976 resultados para composted sewage sludge


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Pós-graduação em Agronomia (Ciência do Solo) - FCAV

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Understanding soil responses to the application of urban or industrial residues is necessary. In the current experiment, both sources of residues were applied to the soil surface of a Hapludox soil for 8 years. The four residues studied were biodigested and centrifuged sewage sludge (LB and LC, respectively), steel slag from the metallurgic industry (E), and limed mud from the pulp and cellulose industry (LCal). The residues were applied at 0, 2, 4, and 8 Mg ha(-1) four times from 2002 to 2010 when soybean was cultivated in the summer and lopsided oat and sorghum were cultivated during the winter. The contents of heavy metals were evaluated with diethylenetriaminepentaacetic acid (DTPA) and organic acids. The LB was the residue that increased the contents of soil micronutrients and heavy metals to their greatest levels, although within limits that impair the risks of environmental contamination.

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Pós-graduação em Agronomia (Produção Vegetal) - FCAV

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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This experiment aim was to evaluate the contamination of the trace elements (TE) arsenic, barium, cadmium, chromium, copper, mercury, molybdenum, nickel, lead, selenium, and zinc considered in the CONAMA resolution 375 after 13 years long using sewage sludge (SS) as fertilizer in two soils: an Eutroferric Clayed Red Latosol (Rhodic Eutrudox - RE) and a Dystrophic Red Latosol (Typic Haplorthox - TH). Experiment in the field under maize cultivation had four treatments (0, 5, 10, and 20 t of SS ha(-1), dry weight), five replications and an experimental design in randomized blocks. The agrochemicals (dolomitic limestone, single superphosphate, and potassium chloride), SS, soils, and the certified reference materials were digested according to the USEPA 3051A method and the chemical elements were quantified by ICP OES. The TE contents found in the agrochemicals used should not cause immediate environmental impact. The higher TE values were found in the RE and they did not reach the agricultural (more stringent) Investigation Level (IL) yet, according to 420 CONAMA resolution. Persisting the actual SS fertilization amount applied in the soil and the TE concentration in the SS is foreseen that Ba, Cd, Cr, Cu, Ni, and Zn will be the first elements to reach the IL in the RE.

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The treatment of domestic and industrial effluents through Wastewater Treatment Plants (WTPs) generates a residue termed sewage sludge, rich in organic matter, high-volume, occasionally containing pathogens and heavy metals. The sludge generation can minimize the benefits brought by the treatment of sewage, because this residue does not always receive appropriate treatment before final disposal. The disposal is another problem related to sludge. Landfills generally does not have physical space and alternatives such as the use in agriculture requires an intense treatment that could be in many cases operational or economic unfeasible. The objective of this work is the theoretical research about the processes of stabilization of the sludge by anaerobic digestion and the methanogenic activity during the process. Through analysis of each step and contemplating each relevant factor in anaerobic digestion process in order to optimize them, we proposed a theoretical model of reactors capable of stabilize the sludge, reduce its volume and eliminate pathogens. The obtained configuration consists of two anaerobic reactors connected in series. The first one operates in the range mesophilic temperature (35 ° C) and has higher hydraulic retention time (25 days) working primarily in the stabilization of organic matter present in the sludge and producing biogas, whereas the second one operates in the thermophilic range (55 ° C) in order to eliminate pathogens, and to reduce the volume. The hydraulic retention time in the second reactor is lower (10 days). Both mesophilic and thermophilic processes were efficient in what was proposed, promoting the stabilization of organic matter present in the sludge and significant reduction of pathogens. As a final step with the sludge previously digested, it is indicated a final dehydration... (Complete abstract click electronic access below)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pós-graduação em Agronomia (Agricultura) - FCA