Uso agronômico de biossólidos em culturas anuais: avaliação quantitativa de riscos microbiológicos para trabalhadores rurais

Abstract

Sewage Treatment Stations generate solid by-products that need to be managed safely so as not to compromise the environment and the health of the population. Among these by-products, the sludge generated in the primary, biological and physical-chemical treatment units stand out, which concentrates a large part of the pollutants and contaminants removed during the treatment of raw sewage. After adequate treatment, the sewage sludge is transformed into a new material, biosolids, with great potential for agricultural use, due to its nutritional properties for plants and retention of water in the soil. The agricultural use of these by-products is an alternative for final disposal, however, the health risk associated with the presence of pathogens is an obstacle to this practice. The laws that regulate the application and use of biosolids are sometimes very restrictive, and do not take into account the risk assessment. In this scenario, the Quantitative Microbiological Risk Assessment (QMRA) is a mathematical tool that can be used to calculate the risks associated with different pathogens in different exposure scenarios. Given this context, this work aims to evaluate the microbiological risks due to the use of biosolids in the soil, for agricultural purposes, using the QMRA for different scenarios of exposure of rural workers involved in the processes of management and cultivation of sugarcane and bean plantations, targeting Ascaris lumbricoides, based on secondary data from sewage sludge obtained in a literature review. After the application of the QMRA, the results indicated that the annual risk of infection by Ascaris for rural workers during the application of biosolids ranged from 3.35 x 10-1 to 9.15 x 10-1 pppa (per person per year), and the annual risk related to crop management ranged from 1.10 x 10-3 pppa to 8.10 x 10-3 pppa, respectively for sugarcane and bean crops evaluated in the study.