Effect of the temperature on the performance of a sludge activated petrochemical wastewater treatment plant

Petrochemical Morelos is located in an industrial zone among 50 refineries and petrochemical industries, in the coastal region of Mexico. All these industries produce 111 Mm(3)/d of wastewaters which are discharged into the Coatzacoalcos River, previous treatment in their wastewater plants. However, the high temperatures in the region negatively affect the performance of the different wastewater plants increasing the discharge of pollutants into the river during the high temperatures in the year. Petrochemical Morelos has an activated sludge system to treat its wastewater flow which is about 7000 m(3)/d. The aeration is supplied by a fine bubble diffusers system. Four compressors supply the air to the bioreactors. The high temperatures in the region and the compression effect on the air supply cause the temperature of the air exiting from the compressor to reach up to 82 degrees C. As a direct consequence of the high air temperature, the temperature in the bioreactor reaches 32 degrees C during the fall, whereas in the spring and summer, the bioreactor temperature reaches up to 41 degrees C. The high temperatures have an adverse effect on the microbial activity and affect the performance of the biological process. In this study, the effect of temperature on the process is considered. A dynamic model, based on actual operation data, was validated at five scenarios presented during the year. The effect of temperature on mu(max), kla and kd, was incorporated in the mass balance equations of the model. Moreover, the model is applied to find the operating space of the process at different scenarios with the high temperatures, to reach the effluent quality standards required by Mexican environmental laws.