Ultrafiltration at St Marys Water Recycling Plant
Summary
TLDRThe ultra filtration system at St. Mary's employs hollow membrane fibers with microscopic pores to filter out suspended solids, bacteria, and viruses from tertiary treated wastewater. The system, consisting of 48 membrane modules in 16 stacks, operates efficiently, producing 58 million liters of filtrate daily. It includes a cleaning mechanism with backwashing and chemical cycles to maintain optimal performance. The filtrate is then sent for further treatment, while used cleaning solutions are treated and recycled.
Takeaways
- 💧 The ultra filtration system at St. Mary's uses hollow membrane fibers to purify tertiary treated wastewater.
- 🌌 Each membrane fiber contains millions of microscopic pores, each about 0.02 microns in diameter, significantly smaller than a human hair at 75 microns.
- 🚰 The filtration process involves drawing water through the pores, leaving behind suspended solids, bacteria, viruses, and pathogens.
- 🔨 Membrane fibers are arranged in modules, each holding 30,000 fibers, and are secured by resin at both ends.
- 🔩 Modules are connected to a common header for filtrate collection, and are protected by plastic shrouds that facilitate upward water flow.
- 🏗️ Three membrane modules form a stack, with 16 stacks making up one cassette, for a total of 48 membrane modules per cassette.
- 🔄 The system is designed for high filtration efficiency, with 6 ultrafiltration cells in total.
- 🌡️ Treated wastewater from the feed water balance tank is first strained to remove larger solids before entering the ultrafiltration system.
- 🚰 The system produces 58 million liters of filtrate daily, which is then sent to a reverse osmosis system for further treatment.
- 🧼 Over time, fibers can become blocked, necessitating cleaning through backwashing and chemical cleaning cycles to maintain flow.
- 🔄 Backwashing is performed every 20 to 30 minutes in one cell at a time, while chemical cleaning occurs every 24 hours, also in a staggered manner.
- ♻️ Used cleaning solutions and removed contaminants are treated and returned to the wastewater treatment process.
Q & A
What is the purpose of the ultrafiltration system at St. Mary's?
-The ultrafiltration system at St. Mary's uses hollow membrane fibers to remove suspended solids, bacteria, and viruses from tertiary treated wastewater.
How small are the pores in the membrane fibers used in the ultrafiltration system?
-Each pore in the membrane fibers is about 0.02 microns in diameter.
How does the size of the membrane pores compare to the diameter of a human hair?
-The pores are approximately 0.02 microns in diameter, while a human hair is about 75 microns in diameter.
What is the function of the membrane fibers in the ultrafiltration system?
-The membrane fibers act as a physical barrier that allows only filtrate to pass through while leaving behind suspended solids, bacteria, viruses, and pathogens.
How are the membrane fibers arranged within the ultrafiltration system?
-The membrane fibers are arranged horizontally into modules, with each module containing 30,000 fibers held by resin at each end.
What role do the plastic shrouds play in the ultrafiltration modules?
-The plastic shrouds encase the sides of the modules, protect the fibers, and draw the feed water upward through the modules.
How many membrane modules are loaded into one cassette in the ultrafiltration system?
-Each cassette contains 48 membrane modules, arranged into 16 stacks of three modules each.
What happens to the filtrate after it passes through the ultrafiltration system?
-The filtrate is sent to the reverse osmosis system for further treatment.
How are the membrane fibers cleaned when they become blocked?
-The fibers are cleaned through cycles of backwashing and chemical cleaning. Backwashing pushes filtrate through the membrane pores to dislodge particles, while chemical cleaning removes any remaining material stuck to the membranes.
What is the frequency of the backwash and chemical cleaning cycles in the ultrafiltration system?
-Backwashing occurs every 20 to 30 minutes, while chemical cleaning cycles occur every 24 hours, each in one cell at a time.
Outlines
💧 Ultrafiltration Process Overview
The ultrafiltration system at St. Mary's utilizes hollow membrane fibers with microscopic pores (0.02 microns in diameter) to filter out suspended solids, bacteria, and viruses from tertiary treated wastewater. The system comprises modules with 30,000 fibers each, arranged horizontally and connected to a common header for filtrate collection. The modules are protected by plastic shrouds and organized into stacks and cassettes for efficient filtration. The process involves pumping feed water to maintain cell levels and uses strainers to remove larger solids before filtration. The system produces 58 million liters of filtrate daily, which is then sent for further treatment. Periodic cleaning through backwashing and chemical cleaning maintains membrane efficiency, with the used cleaning solutions being treated and recycled.
Mindmap
Keywords
💡Ultra Filtration System
💡Hollow Membrane Fibers
💡Micron
💡Filtrate
💡Feed Water
💡Module
💡Backwashing
💡Chemical Cleaning
💡Strainers
💡Cassette
💡Cryptosporidium and Giardia
Highlights
The ultra filtration system at St. Mary's uses hollow membrane fibers to remove suspended solids, bacteria, and viruses from tertiary treated wastewater.
