Disinfection of enteric bacterial pathogens and indicators in biosolids using solar drying in Jordan

This study focuses on the use of solar drying to reduce the density level of enteric pathogens and indicators In biosolids In semi-arid locations. Seasonal solar drying studies were conducted in Wadi Hassan, Jordan by studying the die-off patterns of Salmonella spp. and fecal coliforms in biosolids. Two drying experiments were conducted in Wadi Hassan during warm dry periods and one was completed during a cold wet period. The average fecal coliform inactivation rates (K_d) during the warm dry periods were 0.18 days^-1 and 0.19 days^-1 during the summer 2004 and spring 2005 seasons, respectively. Class A criteria was met in roughly 20 days for both experiments. The average inactivation rate for fecal coliforms during the winter season was 0.04 days^-1. Salmonella spp. densities dropped below Class A levels on Day 14 and on Day 19 In the summer 2004 and in the spring 2005 drying seasons, respectively. During the winter season, the colder temperatures, high relative humidity and rainfall events prevented the biosolids from reaching Class A bacterial levels. In semi-arid regions, during dry periods, open solar drying Is an economically viable and technically feasible method of disinfecting biosolids prior to reuse during warm dry periods. However, during the cold and wet months, open solar drying is not an effective method for disinfecting biosolids.