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 CCHHEEMMIICCAALL  EENNGGIINNEEEERRIINNGG  TTRRAANNSSAACCTTIIOONNSS  
 

VOL. 39, 2014 

A publication of 

 
The Italian Association 

of Chemical Engineering 

www.aidic.it/cet 
Guest Editors: Petar Sabev Varbanov, Jiří Jaromír Klemeš, Peng Yen Liew, Jun Yow Yong  

Copyright © 2014, AIDIC Servizi S.r.l., 

ISBN 978-88-95608-30-3; ISSN 2283-9216 DOI: 10.3303/CET1439099 

 

Please cite this article as: Leite S.A.F., Leite B.S., Isola A.T.P.D., Freitas L.S.F., Souza J.K.S., 2014, Application of cleaner 

production methodology to evaluate the generation of bioenergy in a small swine farm, Chemical Engineering Transactions, 

39, 589-594  DOI:10.3303/CET1439099 

589 

Application of Cleaner Production Methodology to Evaluate 

the Generation of Bioenergy in a Small Swine Farm 

Sibele A.F. Leite, Brenno S. Leite*, Ana T.P.D. Isola, Lohanne S.F. Freitas, 

Janayna K.S. Souza 

Universidade Federal de Viçosa (UFV- Campus Florestal), Institute of Science and Technology, Rodovia LMG, 818 km 

6 – CEP: 35.690-000, Florestal-MG, Brazil 

sibeleaugusta@ufv.br  

The swine production is an animal husbandry activity of great commercial importance in Brazil although 

the environmental organization considers the confined systems of low environmental quality and high 

polluter potential since it generates a great amount of waste and consumes a high amount of water. 

Against that background, the aim of this work was to apply the Cleaner Production (CP) methodology in a 

small swine farm with the purpose of identifying the bottlenecks of processes (considering environmental 

impacts) and propose sustainable and safe solutions. Based on the first results this research analyzed the 

economical and environmental feasibility of biogas production, due to the implementation of anaerobic 

digestions system. To achieve the first goal of this work, the authors developed a schematic flowchart of 

the process, then identified and evaluated the environmental impacts, to finally select the specific stages 

necessaries to implement CP actions. The main short and long term actions proposed were: the 

installations of a septic tank; the improvement of the drainage system; the installation of a hydrometer and 

a powered watch; the implementation of safety standards to storage chemical and medical products, the 

improvement of the residues management and the implementation of a biological treatment for the sewage 

which can be combined to a cogeneration system to produce electricity from the biogas. The technical 

feasibility study for the implementation of an efficient cogeneration system from the biogas has been 

developed considering three specific mathematics models (MM): 1st MM: Ratio between animal waste 

(manure generation) and amount of the biogas produced; 2nd MM: Ratio between the concentration of 

volatile solids (VS) from animal waste and amount of the biogas produced and 3rd MM: Empirical 

correlation between the amount of methane produced and the waste digested in the anaerobic reactor, 

considering influent Biological Oxygen Demand (BOD) value. The VS and BOD methods seem to be the 

most proper models and had close values for the predictions of biogas produced. According to these 

results the use of biogas for the energy cogeneration seems to be economically and environmentally 

practicable.  

1. Introduction 

The swine production is an animal husbandry activity of great commercial importance in Brazil. This 

activity employs approximately 1,000,000 people in the 26 federation states. Since 2001, Brazil has 

achieved the 4
th

 position of swine production with approximately 10 Mt/y, just behind the Republic of 

China, the European Union and the United States of America (Dias et al., 2011).   

The Brazilian swine production chain is formed by 50 thousands farmers which work in a different range 

and type of production. However, this activity has been mostly carried out in confined systems with 

controlled feeding and health care. Despite the economical relevance, Brazilian Environmental 

Organization considers the confined systems of low environmental quality and high polluter potential, since 

it generates a great amount of waste and consumes a high amount of water. It is noteworthy that swine 

production is the mainstream activity of the small rural proprieties. In North and Northeast of Brazil the 

swine production is performed in traditional production practices and subsists as one of the mainstream 

activity of the small rural proprieties while in South, Southeast and Midwest regions it is predominant the 

mailto:sibeleaugusta@ufv.br


 

 

590 

 
industrial swine production. The development of this industrial production showed the necessity of more 

advanced technologies seeking more efficiency and lower inputs consumption and the reduction of 

residues and wastewater (Souza et al., 2009). The Cleaner Production arises as an important 

methodology since it considers the necessity of a more efficient use of raw materials and energy, the use 

of renewable sources of energy, the improvement of energy technologies and the reduction of emissions 

and pollutants (Bonila et al., 2010).  

