Question

3. The Vitebsk, Belarus POTW on the Daugava River is experiencing excessive wear and failure of sludge pumps as well as loss of anaerobic digester capacity due to large accumulations of grit. The POTW has decided that it must remove 100% of the incoming grit with sand equivalent size of 0.105 mm or larger at the design maximum flow of 4.8 m'/s. The facility has a peaking factor of 2.1. No grit removal facility currently exists. The POTW wants the new grit facility to consist of two equal sized aerated grit removal tanks. Please provide the following calculations: a. The critical particle settling velocity using MWRD TM Appendix A Equation 5 wherce Ve . [0.707 x (Ss-1) x d», μ4s?", assume viscosity-1.003 x 106 m'/s b. Surfaceareanecessariocapture 100%ofthecriticalparticle based on a. Tank volumes and hydraulic retention time, based on preliminary selection of 4 m depth, c. d. Recommended tank length and width based on typical aerated grit chamber design Briefly discuss any factors you can think of that may affect the sizing of the tank in final (detailed) design e.

Answer 1