Development of an electron beam irradiation design for use in the treatment of municipal biosolids and wastewater effluent

摘要

The need for pathogen-free water supplies has spurred investigations into the useof ionizing radiation for the treatment of wastewater effluent and municipal biosolids.The objective of this research was to develop an electron-beam irradiation scenario toeffectively eliminate microbial pathogens from municipal biosolids and wastewatereffluent. The Monte Carlo N-Particle (MCNP5) radiation transport code was used tosimulate the irradiation scenario.Using MCNP5, dual electron-beam sources were modeled as planarsurface sources above and below a stainless steel delivery trough containing eithereffluent water or one of two biosolids material compositions. A dose deposition analysiswas performed to assess both the planar dose distribution and 25 depth-dose curves. Inaddition, a density perturbation study was performed to assess the variance in the dosedeposition for different mass solids concentrations. To validate the MCNP5 code for this type of application, a benchmark study wasperformed. Two municipal biosolids materials and water were irradiated in plastic bagson a conveyor belt using a 10-MeV electron accelerator with the exit window below thematerial. The experimental configuration was modeled with the MCNP5 radiationtransport code. Simplified and detailed models were created and analyzed.Lastly, an economic analysis was performed to assess whether this treatmentmethod is a financially viable alternative to current wastewater treatment methods.Processing capacity was calculated for two accelerator specifications. These capacityrates in conjunction with the operating and capital costs per dry ton to irradiate thematerial were compared with existing data for electron beam processing of municipalbiosolids. The cost breakdown was also compared with quoted costs for existingconventional methods.The models developed showed that the use of 10MeV electron-beam technologyfor the treatment of wastewater effluent and municipal biosolids is effective andeconomically feasible. The benchmarking study illustrated the accuracy of Monte Carlosimulation for this type of application. The method development process was shown tobe adaptable for various material compositions and irradiation configurations.