 30.5 6.10 25 17.30 19.20 7.30

11 16.3 33.2 5.98 26 19.40 17.00 7.20

12 15.9 35.0 7.00 27 15.90 18.00 6.58

13 16.2 30.8 7.40 28 18.40 22.90 6.50

14 15.2 30.0 5.72 29 17.50 21.40 6.35

15 17.4 25.0 7.00 30 19.50 18.30 6.80

Table 4 shows the characteristics of the by-product (digestate) generated in the biodigester. It can be seen that

the pH was 6.35, a value that is close to neutral, but not in the range of 7 to 8, a value recommended to prevent

problems of action and with favorable conditions for the action of microorganisms (Chen et al., 2008);

It is also mentioned that acetogenic and methanogenic bacteria are susceptible to pH and that the optimal range

is between 6.5 and 8 (Toledo-Cervantes et al., 2017). When pH is below 6.2, acidity inhibits the activity of

methanogenic bacteria, at values between 4.5 and 5.0, inhibition of fermentative bacteria occurs, and it is also

364

not advisable to work at pH above 8.0 - 8.5 (Canales et al., 2010). This was the difficulty faced by the research,

with the pH being mostly below 7 (see Table 3), which affected the biogas generation yield.

Table 4: Characteristics of the generated digestate

Parameters Value unit Retention time (days)

pH 6.35 -

85 Electrical conductivity 9.45 µS/cm

Totals solids 11.90 mg/L

3.3 Biogas composition

Table 5 shows the results of the analysis of the biogas samples at 57, 62 and 85 days of retention. The total

volume of biogas was 0.39 m3, and the results in sample 1 correspond to unfiltered biogas, while sample 2 and

sample 3 were passed through a treated iron chip filter.

The iron chip filter helped to reduce the presence of unpleasant odors caused by hydrogen sulfide (H2S), through

adsorption on its inner surface forming iron sulfide and water (Torres-Calderón et al., 2020). This allowed

obtaining better quality biogas, as was done in the research of Ortega Viera et al. (2015) that reduced by physical

methods of adsorption H2S from 1,781 to 350 ppm. In another case, 15.6 % decrease of this pollutant was

achieved (Huertas, 2019). On the other hand, Bernal and Palacios (2020) indicate that steel wool can be used

in the removal of hydrogen sulfide.

Table 5: Composition of the generated biogas

Methane

(%)

Carbon dioxide

(%)

Oxygen

(%)

Hydrogen sulphide

(ppm)

Carbon

monoxide (ppm)

Retention time

(days)

Sample 1 5.5 67 10.8 1,800 190 57

Sample 2 2.3 19 16.8 69.0 30 62

Sample 3 16.6 37 11.8 550.0 19 85

Considering the monitoring of sample 3 conducted at 85 days, the highest percentages of methane and carbon

dioxide equivalent to 16.6 and 37%, respectively, were found. This percentage of methane generation is

relatively low compared to other investigations that reached values of 70% methane and 15% carbon dioxide

(Linares et al., 2017). This effect was due to the ambient temperature factor, which varied and changed abruptly

from day to night, indicating that the conditioning of the biodigester should be improved to a more conducive

environment that maintains a high temperature suitable for biogas generation. Literature indicates that between

30 to 35 °C is the best interval that favors optimal growth and high operation of mesophilic microorganisms in

biogas production (Poh et al., 2015). The probable presence of inhibitory substances such as lignin compounds

that are harmful to methanogenesis, hindering the action of microorganisms and consequently the generation

of biogas, is not ruled out (Chen et al., 2008).

4. Conclusions

It was found that biogas can be generated from bovine, porcine and ovine rumen residues using a tubular

biodigester. The total volume of biogas obtained was 0.39 m3, with percentages of 16.6% methane and 37%

carbon dioxide. It was verified that the operating conditions such as temperature and pH influenced the biogas

production yield, not discarding that probably other inhibitors such as the presence of lignin in the rumen residue

impaired the anaerobic digestion of the microorganisms. With all the above mentioned, it is concluded that

rumen residues can be used to obtain biogas to be converted into sustainable energy for the benefit of rural

populations.

Acknowledgments

The authors would like to thank "Investiga UCV" of the Universidad César Vallejo for financial support for the

publication of this research.

References

Bernal, E.N.G., Palacios, N.R., 2020, Desarrollo de una herramienta para diseño de un sistema de remoción

de sulfuro de hidrógeno presente en el biogás empleando lana de acero, Fundación Universidad de

América.

365

Canales, M. celeste, Rivas, L., Sorto, 2010, Estudio del proceso bioquímico de fermentación en digestores para

la producción de biogás y biofertilizante a partir de residuos orgánicos provenientes del campus de la

Universidad de El Salvador, Universidad de El Salvador.

Chen, Y., Cheng, J.J., Creamer, K.S., 2008, Inhibition of anaerobic digestion process: a review. Bioresour

Technol, 99, 4044–4064.

Chukwuka, D., Owuama, K.C., Chukwuneke, J.L., Falowo, O.A., 2021, Optimization of biogas yield from

anaerobic co-digestion of corn-chaff and cow dung digestate: RSM and python approach, Heliyon, 7,

e08255.

