Biodegradação de lodo de ETA e ETE avaliada mediante ensaios de toxicidade e caracterização microbiológica
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Data
2023-02-16
Autores
Santos, Ralyvan Araújo dos
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A população mundial em 2022 atingiu cerca de 8 bilhões de pessoas e, consequentemente, levou ao aumento no consumo de fontes de energia e na geração de resíduos oriundos da atividade humana como resultado do processo de tratamento das águas brutas e residuais (esgoto). Os lodos derivados de Estações de Tratamento de Água (LTA) e do tratamento do esgoto (LE), embora apresentem grandes quantidades de matéria orgânica e nutrientes, também contém microrganismos, dentre eles alguns patogênicos e contaminantes químicos de origem orgânica e inorgânica, de modo que, se não descartados em locais adequados, acabam gerando alteração no ambiente negativa em que se encontram. Contudo, um tratamento apropriado poderia possibilitar a utilização desses lodos como condicionadores de solos agrícolas. Diante destes fatos, o objetivo deste trabalho foi propor tratamentos para o LTA e o LE, isolados ou em associação, a partir do emprego de biofertilizantes (Bokashi (Inóculo I - In I) e Fermentado líquido (Inóculo II - In II) como indutores da biodegradação, a fim de diminuir sua carga poluidora e toxicidade, bem como caracterizar a microbiota de fungos e bactérias, buscando elucidar o processo de biorremediação dos lodos. Para isso, a biodegradação dos lodos foi avaliada por respirometria, mensurando alterações nas quantidades de CO2 produzidas pelos diferentes tratamentos durante 68 dias. Foram testados dois biofertilizantes comercialmente disponíveis (In I e In II) para promoção da bioestimulação e bioaumentação. A toxicidade dos tratamentos, antes e após a biodegradação, foi avaliada por ensaios de toxicidade aguda com microcrustáceos (Artemia salina e Daphnia similis) e germinação de sementes (Lactuca sativa e Eruca sativa). Alterações na comunidade microbiana durante a biodegradação desses resíduos foram avaliadas por sequenciamento de alto rendimento. A incorporação dos biofertilizantes aos tratamentos não resultou em aumento da eficiência da biodegradação. Além disso, o biofertilizante In I, quando adicionado ao LTA ou ao LE, ocasionou elevada toxicidade nas amostras iniciais, porém esse efeito foi diminuído ao longo do processo de biodegradação e consequentemente a comunidade bacteriana. O filo das Proteobacteria foi o mais predominante para os tratamentos de LTA+ In I e LE+ In I. A ausência de toxicidade nas amostras biodegradadas sugere que os lodos, após tratamento adequado, podem ser destinados para solos agrícolas como uma alternativa mais sustentável à sua disposição.
The world population in 2022 reached about 8 billion people and, consequently, led to an increase in the consumption of energy sources and in the generation of waste from human activity as a result of the treatment process of raw and wastewater (sewage). The sludge derived from Water Treatment Plants (WTS) and sewage treatment (SS), although they contain large amounts of organic matter and nutrients, also contain microorganisms, including some pathogens and chemical contaminants of organic and inorganic origin, so that which, if not disposed of in suitable places, end up causing changes in the negative environment in which they are found. However, an appropriate treatment could enable the use of these sludges as agricultural soil conditioners. In view of these facts, the objective of this work was to propose treatments for WTS and SS, isolated or in association, from the use of biofertilizers Bokashi (Inoculum I - In I) and Liquid Fermented (Inoculum II - In II) as inducers of biodegradation, in order to reduce its polluting load and toxicity, as well as to characterize the microbiota of fungi and bacteria, seeking to elucidate the sludge bioremediation process. For this, sludge biodegradation was evaluated by respirometry, measuring changes in the amounts of CO2 produced by the different treatments during 68 days. Two commercially available biofertilizers (In I and In II) were tested to promote biostimulation and bioaugmentation. The toxicity of the treatments, before and after biodegradation, was evaluated by acute toxicity tests with microcrustaceans (Artemia salina and Daphnia similis) and seed germination (Lactuca sativa and Eruca sativa).Changes in the microbial community during biodegradation of these residues were evaluated by high-throughput sequencing. The incorporation of biofertilizers into treatments did not result in an increase in the efficiency of biodegradation. In addition, the In I biofertilizer, when added to WTS or SS, caused high toxicity in the initial samples, but this effect was reduced throughout the biodegradation process and consequently the bacterial community. The Proteobacteria phylum was the most predominant for the WTS+ In I and SS+ In I treatments. The absence of toxicity in the biodegraded samples suggests that the sludge, after adequate treatment, can be destined for agricultural soils as a more sustainable alternative at its disposal.
The world population in 2022 reached about 8 billion people and, consequently, led to an increase in the consumption of energy sources and in the generation of waste from human activity as a result of the treatment process of raw and wastewater (sewage). The sludge derived from Water Treatment Plants (WTS) and sewage treatment (SS), although they contain large amounts of organic matter and nutrients, also contain microorganisms, including some pathogens and chemical contaminants of organic and inorganic origin, so that which, if not disposed of in suitable places, end up causing changes in the negative environment in which they are found. However, an appropriate treatment could enable the use of these sludges as agricultural soil conditioners. In view of these facts, the objective of this work was to propose treatments for WTS and SS, isolated or in association, from the use of biofertilizers Bokashi (Inoculum I - In I) and Liquid Fermented (Inoculum II - In II) as inducers of biodegradation, in order to reduce its polluting load and toxicity, as well as to characterize the microbiota of fungi and bacteria, seeking to elucidate the sludge bioremediation process. For this, sludge biodegradation was evaluated by respirometry, measuring changes in the amounts of CO2 produced by the different treatments during 68 days. Two commercially available biofertilizers (In I and In II) were tested to promote biostimulation and bioaugmentation. The toxicity of the treatments, before and after biodegradation, was evaluated by acute toxicity tests with microcrustaceans (Artemia salina and Daphnia similis) and seed germination (Lactuca sativa and Eruca sativa).Changes in the microbial community during biodegradation of these residues were evaluated by high-throughput sequencing. The incorporation of biofertilizers into treatments did not result in an increase in the efficiency of biodegradation. In addition, the In I biofertilizer, when added to WTS or SS, caused high toxicity in the initial samples, but this effect was reduced throughout the biodegradation process and consequently the bacterial community. The Proteobacteria phylum was the most predominant for the WTS+ In I and SS+ In I treatments. The absence of toxicity in the biodegraded samples suggests that the sludge, after adequate treatment, can be destined for agricultural soils as a more sustainable alternative at its disposal.
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Palavras-chave
Biorremediação, Biofertilizante, Daphnia similis, Artemia salina, Fitotoxicidade, Bioremediation, Biofertilizer, Phytotoxicity