Manejo de lodo de Estação de Tratamento de Água, visando ao aproveitamento na agricultura como condicionante de solos
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Data
2019-11-12
Autores
Franco, Natália Molina
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Universidade Estadual Paulista (Unesp)
Resumo
As Estações de Tratamento de Água (ETAs) são responsáveis pela captação, transporte, tratamento e distribuição da água, garantindo o atendimento aos parâmetros de potabilidade. O método de tratamento mais utilizado é do tipo convencional, onde a água passa pelas etapas de coagulação, floculação, decantação, filtração e desinfecção. Esse tipo de tratamento gera uma quantidade significativa de resíduos conhecidos como lodo que são provenientes da lavagem dos decantadores e dos filtros. Como, ao longo do tratamento, são usados produtos químicos para a remoção de impurezas da água, o lodo pode apresentar substâncias tóxicas em sua composição e, portanto, deve ter uma disposição final ambientalmente adequada. Nesse contexto, o presente trabalho teve como objetivo avaliar, por meio de respirometria, a biodegradabilidade de lodo de ETA I do município de Rio Claro/SP quando aplicado ao solo, na ausência ou em associação com material bioestimulante (lodo de esgoto), visando sua utilização na agricultura. Também foi realizada uma caracterização físico-química, microbiológica e do potencial fitotóxico dos diferentes tratamentos contendo solo, lodo de ETA e lodo de esgoto, antes e após o processo de biodegradação. Como resultado, foi possível estimar que a ETA I produz, aproximadamente, 460 ton/ano de lodo, contendo apenas cerca de 15% de sólidos. A relação DQO/DBO indicou a presença de compostos menos biodegradáveis no lodo de ETA, quando comparado ao de esgoto. O ensaio de respirometria revelou que as amostras contendo lodo de esgoto apresentaram a maior produção de CO2 e eficiência da biodegradação. Nenhum dos tratamentos realizados foi considerado fitotóxico e um aumento significativo do crescimento da raiz foi observado para a maior concentração de lodo de ETA e em associação com lodo de esgoto, após biodegradação. Assim, a adição de lodo de esgoto leva a um aumento do potencial agronômico da mistura. Desse modo, pelas características apresentadas, o uso do lodo de ETA como recondicionante de solo parece ser uma alternativa promissora para o aproveitamento deste resíduo.
Water Treatment Plants (WTPs) are responsible for the collection, transport, treatment, and distribution of water, ensuring compliance with potability parameters. The most commonly used treatment method is the conventional one, where the water goes through the coagulation, flocculation, decantation, filtration and disinfection steps. This type of treatment generates a significant amount of waste known as sludge that comes from washing the decanters and the filters. As chemicals are used throughout the treatment to remove impurities from water, the sludge may have toxic substances in its composition and therefore must have an environmentally appropriate final disposal. In this context, the present work aimed to evaluate, by respirometry, the biodegradability of WTP I sludge from the municipality of Rio Claro / SP when applied to the soil, in the absence or in association with biostimulant material (sewage sludge), enabling its use in agriculture. A physicochemical, microbiological and phytotoxic potential characterization of the different treatments containing soil, WTP sludge, and sewage sludge was performed before and after biodegradation. As a result, it was estimated that WTP I produces approximately 460 tons/year of sludge, containing only about 15% solids. The COD/BOD ratio indicated the presence of less biodegradable compounds in the WTP sludge when compared to the sewage sludge. The respirometry test revealed that the samples containing sewage sludge presented the highest CO2 production and biodegradation efficiency. None of the treatments performed were considered phytotoxic and a significant increase in root growth was observed for the highest concentration of WTP sludge and in association with sewage sludge after biodegradation. Thus, the addition of sewage sludge leads to an increase in the agronomic potential of the mixture. Therefore, due to the characteristics presented, the use of WTP sludge as a soil reconditioner seems to be a promising alternative for the use of this residue.
Water Treatment Plants (WTPs) are responsible for the collection, transport, treatment, and distribution of water, ensuring compliance with potability parameters. The most commonly used treatment method is the conventional one, where the water goes through the coagulation, flocculation, decantation, filtration and disinfection steps. This type of treatment generates a significant amount of waste known as sludge that comes from washing the decanters and the filters. As chemicals are used throughout the treatment to remove impurities from water, the sludge may have toxic substances in its composition and therefore must have an environmentally appropriate final disposal. In this context, the present work aimed to evaluate, by respirometry, the biodegradability of WTP I sludge from the municipality of Rio Claro / SP when applied to the soil, in the absence or in association with biostimulant material (sewage sludge), enabling its use in agriculture. A physicochemical, microbiological and phytotoxic potential characterization of the different treatments containing soil, WTP sludge, and sewage sludge was performed before and after biodegradation. As a result, it was estimated that WTP I produces approximately 460 tons/year of sludge, containing only about 15% solids. The COD/BOD ratio indicated the presence of less biodegradable compounds in the WTP sludge when compared to the sewage sludge. The respirometry test revealed that the samples containing sewage sludge presented the highest CO2 production and biodegradation efficiency. None of the treatments performed were considered phytotoxic and a significant increase in root growth was observed for the highest concentration of WTP sludge and in association with sewage sludge after biodegradation. Thus, the addition of sewage sludge leads to an increase in the agronomic potential of the mixture. Therefore, due to the characteristics presented, the use of WTP sludge as a soil reconditioner seems to be a promising alternative for the use of this residue.
Descrição
Palavras-chave
Lodo de ETA, Respirometria, Fitotoxicidade, Gerenciamento de resíduo, Resíduo sólido, Lodo de esgoto, Waste management, Solid waste, WTP sludge, Sewage sludge, Respirometry, Phytotoxicity