The effects of crystal seeding on the handling characteristics of nickel hydroxide sludge

• Main Author: Kelley, Roy Thomas
• Other Authors: Sanitary Engineering
• Format: Others
• Language: en_US
• Published: Virginia Polytechnic Institute and State University 2019
• Subjects: LD5655.V855 1982.K447; Sewage sludge; Sewage disposal
• Online Access: http://hdl.handle.net/10919/87218

The objectives of this study were to investigate the effects of the crystal seeding technique on certain handling characteristics of nickel hydroxide sludge and to investigate the changes in sludge particle properties that mediated any changes in those characteristics. A continuous-flow nickel hydroxide precipitation reactor was operated with and without solids recycle to produce sludge for analysis. The concentration of solids produced in the reactor clarifier was monitored and the specific resistance of the sludge was measured. Batch settling tests were also conducted on the sludge samples. The particle size distribution of the sludge produced was measured by an electronic particle counter and the density of the sludge flocs were measured. After the initiation of solids recycle in experiment I, the concentration of sludge solids increased from a range of 9,510-13,720 mg/l to 27,500-76,000 mg/l. Specific resistance values decreased an order of magnitude from an average of 4.01 x 10¹² m/kg before recycle to an average of 2.73 x 10¹¹m/kg during recycle in experiment I. Also, batch settling tests indicated an improvement in solids settling velocity. Similar results were obtained in the second experimental run. The improvement in these sludge handling parameters was attributed to an increase in particle size and particle density. Mean sludge particle diameter increased from an average of 2.9 microns before solids recycle to an average of 3.9 microns during recycle. Sludge particle density also increased during the recycling of sludge. These changes in sludge particle size and density were produced by an alteration of the crystal growth process. === Master of Science