Assessment of ecological safety and economic efficiency of biosorption technology for soil protection after hostilities

• Military actions cause a high level of soil pollution with heavy metals (Zn, Cu, Pb). • Biocomposite from digestate and phosphogypsum was proved to immobilize heavy metals. • Digestate from chicken manure binds heavy metals stronger than from sewage sludge. • Risk assessment based on the Bayesian theorem showed a decrease from high to medium. • Biosorption technology was proved as economically feasible and ecologically safe. The problem of chemical soil pollution after military actions on the territory of Ukraine is becoming quite urgent in terms of ecological risks. The aim of the article was to establish the level of ecological safety of soils after the application of biosorption technology and to substantiate its ecological and economic feasibility. Within the scope of the study, three scenarios were set to evaluate the level of ecological risk under the condition of actual complex contamination of soils with five heavy metals (Zn, Cu, Ni, Pb, and Cd) – Scenario 1 and in the case of biosorption technology application for soil protection – Scenarios 2 and 3. Scenarios 2 and 3 differed in the type of substrate for anaerobic digestion (chicken manure and sewage sludge, respectively) compatible with phosphogypsum to obtain a biocomposite. Innovative approach for ecological risk assessment was improved based on the Bayes’ theorem and developed set of qualitative and quantitative parameters. Based on the theoretical substantiation of the complex formation indicator and the fluorescent properties of digestate organic matter, the efficiency of heavy metal immobilisation in the soil was evaluated, which contributed to the reduction of ecological risk from moderate to low level for both scenarios. The results of the risk assessment based on Bayes’ theorem showed a decrease in the level of risk from high to medium. Ecological and economic efficiency was assessed according to methodology of ecological damage after hostilities. The economically effective technology developed can be recommended for the comprehensive soil restoration scheme due to the obtained results.