**3. Use of veterinary drugs**

The indiscriminate use of veterinary medicinal products in animal husbandry, especially in pig farming, has become the gateway of these pollutants to the environment [12]. Antibiotics used since prevention, therapeutic use, helping in the treatment of diseases such as infections, diarrhea, still being able to act as growth promoters [13–16]. Currently, there is a great concern in the academic community, with residues derived from veterinary drugs, due to their potential contaminant, but also, by the non-absorption completely, by the animal organism. Several authors, such as [15–19] point out that on average 60% of the veterinary medicinal product dosed to animals are excreted through urine and feces [20], and the group of drugs most commonly used today are antibiotics [15, 21], and among them, tetracyclines, sulfonamides, lincosamides, β-lactamines and macrolides [22].

After their non-absorption by the body, veterinary drugs can reach soil and water resources [13, 16, 22] as unaltered substances or metabolites. The use of pig effluents as fertilizer may be emphasizing the spread and increase of antibiotic residues in the environment [12, 20]. Several studies have proven environmental contamination around the world through antibiotics, such as tetracycline in Brazil, Canada and China, [20, 23, 24], by sulfonamines in Bolivia, Czech Republic and USA, [25–27], macrolides in South Korea, United Kingdom and Hong Kong [28–30], fluroquinolonas in Poland, Austria and Thailand [31–33], and kilane in China and Malaysia [25, 34].

In addition, to soil contamination by heavy metals [35], contamination of water resources [36], the application of biofertilizers, directly or indirectly in the soil [34], has caused change in the soil biotic community [37]. Another point that draws attention, and more significant is the resistance of microorganisms to antibiotics, several authors have found evidence of the resistance of microorganisms [38–42] thus enhancing the risk to human health [34, 38, 43].

The availability and use of pig effluent are justified by the size of the production chain. Brazil is among the four largest producers of pigs in the world, behind China, the United States and the European Union, with an estimated herd of 42 million heads, representing US\$ 1 billion annually in meat sales [44, 45]. The Southern Region of the country, where the states of Paraná, Santa Catarina and Rio Grande do Sul are located, account for 49.3% of the national production [46]. With a well-established production chain, a large amount of waste generated. Point out that a pig in the finishing phase can produce up to 7.6 liters of manure/day [47], often causing failures and overload in effluent treatment systems, which mostly treated by biological ponds.

Many of these existing environmental problems and pressures are due to traditional organic effluent treatment systems, widespread in pig-producing units, which are not efficient in the treatment of these pollutants [48]. Compliance with environmental laws, as well as the feasibility of managing waste produced in farms, generated the need for alternatives for the treatment of effluents.

With this, composting emerged as a treatment proposal, which is a natural process of nutrient recycling, through aerobic microbial decomposition of organic matter [4], under favorable conditions of temperature, pH, oxygen, humidity, presence of chemical substances, raw material and C/N ratio [3, 47], resulting in a material with relative stability and quality [49]. The advantages range from minimizing the volume of effluents of about 90% [4], reducing the emission of greenhouse gases and the proliferation of vectors. Another important factor is the technical feasibility, to expand the current pig production systems [2–5], showing be a practical proposal, low cost [23, 25, 50], still classified as a clean and viable method [28], for the correct management of waste. Another advantage is the inactivation and immobilization of pathogens, nutrients and veterinary drugs [13, 48, 51, 52], thus becoming a potential proposal for the treatment of veterinary antibiotics [23, 25, 48, 53].

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**Figure 2.**

*Composting of Pig Effluent as a Proposal for the Treatment of Veterinary Drugs*

**4. Composting as a proposal for treatment of swine effluents**

Technologies that seek to reduce residues of veterinary medicinal products (RMV), mainly veterinary antibiotics (AVs) found in organic and industrial effluents disposed as fertilizer in the soil is a necessity to minimize the environmental impacts generated by these compounds [25]. Traditional organic effluent treatment systems, widespread in pig-producing units, are not efficient in the treatment of

Among the various technologies and treatment systems for different origins and compositions of organic effluents, including pigs, composting has been shown to be a practical proposal, low cost [23, 25, 50], classified as a clean and viable method [28] for the correct management of waste. This technique can be developed as an alternative for the treatment of effluents in small properties, located in regions with high concentration of pigs and with little agricultural area available for final disposal [4], as well as proposal for treatment of veterinary antibiotics [23, 25, 48, 53]. Composting can be defined as a process of aerobic microbial decomposition of organic matter, being a natural process of nutrient recycling, used since ancient civilizations [4], under favorable conditions of temperature, pH, oxygen, humidity [47], presence of chemicals, raw material and C/N ratio [3], resulting in a material with relative stability and quality [49]. Treatment by composting reduces the volume of effluents, inactivates and immobilizes pathogens, nutrients and veterinary drugs [13, 48, 51, 52], and finally produces a by-product (substrate), with economic and agronomic value [49, 50]. **Figure 2**, shows the cycle of inputs and outputs

This treatment proposal has been shown to be effective in the management of organic waste from production processes confined to pigs, poultry and cattle, and has the potential to treat emerging organic pollutants (POEs) [57]. The decay of the concentration of veterinary medicinal products through composting has been researched by several authors [13, 48, 49, 51, 54–56], for different types of effluents

The decline of 27% OF CTC was observed in swine effluents [57] and 92% in poultry manure in a composting system for 42 days. When analyzing the decline of

*Flow of entry and exits in the composting process. Source: Author (2017).*

Studies indicate that composting has potential in the treatment and decay of drug concentrations [3, 13, 48, 49, 51, 54–56]. Antibiotic residues such as florfenicol, sulfadimetoxin, sulfametazin and tylosin reached 95–99% decline in 21 days of composting [51]. Tetracycline, sulfonamides and macrolides had 99%, 96% and 95% decaine, respectively, through composting [53] in 35 days of testing. [48], they did not detect the presence of a group of sulfonamides (Sulfametazin (SMZ) and

*DOI: http://dx.doi.org/10.5772/intechopen.94758*

these pollutants [48].

during the composting process.

and organic residues.

Sulfamethoxazole (SMX)) in the final compound.

#### *Composting of Pig Effluent as a Proposal for the Treatment of Veterinary Drugs DOI: http://dx.doi.org/10.5772/intechopen.94758*

Studies indicate that composting has potential in the treatment and decay of drug concentrations [3, 13, 48, 49, 51, 54–56]. Antibiotic residues such as florfenicol, sulfadimetoxin, sulfametazin and tylosin reached 95–99% decline in 21 days of composting [51]. Tetracycline, sulfonamides and macrolides had 99%, 96% and 95% decaine, respectively, through composting [53] in 35 days of testing. [48], they did not detect the presence of a group of sulfonamides (Sulfametazin (SMZ) and Sulfamethoxazole (SMX)) in the final compound.