In this context, the use of the anaerobic digestion is considered promising for the energetic valorisation of 

the waste produced in the swine process. The biogas produced from the sewage is known as a waste-to-

energy technology since it reduces the volume and hazardousness of the sewage/sluge and at the same 

time can produce heat or electricity. It also reduces the environmental impacts generated by improper 

waste disposition and generates an extra income for the farmers, in additional to provide improvement on 

sanitary standards in rural areas (Lauwers et al., 2012). 

Thus, the aim of this work was to apply the Cleaner Production (CP) Methodology in a small swine farm 

with the purpose of identifying the bottlenecks of processes (considering environmental impacts) and 

propose sustainable and safe solutions. Based on the first results this research analyzed the economical 

and environmental feasibility for the implementation of a cogeneration system from the biogas using the 

sewage of the swine production. 

2. Experimental 

2.1 Cleaner Production (CP) Program  

This work was carried out in a small swine farm at Universidade Federal de Viçosa (University of Viçosa), 

Florestal, Brazil. In the present study a schematic flowchart of the process was made and then the 

environmental aspects and impacts were identified (Figure 1). In order to apply the Cleaner Production 

(CP) methodology, the aspects were evaluated and quantified (when possible). The evaluation considered 

the severity of the correlated impact and the application of the environmental legislation. Aspects which 

were severe and did not attend the legislation were considered significant and important for Cleaner 

Production analysis. Short and long term actions were proposed to avoid environmental impacts and 

improve sustainable solutions. Data collected is summarized in Table 1. 

2.2 Prediction of Biogas production 

From Table 1 it can be seen that the implementation of a cogeneration system from the biogas using the 

sewage of the swine production was considered a priority action in order to minimize the risk of water 

pollution, the consumption of energy and the smell. So, the present paper presents a technical feasibility 

study which was developed considering three specific mathematics models as follow.   

The first model uses the ratio between animal waste (manure generation) and amount of the biogas 

produced. According to Oliveira and Higarashi (2006) one kilogram of manure can produce between 0.35 

and 0.60 m
3
 of biogas. In addition, the quantity of manure that each animal produces depends on their 

growth stage (Bonett and Monticelli, 1998). Hence, the animals were classified and counted in order to 

estimate the amount of biogas that can be produced.  

The second model uses the ratio between the concentration of volatile solids from animal waste and 

amount of the biogas produced. One kilogram of volatile solids can produce 0.45 m
3
 of biogas (Oliveira 

and Higarashi, 2006).The sewage produced each day was quantified and samples were collected and 

analysed in accordance with Standard Methods for the Examination of Water and Wastewater (APHA, 

1995). 

Finally, the third model consists of the empirical correlation for the amount of methane produced and the 

wastewater digested in the anaerobic reactor as follow in Eq(1) (Bhattacharyya and Banerjee, 2007): 

 

   
x

P
i

EQS.
CH

V 42.1350
4

  (1) 

where VCH4 is the quantity of methane gas produced  (m
3
/kg.BOD.d), E is the efficiency of waste utilization 

(0.6), Q is the volumetric flow rate of wastewater (m
3
/day), S is the influent Biological Oxygen Demand 

(BOD kg/day) and Px (Eq(2)) is the net mass of cell tissue into BOD.  

 

cd
k

i
ESYQ

x
P












1

 
(2) 



 

 

591 

where Y is the yield coefficient (0.06), kd is the endogenous coefficient (0.03) and θc (14) is the mean cell 

residence time. The total volume of biogas produced can be estimated since it contains two-thirds 

methane.  

2.3 Economical study for implementation of a cogeneration system  

In the present work, the cost of the electrical energy produced by the cogeneration system was calculated 

considering the method described by Souza et al. (2004) and the results of the amount of biogas obtained 

according to section 2.2. The mathematic model considers the cost of the biodigester construction and 

maintenance (approximately USD 75.00/swine) and cost of the motor-generator system purchase 

(approximately USD 175.50/swine). 

