sewage treatment plant onboard ship - biological sewage treatment plant in ship

Basic Marine Engineering Knowledge

11 Dec 202102:10

Summary

TLDRThis video explains the workings of a biological sewage treatment plant, consisting of four compartments. Raw sewage is first broken into smaller particles by a bar screen, then passes into the primary compartment. Overflow moves it to the aeration compartment, where bacteria break down the waste with the help of oxygen and nutrients. The liquid then flows to a settlement compartment for sludge separation. The sludge is recycled back, and the clear effluent undergoes disinfection with sodium hypochlorite before being pumped out. The process is automated using level floats for efficient operation.

Takeaways

🔍 The biological sewage treatment plant is composed of four interconnected compartments.
🔗 Raw sewage or effluent first passes through a bar screen that breaks it into smaller particles.
💧 The liquid then moves to the primary compartment, where it rises until it overflows into the aeration compartment.
🦠 The aeration compartment contains bacteria that require oxygen and nutrients to propagate, with the nutrient being solid waste material.
💨 Oxygen is supplied by bubbling compressed air through the broken-down waste, enabling aerobic activation.
📉 The liquid from the aeration compartment then passes to a settlement compartment, where activated sludge settles, leaving clear effluent.
♻️ The settled sludge is continuously recycled back to the aeration compartment to assist in the treatment process.
🧼 The clear effluent is then disinfected using a solution or tablets of sodium hypochlorite in the chlorination compartment.
📦 The discharge pump automatically lowers the level in the chlorination tank by pumping overboard.
⚙️ Automation is managed by high and low-level floats, with the discharge pump operating based on these levels.

Q & A

What is the primary purpose of the biological sewage treatment plant described in the script?
-The primary purpose of the biological sewage treatment plant is to treat raw sewage or effluent by breaking it down into smaller particles, aerating it to encourage bacterial breakdown, settling activated sludge, and disinfecting the clear effluent before discharging it.
What is the function of the bar screen in the treatment plant?
-The bar screen's function is to break up raw sewage or effluent into smaller particles as it passes through it.
What happens when the level in the primary compartment rises sufficiently?
-When the level in the primary compartment rises sufficiently, overflow of the liquid takes place into the aeration compartment.
Why is the aeration compartment important in the treatment process?
-The aeration compartment is important because it contains bacteria that require oxygen and nutrients to propagate. The solid waste material serves as the nutrient, and oxygen is supplied by bubbling compressed air through the broken waste, facilitating aerobic activation and breakdown of the sewage.
What is the role of the settlement compartment in the treatment plant?
-The settlement compartment's role is to allow the activated sludge to settle, leaving a clear effluent. The settled sludge is then continuously recycled back to the aeration compartment to assist in the treatment process.
How is the sludge managed in the settlement compartment?
-Since there is no oxygen in the settlement compartment, the sludge is continuously recycled to the aeration compartment, where it mixes with incoming waste to aid in the treatment process.
What process is used to disinfect the clear effluent before discharge?
-The clear effluent is disinfected by treating it with a solution or tablets of sodium hypochlorite in the chlorination compartment.
How is the level in the chlorination tank managed?
-The level in the chlorination tank is managed automatically by a discharge pump, which lowers the level by pumping the treated effluent overboard.
What role do high or low-level floats play in the automation of the discharge pump?
-High or low-level floats automate the discharge pump. The pump cuts in at high levels and cuts out at low levels, ensuring the chlorination tank maintains the correct effluent levels.
Why is it necessary to recycle the sludge back to the aeration compartment?
-Recycling the sludge back to the aeration compartment is necessary because it mixes with incoming waste, assisting in the biological treatment process by providing additional bacteria that help break down the sewage.

Outlines

00:00

💧 Introduction to Biological Sewage Treatment

The biological sewage treatment plant consists of four interconnected compartments. The process begins with raw sewage or effluent passing through a bar screen, which breaks it into smaller particles before it enters the primary compartment. Once the liquid level rises sufficiently in this compartment, it overflows into the aeration compartment, where bacteria requiring oxygen and nutrients break down the waste through aerobic activation.

🔄 Aeration and Settlement Process

In the aeration compartment, solid waste serves as nutrients for bacteria, while oxygen is supplied by bubbling compressed air through the broken waste. This process breaks down the sewage. The liquid then moves to the settlement compartment, where the activated sludge settles, leaving a clear effluent. The sludge is recycled back to the aeration compartment to assist in the ongoing treatment process, ensuring efficient waste breakdown.

