OPTIMIZATION PARTICLE SEPARATION FOR BETTER WATER QUALITY IN TREATMENT
The goal of the flocculation, sedimentation, dissolved-air-flotation (DAF) processes are to change the particle size distribution to best suit the subsequent processes. Although several methods exist to evaluate each process, no single universally accepted method has yet to be developed. The purpose of this paper is to present experiences whereby particle counting was used in the diagnosis and optimization of each process. The evaluation is based on particle dynamics, i.e., the change of the number of small and large particles. Some design deficiencies and inappropriate operational conditions in each process have been identified from this method. The effects of changed design in each process have been evaluated by comparing the particle counts at the existing design with particle counts after modification. Because the diagnosis of design may be site-specific, the method presented in this paper will be beneficial in the evaluation of the treatment processes at other water treatment plants leading to low cost, low energy operation.
Integrated design and operation of water treatment facilities
Management of a Design Project. Preliminary Studies. Design of Basic Treatment Process Units. Subordinate Plant Facilities. Design of Plant Components. Elements of Detailed Designs. Specific Water Treatment Processes. Management of Procurement and Construction Phases. Operations and Maintenance Manual and Operator Training. Plant Startup and Follow-Up Services. Appendices. Index.
Neutron Residual Stress Measurements on Rail Sections for Different Production Conditions
Rail sectioning with subsequent neutron diffraction experiments has been used to assess residual stresses in the rails. In this study we present the results of neutron stress measurements performed at the NIST Center for Neutron Research (NCNR) on rail sections from rails that were produced under various conditions. Specifically, these are air-cooled, air-cooled and roller-straightened, head-hardened and head-hardened and roller-straightened. More significantly, a head-hardened and roller-straightened rail was also studied after service to elucidate evolution of the service-induced residual stresses. In the latter case both a transverse-cut slice and the central region of a 0.53 m long piece were studied. Measurements on this piece are the first in which triaxial stresses have been determined for an intact rail. Neutron strain measurements with 3×3×3 mm3 spatial resolution were successfully employed for transversally cut slices to verify the difference in the stress state depending on the production process. Although examination of slices allows determination of only two-dimensional stresses in the plane of the slice, additional measurements on obliquely-cut slices, which were also carried out, and utilization of FEM gives the possibility of reconstructing the full triaxial stress distribution. Together, these approaches provide a better understanding of rail fabrication and the possibility of improving the durability and safety of rails in the future.Copyright © 2004 by ASME