Estudo de possibilidades de tratamentos microbiológico e com adsorventes para chorume e influências ecotóxicas do seu descarte no ambiente
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Data
2017-12-18
Autores
Almeida, Nair Conde de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O chorume produzido em aterros sanitários é o resultado da decomposição físico-química e microbiológica dos resíduos urbanos, podendo variar muito em sua composição. Para se desenvolver tratamento e descarte eficientes e seguros há a necessidade de caracterização, desenvolvimento de técnicas adequadas de tratamento e estudo sobre o impacto do descarte dos resíduos destes tratamentos no ambiente. Este trabalho testou tratamento microbiológico com microrganimos isolados do chorume e com microalgas; tratamento com adsorventes como carvão ativado, hidrotalcita e sementes de M. oleifera; aprofundou estudos sobre a introdução dos resíduos do tratamento com hidrotalcita no ambiente. Foram feitas análises físico-químicas, microbiológicas, respirométricas e de toxicidade com o chorume bruto, tratado e com o lodo do tratamento. A caracterização do chorume constatou pequeno número de bactérias heterotróficas e fungos indicando condições desfavoráveis para crescimento microbiológico. Coliformes totais e E. coli alcançaram valores médios de 17900 e 890 NMP/100mL, respectivamente. As análises físico-químicas do lixiviado indicaram valores elevados para condutividade, cor, turbidez, DQO, DBO5, amônia, boro, sódio e cloretos. Os tratamentos biológicos não se mostraram eficientes na remoção dos parâmetros exigidos pela legislação, devido às altas concentrações de sais, amônia e matéria orgânica recalcitrante. O tratamento com hidrotalcita produziu os melhores resultados, para remoção de condutividade (51%), turbidez (58%), DBO5 (95%), boro (40%) e amônia (35%), removeu também DQO (43%) e cor (70%) porém houve elevação do pH. A hidrotalcita reaproveitada apresentou menor eficiência que hidrotalcita, não removeu boro e os níveis de alumínio e magnésio aumentaram. Carvão ativado a 4% (CA4%) obteve melhores resultados para remoção de cor (98%) e DQO (48%), mas não removeu boro e amônia satisfatoriamente. O carvão ativado 1% mostrou resultados semelhantes ao CA4%, com níveis de remoção inferiores. Semente e extrato de M. oleífera, obtiveram resultados insatisfatórios. Todos os adsorventes diminuíram em cerca de 10 vezes a quantidade de bactérias heterotróficas, exceto o extrato de M. oleífera. Os tratamentos removeram coliformes totais e E. coli. Nenhum dos adsorventes removeu sódio, cloreto ou a toxicidade do chorume para D. similis. Nos ensaios sobre efeitos dos resíduos do tratamento de chorume, com hidrotalcita, no ambiente, os testes de toxicidade demonstraram que houve diminuição de 21,63% na toxicidade para Artemia sp e de 42% para testes de germinação de sementes de L. sativa. A disposição de chorume no solo provocou inibição na germinação e desenvolvimento de L. sativa em relação ao controle. Nos vasos com chorume bruto houve inibição de 12% e com lixiviado tratado 5%. Inicialmente o chorume a 50m3/ha potencializou o crescimento bacteriano e inibiu crescimento fúngico, após 84 dias de experimento houve uma estabilização da microbiota, exceto nos ensaios com 200m3/ha onde a inibição permaneceu para os fungos. A disposição de 200m3/ha de chorume no solo demonstrou que repetidos lançamentos podem tornar o solo inviável para o plantio. O solubilizado do solo dos vasos mostrou que o chorume bruto, acarretou toxicidade para D. similis. A disposição de 2,5% de lodo do tratamento no solo, aumentou em 42% a biomassa de L. sativa em relação ao controle, não apresentando impacto negativo sobre a microbiota do solo e nem toxicidade para D. similis. O ensaio de biodegradação com chorume a 5% mostrou que o inóculo introduzido ativou a biodegradação, aumentando a eficiência diária do processo em média 6% e 9% para os chorumes tratado e bruto, respectivamente. Apesar da biodegradação eficiente (50% em 24 horas), o potencial tóxico do lixiviado não foi eliminado como pode ser comprovado pelo experimento em vasos. O experimento de respirometria não se mostrou uma técnica eficiente para determinar a biodegradação do lodo, pois o sistema sofre influência das características químicas da hidrotalcita.
