Solar disinfection and lime stabilization processes for reduction of pathogenic bacteria in sewage effluents and biosolids for agricultural purposes in Yemen

Yemen is the least advanced country among Middle Eastern countries in sewage reuse and safety control. The current sewage effluent quality in Yemen is generally poor as none of the existing sewage treatment plants produces effluents that comply with the effluent quality regulations. There is no plan to build tertiary treatment systems. However, the oxidation and stabilization ponds are considered most appropriate for the warm climate conditions in the country. Sewage effluents and biosolids generated from these ponds are used extensively for agricultural purposes. This review discusses the potential use of solar disinfection (SODIS) and lime treatment for the reduction of pathogens in sewage effluents and biosolids before reuse. SODIS and lime treatment are natural processes, simple, easily implemented, produce non-toxic by-products and are low cost. The merits of these processes are enormous, and they are suitable for application in developing countries such as Yemen.