Estudo da remoção de nitrogênio via nitrito e via nitrato em sistemas de lodo ativado alimentados por despejo com elevada concentração de fenol.

Abstract

Wastewaters containing high phenol and ammonium concentrations present a great pollutant potential to the environment. An example of this kind of effluent is the discharge of coke-plants, which presents, quantitatively, the phenols as the main organic compound. Inorganic compounds are also present in these wastewaters and are mainly cyanide, thiocyanate, sulphate and ammonium, the last one being able to achieve hundreds of milligrammes per litre. In Sao Paulo State, there are two legislations to be accomplished, State Decree 8468/76 and CONAMA Resolution 357/05 that stand that the polluters must accomplish the discharge limits of 20 mg N/L to total ammonium nitrogen and 0,5 mg C 6 H 5 OH/L to phenols, as well as accomplish the waterbody classification. The present research was planned after well succeded results of former researches in EPUSP's Hydraulic and Sanitation Engineering Department aiming to remove phenolic compounds and ammonium from a synthetic coke-plant wastewater, by nitrification/denitrification of the influent in activated sludge plants. The main purpose of this work was to remove nitrogen of a similar wastewater containing high phenol (1000 mg/L) and ammonium (500 a 1000 mgN/L) concentrations in two activated sludge pilot plants (single sludge): a partial one ("P") to remove nitrite (or "nitritation/denitritation") in the first case, only with internal carbon source for the denitrification, and a total one ("T") in a second case, with internal and external carbon sources. It was also aim of this work to compare the results obtained by the Partial ("P") pilot system with a parallel batch sequence reactor operated to remove nitrogen via nitrite. The research concluded that the continuos system, due to its operational characteristic, was not efficient to remove nitrogen via nitrite that does not favor the maintenance of free ammonia in the oxic phase in inhibitory concentrations to the nitrite oxidizers, as according to the wellsucceeded batch system, the existance of free ammonia and the pH have been the main parameters to raise the nitrite accumulation in the reactor. Nevertheless, the system presented satisfactory results to the denitrification with phenol as carbon source and, during the whole experimental work, the final effluent just showed despicable phenol concentrations. Summing up, continuos system was just adequate to remove nitrogen via nitrate, while the batch system favored its removal via nitrite. Due to the Total ("T") system which aims to complete nitrification/denitrification with internal and external carbon sources, the results showed that, despite ethanol having been successfully used by the heterotrophic bacteria to denitrification, its use as external carbon source was not adequate in single sludge system, because the microorganisms do not use phenol in denitrification, just using ethanol, causing phenol accumulation and unbalance of the system. Therefore, it was concluded that the use of ethanol as external carbon source to denitrification would be recommended only in anoxic ...

Monitoramento De Qualidade De Água: Suporte Para Gestão Ambiental Na Microbacia Do Córrego Da Olaria

“…O nitrogênio total apresentou valores acima do estabelecido pelo CONAMA 357 em todos os pontos de coletas (figura 2), possivelmente ao acúmulo de nutrientes derivados da mata. Este resultado condiz com Aun (2007), o qual confirma que a quantificação do nitrogênio orgânico, é constituído principalmente por ureia, aminoácidos e outras substâncias orgânicas com o grupo amino. É importante ressaltar que no ponto 1 -marangoni houveram apenas coletas de sedimentos em todo o período devido a ausência de água na nascente, e que não há limite de detecção de qualidade no solo para os parâmetros apresentados.…”

Eficiência do melaço como fonte de carbono na remoção de nitrito em lixiviados de aterros sanitários

“…Para que essa reação aconteça, ocorre a necessidade de disponibilidade de matéria orgânica (demanda bioquímica de oxigênio -DBO) doadora de elétrons. (AUN, 2007;CARRERA;VICENT;LAFUENTE, 2003).…”

Desenvolvimento de lodo granular aeróbio para tratamento de esgoto sanitário: remoção de nutrientes em ciclo de três estágios.

“…Também possibilitam o aumento da velocidade de desnitrificação (AUN, 2007;VAN HULLE et al, 2010), pois apenas o nitrito e não o nitrato deve ser reduzido a N2 (SCHMIDT et al, 2003 Em relação a esses compostos, a amônia livre é o principal inibidor da nitrificação sob elevado valor de pH (maior que 8,0), enquanto que o ácido nitroso é o principal inibidor em pH baixo (menor que 7,5). Na literatura, diferentes valores limiares foram propostos para inibição da nitrificação, mas esses são muito sensíveis à adaptação bacteriana (VAN HULLE et al, 2010).…”