**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 these pollutants [48].

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 during the composting process.

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 and organic residues.

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

**Figure 2.** *Flow of entry and exits in the composting process. Source: Author (2017).*

#### **Figure 3.**

*Mechanized composting system of swine effluents (a) [58], shaving bed after effluent injection and revolving (b) municipality of Concordia, SC.*

4 antibiotics (florfenicol, sulfadimetoxin, sulfametazin and tylosin) [51] during the composting process of domestic effluents, approximately 95–99% of antibiotics were degraded after 21 days of testing. Antibiotic decline [53] was evaluated (tetracycline 96%, 99% sulfonamides and macrolides 95%) during the composting process, [48], after 35 days of bench-scale composting, they did not detect the presence of antibiotics from the Sulfonamide Group (Sulfametazin (SMZ) and Sulfametoxazole (SMX)).

**Figure 3** shows one of the processes of composting of existing pig effluents, the mechanized one, which consists of mixing the waste produced by pigs in the rearing systems, with shavings, sawdust or straw in beds/beds [50].

However, this process as a proposal for the treatment of veterinary medicines of different classes, has yet been developed in the country, justifying the proposal, having presented good results in research already developed, its application becomes important in the search for new alternatives to minimize the potential environmental risks caused by these contaminants, since in contact with environmental matrices can be accumulated in the soil, as well as being leached for water resources [56].

#### **5. Use of composting in the treatment of veterinary drugs**

One of the determining points for the development of research and its scientific relevance is the potential for contamination by veterinary antibiotics. Currently the pig production chain in the south of the country is estimated at 20.5 million heads. Considering only the state of Rio Grande do Sul (7 million heads), and assuming that the main group of antibiotics, tetracycline [15, 21], which is given in the order of 400 mg/animal/80 kg. The medicated with the main antibiotic group, and 70% of the dose is excreted by urine and feces [18]. If this residue is deposed in current treatment systems, which can reduce its concentration by 50%, this would result in 0.140 g/tetracycline/animal, representing 0.98 tons of antibiotics that would be dumped into the soil annually along the effluent in the form of biofertilizer [59].

The search for technical alternatives for the treatment of pig manure contaminated with residues of veterinary drugs was decisive for the accomplishment of the

**245**

was found.

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

they generate some kind of metabolites or other substance.

**6. Microbial communities of the composting process**

temperatures should be higher than 40°C [48].

work, considering the size of the production chain in the country, due to the lack of research at the national level, but mainly in minimizing the potential damage, they can cause to the environment. The results observed in the research point a potential for chronic contamination and disturbances at the environmental level, but also at the social level, very expressive, but also point to the need for research aimed at the search for technological alternatives for the treatment of these residues, often left aside. Based on the results obtained [58], it was observed that composting proved to be effective in the degradation of 19 veterinary drugs, divided into 8 groups. The decay/degradation rate ranged from 33.7–100% in 150 days. The antibiotics sulfatiazole, tetracycline and chlortetracycline showed 100% decay. The mean degradation of antibiotics was 97.2%, proving composting as a technique for the treatment of swine effluents contaminated by antibiotics, however, at the end of composting, some antibiotics presented residues in the order of milligrams per kg in the final compound. Therefore, further research on the behavior of these compounds during composting would elucidate whether these compounds are actually degraded or if

Regarding the community of microorganisms for Bacteria and Fungi [58], a great diversity in the level of phylum and genera observed in both kingdoms throughout the composting. Regarding phyla and genera of bacteria, 7 phylum and more than 70 genera of bacteria were observed over time (0, 15, 30, 45, 60, 75, 90, 120 2150 days). Fungal diversity at phylum and gender level was 2 phylum and 16 genera. This abundance and diversity may be related to the proposed identification methodology, new generation sequencing, which proved to be able to identify a wide range of the micro biota found during composting. In this context, a correlation between environmental variables and antibiotics with microorganisms was, also observed, proving through redundancy analysis that the main factors to have significance in the bacterial community were humidity, but not influencing the fungal community. Veterinary antibiotics (Tilcomisin and Ciprofloxacin) showed a positive correlation in the vast majority of bacteria genera, an effect not observed in fungi. In the fungal genera, the antibiotic Tilmicosin has a positive correlation with the genera *(Apiotrichum* and *Penicillium)* and Ciprofloxacin has a positive relationship with the genera (*Tricosporium, Parascedosporium, Petriella* and *Cryptococcus*).

The application of animal waste contaminated with residues of veterinary medicinal products has become the gateway to the expansion of several types of antibiotic resistance genes, caused by the indiscriminate use of antibiotics in the production of animal protein [60, 61]. In the composting process, there are different types of microorganisms, among them the predominance of bacteria, fungi and actinomycetes, divided into aerobic, thermotolerant and mesophilic [48], which are responsible for about 95% of microbial activity [3]. One of the most important parameters for the proliferation of these microorganisms is temperature, which should not exceed 65°C, for fungi and actinomycetes, and for bacteria,

Another important aspect is the presence of microorganisms, which are capable of contaminating the environment [9] including *E. coli and* other pathogens. Also according to the authors, during the experiment, carried out with composting of swine effluents, the average presence of 2 to 5 (log10 NMP g−1) of total coliforms

It found 39 species of fungi in the composting process [50], many of which were

identified only at the beginning or at the end of the experiment (**Table 1**).

