Wastewater Operations Level 1 Review

What are the three parts of a wastewater system?

  1. Collections: force mains, lift stations, and pumps
  2. Treatment Facilities: The actual plant where the processing of waste takes place.
  3. Discharge or Disposal: the pumps and infrastructure required to dispose of the treated water.

What are the three types of wastewater collection systems? 

  1. Storm Sewer : Carrying water from storm drains, run offs, roof drains, and drainage systems.
  2. Sanitary Sewer : carrying sewage from households, businesses, and  industries.
  3. Combines Sewer : Carrying both sanitary sewage and storm water.

Ground Water that gets into a sewer system through cracks and bad joints is called :
Water that leaks out of a sewer through cracks and bad joints is called :
Unwanted Water that is piped into a sewer system from roof drains and pool drains is called :
The combination of  unwanted water getting into a sewer system through direct piping or bad joints and cracks is called :
I and I , Inflow and Infiltration
The minimum flow through a gravity sewer system, when flowing full,   in ft. / sec.  is :
 2 ft. / sec., 2 fps
How far apart are Manholes usually  spaced ?
300 to 500 feet
What are the four types of pollution found in wastewater?

  1. Organic : waste matter, vegetable scraps, fats oils grease, leaves.
  2. Inorganic : sand , grit , plastics.
  3. Thermal : cold water from chillers and hot water from boilers drains and steam plants.
  4. Radioactive : waste from medical facilities, x ray dyes.

Why treat wastewater?
Wastewater is treated to remove organic and inorganic wastes and to protect receiving waters from oxygen depletion and pathogenic organisms.
What is a Pathogenic organism ?
A disease causing organism.

  1. Cholera
  2. Typhoid
  3. Hepatitis
  4. Dysentery
  5. Cryptosporidium
  6. Giardia

The above are examples of :  

Pathogenic Organisms
Preliminary treatment includes :
Bar screens, racks and grit removal systems.
What is a Parshall flume ?
A device for measuring flow through an open channel.

Flow measurement should be done _________ to properly determine the quantity of waste being treated and adjustments can be made.
at the Influent of the plant
Primary treatment is also referred to as :
Trickling filters, RBC’s, and Aerated activated sludge are examples of : 
Secondary Treatment
Secondary treatment processes that require oxygen to operate properly are referred to as _______ processes.
Air is supplied to the Mixed liquor in the activated sludge process for Two reasons : 

  1. To supply oxygen to the microorganisms
  2. To bring the microorganisms into contact with the incoming food.

With the exception of the Complete Mix process, all Activated Sludge processes are _____flow designs.
With the exception of the Complete Mix process, all Activated Sludge processes are _Plug_flow designs. This means the flow runs from one end to the other as in a pipe. Complete mix systems in corporate flow and aeration to cause mixing through turbulance.

Name the Two way air is supplied in the activated sludge process.
1)      Air is supplied in two ways:a)      Mechanical aeration: using propellers or rotors to agitate the surface of the water to mix the air into the water.b)      Diffused air: The use of blowers (either centrifugal or positive displacement) to supply the air through a series of air pipes (Headers) and perforated devices called diffusers.
Name the three classifications of air diffusers.

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1)      Diffusers can be classified by their bubble size;a)      Fine bubble diffusers: Plate and tube or dome diffusers.b)      Medium bubble diffusers: Porous nylon or Dacron socks or saran fiber glass wrapped tubes.c)      Coarse bubble diffusers: are generally plastic tubes with holes in them or large bore duck bills. 
How many pounds of DO is required to convert one pound of CBOD into CO2 and Water.

It takes about 1.5 lbs. of DO to convert 1 lb. of CBOD to CO2 and Water. 
How many pounds (lbs.) of DO does it take to convert one pound (lb.) of ammonia to nitrate?
      It takes approximately 4-5 pounds of D.O. to convert one pound  of ammonia to  nitrate.
List Five test that can be used  as process control tests to control the activated sludge process.

  1.     MCRT= Mean Cell Residency Time, (SRT Sludge Retention Time), the average time a microorganism will spend in the activated sludge process, controlled by wasting.
  2.       F/M Ratio = Food to Microorganism ratio, measure the amount of food (CBOD) compared to the amount of microorganisms there is to consume it.
  3.       Sludge age (GSA Gould Sludge Age) = Measure of how old your sludge is. Controlled by wasting.
  4.       MLSS target mg/L = Keeping you MLSS mg/L at a specific range through wasting.
  5.       Settleometer ml/L= a measure of how well your sludge is settling. Controlled by D.

    O. and RAS and WAS flow control.

Which is considered more accurate the MCRT calculation or the Sludge age calculation?
      Of the two, Sludge age and MCRT, MCRT is considered the most accurate.
What is criteria is used to classify wastewater ponds?
    Ponds are classified by the type of treatment the water receives coming to the pond.

Ponds receiving raw waste are called ____________.
    Ponds receiving raw waste are called Stabilization ponds.
Ponds receiving water after primary treatment are called _____________.
     Ponds receiving water after primary treatment are called Oxidation ponds.

Ponds receiving water after secondary treatment are called ____________________.
   Ponds receiving water after secondary treatment are called Tertiary treatment ponds.
Wastewater Ponds can be categorized as one of these three types.
The three types of ponds are Aerobic, Anaerobic, and Facultative. 
What is an Aerobic pond?
   Aerobic Ponds = Having D.O.

distributed throughout the pond.     Air can be supplied by algae during the day or mechanical aeration.

