Ultrafiltration at St Marys Water Recycling Plant

SydneyWaterTV

28 Oct 201304:02

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

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💧 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

Ultra filtration is a membrane-based separation process that uses pressure to filter out suspended solids, bacteria, and viruses from water. In the context of the video, the ultra filtration system at St. Mary's is a critical component of the wastewater treatment process, using hollow membrane fibers to purify tertiary treated wastewater. The system's efficiency and ability to remove contaminants are central to the video's theme of advanced water purification.

💡Hollow Membrane Fibers

Hollow membrane fibers are the core components of the ultra filtration system, characterized by their microscopic pores that allow only certain particles to pass through. Each fiber in the video has millions of pores, each about 0.02 microns in diameter, which is significantly smaller than the 75 microns diameter of a human hair. These fibers are essential for the physical separation of unwanted materials from the water, illustrating the precision of the filtration process.

💡Micron

A micron is a unit of length equal to one-millionth of a meter, often used to describe the size of particles or pores in filtration systems. In the script, the micron is used to convey the minuscule scale of the pores in the membrane fibers, emphasizing the system's ability to filter out very fine contaminants from the water.

💡Filtrate

Filtrate refers to the water that has passed through the filtration process and is free of the contaminants that were removed. In the video, the filtrate is the purified water produced by the ultra filtration system, which is then sent to a reverse osmosis system for further treatment. The term is central to understanding the output of the filtration process.

💡Feed Water

Feed water, also known as the influent, is the wastewater that enters the filtration system for treatment. In the context of the video, feed water is the tertiary treated wastewater that is pumped into the ultra filtration cells, where it undergoes the purification process. The term is important for understanding the starting point of the filtration process.

💡Module

A module, in the context of the video, refers to a group of membrane fibers arranged in a specific configuration to facilitate the filtration process. Each module contains 30,000 membrane fibers and is a part of the larger ultra filtration system. The modules are a key structural component that contributes to the system's efficiency and capacity.

💡Backwashing

Backwashing is a cleaning process used to maintain the filtration system's effectiveness by removing accumulated particles from the membrane fibers. As described in the script, backwashing involves pushing some of the filtrate back through the membrane pores to dislodge any stuck material. This process is crucial for preventing blockages and maintaining the system's performance.

💡Chemical Cleaning

Chemical cleaning is another method of maintaining the ultra filtration system, where cleaning solutions are used to remove stubborn contaminants that may remain on the membranes after backwashing. The script mentions that each cell undergoes a chemical cleaning cycle every 24 hours, which is essential for ensuring the long-term effectiveness of the filtration system.

💡Strainers

Strainers are devices used to remove larger solids such as weeds and plastics from the wastewater before it enters the ultra filtration system. In the video, the ultra filtration strainers play a crucial role in pre-treating the feed water, ensuring that only smaller particles reach the membrane fibers for filtration.

💡Cassette

A cassette, as used in the video, is an assembly of membrane stacks that are part of the larger ultra filtration system. The cassettes are arranged in cells, with each cell containing multiple cassettes. The term is important for understanding the modular design of the system, which allows for efficient filtration and maintenance.

💡Cryptosporidium and Giardia

Cryptosporidium and Giardia are types of pathogens, or disease-causing microorganisms, that can be found in water. The script highlights that the ultra filtration system is effective at removing these pathogens, along with other contaminants, ensuring that the produced filtrate is safe for further treatment and use.

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.