The leachate produced in landfills is the result of physicochemical and microbiological decomposition of urban waste and its composition can vary widely. In order to develop efficient and safe treatment and disposal, there is a need for characterization, development of adequate treatment techniques and study of the impact of these treatment residues on the environment. This work tested microbiological treatment with microorganisms isolated from landfill leachate and with microalgae; treatment with adsorbents like activated carbon, hydrotalcite and M. oleifera seeds and deepened studies about introduction of residues of treatment with hydrotalcite in the environment. Physical-chemical, microbiological, respirometric and toxicity analysis were performed with the treated and raw leachates and with the sludge of treatment. The leachate characterization revealed a small number of heterotrophic bacteria and fungi. Total coliforms and E. coli reached mean values of 17900 and 890 NMP/100 mL, respectively. The physicochemical analysis indicated high conductivity, color, turbidity, COD, BOD5, ammonia, boron, sodium and chlorides. The biological treatments were not efficient in removing the parameters required by the legislation due to high concentrations of salts, ammonia and recalcitrant organic matter.Treatment with hydrotalcite produced the best results to remove conductivity (51%), turbidity (58%), BOD5 (95%), boron (40%) and ammonia (35%), also removed COD (43%) and color (70%) but led to an increase in pH. The reused hydrotalcite presented lower efficiency than hydrotalcite, failed to remove boron and aluminum and magnesium levels increased. Four percent activated carbon (AC4%) obtained better results regarding color (98%) and COD (48%), but failed to remove boron and ammonia efficiently. One percent activated carbon achieved similar results to AC4%, but with lower degrees of removal. M. oleífera seed and extract achieved unsatisfactory results. All adsorbents, except M. oleifera extract, decreased the amount of heterotrophic bacteria approximately tenfold. Treatments removed total coliforms and E. coli. None of the adsorbents removed sodium, chloride or the toxicity to D. similis of the leachate. In the tests about the effects of residues of hydrotalcite treatment on the environment, toxicity tests showed that there was decrease of 21.63% in the toxicity to Artemia sp and 42% to L. sativa seed germination tests. The leachate discarded in the soil caused inhibition in the germination and development of L. sativa in relation to the control. In vessels with raw leachate there was inhibition of 12% and with treated leachate 5%. Initially 50m3/ha landfill leachate potentiated bacterial growth and inhibited fungal growth, after 84 days of experimentation there was a microbiota stabilization, except in the high concentration trials where the inhibition remained for the fungi. The use of 200m3/ha landfill leachate in the soil has demonstrated that repeated releases may render the soil unfeasible for planting. The analysis of the vessel soil showed that the raw leachate, caused toxicity to D. similis. The introduction of 2.5% of sludge from the treatment in the soil increased by 42% the biomass of L. sativa in relation to the control, with no negative impact on the soil microbiota or toxicity to D. similis. The biodegradation test with 5% leachate showed that the inoculum encouraged biodegradation, increasing the average daily efficiency of the process by 6 and 9% for treated and raw leachates, respectively. Despite the efficient biodegradation (50% in 24 hours), the toxic potential of the leachate was not eliminated as could be proved by the experiment in pots. The respirometry experiment did not prove to be an efficient technique to determine the sludge biodegradation, since the system is influenced by the hydrotalcite chemical characteristics.
The leachate produced in landfills is the result of physicochemical and microbiological decomposition of urban waste and its composition can vary widely. In order to develop efficient and safe treatment and disposal, there is a need for characterization, development of adequate treatment techniques and study of the impact of these treatment residues on the environment. This work tested microbiological treatment with microorganisms isolated from landfill leachate and with microalgae; treatment with adsorbents like activated carbon, hydrotalcite and M. oleifera seeds and deepened studies about introduction of residues of treatment with hydrotalcite in the environment. Physical-chemical, microbiological, respirometric and toxicity analysis were performed with the treated and raw leachates and with the sludge of treatment. The leachate characterization revealed a small number of heterotrophic bacteria and fungi. Total coliforms and E. coli reached mean values of 17900 and 890 NMP/100 mL, respectively. The physicochemical analysis indicated high conductivity, color, turbidity, COD, BOD5, ammonia, boron, sodium and chlorides. The biological treatments were not efficient in removing the parameters required by the legislation due to high concentrations of salts, ammonia and recalcitrant organic matter.Treatment with hydrotalcite produced the best results to remove conductivity (51%), turbidity (58%), BOD5 (95%), boron (40%) and ammonia (35%), also removed COD (43%) and color (70%) but led to an increase in pH. The reused hydrotalcite presented lower efficiency than hydrotalcite, failed to remove boron and aluminum and magnesium levels increased. Four percent activated carbon (AC4%) obtained better results regarding color (98%) and COD (48%), but failed to remove boron and ammonia efficiently. One percent activated carbon achieved similar results to AC4%, but with lower degrees of removal. M. oleífera seed and extract achieved unsatisfactory results. All adsorbents, except M. oleifera extract, decreased the amount of heterotrophic bacteria approximately tenfold. Treatments removed total coliforms and E. coli. None of the adsorbents removed sodium, chloride or the toxicity to D. similis of the leachate. In the tests about the effects of residues of hydrotalcite treatment on the environment, toxicity tests showed that there was decrease of 21.63% in the toxicity to Artemia sp and 42% to L. sativa seed germination tests. The leachate discarded in the soil caused inhibition in the germination and development of L. sativa in relation to the control. In vessels with raw leachate there was inhibition of 12% and with treated leachate 5%. Initially 50m3/ha landfill leachate potentiated bacterial growth and inhibited fungal growth, after 84 days of experimentation there was a microbiota stabilization, except in the high concentration trials where the inhibition remained for the fungi. The use of 200m3/ha landfill leachate in the soil has demonstrated that repeated releases may render the soil unfeasible for planting. The analysis of the vessel soil showed that the raw leachate, caused toxicity to D. similis. The introduction of 2.5% of sludge from the treatment in the soil increased by 42% the biomass of L. sativa in relation to the control, with no negative impact on the soil microbiota or toxicity to D. similis. The biodegradation test with 5% leachate showed that the inoculum encouraged biodegradation, increasing the average daily efficiency of the process by 6 and 9% for treated and raw leachates, respectively. Despite the efficient biodegradation (50% in 24 hours), the toxic potential of the leachate was not eliminated as could be proved by the experiment in pots. The respirometry experiment did not prove to be an efficient technique to determine the sludge biodegradation, since the system is influenced by the hydrotalcite chemical characteristics.
Descrição
Palavras-chave
Chorume, Adsorventes, Hidrotalcita, Respitrometria, Toxicidade, Landfill leachate, Adsorbents, Hydrotalcite, Respitrometry, Toxicity