Estudo do processo de tratamento aeróbio conjugado de resíduos sólidos orgânicos.

Abstract

In this work, the process of aerobic treatment of urban solid residues was evaluated. This material was inoculated with waste stabilization pond sludge from the sewage treatment plant called EXTRABES (Campina Grande - 7° 13T1"S, 35° 52'31"W to 550m above sea level - Paraiba State). The percentiles of 5, 10 and 15% (percentage in weight) of sludge were inoculated in an experimental system of four treatments in triplicates with three rows as control, where only the organic fraction of solid urban waste was used. The experimental design adopted was the factorial arrangement of 4 x 7 and three repetitions with sample collection each 15 days for physical and chemical analysis; the factorial arrangement of 4 x 4, with three repetitions and sampling at regular intervals of 30 days where used for microbiological analysis in all the experimental system. This monitoring was carried out during a period of 90 days. The results showed significant reductions of Total Organic Carbon, Total Kjeldahl Nitrogen and Total Phosphorous. The treatment using sludge at 5% presented the best efficiency of mass transformation: TOC (78,7%), TKN (79,7%) and TP (70,44%). Composting process presented a good microbiological decline in all the treatments with total coliforms and Escherichia coli removed more quickly than fecal streptococci, making the last a better indicator of compost contamination. The residues colonization by fungi was slowly during the process of composting and highest values appeared at the end of the process, probably due the bacterial decay and the predominance of residues of more difficult biodegradation such as cellulose, lignine and hemiceluloses. The largest fungi diversity occurred in the treatment with sludge at 15%, and the smallest in the treatment without sludge indicating that sludge stimulated the biota diversity of the residues. The maximum temperature was 41°C, in the beginning of the process, but along the monitoring period it varied from 28 to 35°C, what did not allow total sanitition of the compost. Therefore it still presented remaining concentrations of microorganisms (FE -104 MPN/g) above the acceptable levels for direct use in soil.