Effect of different substrates on composting of poultry litter

The objective was to evaluate the differences between distinct types of litter material and their combinations in the dynamics of degradation on the organic matter fractions and the quality of the final compound. The treatments were established according to material used as substrate for broiler litter: treatment 1 - rice husks; 2 - sugar cane bagasse; 3 - wood shavings; 4 - wood shavings + sugar cane bagasse; 5 - rice husks + sugar cane bagasse; and 6 - Napier grass. The following variables were monitored: temperature, levels of total solids (TS), volatile solids (VS), mass and volume of the pile, fibrous fraction, and levels and reductions of N, P and K during the process. Piles formed with Napier grass and sugar cane bagasse presented the highest average temperatures during composting. The greater average reductions in TS and VS were attained in piles with sugar cane bagasse (68.12 and 73.07%, for TS and VS, respectively). The reductions of greatest volume occurred in piles with sugar cane bagasse (52.08%), followed by Napier grass (50.56%). Poultry litters composed of rice husks and wood shavings presented 13.21 and 10.23% of lignin, respectively, which contributed to the lower degradation of fibrous fraction and degradability. Substrates with lower lignin content were those with greatest organic matter degradation rate and had reduced losses of N levels during the process. Composting performance is affected by the initial substrate used to compose the poultry litter

Biodigestão anaeróbia de dejetos de suínos com e sem separação da fração sólida em diferentes tempos de retenção hidráulica Anaerobic biodigestion of swine manure with and without separation of the solid fraction in different hydraulic retention times

O objetivo deste trabalho foi avaliar o processo de biodigestão anaeróbia utilizando dejetos de suínos, com e sem separação da fração sólida, considerando-se diferentes tempos de retenção hidráulica. Para tanto, foram utilizados biodigestores tubulares semicontínuos abastecidos com água residuária de suinocultura, com e sem separação da fração sólida (CSFS e SSFS, respectivamente), manejados com tempos de retenção hidráulica (TRH) iguais a 36; 29; 22 e 15 dias. A eficiência dos tratamentos foi avaliada pela redução dos números mais prováveis de coliformes totais e fecais, teores de fibra em detergentes neutro e ácido, demandas química e bioquímica de oxigênio e dos potenciais de produção de biogás e metano. A qualidade do biofertilizante foi avaliada quanto aos teores de macro e micronutrientes. A separação da fração sólida acarretou decréscimo nos teores de fibra dos afluentes, o que contribuiu para o aumento da eficiência da produção de metano. Foram observados valores de 0,47 e 0,75 m³ CH4 kg-1 SV adicionado para os afluentes SSFS e CSFS, respectivamente, no TRH de 15 dias. Com o aumento do TRH, houve acréscimo médio de 50% no potencial de produção de metano kg-1 de SV adicionado. Não foram observadas diferenças significativas nas reduções de coliformes fecais e totais, sendo a maior redução de 3,6 10(9) para 3,6 10² NMP 100 mL-1 para o TRH de 36 dias CSFS.<br>This work aimed to evaluate the anaerobic biodigestion process by using swine manure with and without separation of the solid fraction and considering different hydraulic retention times. For such purpose semi continual plug flow biodigestors were used, with residual water from a pig farm with and without separation of the solid fraction, managed with 36; 29; 22 e 15 days of hydraulic retention. Efficiency of the treatments was evaluated by the reduction of the most probable number of total and fecal coliforms, fiber content, chemical and biochemical oxygen demands, besides the biogas and methane production potential and biofertilizer quality. The separation of the solid fraction decreased in fiber content from effluents, what contributed to an increase in the efficiency in the methane production. The observed values were: 0.47 and 0.75 m³ CH4 kg-1 VS added to the effluent with and without separation of the solid fraction respectively, in the HRT of 15 days. With the increase of HRT there was a medium increase of 50% in the production of potential of methane kg-1 VS added. It was not observed significant differences in reduction of fecal and total coliforms. The largest reduction was 3.6 10(9) to 3.6 10² NMP 100 mL-1 for the 36 days HRT