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

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

work, considering the size of the production chain in the country, due to the lack of research at the national level, but mainly in minimizing the potential damage, they can cause to the environment. The results observed in the research point a potential for chronic contamination and disturbances at the environmental level, but also at the social level, very expressive, but also point to the need for research aimed at the search for technological alternatives for the treatment of these residues, often left aside.

Based on the results obtained [58], it was observed that composting proved to be effective in the degradation of 19 veterinary drugs, divided into 8 groups. The decay/degradation rate ranged from 33.7–100% in 150 days. The antibiotics sulfatiazole, tetracycline and chlortetracycline showed 100% decay. The mean degradation of antibiotics was 97.2%, proving composting as a technique for the treatment of swine effluents contaminated by antibiotics, however, at the end of composting, some antibiotics presented residues in the order of milligrams per kg in the final compound. Therefore, further research on the behavior of these compounds during composting would elucidate whether these compounds are actually degraded or if they generate some kind of metabolites or other substance.

Regarding the community of microorganisms for Bacteria and Fungi [58], a great diversity in the level of phylum and genera observed in both kingdoms throughout the composting. Regarding phyla and genera of bacteria, 7 phylum and more than 70 genera of bacteria were observed over time (0, 15, 30, 45, 60, 75, 90, 120 2150 days). Fungal diversity at phylum and gender level was 2 phylum and 16 genera. This abundance and diversity may be related to the proposed identification methodology, new generation sequencing, which proved to be able to identify a wide range of the micro biota found during composting. In this context, a correlation between environmental variables and antibiotics with microorganisms was, also observed, proving through redundancy analysis that the main factors to have significance in the bacterial community were humidity, but not influencing the fungal community. Veterinary antibiotics (Tilcomisin and Ciprofloxacin) showed a positive correlation in the vast majority of bacteria genera, an effect not observed in fungi. In the fungal genera, the antibiotic Tilmicosin has a positive correlation with the genera *(Apiotrichum* and *Penicillium)* and Ciprofloxacin has a positive relationship with the genera (*Tricosporium, Parascedosporium, Petriella* and *Cryptococcus*).

## **6. Microbial communities of the composting process**

The application of animal waste contaminated with residues of veterinary medicinal products has become the gateway to the expansion of several types of antibiotic resistance genes, caused by the indiscriminate use of antibiotics in the production of animal protein [60, 61]. In the composting process, there are different types of microorganisms, among them the predominance of bacteria, fungi and actinomycetes, divided into aerobic, thermotolerant and mesophilic [48], which are responsible for about 95% of microbial activity [3]. One of the most important parameters for the proliferation of these microorganisms is temperature, which should not exceed 65°C, for fungi and actinomycetes, and for bacteria, temperatures should be higher than 40°C [48].

Another important aspect is the presence of microorganisms, which are capable of contaminating the environment [9] including *E. coli and* other pathogens. Also according to the authors, during the experiment, carried out with composting of swine effluents, the average presence of 2 to 5 (log10 NMP g−1) of total coliforms was found.

It found 39 species of fungi in the composting process [50], many of which were identified only at the beginning or at the end of the experiment (**Table 1**).


#### **Table 1.**

*Fungi identified during the process of composting of swine effluents with residues of treated seeds.*

**247**

**7. Conclusions**

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

Evaluating the resistance of microorganism genes to the antibiotic

Oxytetracycline (OTC) [13], observed the predominance in 95.3% of the bacteria found, with the following phylos (kingdoms) Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes and Proteobacteria, and that of these kingdoms, 50 generos (*Clostridium sensu stricto, Aquamicro Aquabium; Paenibacillus; Azoarcus; Jonesia; Gracilibacillis; Devosia; Celivibrio; Marinobacter; Tepidimicrobium; Ornithinibacillus; Paracoccus; Pelagibacterium; Turicibacter; Streptomyces; Leucobacter; Vulgatibacter; Steroidobacter; Bordetella; Chelatococcus; Trupera; Nonomuraea; Thermovum; Brumimicrobium; Caldalkalibacillus; Ornithinimicrobium; Jeotgalicoccus;* 

*Ureibbacillus; Sphaerobacter; Saccharibacteria\_genera\_incertae\_sedis; Pseudomonas;* 

Also in relation to the resistance of microorganisms with antibiotics, [57] they state that CTC inhibited the growth of 12 soil bacteria at different concentrations. In addition to the increased intake of antibiotics in the environment, this can pose risks to human health, such as increased allergy to antibiotics and increased resistance to antibiotics, as many foods develop in places with inadequate effluent

Microorganisms such as *E. coli have* shown antibiotic resistance in several studies [58, 62–64]. *E. coli resistance* was tested from wastewater and wastewater treatment system in 24 antibiotics [64], distributed in 6 classes (Penicillins, Cephalosporins, Chynomas, AminoGlycosides, Sulfonamides and Tetracycline). The results showed that the groups of antibiotics with the highest resistance were, Penicillin;

