BIODEGRADACIÓN ANAEROBIA DE ÁCIDO TEREFTÁLICO.

Abstract

Terephthalic acid (TA) is a monoaromatic compound widely used as plasticizer in several types of industries, varying from production of plastic toys, textiles, medical devices to the manufacturing of bottles used for drinking water and several other beverages. For each ton of terephthalic acid production, 3 to 10 m3 of wastewater are generated containing as the main pollutant TA itself in a mixture involving other monoaromatics and organic compounds with a simpler chemical structure. In general, these waters are highly toxic, therefore, is necessary to include an adequate treatment process for these water streams in order to avoid damage to the environment. Anaerobic processes are an option that may offer certain advantages over aerobic processes such as low generation of sludge and the potential to generate energy through the production of methane. In the present work it was possible to adapt a microbial culture taken from a wastewater treatment plant (Iztapalapa, Mexico City) to a two different anaerobic conditions (denitrification and methanogenesis) in order to biodegrade TA . The cultures were incubated in microcosms under the mentioned conditions and were able to degrade 500 mg/L of TA in 4 days under denitrifying conditions, whereas they took 6 days to biodegrade the same TA concentration under methanogenic conditions. The rates of TA biodegradation were: 12.13 mg TA/L h and 9.25 mg TA/L h for denitrifying and methanogenic conditions respectively. A UASB reactor was inoculated with the adapted cultures used in the microcosms and it was operated under semi continuous regime for TA biodegradation. Two HRT were used (7 and 13 min). The best results were obtained at a HRT of 13 min at which 2 g/L of AT were biodegraded at a rate of 187 mg TA/L d, whereas at the same HRT, 3 g/L of AT were biodegraded at a rate of 115.52 mg TA/L d. The main intermediate product detected in the process was acetate. The results obtained in this work demonstrate that is possible to biodegrade TA with the pre-adapted inoculum (initially aerobic) at reasonable rates compared to the obtained in systems of bioreactors inoculated with methanogenic granular sludge. These results can be used as a reference for future work on TA biodegradation in continuous regime under methanogenic conditions at the suggested operation conditions.