Ratio and Proportion A ratio is the relationship between two numbers. A ratio can be written using a colon such as: 1:2, 5:9, 20:60 or as a fraction 1/2, 5/9 or 20/60 A proportion exists when the relationship between one ratio is the same as the relationship between the second ratio. To determine if the…
1. What determines the amount of hydrogen sulfide produced in a sewer? a. BOD concentration b. D.O. concentration c. pH d. SS concentration 2. Four conditions are necessary to create an explosion. Three of these conditions are: combustible gas, adequate oxygen and sufficient heat. The fourth is _. a. constant supply of combustible gas b….
Questions: 1. Bar racks and bar screens have clear spacing respectively of _. a. 0.25 to 2.0 inches and 2.0 and 4.0 inches b. 0.2 to 1.0 inch and 1.0 to 2.0 inches c. 2.0 to 4.0 inches and 0.25 to 2.0 inches d. 1.0 to 2.0 inches and 0.2 to 1.0 inches 2. The…
Disinfection – A process used to destroy most pathogens in the effluent to a safe level. Disinfection does not destroy all microorganisms. Biosolids – The nutrient-rich, organic byproduct of a municipal wastewater treatment plant that is utilized as fertilizer. Process Control – The tools and methods used to optimize treatment plant operations. Return Activated Sludge…
Because of the time delay involved in generating the data used to determine the F:M ratio, it is not used to control the secondary treatment process. The mean cell residence time (MCRT) approach to balancing the solids in the activated sludge treatment system offers a simple and effective way to operate the activated sludge process…
Because the failure of a lift station could result in damage to homes, property and the environment all lift stations should be equipped with some type of audible and visual alarm at a minimum. For large installations a computer will automatically contact operators in the event of a failure or the system will be monitored…
Lift stations generally employ centrifugal pumps, pneumatic ejectors or screw type pumps, (centrifugal pumps are the most common). The wet well can be constructed of pre-cast concrete rings (similar to manhole rings), poured in place concrete, fiberglass or metal. It should be designed to withstand characteristics common in the wastewater it will pump. The wet…
The settleometer test yields a great deal of information about how well sludge will settle and compact, but it does not reveal the MLSS concentration. It would seem obvious that if the MLSS concentration increases, the settling rate would slow down. (That is; thicker mixed liquor should settle more slowly). To some extent, this holds…
Preliminary Treatment – A treatment process consisting of screening and grit removal before the wastewater flows on to other treatment processes. Primary Treatment – A treatment process that usually consists of clarification by solid-liquid separation that removes a substantial amount of suspended and floating matter. Secondary Treatment – A treatment process that uses biological processes…
Detention time is expressed in units of time. The most common are seconds, minutes, hours and days. The simplest way to calculate detention time is to divide the volume of the container by the flow rate into the container. The theoretical detention time of a container is the same as the amount of time it…