In this calculation, the appropriate operation and maintenance conditions were considered. It was admitted 

that all the biogas produced was completely consumed by the motor-generator, which may be operating in 

steps of 4, 6, 8, 10 and 12 h/d. It was also considered, as the discount rate used, 8 %/y (this is the rate of 

the Brazilian federal government for the financing of agricultural and livestock activities) and amortization 

of 10 y. The annual cost of the maintenance per year is approximately 4 % of the total investment. 

3. Results and Discussion 

3.1 Cleaner Production (CP) Program 
The swine farm studied is considered small and has the maximum capacity for about 500 animals.  At the 

moment of the investigation there were 323 pigs. A schematic flowchart of the swine production was the 

first step of this study to apply the Cleaner Production (CP) methodology, as show in Figure 1. As can be 

seen in Figure 1, this process has inputs such as water, energy, animal feed and veterinary medication 

and also has important outputs such as sewage, smell and health services residues. The consumption of 

the inputs (natural resources) and the release of this output (residues) are the environmental aspects that 

were evaluated considering the severity of the correlated impact and the application of the environmental 

legislation. These aspects are rarely quantified and the only one usually controlled is the sewage that is 

about 2,285.00 L/d (2.285 m
3
/d).  

According to data present in Table 1 the production/release of sewage, smell, health services residues and 

the consumption of water and energy are some examples of the aspects that were considered significant 

and a priority for Cleaner Production analysis, since they were severe and did not satisfy the applicable 

legal.  As a consequence of these results short term actions such as: the installations of a septic tank;  the 

improvement of the system of drainage; the installation of a hydrometer and a powered watch; the 

implementation of safety standards to storage of chemical and medical products and the improvement of 

the residues management were proposed to minimize environmental impacts. In addition the most 

comprehensive long term action proposed was the implementation of a biological treatment for the sewage 

which can be combined to a cogeneration system to produce electricity from the biogas. 

Due to this fact it may be assumed the importance of a technical, economic and environmental feasibility 

study for the implementation of a bio digester and a cogeneration system to produce electricity from the 

biogas. 

 

 

Figure 1: Schematic flowchart of Swine Production 

 



 

 

592 

 
Table 1: Data collected for Cleaner Production analysis and actions proposed 

*S=?: Aspect considered severe?; R.L: legal requirements; CP: Cleaner Production 

 

Aspect Impact S=? 
Analysis of 

L.R 

Focus of 

CP 

(priorities) 

Short-term 

proposals 

Long-term 

proposals 

  
  

Have 

L.R? 
Satisfy 

L.R? 
   

 

Biological 

effluent 

generation 

Pollution of soil 

and water 
Yes Yes No 1 

Septic tanks; 

Drainage  

system  

System of 

wastes 

collection 

with inclination; 

 

Biological 

treatment for 

the sewage  

 
Consumption 

of water 

Depletion of 

natural 

resources 

Yes Yes No 1 Hydrometer 
Drinkers 

more efficient 

 

Consumption 

of energy 

Depletion of 

natural 

resources 

Yes No - 1 Powered watch 

Transparent 

roof to higher 

luminosity and 

heat; 

 

Cogeneration 

system to 

produce 

electricity from 

the biogas  

 

Appropriate 

facilities for 

use of space 

and with 

natural light 

 

 

Consumption 

of medical 

and chemical 

products 

Pollution of soil 

and water 
No No - 2 

Storage 

following 

safety standards 

Ensures good 

sanitation 

conditions of 

the farm and 

presence of 

veterinary 

professional 

 Waste 

generation 

(health 

services 

residues) 

Pollution of soil 

and water 
Yes Yes No 1 

Direct to 

incineration 
Not apply 

 
Release of 

gases 

(smell) 

Discomfort 

of the population 
Yes No - 2 

Cover the boxes 

of effluent  

Biological 

treatment for 

the sewage   



 

 

593 

Table 2: Experimental values of biogas (m³/day) in samples and Electrical Energy Cost (USD/m³ of biogas) 

calculated. 