Each membrane fiber has millions of microscopic pores, each about 0.02 microns in diameter, smaller than a human hair at 75 microns.
Pumps draw the filtered water or filtrate through the microscopic pores into the fibers, acting as a physical barrier to only allow filtrate to pass through.
Unwanted materials like suspended solids, bacteria, viruses, and pathogens like cryptosporidium and giardia are left behind.
The membranes are arranged horizontally into modules, each containing 30,000 membrane fibers held by resin at each end.
Each module connects to a single common module header where the filtrate is collected.
Two plastic shrouds encase the sides of the module to protect the fibers and draw the feed water upward through the modules.
Three membrane modules are loaded vertically to form a stack, each with its own filtrate collection pipe.
The design limits the number of individual connections in the system, increasing efficiency.
There are 16 stacks or 48 membrane modules loaded into one cassette, an assembly of membrane stacks.
Four cassettes are arranged in one cell, with six ultrafiltration cells in total.
Tertiary treated wastewater from the feed water balance tank is pumped to the ultrafiltration strainers.
Strainers remove solids such as weeds and plastics from the wastewater before it enters the ultrafiltration system.
Filtered water or filtrate is carried by stack collection pipes to a single manifold header on top of each cassette.
Feed water is continually pumped to maintain a constant level in the cells.
The St. Mary's ultrafiltration system produces 58 million liters of filtrate every day, sent to the reverse osmosis system for further treatment.
Fibers become blocked by retained particles over time, restricting water flow.
Fibers are cleaned through cycles of backwashing and chemical cleaning to remove stuck material.
Backwashing pushes some of the filtrate through the membrane pores to dislodge particles, occurring every 20-30 minutes in one cell at a time.
Chemical cleaning cycles remove any remaining material stuck to the membranes, occurring every 24 hours in one cell at a time.
Used cleaning solutions are treated and returned to the start of the wastewater treatment plant, along with removed materials and contaminants.
Transcripts
the ultra filtration system at st
mary's uses hollow membrane fibers to
remove suspended solids
bacteria and viruses from the tertiary
treated wastewater
each membrane fiber has millions of
microscopic pores
each pore is about 0.02 of a micron in
diameter
a human hair is about 75 microns in
diameter
these membrane fibers sit in cells
filled with tertiary treated wastewater
also called feed water pumps draw the
filtered water or filtrate through the
microscopic pores
into the fibers themselves the pores act
as a physical barrier
only filtrate can pass through the pores
unwanted materials
suspended solids bacteria viruses and
pathogens
like cryptosporidium and giardia are
left behind
the membranes are arranged horizontally
into modules
each module contains 30 000 membrane
fibers held by
resin at each end the membrane fibers
connect to a single common module header
this is where the filtrate is collected
two plastic shrouds encase the sides of
the module
the shrouds protect the fibers and draw
the feed water upward
through the modules
three membrane modules are loaded
vertically to form a stack
each stack has its own filtrate
collection pipe
this design limits the number of
individual connections in the system
there are 16 stacks or 48 membrane
modules
loaded into one cassette a cassette is
an assembly of membrane stacks
there are four cassettes arranged in one
cell
there are six ultrafiltration cells the
design
maximizes filtration efficiency tertiary
treated wastewater from the feed water
balance tank
is pumped to the ultrafiltration
strainers the ultra filtration strainers
remove solids such as weeds and plastics
from the waste water
before it enters the ultra filtration
system
stack collection pipes carry the
filtered water or
filtrate to a single manifold header on
the top of each cassette
feed water is continually pumped to
maintain a constant level in the cells
the saint mary's ultra filtration system
produces 58 million liters of filtrate
every day this filtrate is then sent to
the reverse osmosis system for further
treatment
after a period of operation the fibers
become blocked by the retained particles
this restricts the flow of water
the fibers are cleaned through cycles of
backwashing and chemical cleaning
back washing pushes some of the filtrate
through the manifold header
into the cassettes and through the
membrane pores to dislodge any stuck
material the backwash cycle removes
particles blocking the membrane fibers
the backwash cycle occurs every 20 to 30
minutes
in one cell at a time to allow the other
cells to continue working
in addition to backwashing chemical
cleaning cycles remove any material
still stuck to the membranes
each cell is drained and its membranes
are soaked in a cleaning solution for
several minutes
this solution is then drained and
flushed from the cell
before the regular ultrafiltration cycle
begins again
chemical cycles occur every 24 hours in
one cell at a time
the used cleaning solutions are treated
and returned to the start of the
wastewater treatment plant
along with the removed materials and
contaminants
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