OLIVEIRA, M.M.1,4, SCHELL, D.R.2, SMOZINSKI, N.G.1, BELLI FILHO, P1., OLIVEIRA, P.A.V.3
1 Santa Catarina Federal University-UFSC, Brazil;
2 Concórdia Faculty- FAC, Brazil;
3 Embrapa Swine and Poultry, Brazil;
4 Catarinense Federal Institute of Education Science and Technology, Brazil
ABSTRACT: The objective of this work was to evaluate the GHG and ammonia emissions in the composting of chicken carcasses in drums reactors. The experiments were developed in four rotating drums reactors with a volume of 4 m3. The study comprised 4 treatments, regarding the time which reactor remained in pause between the rotation movements: 1 hour (T1), 2 hours (T2); 3 hours (T3) and 4 hours (T4). Gaseous concentrations were determined using a photoacoustic equipment (INNOVA 1412). It was verified that T4 presented higher C-CO2
emission and T1 presented the highest N-NH3 emission. For the emission of C-CO2 and N-NH3, a correlation with the pause time of the reactor was observed, demonstrating the existence of the relation of the emission of gases with the treatments used.
Keywords: accelerated composting, rotating drums reactors, gaseous emissions, chicken carcass.
INTRODUCTION: Composting is an effective method to solve the problem of dead animals on farms (Mukhtar et al., 2004), becoming an important technology for the disposal of these wastes (Price and Carpenter-Boggs, 2008) and is able to increase the efficiency of this process with the use of biological reactors (Misra and Roy, 2003). In southern Brazil, the implantation of these rotary drum type reactors is being encouraged as technology for disposal of dead animals in production systems. In this context, the objective of this work was to evaluate the GHG and ammonia emissions in the composting of chicken carcasses in drums reactors.
1. MATERIAL AND METHODS: The experiments were developed in batch mode in four rotating drums reactors, with a volume of 4 m3 and a continuous ventilation system, which ensured the exchange of internal air. The study comprised 4 treatments, with respect to the time between the rotations, of 24 minutes, in which the reactor remains in pause: 1 hour (T1), 2 hours (T2); 3 hours (T3) and 4 hours (T4). Each reactor was loaded with 300 kg of crushed chicken carcass and sawdust added in a 1:1 ratio (carcass: sawdust), filling 50% of its volumetric load. For temperature monitoring, four ibutton type meters were used, mixed with biomass inside the
G = M − M (2) (mg/m3). The emission of N2 was determined by the difference between the amount of nitrogen lost in the mass of the material during the composting process and the sum of the emissions of N-NH3 and N-N2O.
2. RESULTS AND DISCUSSION: As regards temperature, for T1 and T2, the organic material remained on average for 6 and 7 days above 50 °C, whereas for T3 and T4 it was 10 and 13 days, respectively. The pH was similar for all treatments. At the beginning of the process, values of approximately 5.8 were obtained for all reactors, ending with values close to 7.1, presenting a range suitable for microbiological decomposition (Sesay et al., 1996). In all treatments, the CO2
emission was responsible for approximately 99% of the carbon loss present in the decomposing material, characteristic of aerobic processes, with the rest of the carbon loss attributed to CH4
emission, indicating the low formation of anaerobic zones (Paillat et al., 2005). In total, 31.03 kg C-CO2 was emitted during the 21 days of experiment for the first treatment, while for T2, T3 and T4 the emission of C-CO2 was 33.76 kg; 34.85 kg and 36.02 kg, respectively (Figure 1-b). The emission of C was higher in T4, which had a longer time of pause between the rotational movements of the reactor, while the treatment in which the reactor was programmed with the shortest pause time presented the smallest loss of C. A correlation between the C-CO2 emissions and the pause time of the reactors (Figure 2), a logarithmic curve was obtained, with r2 = 0.99, which shows that the emission of this gas is directly correlated with the time in that the reactor is at pause. This correlation is in agreement with the material temperature measurements, in which the reactors that had higher days at high temperatures were responsible for the higher emissions of C-CO2, these two parameters being the result of the activity of the biochemical reactions in the organic material (Epstein, 1997). On the other hand, the losses due to NH3
emission had the opposite behavior, because for the treatments with less pause time between the rotations (greater number of turns), the N-NH3 emission was higher due to the contribution of the rotation process, which favors release of the gases present in the organic mass. The correlation between the total amount of nitrogen emitted in each reactor and the paused time of the reactors between the rotational movements was linear and negative, with r2 = 0.988 (Figure 2). A total emission of 1.53 kg N-NH3 was found for T1 and 1.26; 1.09 and 0.9 kg N-NH3 for treatments T2, T3 and T4, respectively. The losses of N via ammonia emission represented 42.02%, 46.80%, 30.44% and 27.95%, and N2 generation was responsible for the highest loss of this element (Figure 1-b). It was also observed that for all treatments, the highest emission of C-CO2 and N-NH3 occurred in the first week of experiment, a considerable reduction occurred in the subsequent days, along with the reduction of humidity, a factor that affects the biological
Emission factors and air quality increased during the process (Tiquia and Tam, 2002).
Figure 1. a) Total emission of nitrogenous gases b) Total loss of carbon.
Figure 2. Correlation between the total emission (N-NH3 and C-CO2) and the pause time of the reactor.
Table 1 shows the mass balance of the reactors for carbon and nitrogen. The dry mass reduction (Table 2) was 16%, 18%, 19% and 20%, respectively for T1, T2, T3 and T4, being close to that found by Paillat et al. (2005), 20%. The difference between the mass of phosphorus in the material placed and withdrawn from the reactor was 1%, 2%, 3% and 4% for the reactors A, B and C, respectively, being these values below the maximum value recommended by Paillat et al.
(2005), 10%, which demonstrates the confidence of the process.
Y = 1,71-0.20*x r2=0.988
Table 1: Material balance in the reactor for carbon and nitrogen.
Table 2: Material balance in the reactor for dry matter and phosphorus.
Parameter Dry Matter Phosphorus for the disposal of carcasses of dead chickens. it was verified that the longer the pause time of the reactor smaller the will be the emission of n-nh3 and the greater the emission of C-CO2. Acknowledgments: The EMBRAPA- Swine and Poultry for the infrastructure and the financial contribution for the study and the UNIEDU/FUMDES for the granting of a scholarship.
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Emission factors and air quality
DUST, AMMONIA AND GREENHOUSE GASES EMISSIONS ASSOCIATED WITH THREE HOUSING