Avaliação e critérios de eficiência nos processos de tratamento de fluido de corte por eletroflotação / Evaluation criteri and efficiency in the procedures for treatment of fluid cutting by eletroflotation

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

In the machining process cutting fluids are used to facilitate the manufacture of metal parts, which has resulted in problems of various orders, ranging from the generation of harmful effects on the desktop to the aggression of the environment with their improper disposal. The cutting fluids are composed of oils and minerals, synthetic solutions and water, carcinogenic substances due to the formation of nitrosamines, as well as chlorine-based additives, nitrite, phosphorus and amines. Many of the processes used in sewage treatment stations involve the addition of coagulants and flocculants agents, such as polymers and iron and aluminum salts. These substances even at low concentrations cause environmental impacts, altering the balance of the receiver body. In this research project it was developed a method to treat synthetic cutting fluid using the Eletroflotation, an electrochemical technique, which uses aluminum sacrifice electrodes to generate in situ a coagulating agent. Simultaneously, micro-gas bubbles are generated as a result of the water electrolysis due to the application of a potential difference between the electrodes. After coagulation, the colloids can be float and removed. To check the efficiency of the procedure it was performed a characterization of the cutting fluid before and after treatment comparing some values with the results relevant legislation in the State of São Paulo, the Decree nº. 8468 of September 8th, 1976.The characterizations were: determination of pH and turbidity, metals, total phosphorus, total nitrogen, nitrite, chemical oxygen demand, biochemical oxygen demand, dissolved oxygen, total solids, total carbon, concentration of oils and greases, conductivity, polycyclic aromatic hydrocarbons (PAHs), benzene, toluene and xylenes (BTEX) and nitrosamines. The results showed that the polarity reversion did not result in more efficient processing of cutting fluid with the EF. The metals reduction has been satisfactory under the law. The total solids, nitrates and phosphates present were partially removed noting the effectiveness of EF in the reduction of inorganic compounds. The decrease of oils and greases concentration, total organic carbon, demand chemical and biochemical oxygen showed the efficient removal of organic compounds present in the residue. The treatment with Eletroflotation resulted in total removal of BTEX and PAHs. The nitrosamines were not found in the residue. The pollutants during the Eletroflotation were transferred to the mud, reducing the volume to be subsequently destroyed.

ASSUNTO(S)

eletroflotation tratamento fluido de corte eletroflotação treatment fluid cutting

ACESSO AO ARTIGO

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