AEROBIC (or OXIC):  a condition in which the Aquatic (water) environment contains dissolved molecular oxygen
ANOXIC: a condition in which the Aquatic environment does not contain dissolved molecular oxygen, which is called an oxygen-deficient condition
Generally refers to environments in which chemically bound oxygen, such as nitrate, she was present
 Anaerobic:
 it's addition with the Aquatic environment does not contain dissolved molecular oxygen or chemically bound oxygen. stabilisation of waste under anaerobic conditions can be compressed through three stages:
Hydrolysis,Acid formation, and methane production.
two other
Terms
SELECTOR:  is a reactor or Basin in which baffles or other devices create a series of compartments
 the environment
 within each compartment can be controlled
 the environmental conditions
( food, lack of dissolved oxygen)
 intended to favor the growth of certain organisms over others. the conditions there by select certain organisms
MCRT:  mean cell residence time
 average time that are microorganisms in the activated sludge process
 to calculate the MCRT
 mass of suspended solids
 contained in a process is divided by the mass of solid removed from the process per day
Solids removed
 include both the SS mass removed as waste activated sludge and the SS discharge from the plant with effluent
MCRT is used interchangeably with solids retention time (SRT), which is a measure of sludge age
 types of microorganisms
 for general pipe
 Autotrophs
 which used in organic carbon materials as their food store
Heterotrophs
 can use organic carbon materials as their food source
 both types
 Can be obligate aerobes^11
 autotrophic: describes an organism ( plants and some bacteria) that use inorganic materials for energy and growth
 Heterotrophic: describes organisms that use organic matter for energy and grow. animals, fungi, and most bacteria are heterotrophs
Obligate Aerobes: Bacteria that must have atmospheric or dissolved molecular oxygen to live and produce
 two general layout
for biological phosphorus removal
Mainstream,
Use of an anaerobic selector at the who's winning of the processing sequence
 Second process
Use of a sidestream and anaerobic stripper and a phosphorus extractor
Or a clarifier
Luxury uptake of phosphorus
Luxury Uptake
Is a modification of the basic activated sludge treatment process
Routinely re whatmove some phosphorus
In their own life processes
 Higher
 Removals
 I can
Setting up conditions that will cause the microorganisms to pick up and store in their cells
more phosphorus than they actually need
Takes place under aerobic condition
The phosphorus is stored as polyphosphate, that is, a polymer of phosphorus
Once
Maximum amount of phosphorus in the cells, they are transferred to anaerobic environments
 Microorganism
Convert some of the carbon materials in their cells to get the oxygen they need for METABOLISM^15
Come from the polyphosphate stored in the organisms’ cells
phosphorus is released
After
The microorganisms are returned to the aeration tank where food, oxygen and phosphorus are plentiful
(The process is called “luxury” uptake for this very reason -- the organisms take up more phosphorus than they actually need)
In the Phostrip sidestream process, lime is added to the supernatant from the phosphorus stripping take to cause the phosphorus to precipitate out in a clarifier
Polymer: A long-chain molecule formed by the union of many monomers (molecules of a lower molecular weight). Polymers are used with other chemical coagulants to aid in binding small suspended particles to larger chemical flocs for their removal from water. Alse see POLYELECTROLYTE
Metabolism: All of the processes or chemical changes in an organism or a single cell by which food is built up (anabolism) into living protoplasm any by which protoplasm is broken down into simpler compounds with the exchange of energy
Basic Principles of the Luxury Uptake Process
Can only take place in a very controlled environment
Basic operation
Remove the activated sludge from the secondary clarifier and provide enough detention time in the anaerobic stripping tank
Strict anaerobic conditions must be maintained in the stripping tank at all times
Must regulate the detention time
To remove as much phosphorus as possible but not so long that the microorganisms die of starvation
The activated sludge
Must be quickly returned to the aeration tank
The sludge recycle
Is very important
Ensure that the sludge return is neither too not nor too slow
In the Phostrip process
Lime is added to coagulate with phosphorus
The luxury uptake and phosphorus stripping process only requires addition of lime to approximately ten percent of the entire plant flow stream. Once the phosphorus has been removed
The remaining liquid is combined with the secondary effluent from the plant for further treatment or final disposal
LIME FEED EQUIPMENT
Lime is usually added to the wastewater by a slaker,
The mixes dry powdered lime with water to obtain a slurry
MIXING BASIN
In the mixing basin, a high speed mixer called a “flash mixer” blends the lime slurry as rapidly as possible with the phosphorus release tank effluent. Following this instant mixing process called flocculation forms floc consisting of suspended and COLLOIDAL matter, including the phosphorus precipitate
After the lime phosphorus mixture settles to the bottom of the chemical clarifier, the sludge is withdrawn and pumped to a thickening process for dewatering and disposal
Colloids: Very small, finely divided particles (solids that do not dissolve) that remain dispersed in a liquid for a long time due to their small size and electrical charge. When most of the particles in water have a negative electrical charge, they tend to repel each other. This repulsion prevents the particles from clumping together, becoming heavier, and settling out.
Polymers are often used to help flocculate colloidal particles of lime and phosphorus to provide faster sedimentation in a chemical clarification unit
Monitoring daily operation
Need to carefully monitor the lime feed and mixing systems, the pH level in the chemical clarifier
Keep the pH above 11 to promote substantial floc formation and encourage rapid settling of the largest possible floc.
