Utilização de efluente tratado em complexo industrial automotivo / Effluent use in an automotive industrial complex

RESUMO Neste trabalho, realizaram-se modificações nos sistemas produtivo e de tratamento de efluentes em um complexo industrial automotivo a fim de possibilitar a utilização do efluente tratado no sistema de torres de resfriamento. Inicialmente, realizou-se um balanço hídrico nos processos industriais para determinar o consumo de água e analisou-se a qualidade do efluente tratado quanto aos parâmetros físico-químicos em dois pontos do sistema de tratamento de efluentes: no decantador secundário (P1) do tratamento físico-químico e na saída da lagoa de polimento (P2). Essas análises mostraram que o efluente tratado no decantador secundário não tem capacidade de atender às especificações da água de circulação das torres de resfriamento sem a realização de muitas alterações em seu tratamento, optando-se pela utilização do efluente tratado na saída da lagoa de polimento após modificações, como: alteração na concentração de ácido fosfórico e de ácido nítrico da solução de limpeza dos tanques de fosfatização, elevação em 50% da capacidade de aeração da lagoa aerada e troca do coagulante sulfato de alumínio pelo cloreto férrico no tratamento físico-químico. Assim, os parâmetros do efluente tratado na lagoa de polimento aproximaram-se aos parâmetros especificados para água de torres de resfriamento. A introdução desse efluente na proporção de 40% do volume da água de circulação na torre de resfriamento resultou em elevação do ciclo de dureza e redução no ciclo de sílica. A utilização de um filtro abrandador na saída da lagoa de polimento proporcionou a redução dos parâmetros de qualidade da água para valores similares aos da água de recirculação nas torres de resfriamento.

ABSTRACT In this work, some changes in the productive system and in the effluent treatment plant of an automotive industrial complex have been performed in order to enable the treated effluent use in the cooling towers of the industry. Initially, a hydric balance in the industrial processes was performed, allowing the determination of water consumption. After, the effluent quality was analysed through its physico-chemical parameters at two sites of the effluent treatment plant: in the secondary settling tank (P1) of the physico-chemical treatment and in the exit of the polishing pond (P2). These analyses showed that the effluent from the settle tank does not have the ability to contemplate the specifications for water used in the cooling towers without much change in effluent treatment so that the effluent from polishing pond was used for testing in the cooling towers after some changes. These changes have included: phosphoric acid and nitric acid concentration changes in the cleaning solution of phosphating tanks, 50% increase in the aeration capacity of the aerated lagoon and replacement of aluminum sulfate coagulant by ferric chloride in physico-chemical treatment. With these modifications, the effluent from polishing pond approached the parameters specified for water cooling towers. The use of this treated effluent as 40% of water volume of the cooling tower resulted in hardness cycle increase and reduction in silica cycle. The use of a softener filter after the polishing pond decreased the effluent quality parameters to similar values to those for water cooling towers.

Genotypic variability and persistence of Legionella pulsed-field gel electrophoresis patterns in 16 cooling towers in Shanghai, China / 中华流行病学杂志

Objective To investigate the genotypic characteristics and persistence of Legionella pulsed-field gel electrophoresis (PFGE) patterns in 16 air-conditioner cooling towers in six different public sites of Shanghai. Methods From May to October, continuous sampling was operated once per month in 2007. Legionella strains isolated from the 16 cooling towers were confirmed by serological and latex agglutination. PFGE was applied for the fingerprinting of the isolates, while the culster results of PFGE were analyzed by BioNumerics software. Results 131 strains of Legionella were isolated, including L. pneumophila, L. bozemanae, L. micdadei and L anisa.52 distinguishable PFGE patterns were differentiated among the 16 cooling towers, with 37 patterns were owned by just one cooling tower, which was not shared with other cooling towers, while 15 patterns were shared by more than 2 cooling towers. All the cooling towers had ≥2 PFGE patterns,while in 13 cooling towers the same PFGE patterns were recovered during the six months. From June to October of 2007, 18 strains of Legionella belonging to the PFGE pattern of LPAs. SH0078 were isolated continuously from 6 cooling towers. Conclusion This study demonstrated great genotypic diversity and complexity of Legionella in cooling towers. Persistence of the PFGE patterns was observed in 81.25% of the cooling towers. The PFGE pattern of LPAs. SH0078 was distributed widely,suggesting it might be the dominate strain in Shanghai.