ECONOMIC AND TECHNOLOGICAL PRINCIPLES OF SAFE USE OF SEWAGE SLUDGE IN AGRICULTURE

Abstract

Topicality. Spreading the philosophy of sustainable development, where activities preserve natural and social resources for use by future generations without harming the business economy, as well as significant increases in the price of chemical fertilizers due to rising gas prices require ways to reduce the chemical burden on agriculture. The trend of abandoning intensive technologies will be exacerbated by economic leverage - European Union regulations are increasingly banning agrochemicals and introducing a "carbon tax". Therefore, the use of sewage sludge as fertilizer for agricultural production is becoming an urgent issue. Therefore, the use of sewage sludge as fertilizer for agricultural production on the basis of economic efficiency is becoming an urgent issue.Aim and tasks. The aim of the article is to consider the economic and technological principles aimed at improving the bioavailability of nutrients and reducing the risk of using biowaste before entering the soil, in the context of the idea of sustainable development.Research results. Sewage sludge (SS) application in agriculture has a beneficial effect on soil organic matter content, sorption capacity and an overall improvement in physical properties. Conversion of SS to a soil amendment can be performed by a broad spectrum of methods, which greatly differ by substrate/amendment composition, treatment time, and physicochemical conditions. Sanitary and epidemiological safety is essential, which is why bio-wastes require processing according to selected technologies that aim to improve the bioavailability of nutrients and reduce hazards before entering the soil. This review provides a more complete overview of the present status of the methods for SS disinfection. The review is focused on i) environmental and legislative aspects of SS application in agriculture; ii) risk factors related to the abundance of bacterial, viral, protozoan and other pathogens in SS and methods of SS hygienization by various physical and chemical treatments; iii) risks of soil pollution with biologically active compounds (e.g., antibiotic resistance genes and other emerging contaminants). For the life cycle assessment, an environmental performance and pathogen risk was considered. The results of such consideration have direct impact on the nature of the applied economic and technological measures. Conclusions and perspectives in this field were formulated, using 102 references, including 49 citations dated by the last five years.Conclusion. Numerous technological approaches on SS treatment have their particular advantages, although disinfection efficiency remains unsatisfactory. Legislative requirements are still based on less resistant indicator organisms. Further comprehensive research on SS treatment should be focused on combination of different physical (especially, thermal) and chemical processes, which would convert SS into a qualitative fertilizer with safe microbiological characteristics. The decrease in energy consumption during drying and the reduction of the management costs of these residues can be relevant economic gains. In general, the application of drying to remove water from sewage sludge should be a balance between energy costs in the process and the management costs without drying.