In another study [14] they found 14 tetracycline-resistant genes and three antibiotic resistance genes Sulfonamines, which modified ribosomal protection proteins, enzymatic inactivation proteins. These results can also be confronted by the high persistence and accumulation capacity that antibiotics have when they are in environmental matrices, especially in soils. Evaluated the persistence of 5 antibiotics in the soil (Tetracycline, Sulfametazin, Norfloxacin, Erythromycin and Chloramphenicol), where the highest rate of antibiotic adsorption in the soil was: Tetracycline > Norfloxacin > Erythromycin> Chloramphenicol> Sulfametazin, thus

In the end, we can admit that the composting process presented itself as an alternative to the current treatment systems, since it combines, at the same time, the treatment of swine effluent, but it has the capacity to degrade antibiotic residues found in swine effluents, minimizing their effects. Impacts on the environmental matrices (soil and water), and still at the end, generate a product (compost) with

agricultural potential superior to the use of effluents directly in the soil.

*Corynebacterium; Dietzia; Clostridium XI; Sphingobacterium; Pusillimonas; Luteimonas; Flovobacterium; Actinomadura; Rhodopirellula; Verrucosispora; Nocardioids; Bacillus; Ammoniibacillus; Planifilum; Georgenia; Idiomamarina; Saccharomonospora and Thermobifida)* during aerobic composting of bovine effluent, as well as the increase in OTC resistance in some genders [13].

It is observed that of the total fungi, five species were found since the beginning of the process (*Alternaria alternata\* Aureobasidium floccosum\* Fusarium oxysporum\* Helminthosporium spp\*).* In a system of composting of poultry, waste found 3 phylos (kingdoms) in greater quantity: Betaproteobacteria; Firmicutes and Bacteria [49].

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

disposal and transfer a contaminated load.

increasing the risk to the environment [61].

Cephalosporin; Kilonomonas; Sulfonamides and Tetracycline.

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

It is observed that of the total fungi, five species were found since the beginning of the process (*Alternaria alternata\* Aureobasidium floccosum\* Fusarium oxysporum\* Helminthosporium spp\*).* In a system of composting of poultry, waste found 3 phylos (kingdoms) in greater quantity: Betaproteobacteria; Firmicutes and Bacteria [49].

Evaluating the resistance of microorganism genes to the antibiotic Oxytetracycline (OTC) [13], observed the predominance in 95.3% of the bacteria found, with the following phylos (kingdoms) Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes and Proteobacteria, and that of these kingdoms, 50 generos (*Clostridium sensu stricto, Aquamicro Aquabium; Paenibacillus; Azoarcus; Jonesia; Gracilibacillis; Devosia; Celivibrio; Marinobacter; Tepidimicrobium; Ornithinibacillus; Paracoccus; Pelagibacterium; Turicibacter; Streptomyces; Leucobacter; Vulgatibacter; Steroidobacter; Bordetella; Chelatococcus; Trupera; Nonomuraea; Thermovum; Brumimicrobium; Caldalkalibacillus; Ornithinimicrobium; Jeotgalicoccus; Ureibbacillus; Sphaerobacter; Saccharibacteria\_genera\_incertae\_sedis; Pseudomonas; Corynebacterium; Dietzia; Clostridium XI; Sphingobacterium; Pusillimonas; Luteimonas; Flovobacterium; Actinomadura; Rhodopirellula; Verrucosispora; Nocardioids; Bacillus; Ammoniibacillus; Planifilum; Georgenia; Idiomamarina; Saccharomonospora and Thermobifida)* during aerobic composting of bovine effluent, as well as the increase in OTC resistance in some genders [13].

Also in relation to the resistance of microorganisms with antibiotics, [57] they state that CTC inhibited the growth of 12 soil bacteria at different concentrations. In addition to the increased intake of antibiotics in the environment, this can pose risks to human health, such as increased allergy to antibiotics and increased resistance to antibiotics, as many foods develop in places with inadequate effluent disposal and transfer a contaminated load.

Microorganisms such as *E. coli have* shown antibiotic resistance in several studies [58, 62–64]. *E. coli resistance* was tested from wastewater and wastewater treatment system in 24 antibiotics [64], distributed in 6 classes (Penicillins, Cephalosporins, Chynomas, AminoGlycosides, Sulfonamides and Tetracycline). The results showed that the groups of antibiotics with the highest resistance were, Penicillin; Cephalosporin; Kilonomonas; Sulfonamides and Tetracycline.

In another study [14] they found 14 tetracycline-resistant genes and three antibiotic resistance genes Sulfonamines, which modified ribosomal protection proteins, enzymatic inactivation proteins. These results can also be confronted by the high persistence and accumulation capacity that antibiotics have when they are in environmental matrices, especially in soils. Evaluated the persistence of 5 antibiotics in the soil (Tetracycline, Sulfametazin, Norfloxacin, Erythromycin and Chloramphenicol), where the highest rate of antibiotic adsorption in the soil was: Tetracycline > Norfloxacin > Erythromycin> Chloramphenicol> Sulfametazin, thus increasing the risk to the environment [61].
