Gravity Systems These sewers, known as conventional gravity sewers, are designed so that the slope and size of the pipe is adequate to maintain flow towards the discharge point without surcharging manholes or pressurizing the pipe. Sewers are commonly referred to according to the type of wastewater that each transports. For example, storm sewers carry…
Population Equivalent Estimates Population equivalents that are used to calculate hydraulic and organic loadings for domestic wastewater treatment if actual operating information is not available are as follows: BOD5 = 0.17 lbs./capita/day TSS = 0.20 lbs./capita/day Phosphorus = 0.0048 lbs/capita/day Flow = 100 gallons/capita/day Note – Capita is the same as Person Estimate the population…
CHANGES IN INFLUENT FLOWS AND CHARACTERISTICS Although it is typical for large municipal wastewater treatment plants to receive very stable hydraulic and organic loadings, other systems are faced with plant loadings that change on a day-to-day basis. Of all of the secondary treatment systems, activated sludge is particularly ill suited to deal with this problem….
Progressive Cavity Pumps Operation of a progressive cavity pump is similar to that of a precision incline screw pump. The progressive cavity pump consists of a screw-shaped rotor snugly enclosed in a non-moving stator or housing. The threads of the screwlike rotor make contact along the walls of the stator (usually made of synthetic rubber)….
Rounding Round down numbers with digits less than ‘5’ and round up numbers with digits ‘5’ or greater. Example: 7.3 would be rounded down to 7.0 or 7; but 7.7 would be rounded up to 8. You can round off the number to fewer digits following these rules for rounding off: * Determine how many…
1. What gas is associated with the formation of foam? a. carbon dioxide b. methane c. nitrogen d. hydrogen sulfide 2. The most commonly found scaling problem in an anaerobic digester is _. a. calcium carbonate b. magnesium ammonium phosphate c. sodium chloride d. calcium ammonium phosphate 3. Which of the following can cause foaming…
1. Construction defects that cause problems in wastewater collection systems include _. a. improper grade of sewers b. improper taps c. structure failure of manholes d. all the above 2. A venturi meter measures quantities of fluid by _. a. difference in pressure between a constricted and a full-sized portion b. electronic measurement c. velocity…
PROPELLER PUMPS There are two basic types of propeller pumps, axial-flow and mixed-flow impellers. The axial-flow propeller pump is one having a flow parallel to the axis of the impeller. The mixed-flow propeller pump is one having a flow that is both axial and radial to the impeller. VERTICAL WET WELL PUMPS A vertical wet…
Foaming Problems Operators of activated sludge systems may encounter a variety of foam and scum problems. Non-degradable detergents, grease, oil and other unknown substances can all create foam and scum. Most types of foams that are caused by detergents can be controlled by simply hosing them down regularly. Other foams can be extraordinarily persistent and…
Aerobic Bacteria Water, the home of most bacteria, contains oxygen in two forms. The first form, free oxygen, is the most readily available form. Free oxygen is basically the same as dissolved oxygen oxygen from the atmosphere that has become dissolved in water. Aerobic bacteria require free oxygen in order to survive. Bacteria may be…
