The present invention provides a process for the production of a purified aromatic dicarboxylic acid. A coolant system is configured to direct at least a portion of a second coolant liquid from a position in the coolant system downstream of a first condenser to a position in the coolant system upstream of the first condenser via a feedback system configured to cool the second coolant liquid if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to a first pre-set temperature and/or the measured flow rate of the second coolant liquid is less than or equal to a pre-set flow rate. The present invention further provides an apparatus for carrying out the process.