Wastewater Flashcards
Why is mechanical ventilation required in a lift station?
Waste water can create toxic gas, the ventilation protects workers
inflow that rapidly increases shortly after teh start of a storm and decreases quickly after the conlcusion of the storm is called
Direct inflow -
what are the characteristics of Delayed inflow?
Decreasing gradually after the conclusion of a storm and after the peak inflow
Describe peak inflow
ITs the largest rate difference in an hour between the storm event flow and the dry weather flow
What is estimated inflow?
the calculated approximation of the inflow
What type of settling behavior is the non-interactive settling of particles from a dilute suspension that typically occurs during grit and sand removal?
Discrete settling
What does TKN stand for and what are the components of it?
Total Kjeldahl Nitrogen,
Organic nitrogen and Inorganic ammonia and ammonium
Describe Biogas
It is the product of anaerobic digestion
What is biogas composed of?
Methane
Hydrogen Sulfide
Carbon Dioxide
trace amounts of Nitrogen, oxygen and volatile hydrocarbons
What are the four stages of anaerobic digestion
Hydrolysis, acidogenesis, acetogenesis and methanogenesis
3 things to consider when designing a system for disinfecting a waste water treatment
The quality of the inflow water that is disinfected
the potential byproducts of disinfection
The effectiveness of the disinfection process for eliminating pathogens
what is the chemical formula for Ozone?
O3
how is oxygen formed into Ozone for treatment?
Oxygen is passed through a high voltage potential to form O3
Clear water in a sewer collection system is likely causes by what?
infiltration from a high-water table
What is Dry weather flow?
is the flow of wastewater in a sanitary sewer system when there are periods of dry weather that have minimum inflow and infiltration
When does Aeration take place?
in secondary treatement
What do Grit removal, shredding and screening all have in common
They are all part of the preliminary treatement of wastewater
Name three things that affect the efficiency of a primary sedimentation
The shape of the tank
The type of waste water entering
the tank capacity
name three advantages of the trickling filter
cheap method of oxygen delivery
Construction costs are low
the system can be made non-electric
Why does temperate matter for a trickling filter?
the media is exposed to the elements, extreme hot and cold weather can make the treatment less effective
what causes nitrification happen? and name three things that affect the rate of nitrification
it occurs because of microbes, which are sensative to temperature and the oxygen levels ( too low it will be seriously affected) lastly pH - which needs to be 8-9
Define Eutrophication
the process of enriching an ecosystem with natural or chemical nutrients that results in the dense growth of algae and other organisms
What chemical/ nutrient goes hand and hand with Eutrophication
Phosphates
What are the most common chemicals that remove phosphorus?
Metal salts
Aluminum Sulfate
Ferrous sulfate
Ferrous chloride
Name 3 treatment technologies to remove phosphorus and briefly describe each
Physical - Some phosphorus can be removed from the physical filtration of particulate matter or by using different types of membranes
Chemical - different types of metal salts can be added to the influent to precipitate phosphorus
Biological - this occurs when biological systems consume phosphorus
Which type of sludge is most commonly thickened by a centrifugal thickener, and why?
Secondary Sludge,
secondary sludge has a lack of bulkly, stringy materials that can potentially cause clogging unlike Primary Sludge
Does incineration of disposed sludge kill pathogens?
yes
what is a drawback to sludge incineration?
the cost of heating up sludge is high because sludge typically has a high heat capacity
Name 4 components required for composting
Carbon, oxygen, nitrogen and water
What component of composting is used by microbes for energy?
Carbon
What component of composting critical in the decomposition process to oxidize another component of the compost
Oxygen oxidizes carbon in this process
What component of composting helps the organisms multiply
Nitrogen
What component of composting helps the system form going anaerobic?
Water
what impact does Nitrogen have on drying bed performance?
NONE
Name 3 things that impact drying bed performance?
Climate/humidity
quality of the sludge
and depth of the sludge layers
Name 3 disadvantages of thermophilic aerobic digestion
high initial cost
Complex process to operate
Large free board requirement
describe thermophilic aerobic digestion
finsih this
what is the most common form of waste water disinfection in America and what is the main disadvantage
Chlorination, the byproducts can produce harmful carcinogenic compounds
how does effluent polishing affect filter management?
filters must be backwashed frequently, this is because you must ensure that suspended solids present do not cause the bed to develop anaerobic or septic conditions
is Aeration a type of disinfection?
No, it is used to remove dissolved gases like Carbon dioxide and oxidize dissolved metals
Is Nitrification an anaerobic process?
