ORIGINAL PAPER Hydrocarbon degradation in oily sludge by bacterial consortium assisted with alfalfa (Medicago sativa L.) and maize (Zea mays L.) Asim Shahzad 1,2 & Samina Siddiqui 3 & Asghari Bano 4 & Shehla Sattar 3 & Muhammad Zaffar Hashmi 5 & Mingzhou Qin 2 & Abdul Shakoor 6 Received: 13 September 2019 /Accepted: 20 August 2020 # Saudi Society for Geosciences 2020 Abstract Hydrocarbons contamination is a worldwide threat to soil ecosystem. The present study was designed to evaluate the remediation potential of bacterial consortium, viz. Bacillus cereus (Acc KR232400), Bacillus altitudinis (Acc KF859970), Commomonas (Delftia sp.) (Acc KF859971), and Stenotrophomonas maltophilia (Acc KF859973), with alfalfa and maize plants in combina- tion with fertilizer to remediate the oily sludge. Oily sludge was mixed with soil in 30:70 ratio, and ammonium nitrate and diammonium phosphate (DAP) were added at a rate of 70 μg/g and 7 μg/g with the consortium (10 6 cells/ml). Different hydrocarbons were extracted by Soxhlet extraction and examined by using gas chromatography and flame ionization detector (GC-FID). Consortium degraded more than 63% total petroleum hydrocarbons, and significant degradation (80%) of n-alkanes (nC 13 to nC 29 ) was witnessed with consortium + fertilizer + alfalfa in 30% oily sludge at 3 days. Degradation of (80%) of n- alkanes (nC 13 to nC 29 ) in oily sludge was also noted. In this study, the consortium along with Alfalfa and fertilizer found most efficient option for remediation of hydrocarbons. Keywords Alfalfa plants . Bacterial consortium . Hydrocarbon degradation . Maize . Oily sludge . Plant microbe interaction . Rhizoremediation Introduction In the last few years, a reasonable amount of oily sludge has been drilled out and stored in open pits within the surroundings of different oil field areas. Moreover, these oil- based industries are also spilling out oily waste to the environ- ment which poses constant threat to the agro-environmental ecosystems. Oily sludge is made up of a wide range of cancer- Responsible Editor: Amjad Kallel * Asim Shahzad Agron12@yahoo.com Samina Siddiqui saminasddq@yahoo.com Asghari Bano Banoasghari@gmail.com Shehla Sattar shehlafazl62@gmail.com Muhammad Zaffar Hashmi hashmi_qau@yahoo.com Mingzhou Qin mzqin@vip.henu.edu.cn Abdul Shakoor abdul_Shakoor954@yahoo.com 1 Department of Botany, Mohi-ud-Din Islamic University, Nerian Sharif, AJ&K, Pakistan 2 College of Environment and Planning, Henan University, Jinming Ave, Kaifeng 475004, China 3 National Center of Excellence in Geology, University of Peshawar, Peshawar, Pakistan 4 Department of Biosciences, University of Wah, Wah Cantt, Pakistan 5 Department of Chemistry, COMSATS University, Islamabad, Pakistan 6 Key laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions, College of Environment and Planning, Henan University, Kaifeng, China Arabian Journal of Geosciences (2020) 13:879 https://doi.org/10.1007/s12517-020-05902-w