Efficacy of Aspergillus sp. for Degradation of Chlorpyrifos in Batch and Continuous Aerated Packed Bed Bioreactors Maya Yadav & Navnita Srivastva & Awadhesh Kumar Shukla & Ram Sharan Singh & Siddh Nath Upadhyay & Suresh Kumar Dubey Received: 26 April 2014 /Accepted: 10 September 2014 # Springer Science+Business Media New York 2014 Abstract Aerobic biodegradation of chlorpyrifos (CP) by Aspergillus sp. was investigated in batch and continuous packed bed bioreactors. The optimal process parameters for achieving the maximum removal efficiency (RE), determined using a batch bioreactor packed with polyurethane foam pieces, were inoculum level: 2.5 mg(wet weight)mL -1 , pH 7.0, tempera- ture 28 °C, DO 5.8 mg L -1 , and CP concentration 300 mg L -1 . The continuous packed bed bioreactor was operated at flow rates ranging from 10 to 40 mL h -1 while keeping other parameters at their optimal level. Steady-state CP removal efficiencies greater than 85 % were obtained up to the inlet loading of 180 mg L -1 d -1 . The continuous bioreactor behaved as a plug flow unit and was able to stabilize quickly after perturbation in the inlet loading. Keywords Bioreactor . Chlorpyrifos . Polyurethane foam . Inlet loading rate . Removal efficiency Introduction The organophosphate chlorpyrifos (CP), a broad-spectrum insecticide, is a risk to human and other biological components of aquatic and terrestrial ecosystems. The conventional chemical and physical methods for the removal of CP are not only time-consuming and uneconomical but also result in the formation of secondary pollutants. Thus, a dependable and economical method for the detoxification of CP present in soil, water, etc. is required. Fungal species have been successfully used for degrading toxic organic compounds in biofilters [1–3]. Fungi are quite resistant to changes in temperature, pH, humidity, etc. In addition, fungal hyphae facilitate adsorption of xenobiotic compounds through increased mass transfer [4, 5]. Application of fungi also improves the partitioning of hydrophobic compounds between liquid and cellular system. Their ability to adapt quickly to the operating conditions of the bioreactor Appl Biochem Biotechnol DOI 10.1007/s12010-014-1244-0 Siddh Nath Upadhyay is a DAE-Raja Ramanna Emeritus Fellow M. Yadav : N. Srivastva : A. K. Shukla : S. K. Dubey (*) Department of Botany, Faculty of Science, Banaras Hindu University, 221005 Varanasi, India e-mail: skdubey@bhu.ac.in R. S. Singh : S. N. Upadhyay Department of Chemical Engineering and Technology, Indian Institute of Technology (Banaras Hindu University), 221005 Varanasi, India