NO, it is an aerobic process
Describe Nitrification
The process of nitrification is the compound biological oxidation of ammonia to nitrite, then nitrite to nitrate. This process is lead by tiny groups of archaea and autotrophic bacteria (A biological process by which nitrate is converted to nitrogen gas)
Name two mechanisms used to remove fat and grease, and how it works
Skimmers and Air Blowers, Fat and grease are hydrophobic they float on the surface of clarifiers
Why cant grease collected from grit removers or settling tanks be re-used as industrial and commercial lubricants?
the possibility that it has been exposed to many pathogens, and making it potentially toxic is very high
is Ammonia an oxidized form of Nitrogen?
No
name three oxidized forms of nitrogen?
Nitrogen gas, Nitrate, Ammonium nitrate
Name 3 major sources of phosphorus in influent wastewater
Industrial waste, Detergents and cleaners
Describe a lagoon
Lagoons hold sludge and work via evaporation, there have no underdrain so it takes a long time to dry.
Why is thickened sludge the optimum feed to a digester?
It has a low amount of of heat required
It decreases the return hydraulic load
It decreases the potential impact of alkalinity changes
Does Biological nutrient removal, remove chlorine?
NO, chlorine serves to kill microorganisms
what type of filtration is needed to filter out Sugar and nitrogen?
Nanofiltration
the intensity of odors are affected by?
pH and temperature
For the sedimentation basins, Why are design overflow rates restricted?
To prevent up flow density current that would transport the solids over the weirs and out of the basin
What is the difference between Aerobic and Anaerobic digestion
what is Biogas and how is it produced in Wastewater
What is Coliform bacteria
What does Coliform bacteria usually indicate?
Name the 4 types of settling and what order they are (Region)
Define Compressive settling
What is Delayed inflow in wastewater system
What is direct inflow in wastewater system
What is Dissolved air flotation and how does it work?
what is Total kjeldahl Nitrogen (TKN)method
what is a Diurnal cycle
what is anaerobic bacteria
what is Escherichia Coliform
what is a neutal pH
7.1
the higher the pH the more_____ ?
Alkaline, alkalinity
The lower the pH the more_____?
Acidic, acidity
What is a Polyelectrolytes
Synthetic chemicals used as a coagulant aid.
what is the proper pH range for digested sludge?
6.8-7.2
what is an Aerobe? and who is its counterpoint?
define Aliquot
Portion of a sample. Often an equally divided portion of a sample.
defione Anoxic
Oxygen deficient or lacking sufficient oxygen
what is the difference between, alkaline, acid, and base
what is sludge Bulking?
Clouds of billowing sludge that occur throughout secondary clarifiers and sludge
thickeners when the sludge does not settle properly. In the activated sludge process bulking is
usually caused by filamentous bacteria or bound water.
what is a Comminutor
A device used to reduce the size of the solid chunks in wastewater by shredding
(comminuting). The shredding action is like many scissors cutting or chopping to shreds all the large influent solids material in the wastewater.
What is Detritus and whats another name for it?
The heavy, coarse mixture of grit and organic material carried by wastewater. (also
called grit)
What is Elutriation
The washing of digested sludge with fresh water, plant effluent or other wastewater.
The goal is to remove fine particles and/or the alkalinity in the sludge. This process reduces the
demand for conditioning chemicals and improves settling or filtering characteristics of the sludge.
What are Filamentous organism and what do they cause in waste water treatmenet?
Organisms that grow in a thread or filamentous form. Common types
are Thiothrix and Actinomycetes.
A common cause of sludge bulking in the activated sludge process.
what causes a septic condition, and what happens if it is severe?
A condition produced by anaerobic bacteria.
If severe, the wastewater produces hydrogensulfide, turns black, gives off foul odors, contains little or no dissolved oxygen, and creates a high
oxygen demand.
what is a Supernatant?
Liquid removed from settling sludge. Supernatant commonly refers to the liquid between the sludge on the bottom and the scum on the surface of an anaerobic digester.
The liquid is usually returned to the influent wet well or to the primary clarifier.
what is a Zoogleal Mass?
Jelly like masses of bacteria found in both the trickling filter and activated sludge
processes - (similar to biomass)
what is a helminths?
“high order” animals, their eggs present in sewage can cause illness
example: Fluke(trematoades), tape worm(cestodes), round worm (nematoads)
What is an Imhoff Cone
What is advection
What is disperson
What is conversion in WW, changing of Concentration refering to
three types of lake circulations and exmaple
- Holomictic Lakes - complete ciruclation over the whole water column
- Meromictic LAkes - Circulation does not occur at the whole water column
- Amictic Lakes - no circulation