Deressa, L., Libsu, S., Chavan, R.B., Manaye, D., Dabassa, A., 2015, Production of Biogas from Fruit and

Vegetable Wastes Mixed with Different Wastes. Environment and Ecology Research, 3, 65–71.

FAO - ONU, 2011, Manual del Biogás, Chile <http://www.fao.org/37as400s/as400s.pdf>.

Gamba, S., Pellegrini, L., Lange, S., 2014, Energy Analysis of Different Municipal Sewage Sludge- Derived

Biogas Upgrading Techniques, Chemical Engineering Transactions, 37, 829–834.

García, R.S.G., Alamo, M., Marcelo, M.D.M., 2017, Diseño de un biodigestor tubular para zonas rurales en la

región Piura, in: XXIV Simposio Peruano de Energía Solar y del Ambiente (XXIV- SPES), Huaraz, Perú.

García-Caro Andreu, L., 2013, Estudio del comportamiento del tratamiento anaerobio de fangos ante

modificaciones en la entrada (Proyecto/Trabajo fin de carrera/grado), Universitat Politècnica de València.

Guerrero, J., Ramirez, I., 2004, Manejo ambiental de residuos en mataderos de pequeños municipios, Scientia

et Technica, X(26), 199-204.

Huertas, Joanna, 2019, Evaluación de la remoción del sulfuro de hidrógeno en el biogás mediante el método

de la aireación, Universidad Nacional Agraria la Molina.

Linares, W.E., López, F.G., Merino, F.A., 2017. Fundamentos teóricos y propuesta de un proceso para la

práctica del envasado de biogás libre de CO2 y H2S en El Salvador. Universidad de El Salvador.

Martí, J., 2008, Manual de instalación de biodigestores familiares: Guía de diseño y manual de instalación.

Bolivia.

Mejía Rosado, G.C. and Peralta Zambrano, J.R., 2019, Producción de biogás mediante biodigestor a escala

piloto con residuos semi-sólidos (excretas y rumen) del camal de Calceta, Bolívar, Escuela Superior

Politécnica Agropecuaria de Manabí.

Ortega Viera, L., Rodríguez Muñoz, S., Fernández Santana, E., Bárcenas Pérez, L., 2015, Principales métodos

para la desulfuración del biogás. Ingeniería Hidráulica y Ambiental, 36, 45–56.

Palacios, L., Obregón, G., Valverde, J., Castañeda, C., Benites, E., 2020, Calorific Value of Biogas Obtained

by Cavia Porcellus Biomass, Chemical Engineering Transactions, 80, 271–276.

Poh, P.E., Tan, D.T., Chan, E.S., Tey, B.T., 2015, Current advances of biogas production via anaerobic

digestion of industrial wastewater, Advances in Bioprocess Technology, 149–163.

Prieto, D.M., Fajardo, J.M., 2017, Análisis de biomasas obtenidas en el sector rural, municipio de Sibaté –

Cundinamarca, Revista Perspectivas, 2, 10–17.

Rahman, Md.A., Møller, H.B., Saha, C.K., Alam, Md.M., 2019, The effect of temperature on the anaerobic co-

digestion of poultry droppings and sugar mill press mud, Biofuels, 1–9.

Sánchez, Y.T., 2017, Evaluación de la viabilidad de la biodigestión como sistema de tratamiento de los residuos

de la granja porcina “Galo Porcino” Cantón Echeandia, Provincia de Bolívar, año 2016, Universidad Técnica

Estatal de Quevedo.

Toledo-Cervantes, A., Lebrero, R., Cavinato, C., Muñoz, R., 2017, Biogas upgrading using algal-bacterial

processes, in: Gonzalez-Fernandez, C., Muñoz, Raúl (Eds.), Microalgae-Based Biofuels and Bioproducts,

Woodhead Publishing Series in Energy. Woodhead Publishing, 283–304.

Torres-Calderón, S., Paucar-Palomino, M.J., Pampa-Quispe, N.B., Torres-Calderón, S., Paucar-Palomino,

M.J., Pampa-Quispe, N.B., 2020, Adsorción de sulfuro de hidrógeno del biogás mediante virutas de hierro

pretratadas para reuso energético. Ingeniería Hidráulica y Ambiental, 41, 18–29.

Uicab, L., Sandoval, C., 2003, Uso de contenido ruminal y algunos residuos de la industria cárnica en la

elaboración de composta, Tropical and Subtropical Agroecosystems, 2(2), 45-63

Venegas Venegas, J.A., Raj Aryal, D., Pinto Ruíz, R., 2019, Biogás, la energía renovable para el desarrollo de

granjas porcícolas en el estado de Chiapas. Análisis económico, 34, 169–187.

Yusuf, S.S., Ismail, M., Jibrin, A., 2021, Analysis of Biogas Production from Digestion of Cattle Dung and Co-

Digestion with Typha Latifolia in Funtua, Katsina State – Nigeria.

Zirngast, K., Petrovic, A., Podricnik, M., Cucek, L., 2021, Synthesis of Biogas Supply Network Based on

Experimental Data from Lab-Scale Anaerobic Digestion of Sewage Sludge and Organic Waste, Chemical

Engineering Transactions, 88, 1051–1056.

366

132cadillo.pdf
Biogas as Clean Energy from Bovine, Porcine and Ovine Rumen Contents: Obtaining and Characterization