Mathematic Model 
Biogas Production  Electrical Energy Cost (Ce)* 

Minimum Mean Maximum  Minimum Mean Maximum 

1
st
  Manure Generation 345.0 432.2 519.4  290.1 289.1 288.5 

2
nd

  Volatile Solids 3.1 13.8 33.2  377.3 377.3 335.6 

3
rd

 Biological Oxygen Demand 7.7 23.3 50.5  306.9 357.0 318.3 

* Values considered the 10 years of amortisation and 6 hours/day operation time  

3.2 Prediction of Biogas production 
The present work reports the results of the biogas estimated from the relations between 1st manure 

generation; 2nd Volatile Solids and 3rd Biological Oxygen Demand consumed and the amount of gas 

produced, as can be seen in Table 2. 

In order to estimate the biogas from the relation manure/biogas produced (1
st
), the animals were counted 

and classified into Breeding/Gestation (33), Farrowing (82), Piglets (71), Growing pigs/ Growth 

finishing (137). The swine farm totalizes 323 animals that in accordance with Bonett and Monticelli (1998) 
produce about 986 kg of manure each day. This quantity may produce at least 432.2 and the maximum of 

519.4 m³ of biogas (Oliveira and Higarashi, 2006).  

Afterward, the Volatile Solids (VS) and the Biological Oxygen Demand (BOD) of the sewage were 

quantified in order to apply the second and third models proposed. The samples were collected and 

analysed during December/2013 and January/2014. VS content varied between 13,378.3 and 32,310.0 

mg/L and BOD varied between 15,098.2 and 32,652.0 mg/L. Although the variation of the results is large, 

they are appropriated to swine sewage. This variation reflects the influence of the swine growth stage, the 

use of water for sanitation and health care and also the rainfall period (Souza et al., 2009).   

Data present in Table 2 suggest that the second and the third models are more reliable since they have 

close values and they consider the chemical relations between organic matter content and the quantity of 

biogas produced. Although the first model is the most common and simple, it may bring an overestimated 

value of biogas production and compromise the economical study for implementation of a cogeneration 

system. 

3.3 Economical study for implementation of a cogeneration system  

For a carrying out of the feasibility study of the implementation of a cogeneration system from the biogas it 

was considered the: investment return; energy production; investment of the cogeneration system 

(construction, acquisition and maintenance) and amortization investment. It was admitted that all the 

biogas produced was completely consumed by the motor-generator, which may be operating in steps of 4, 

6, 8, 10 and 12 hours/day.   

From Figure 2 it possible to see that longer the operating time of the motor-generator system, the minor is 

the cost of electrical energy production and consequently faster will be the return on the investment. In the 

 

 
Figure 2: Comparison of the electric energy cost (USD/MWh) considering the calculation of energy 

production in 4, 6, 8, 10 and 12 h/d operation time and the rural energy provide from electricity 

concessionaire 



 

 

594 

 
case studied, the rural energy provided from electricity concessionaire costs 500 USD/MWh. The cost of 

the energy produced from the biogas is just slightly larger compared with the cost of rural energy when the 

motor-generator operates 4 h/d. However for the operation time greater than 6 hours/day the energy 

produced from the biogas is lesser compared with the cost of rural energy, as can be seen in Table 2. 

Even though the values estimated for the biogas production are different they contribute little in the 

variation of the energy cost when energy production is short (4 hours/day operation) since the input of the 

motor-generator system is predominant compared to the operation cost.  

4. Conclusion 

The application of Cleaner Production (CP) Methodology leads to important actions that may be 

considered in the swine farm. It will bring environmental benefits and it will also improve the performance 

in product quality and working condition. However, this program itself might not be successful without an 

environmental managements system systematized in the organization and the commitment of the leaders 

and all the staff. According to CP program the implementation of a cogeneration system from the biogas 

using the sewage of the swine production was considered strategic in order to minimize the risk of water 

pollution, the consumption of energy and the smell. SV and BOD methods were considered more reliable 

to estimate biogas production from the swine waste. The use of the relation between animal waste 

(manure generation) and amount of the biogas produced should be used with precaution since it may 

overestimate the value of biogas production. Economical study for implementation of a cogeneration 

system indicates positivity the use of the biodigester combined with the motor-generator to provide energy 

in rural areas. The biogas/energy produced from the sewage is known as an important waste-to-energy 

technology that must be encouraged in Brazil.  

Acknowledgements 

Universidade Federal de Viçosa (UFV), Fundação de Amparo à Pesquisa de Minas Gerais –FAPEMIG 
and Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPQ. 

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