CIV342H1 Lecture Notes - Lecture 8: Energy Recovery, Aeration, Nitrification
Document Summary
Extra alkalinity needed depending on type of wastewater. Stabilization ponds: good for small rural communities less than 50000. Used for stabilization of domestic wastewater by natural biological processes. Five types: 1. aerobic 2. facultative 3. Aerobic ponds: detention time 4-6 days (high rate), 10-40 days (low rate) Shallow (0. 15-0. 4 m: allows light penetration to the bottom) - o2 provided by photosynthesis from algae and from air. Soluble bod5 conversion efficiency up to 95% but pond effluent may exert a higher bod5 than original wastewater due to algae and bacteria (consume oxygen) Algae is often removed prior to discharge (coagulation, flocculation, sedimentation) Pond must be sized to store wastewater through winter (cannot discharge. Facultative ponds: detention time 5-30 days, 0. 75-2 m deep. Can handle large fluctuations in flow and strength, low capital and operating costs. Aerobic (aerobic bacteria and algae) near surface. Anaerobic (accumulate solids decomposed by anaerobic bacteria) at bottom facultative (partly aerobic, partly anaerobic) in between.
