Abstract Terephthalic acid is extensively used as an important raw material in polyester fibers, as well as the production of polyethylene terephthalate bottles and textile industries. Especially, in the petrochemical industry, toxic chemicals are released to the atmosphere during the production of polyethylene terephthalate, unless the wastewater treatment is carried out. It's a well-known fact that chemicals have serious side effects on human health, so manufacturing companies should not dispose of such harmful chemicals without treatment. Biodegradation is an effective option for eco-friendly degradation of hydrocarbons. Hydrocarbon-degrading bacteria are everywhere in environment and can utilize these chemicals as sources of carbon and energy. In the present study, aerobic bacterial strains T1, T4, T5, and TK were isolated from activated sludge and crude oil deposits of a petrochemical company in Turkey. The strains were identified to be Pseudomonas sp., Chryseobacterium sp., Burkholderia sp., and Arthrobacter sp. according to morphological, physiological and biochemical characteristics. The strains were able to degrade about 100% of 100 mg/L terephthalic acid within, respectively, 8, 67, 52, 24 hour as sole carbon and energy source. Therefore, these isolates can be effectively used for degradation of terephthalic acid contaminated sites. In addition to this, a Continuous Stirred Tank Reactor (CSTR) was used to test the biodegradation capabilities of the isolates in the activated sludge system. Throughout the biodegradation, bacterial existence and numbers were monitored using designed primer-probe sets in real-time polymerase chain reaction (PCR).