Dissolved oxygen probe into the anaerobic phosphate stripping tank
If dissolved oxygen is detected, it may be a sign that sludge is fed into the tank too fast or that sludge is being withdrawn too quickly from the stripping unit
Detention time in the anaerobic phosphorus stripping tank must be carefully controlled
The detention time can be calculated using the following formula:
*Add the formula yourself, the notes say you’ll do that*
Sludge from the phosphorus stripping tank is returned to the aeration tank
Be sure adequate dissolved oxygen is present (2 to 4 mg.L DO)
Loading Guidelines
Hydraulic Loading Rate for Chemical Clarifier
Typical loading rate
800 gallons per day per square foot
To 1,500 gallons per day per square foot
To calculate the hydraulic loading rate (also called the overflow rate)
To calculate the hydraulic loading rate, divide the average gallons per day (cubic meters per day) of flow to the clarifier by the square feet (square meters) of surface area:
*Once again, the equations here are marked for whoever is using this to add in*
Calculating Process efficiency
Comparing the phosphorus levels in the primary effluent
With the phosphorus level in the effluent from the chemical clarification tank
Process treatment efficiency % = Phos Conc In, mg/L - Phos Conc, Out, mg/L over Phos Conc In, mg/L *100%
Clarifier removal efficiencies are determined by collecting and analyzing clarifier influent and effluent samples. Turbidity is a measure of the clarity of the effluent; therefore, the turbidity removal efficiency measures the effectiveness or performance of the process
*Online add lime facilities (handling sample? safety)*
Phosphorus Removal
Lime precipitation
Three general physical or chemical reactions
Coagulation. When chemicals are added to wastewater, the result may be a reduction in the electrostatic charges that tend to keep suspended particles apart. After chemical addition, the electrical charge on the particles is altered so that the suspended particles containing phosphorus tend to come together rather than remain apart
Flocculation.
Flocculation occurs after coagulation and consists of the collection or AGGLOMERATION of the suspended material into larger particles. Gravity causes these larger particles to settle
Sedimentation
The settling of heavy suspended solid material in the wastewater due to gravity. The suspended solids that settle to the bottom of the clarifiers can then be removed by pumping and other collection of mechanisms
5.31 equipment
Lime feed equipment. Lime usually comes in a dry form (calcium oxide (CaO)) and must be mixed with water to form a slurry in order to be fed to a wastewater treatment process the required results
Calcium Oxide + Water > Calcium Hydroxide
CaO + H20 > Ca(OH)2
Mixing Chamber
A basin
Lime slurry is blended with the wastewater as rapidly as possible
High speed mixer called a “flash mixer”
A slower mixing process called flocculation follows
Floc consists of suspended and colloidal matter, including the phosphorus precipitate
Clarification Process
Is used to allow the floc to settle out
velocity
Must be slowed down
To allow for sedimentation
Pumps and Piping
After the lime phosphorus mixture
Settled to the bottom of the chemical clarifier
Transport the sludge to a thickening process for further dewatering and disposal
Agglomeration: The growing or coming together of small scattered particles into larger flocs or particles, which settle rapidly, also see FLOC
Operation Procedure
Flow rate into chemical clarifier
Check the design specifications
The clarifier operates best at or below the overflow rate that was designed into the facility
Lime feed for pH control
pH adjustment for phosphorus removal means raising the pH
11 or higher
So that phosphorus and calcium hydroxide bond together
75 percent of phosphorus reduction usually occurs before a pH of 10
Clarification and settling process
The hydraulic loading rates must be adjusted to prevent short circuiting or hydraulic washout of the floc prior to its complete settling to the bottom of the clarifier
Pumped and disposal of lime precipitate
Adjust pumping rates so that all of the lime sludge is removed
Two methods are commonly used to dispose of lime phosphorus sludge
First method, a centrifuge is used to remove the phosphorus from the lime mud. The remaining lime sludge can be further processed to recover the lime.
Second method
phosphorus  lime sludge is simply pumped to an appropriate disposal site
Calcium carbonate can make up about ¾ of the mass of the sludge
Daily maintenance
To prevent lime scale plugging
Lime (calcium hydroxide) and carbon dioxide form what is known as limestone or calcium carbonate
Calcium carbonate causes
Scale
Hot water or steam is very effective in dislodging limestone buildup with pipes or pumps
The purpose of lime precipitation and phosphorus is to reduce the phosphorus level in the effluent
And thereby remove a nutrient source for algae in the receiving waters
Calcium oxide content of lime feed
A calcium oxide content of at least 90 percent available calcium oxide is needed
To bring the pH of the secondary treated water up to atleast 11
Flocculation Efficiency
Efficiently operated chemical clarification unit will allow for proper settling of as large and as heavy a floc as possible JAR TESTS can be used to determine what pH levels form the largest floc possible
polyelectrolytes have been used with lime precipitation for phosphorus removal and are added after the fast mix reaction
Recarbonation for pH control and calcium carbonate recapture
Effluent from a high pH chemical clarifier used for phosphorus reduction will usually have a pH of atleast 11. Use of carbon dioxide is the most common method of neutralizing the pH (bringing the pH of the water down to almost 7) A byproduct of the lowered pH is the formation of settleable calcium carbonate
Accomplished by either using a single or a two stage recarbonation and settling process
Single stage
Carbon dioxide gas is bubbled into the effluent stream from a chemical clarifier to allow calcium carbonate to form. As a by-product of the calcium carbonate formation, pH is reduced
Calcium carbonate precipitate formed is captured on filters
Two stage recarbonation and settling process, shown in figure 5.7, is a more effective method to reduce wastewater pH and recapture calcium carbonate. Carbon dioxide gas is bubbled into a basin after the chemical clarification process
Calcium carbonate precipitate formed is allowed to settle
And pumped to dewatering
Or hauled to a landfill
Carbon dioxide gas is again bubbled into the wastewater stream to further reduce the pH
pH is reduced to around 8 to 8.5 in first stage recarbonation and further reduced to 7.0 in second stage recarbonation