Codigestão de lodo de uma ETA composto por tanino e sulfato de alumínio com lodo de ETE
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Data
2017-12-11
Autores
Orientador
Silva, Maria Cristina De Almeida
Banca
Hoehne, Lucélia
Hilgemann, Maurício
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Resumo
A demanda por água potável está atrelada ao crescimento populacional, concentrado nas grandes cidades. As Estações de Tratamento de Água (ETA) de ciclo completo, mais comuns no país, tem como característica a grande produção de resíduos, em especial de lodo. Este lodo tem suas características definidas pela qualidade da água bruta tratada, do sistema de tratamento e consequentemente do coagulante utilizado nas etapas de coagulação/floculação. O lodo de ETA atualmente caracteriza um passivo ambiental, uma vez que sua disposição final é realizada, na maioria das estações do Brasil, nos recursos hídricos. Atualmente buscam-se alternativas a utilização de coagulantes químicos, sais de ferro e de alumínio, sendo uma delas os coagulantes de origem natural, como os taninos. Da mesma forma buscam-se soluções para o tratamento do lodo de ETA que sejam ambiental e financeiramente viáveis. Em função disto este trabalho buscou avaliar os coagulantes tanino e sulfato de alumínio na clarificação de água e na consequente produção de lodo. Em conjunto a isso foram realizados testes de codigestão de lodos de ETA em com lodo de estação de tratamento
de efluentes (ETE), por biodigestão anaeróbia. Na primeira etapa do trabalho foram avaliados os coagulantes tanino e sulfato de alumínio no processo de coagulo/floculação de água de rio através de teste de jarros. Os resultados obtidos evidenciam a eficiência dos dois coagulantes, tendo o tanino apresentado melhores resultados para turbidez, cor, potencial hidrogeniônico (pH) e condutividade elétrica, porém o uso de sulfato de alumínio é mais economicamente viável. Na segunda etapa foi realizado teste de biodigestão anaeróbia constituído de: 2 triplicatas contendo 50% de lodo de tanino mais 50% de lodo de ETE e 50% de lodo de sulfato de alumínio mais 50% de lodo de ETE; e 3 duplicatas contendo os lodos em separado. O teste teve duração de 30 dias e não apresentou resultados satisfatórios quanto a geração de biogás e metano. Quanto à remoção de matéria orgânica, os percentuais variaram para remoção de demanda química de oxigênio (DQO) de 4,3 a 88,3%, e para demanda bioquímica de oxigênio (DBO) de 37,5 a 78,1%. Não houve remoção considerável de teores de nutrientes e carbono orgânico total. Em relação aos parâmetros avaliados após biodigestão anaeróbia conclui-se que os lodos foram estabilizados, porém é necessário um estudo mais aprofundado de suas características inorgânicas para utilização como biofertilizante.
The drinking water demand is linked to the population growth, concentrated in the big cities. The Water Treatment Plants (WTP, in portuguese ETA) complete cycle, usually more common in the country, have as attribute the production of residues, particularly the production of mud. The mud’s characteristics are defined by the quality of the raw water, by the treatment system and therefore by the coagulant used on the stages from coagulation/flocculation. Currently the WTP’s mud marks an environmental liability, as it’s final disposition is, in the most part of Brazil’s plants, carried out at hydric resources. Another alternatives to the use of chemical coagulants, aluminium and iron salts are being researched currently, one of them is the use of natural coagulants like tannin. In the same way solutions for the treatment of the WTP’s mud financially and environmentally viable are also being seeked. Based on this, this work pursued to evaluate the coagulants tannin and aluminium sulphate on the water clarification and consequential on the mud’s production. Together with this, other tests from codigestion of WTP’s sludge were conducted with sludge of the Effluent Treatment Plant (ETP, in portuguese ETE) through anaerobic biodigestion. In the initial work’s stage, the tannin and aluminium sulphate coagulants were evaluated on the process of coagulation/flocculation of river water through jars’ test. The results obtained demonstrated both coagulants’ efficiency, being the tannin the one which reported the best results for turbidity, color, hydrogenionic potential (pH) and electrical conductivity; yet the use of aluminium sulphate is more viable cost-effective wise. In the second stage the test of anaerobic biodigestion was held. This test was composed of: 2 triplicates containing 50% of tannin’s sludge more 50% of ETP’s sludge and 50% of aluminium sulphate sludge more 50% of ETP’s sludge; and 3 duplicates containing the separate sludges. The test had a duration of 30 days and it did not present satisfactory results in terms of biogas and methane production. In respect to the removal of organic material, the percentages of the removal of chemical oxygen demand (COD) ranged from 4.3% to 88.3% and of the biochemical oxygen demand (BOD) from 37.5% to 78.1%. The removal of considerable nutrient and total organic carbon contents did not happen. In relation to the evaluated parameters after the anaerobic biodigestion, it is concluded that the sludges were stabilized, but it’s necessary a deeper analysis of its inorganic characteristics to its use as biofertilizer.
The drinking water demand is linked to the population growth, concentrated in the big cities. The Water Treatment Plants (WTP, in portuguese ETA) complete cycle, usually more common in the country, have as attribute the production of residues, particularly the production of mud. The mud’s characteristics are defined by the quality of the raw water, by the treatment system and therefore by the coagulant used on the stages from coagulation/flocculation. Currently the WTP’s mud marks an environmental liability, as it’s final disposition is, in the most part of Brazil’s plants, carried out at hydric resources. Another alternatives to the use of chemical coagulants, aluminium and iron salts are being researched currently, one of them is the use of natural coagulants like tannin. In the same way solutions for the treatment of the WTP’s mud financially and environmentally viable are also being seeked. Based on this, this work pursued to evaluate the coagulants tannin and aluminium sulphate on the water clarification and consequential on the mud’s production. Together with this, other tests from codigestion of WTP’s sludge were conducted with sludge of the Effluent Treatment Plant (ETP, in portuguese ETE) through anaerobic biodigestion. In the initial work’s stage, the tannin and aluminium sulphate coagulants were evaluated on the process of coagulation/flocculation of river water through jars’ test. The results obtained demonstrated both coagulants’ efficiency, being the tannin the one which reported the best results for turbidity, color, hydrogenionic potential (pH) and electrical conductivity; yet the use of aluminium sulphate is more viable cost-effective wise. In the second stage the test of anaerobic biodigestion was held. This test was composed of: 2 triplicates containing 50% of tannin’s sludge more 50% of ETP’s sludge and 50% of aluminium sulphate sludge more 50% of ETP’s sludge; and 3 duplicates containing the separate sludges. The test had a duration of 30 days and it did not present satisfactory results in terms of biogas and methane production. In respect to the removal of organic material, the percentages of the removal of chemical oxygen demand (COD) ranged from 4.3% to 88.3% and of the biochemical oxygen demand (BOD) from 37.5% to 78.1%. The removal of considerable nutrient and total organic carbon contents did not happen. In relation to the evaluated parameters after the anaerobic biodigestion, it is concluded that the sludges were stabilized, but it’s necessary a deeper analysis of its inorganic characteristics to its use as biofertilizer.
Descrição
Palavras-chave
Tanino; Codigestão; Lodo de ETA; Biodigestão anaeróbia
Citação
BORN, Betina. Codigestão de lodo de uma ETA composto por tanino e sulfato de alumínio com lodo de ETE. 2017. Monografia (Graduação em Engenharia Ambiental) – Universidade do Vale do Taquari - Univates, Lajeado, 11 dez. 2017. Disponível em: http://hdl.handle.net/10737/1910.