What is an Anaerobic pond?
    Anaerobic = Having no D.O. or oxygen present other than in chemical form, such as NO2 nitrite or NO3 nitrate.


What is a Facultative pond?
      Facultative = Ponds that have a lower anaerobic zone and an upper aerobic zone.
How many pounds of oxygen can a pound of algae produce on a good summers day?
Define Disinfection?
     Disinfection is the process of killing or inactivating most microorganisms in water or wastewater.
What is the difference between Disinfection and Sterilization?
Disinfection targets pathogenic microorganisms, while Sterilization kills all microorganisms.

The three types of Disinfection commonly used in Wastewater Treatment are ?

  1.       Chlorination = the use of chlorine is the most widely used method of disinfection in water and wastewater.
  2.       UV ultraviolet light = the use of UV rays to damage the genetic material of microorganisms to make the unable to reproduce.
  3.       Ozonation = the use of O3 or Ozone, to disinfect water or wastewater.


The main objective of disinfection is :
1)     Prevent the spread of Pathogenic Microorganisms and disease to:a)      Public water suppliesb)      Receiving waters used for public recreation.c)       Water used for shell fisheries.
Chlorine comes in three forms, these are :
a)      Gas = 100 percent chlorine , a greenish yellow gas, highly toxic, it comes in 100 or 150 pound cylinders, one ton cylinders, and Rail Tankers to 90 tons.b)      Calcium Hypochlorite = Granular and tablet form 65 to 75 percent chlorine.

c)      Sodium Hypochlorite = Bleach, industrial strength varies by manufacturer, usually 10-12 percent chlorine.

How many parts per million of chlorine gas are detectable in the air?
    It is detectable at .08 ppm in the air.
Chlorine gas in dangerous for long term exposure at what part per million in air?
     It is dangerous for long term exposure a 5 ppm in air.
Chlorine gas is lethal at what part per million in the air?
    It is lethal at 1000 ppm in air.
When changing a chlorine gas cylinder always use ______ and never ______.
      When changing a gas cylinder for chlorine it is important to use proper safety equipment and to never work alone.
When you change a chlorine gas cylinder never reuse the _________.

When you change a chlorine gas cylinder never reuse the lead gasket. Always use a new gasket each time the valve yoke is loosened.
List the three classifications of chlorine repair kits and the type cylinder they are used for.
1)      Repair kits are available for chlorine cylinders:a)      “A” kit for 100 and 150 pound cylindersb)      “B” kit for one ton cylindersc)      “C” kit is for rail cars.
True or False, Chlorine cylinders contain only gas.

False, chlorine cylinders contain liquid chlorine as well as gas.
There are two valves on a one ton cylinder, they sholud be aligned ________ to the ground.
There are two valves on a one ton cylinder, they sholud be aligned perpendicular  to the ground. ^      top valvev bottom vlave-          ground
The top valve on a ton cylinder dispenses ____ while the valve on the bottom dipenses _____.
The top valve on a ton cylinder dispenses GAS while the valve on the bottom dipenses LIQUID.
Chlorine is a ________colored gas.
Chlorine is a  greenish yellow colored gas.
Chlorine is ____ times _____ than air.
Chlorine is 2.5 times heavier than air.

Chlorine liquid will expand into a gas at a rate of :
Chlorine liduid will expand at a rate of 460 to 1. This means that 1 cc of liquid will expand to 460 cc of gas.
Chlorine cylinders are equipped with fusible plugs to keep the cylinder from rupturing if exposed to  high heat.At what temperature will the plugs melt?
          All cylinders are equipped with fusible plugs that will melt at 158oF to 165oF  to     prevent the tank from rupturing.

What chemical vapor is used to check for chlorine leaks?
      To check for chlorine leaks ammonia is used, a small amount of ammonia vapor is squeezed near the valve and fittings, if a white cloud appears then there is a chlorine leak.
What are the two types of sludge digestion?
     Sludge digestion can take place either anaerobically or aerobically.
Anaerobic digesters can have either a ______ or _______ lid.
Anaerobic digesters can have either a fixed or floating lid.
The most important process control for anaerobic digestinon is ?
The pH is improtant for Methane Fermenter health, but by the time the pH has risen or dropped the process is already in upset.

Methane fermenters require a very specific pH range to operate properly.That range is ?
    Methane fermenters are very particular about their pH requirements the range they function best at is between       6.8 -7.2.
There are three types of bacteria that require specific temperature ranges to function.What are they and at what temperature ranges do they function?
1)      These bacteria  also need specific temperature ranges.a)  Psychrophilic bacteria = like cold temperature to 68oFb)  Mesophilic bacteria = like temperatures between 68oF and 112oF, But prefer 85oF to 100oF, with the best temperature at 95oF. Most Anaerobic digesters operate in this area.c) Thermophilic bacteria = like very high temperatures in the 120oF to 135oF range.        
The flame on the after burner of an anaerobic digester will burn what color if the process is working properly?
      The flame on the afterburner should be Blue to indicate good Methane production, Orange flame is indication of excess CO2.
What are the two main disadvatages of an anaerobic digestion system?
High energy and safety cost are the main disadvantages of anaerobic digestion.