🧼 Disinfection and Final Treatment

The clear effluent from the settlement compartment must be disinfected before discharge. This is achieved by treating it with a solution or tablets of sodium hypochlorite in the chlorination compartment. The discharge pump, controlled by high and low-level floats, automatically lowers the level in the chlorination tank by pumping the treated water overboard. This automated system ensures proper disinfection and safe disposal of the treated water.

Mindmap

Keywords

💡Biological sewage treatment plant

A biological sewage treatment plant is a facility that uses biological processes to treat sewage and effluent. In the video, it consists of four interconnected compartments that work together to break down waste and purify water. This concept is central to the video's theme as it explains the step-by-step process of sewage treatment.

💡Bar screen

A bar screen is a mechanical filter used to remove large objects from sewage before it enters the treatment process. In the video, the bar screen breaks up raw sewage into smaller particles, which is the initial step in the treatment process. This highlights the importance of pre-treatment in sewage management.

💡Primary compartment

The primary compartment is the first major section of the sewage treatment plant where the initial treatment occurs. As mentioned in the video, when the liquid level rises sufficiently, it overflows into the next compartment. This compartment sets the stage for the subsequent aeration and breakdown of waste.

💡Aeration compartment

The aeration compartment is where sewage is mixed with bacteria and oxygen to facilitate the breakdown of solid waste. The video describes this as the stage where compressed air is bubbled through the waste, promoting aerobic activation. This compartment is crucial for the biological treatment process.

💡Bacteria

Bacteria in the aeration compartment require oxygen and nutrients to propagate and break down sewage. The video emphasizes the role of bacteria in transforming solid waste into simpler compounds, which is essential for reducing pollution and making the water safer for discharge.

💡Aerobic activation

Aerobic activation refers to the process where bacteria break down organic matter in the presence of oxygen. In the video, this process occurs in the aeration compartment, where compressed air is supplied to sustain bacterial activity. This term is key to understanding how biological treatment plants function.

💡Settlement compartment

The settlement compartment is where the activated sludge settles, leaving a clear effluent. According to the video, this compartment separates the solid waste from the treated water. This step is vital for ensuring that the effluent is clear and ready for disinfection.

💡Activated sludge

Activated sludge is the result of the aeration process where bacteria have broken down the sewage. The video explains that this sludge settles in the settlement compartment and is recycled back to the aeration compartment to assist in further treatment. This recycling process is integral to the efficiency of sewage treatment.

💡Disinfection

Disinfection is the process of killing or removing harmful microorganisms from the treated water. In the video, this is achieved by treating the clear effluent with sodium hypochlorite in the chlorination compartment. This step ensures that the discharged water is safe and free from pathogens.

💡Chlorination compartment

The chlorination compartment is where the treated effluent is disinfected using sodium hypochlorite. The video details how this compartment ensures that the effluent is safe for discharge by eliminating harmful bacteria and viruses. This final treatment step is crucial for environmental and public health.

Highlights

The biological sewage treatment plant consists of four interconnected compartments.

Raw sewage or effluent passes through a bar screen which breaks it up into smaller particles.

The liquid overflows from the primary compartment to the aeration compartment when the level rises sufficiently.

The aeration compartment contains bacteria that require oxygen and nutrients to propagate.

Nutrients are provided by solid waste material, and oxygen is supplied by bubbling compressed air through the broken waste.

Sewage is broken down in the aeration compartment by aerobic activation.

The liquid from the aeration compartment passes to a settlement compartment where activated sludge settles.

The clear effluent is left after the sludge settles in the settlement compartment.

In the settlement compartment, there is no oxygen, so the sludge is continuously recycled to the aeration compartment.

The recycled sludge mixes with incoming waste to assist in the treatment process.

The clear effluent discharged from the settlement compartment must be disinfected.

Disinfection is achieved by treating the clear effluent with a solution or tablets of sodium hypochlorite in the chlorination compartment.

A discharge pump lowers the level in the chlorination tank automatically by pumping overboard.

Automation of the discharge pump is carried out by high or low-level floats.

The discharge pump cuts in at high levels and cuts out at low levels.