Environmental Engineering Reference
In-Depth Information
6.15 Several large clumps of black, odorous solids are floating on the
surface of the primary clarifier. The total solids concentration of
the underflow from the clarifier at the beginning of the 20-min-
ute pumping cycle is 10%. After 10 minutes of pumping, the sol-
ids concentration drops to 1.0%. What is happening, and what
should the operator do to correct the problem?
6.16 The effluent from a primary clarifier contains an excess amount
of suspended solids. The theoretical detention times based on
flow rates and clarifier volume are well within the design range for
the clarifier. A dye introduced into the clarifier influent appears
in the clarifier effluent in 12 minutes and is no longer seen in
the clarifier after 25 minutes. What is the most likely problem?
What are the possible causes and the appropriate solutions to
the problem?
6.17 The primary settling tank is 150 ft long, 90 ft wide, and 12 ft
deep. The average daily flow is 134 MGD. What is the hydraulic
detention time in hours?
