Utilização de um método híbrido de aeração forçada para compostagem em leiras

Abstract

In this research, it was aimed to evaluate the process of composting using the organic matter available at the bank of seedlings of the city of Sobral - CE, (horse manure and straw of carnauba) in three aeration systems: with injection of air, sucking of the air and injection and sucking in air cycle (hybrid), in compliance with the parameters recommended by Brazilian legislation in force, during the phases of active degradation and maturation. The experiment was installed with three treatments, one (01) under the positive way; one (01) under the negative way and one (01) under the hybrid way, following the proportions of 30% of horse manure and 70% of straw , for all treatments. Each treatment was repeated three (3) times, making, thus, a total of 9 (nine) parcels. It was conducted the evaluation of these processes, and it was observed mainly the influence of aeration and moisture in the performance of these techniques of treatment, on static. During the active phase, the under positive way they developed average reduction of organic matter of 26.55%, the under the negative way of 21.78%, while the, under the hybrid way of 31.21%. During the phase of maturation, it was turned three of each system of aeration. The reduction of organic matter of them was 50,63%, in 50 days; The other ones showed average reduction of 39,54%, in 60 days. During the active phase, the operated under the positive way had, on average, reduction of carbon of 26.55%, in the period of 40 days, the under the negative mode of 21.78%, in the period of 50 days, and the under the hybrid way of 31.21%, within 30 days. During the stage of maturity, for the that suffered of returning, the average reduction of carbon was 50.63%, in the period of 50 days, while the other ones showed an average decrease of 39.54%, in the period of 60 days. On all the, the pH developed in the material and in the beginning of the process of composting was acid. The results showed that the average pH was increasing according to the degradation of organic matter. At the stage of maturity, the pH remained in the alkaline range on all the. During the active phase, the content of nitrogen grown by an average of 41.12% on the under the positive way, 54.21% on the under the negative mode and 32.05% on the under the hybrid way. During the maturation, the content of nitrogen on all, regardless of the used method of aeration, presented quite different results. During active phase, the operated under the positive way showed a reduction of the C/N nitrogen of 47.89% in 40 days, the piles under the negative mode of 44.35% in 50 days; and piles under the hybrid way of 48.33%, in 30 days. It was observed that the C/N in the final stage of maturation of the that were returned, presented average values in the order of 10 to 15 in the period of 50 days. The under the operational way also recorded positive values within this range, but in the period of 60 days, while the piles under the operational mode registered negative average above the recommended by the law, in the period of 60 days. It was observed that in all the systems the Total Coliform and the Fecal Coliform were decreasing during the aeration (active phase of degradation). The under the operational mode recorded positive values of Total Coliform in the order of 9,1x108 to 5,0 x103 CFU.g-1 and of Fecal Coliform of the order of 6,2 x108 to 3,1 x103 UFCg-1, and the operational under the negative way registered values of Total Coliform in the order of 8,4 x108 to 4,8 x103 CFU.g-1 and of Fecal Coliform in the order of 6,1 x108 to 3,5 x103 CFU.g-1, and the piles under the hybrid way recorded values of Total Coliform in the order of 4,1 to 9,2 x107 and x103 CFU.g ¹ and of Fecal Coliform, in the order of 5,2 x108 to 3,2 x103 CFU.g-1. The temperature was the factor used to evaluate the efficiency of the composting process, during the active phase. The end of the stage of maturity was verified by the C/N. The analysis of the results for the physical, chemical and microbiological systems in the three evaluated systems in this research were possible because of the satisfactory performance of the systems operated under the positive and hybrid ways. Regarding the aeration in the first phase of the trial, one can say that its effect contributed satisfactorily for the elimination of pathogens, such as decreasing the time of composting, accelerating the metabolism of organic matter. By the results of the analyses of the experiments and also the interpretation of the data, it was observed that the hybrid system of this research was more efficient than the others ones.