Adventure Tour of the tertiary treatment in Ngong Ping STW

Summary

Join Crystal and the micro submarines, DSD1 and DSD2, on an exciting virtual tour of Hong Kong's first tertiary sewage treatment plant in Ngong Ping. Discover how sewage is treated through multiple stages—from screening and grit removal to biological and chemical treatments. Learn how the plant's advanced processes minimize environmental harm, ensuring clean water that’s safe for reuse in toilets. This educational journey blends fun and facts, showcasing the importance of efficient sewage treatment for preserving Hong Kong's natural beauty and protecting its environment.

Takeaways

• 😀 The first tertiary sewage treatment plant in Hong Kong is located at Ngong Ping, Lantau Island.
• 😀 Ngong Ping is a famous tourist destination with major attractions such as the Giant Buddha and a cable car system.
• 😀 Sewage discharge has become a problem due to increased tourism, prompting the need for the sewage treatment plant.
• 😀 The sewage treatment process consists of four main stages: preliminary treatment, primary treatment, secondary treatment, and tertiary treatment.
• 😀 Mechanical screening is used in preliminary treatment to filter out large solid wastes from the sewage.
• 😀 The grit removal chamber isolates small sand particles from sewage through centrifugal force.
• 😀 A grease separator uses rising bubbles to remove grease from the sewage.
• 😀 The Sequential Batch Reactor (SBR) is the core unit for biological treatment, where microorganisms digest organic matter under anaerobic conditions.
• 😀 Sludge is separated in the SBR and treated further before being disposed of or sent for other processes.
• 😀 Tertiary treatment includes passing the sewage through a dual media filter tank to remove fine particles, followed by UV treatment to kill harmful microorganisms.
• 😀 After treatment, the effluent is chlorinated and used safely for flushing toilets, minimizing environmental harm.

Q & A

What is the primary purpose of the tertiary sewage treatment plant in Hong Kong?

The tertiary sewage treatment plant in Hong Kong was built to treat sewage collected in the Long Ping area, aiming to protect the water gathering ground near Long Ping and minimize environmental harm.

What are the main stages of sewage treatment in the plant?

Sewage treatment at the plant is divided into four main stages: preliminary treatment, primary treatment, secondary treatment, and tertiary treatment.

How does the preliminary treatment process work?

In the preliminary treatment, a mechanical screen filters out large solid wastes from the sewage. These materials are then removed by a mechanical arm.

What happens in the grit removal chamber during sewage treatment?

In the grit removal chamber, centrifugal force is used to separate small sand particles from larger ones, helping to eliminate grit from the sewage.

How does the grease separator function in the sewage treatment process?

The grease separator uses rising bubbles from the bottom of the sewage to carry away grease, separating it from the rest of the sewage.

What is the role of microorganisms in the sequential batch reactor (SBR)?

In the SBR, microorganisms grow and digest organic matters in the sewage under anaerobic conditions, helping to decompose ammonia and nitrates.

What is the significance of the sludge treatment process?

The sludge treatment process is essential for processing the solid waste that is separated from the sewage. It includes thickening, digestion, and dewatering to prepare the sludge for disposal.

What happens during the sludge digestion process?

In the sludge digestion tank, bacteria digest organic matters in the sludge over about 10 days under aerobic conditions, reducing the volume of sludge.

How is the effluent treated in the tertiary treatment stage?

In the tertiary treatment stage, the effluent passes through a dual media filter tank where fine filter materials remove very small particles, improving water clarity.

What is the purpose of the ultraviolet (UV) laser cannon in the treatment process?

The UV laser cannon is used to destroy invisible germs and microorganisms in the treated water, ensuring the water is free from harmful pathogens.

How is chlorine used in the final treatment stage?

In the chlorination chamber, chloride solution is added to the effluent to disinfect it, ensuring that the treated water can be safely used for non-potable purposes like flushing toilets.