Materials Performance

DEC 2016

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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47 NACE INTERNATIONAL: VOL. 55, NO. 12 MATERIALS PERFORMANCE DECEMBER 2016 [K] may also include waste water tempera- ture, roughness of the crown, moisture con- tent of the air space, etc., but it is most likely constant (i.e., [K] = 1). In Equation (12), the effect of turbu- lence creates additional air-water inter- faces in comparison with a slow stream. The factor, velocity of flow (V f ), affects the thickness of the slime layer, as well as the ability of the stream to transport solids in the waste water. Since the slime layer varies in thickness at different locations, differ- ences in solids accumulation will occur at various f low velocities. Velocity of f low is in the form referred to as Manning 's Formula. 13 During the past 40 years, various chem- icals, nearly 100, were examined to find the ones most effective for deactivating, defy- ing, or resisting SOB to prevent sewer cor- rosion. Among those chemicals, the follow- i n g f iv e c h e m i c a l s — Mg (O H ) 2 + Ti O 2 , Mg(OH) 2 , TiO 2 , Ba(OH) 2 , and Ca(OH) 2 — were selected for experimental reaction studies with pH of 2.0, which is the actual pH of H 2 SO 4 at the sewer crown. The selec- tion of these five chemicals was based on toxicity, lower water solubility, higher den- sity, and durability against bacteria. In order to avoid confusion on the per- centages of chemical mix, the % dilution of each chemical with water for the labora- tor y e xp erim ent s w a s cl early d ef in ed (Table 1). Results of the research and laboratory experiments (Figure 3) indicate that life- time expectancies of two different mix- tures, A + B + F and B + F, make them excel- lent chemicals to effectively deactivate the SOB and prevent sewer corrosion. The thickness of the chemical coats for this research and development was 2 mm, w hi le th e thickn ess of th e ch emical A coat—50 to 60% slurr y of Mg(OH) 2 , used by public agencies in the United States— is 4 to 6 mm. 9,11 Therefore, if the thickness of the new chemical mixtures is 4 to 6 mm, t h e l i f e e x p e c t a n c y c o u l d a p p r o a c h permanence. Conclusion Results of the long-term research and laboratory experiments indicate that life expectancies of chemical mixtures A + B + F and B + F, shown in Figure 3, are superior to those for NaOH or Mg(OH) 2 alone. In con- clusion, the newly developed chemical and engineering theories can deactivate SOB and help the world's struggles and agonies with sewer corrosion, eventual collapse, and/or explosion. References 1 E. Esfandi , R . Sydney, "Control Concrete Sewer Corrosion via the Crown Spray Pro- cess," Water Environment Research 68, 3 (1996). 2 C l o e v i s Te c h n o l o g y, A d v a n c e d Wa t e r Mana gem ent C ent er, Th e University of Queens land, 2012, http://www.cloevis.com/ technology.html (Oct. 26, 2016). 3 C.H. Rh ee, "Corrosion Ef fect Caused by In d u st r i a l Wa st e w a t e r s ," p re s e n t e d a t Massachusett s Institut e of Te chno log y, Cambridge, MA, October 1991. 4 D. Apgar, J. Witherspoon, C. Easter, "Minimi- zation of Odors and Corrosion in Collection Sy st ems," Wat er Env ironm ent Re search Foundation Report, 04-CTS-1, 2007. 5 American Water Works Association, External Corrosion—Introduction to Chemistr y and Control (Denver, CO: AWWA, 1987). 6 E. Esfandi, "Proposal to Conduct Research for Control Sewer Corrosion," Los Angeles County Sanitation Districts, 1986. 7 J. James, "Control Sewer Crown Corrosion Using the Crown Spray Process," Under - ground Construction 59, 9 (2004). 8 S.W Guan, "Corrosion Protection by Coat- ings for Water and Wastewater Pipelines," presented at the Appalachian Underground Corrosion Short Course, Morgantown, WV, May 2001. FIGURE 3 Graphical variation of life expectancies. 9 C. Bowker, "Corrosion of an Asbestos Cement Sewer Rising Main due to Hydrogen Sulfide," 75th Annual Water Industry Engineers and Operators' Conference (Shepparton, VIC, Australia: WIOA, 2012). 10 B.I. Cayford, et al., "High-Throughput Ampli- con Sequencing Reveals Distinct Communi- ties within a Corroding Concrete Sewer System," Appl. and Environ. Microbiol. 78, 19 (2012). 11 C.N. Sawyer, P.L. McCarty, Chemistr y for Sanitary Engineers (New York, NY: McGraw- Hill, 1967). 12 W. Stumm, J.J. Morgan, Aquatic Chemistry, 5th ed. (New York, NY: Wiley-Interscience, 1996). 13 H.W. King, E.F. Brater, Handbook of Hydrau- lics, 5th ed. (New York, NY: McGraw-Hill, 1963). CHOONGHEE RHEE is chief operating officer and president of Standard Testing and Engineering, Inc., 18737 S. Reyes Ave., Rancho Dominguez, CA 90221, e-mail: maurisonconsult@gmail.com. He works in the area of protecting under- ground sewer pipelines from corrosion. He has a Ph.D. and is a Professional Engineer (civil). NACE International offers covering every aspect of corrosion control in all industries. For more NACE Store at nace.org. Deactivating Bacteria to Prevent Sewer Corrosion and Collapse

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