Anaerobic sewage sludge treatment by liming / HIGIENIZAÇÃO DE LODO ANAERÓBIO DE ESGOTO POR MEIO ALCALINO ESTUDO DE CASO DA ETE LAGES APARECIDA DE GOIÂNIA - GO

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The aim of the present study was to evaluate the efficiency of the alkaline treatment of sanitary sewage sludge produced in the upflow anaerobic sludge blanket (UASB) of the Lages Sewage Treatment Plant, located in Aparecida de Goiânia, GO, Brazil and operated by Saneamento de Goiás, S.A. Saneago. The sludge, which was dewatered into drying beds until a mean moisture of 47.55%, was mixed in a cement mixer with hydrated lime and quicklime in two experiments. The limes were mixed with sewage sludge and four treatments were established, one of them without lime and the others with concentrations of, 12.6%, 21% and 29.4% for each experiment, with three repetitions. Samples of the treated sludge in each treatment were collected 0, 15, 30, 60, 90 and 120 days after mixing. Thermotolerant coliforms, total helminth eggs, viable helminth eggs, volatile solids, total solids (TS), pH and moisture were evaluated. All treatments in the two experiments met the condition of reduction in vector attractiveness cited in appendix one of Conama resolution no.375 except the hydrated lime treatment, whose lime dosage was 12.6%. Although growth of thermotolerant coliforms occurred in association with the drop in pH in some treatments during the storage period, in all the results of both experiments the values were below the limit established in Conama resolution no.375 for type A sludge: 1,000 NMP.g.MS-1. Among the species of viable helminth eggs identified, Ascaris sp. was predominated. All the treatments with quicklime reached concentrations of viable helminth eggs below 0.25 egg.g.MS-1, the limit for type A sludge, immediately after mixing, except for the treatment with 12.6% of quicklime. For the hydrated lime treatments, this condition was met within 15 days except for the treatment whose lime dosage was 12.6%. Both, hydrated lime and quicklime, were efficient in meeting the requirements of Conama resolution no.375 for type A sludges in regard to the parameters for thermotolerant coliforms and viable helminth eggs. In terms of dosages applied and storage time, the quicklime treatments stood out because of their greater potential for raising and maintaining pH and because of their greater efficiency in removing thermotolerant coliforms and viable helminth eggs

ASSUNTO(S)

lodo de esgoto biossólido estabilização química calagem chemical stabilization sewage sludge biosolids alkaline treatment recursos hidricos; saneamento ambiental; lodo de esgoto; estabilização química;calagem bissódio; tratamento alcalino; saneamento ambiental liming tratamento alcalino

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