Case Studies in Chemical and Environmental Engineering 9 (2024) 100735 Available online 26 April 2024 2666-0164/© 2024 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by- nc/4.0/). Case Report Enhancing field-scale bioremediation of weathered petroleum oil-contaminated soil with biocompost as a bulking agent Qomarudin Helmy a, * , Edwan Kardena b a Environmental Engineering Study Program, Institute of Technology Bandung, Ganesa St. No. 10, Bandung, West Java, Indonesia b Water and Wastewater Engineering Research Group, Faculty of Civil and Environmental Engineering, Institute of Technology Bandung, Ganesa St. No. 10, Bandung, West Java, Indonesia A R T I C L E INFO Keywords: Field-scale Bioremediation Petrophylic Biocompost Petroleum Bioaugmentation ABSTRACT The field-scale cleanup of weathered petroleum oil-contaminated soils from the Minas Oil Fields in Indonesia was investigated using landfarming bioremediation technology. Sawdust produced from palm fronds, trunks, and bushes was used as a bulking agent, fermented with manure from cow, goat, and chicken dung as amylolytic and cellulolytic source microflora. Petrophylic bacteria known for their capability to degrade PAH were used as augmented microflora along with stimulated local indigenous microflora overgrown onsite. The findings demonstrated that, albeit at varying rates, the inoculum of native and augmented microflora raised the total colony-forming units (CFU) and the rate at which total petroleum hydrocarbons (TPH) were degraded in all contaminated soils treated in the soil bioremediation facilities (SBF). After 150 days of bioremediation operation, the bioremediation process for petroleum oil-contaminated soil effectively eliminated 165.79 kg of TPH from 2565 cubic meters of contaminated soil, with a recovery cost of 161 USD per cubic of treated soil. The initial average TPH concentration in the soil was 64,799 ± 9373 mg/kg and decreased to a lower concentration of 163 ± 74 mg/kg after bioremediation was completed. Both native and augmented petrophilic microflora showed significant growth over tenfold, with an average number of colonies at the initial stage of the bioremediation process ranging from 5.9 × 10 5 to 6.6 × 10 6 CFU per gram of soil. We show that a practical and affordable bioremediation technique is the onsite production of petrophylic microflora (both native and augmented) and compost from locally available biomass waste. 1. Introduction Petroleum oil pollution in the soil poses a serious threat to human health. Petroleum oil can reach groundwater sources so that it can pollute groundwater which is used as the main source of clean water needs. One of the oil contaminants that is difficult to decompose is hy- drocarbon compounds. When these compounds pollute the surface of the soil, these substances can evaporate, be washed away by rainwater, and enter the soil, and then be deposited as toxic substances that can disrupt the soil ecosystem and water cycle. Naturally, the environment has the ability to degrade pollutant compounds that enter it through biological and chemical processes, but often the burden of pollution in the environment is greater than the speed of the natural degradation process of these pollutant substances. As a result, pollutant substances will accumulate so human intervention with existing technology is needed to overcome this pollution. One way to overcome this problem is by bioremediation, restoring environmental conditions by utilizing the biological activity of microorganisms to reduce the toxicity levels of polluting compounds. There are two approaches that can be used in oil spill bioremediation: the first is bioaugmentation, where microorgan- isms that decompose hydrocarbon compounds are added to complement the existing microbial population, and the second is biostimulation, where the growth of the native hydrocarbon decomposers is stimulated by adding nutrients or improving the environmental habitat so that growth becomes more optimal. Guerin reported a full-scale on-site remediation of oil sludge using the co-composting method [1]. A cost-effective remediation of oil-contaminated soil and sludge on-site at a petroleum refinery was proven by a co-composting that used readily available organic additives and a relatively modest windrow design. TPH in the organic altered sludge windrows that had been composted at the end of the trial drop- ped from 62 % (w/w) (in air-dried sludge) to 1 % in the final mix, * Corresponding author. E-mail address: helmy@itb.ac.id (Q. Helmy). Contents lists available at ScienceDirect Case Studies in Chemical and Environmental Engineering journal homepage: www.sciencedirect.com/journal/case-studies-in-chemical- and-environmental-engineering https://doi.org/10.1016/j.cscee.2024.100735 Received 27 November 2023; Received in revised form 23 April 2024; Accepted 24 April 2024