Urban Wastewater Treatment – Detailed Treatment Process

1. Pollutants in Urban Wastewater

• Organic matter: From food waste and household waste, biodegradable but can cause significant pollution if not treated.
• Nutrients: Nitrogen and phosphorus from fertilizers and household waste, leading to water eutrophication.
• Suspended solids: Sand, dirt, and waste, causing water turbidity and clogging pipes.
• Pathogenic microorganisms: Bacteria, viruses, and parasites from household waste, posing risks for gastrointestinal and skin diseases.
• Hazardous chemicals: Pesticides, herbicides, industrial chemicals, and heavy metals, negatively impacting human health and wildlife.

2. Consequences of Improper Urban Wastewater Treatment

• Water pollution: Untreated wastewater discharged directly into rivers and lakes contaminates the water, affecting drinking water sources and aquatic ecosystems.
• Disease outbreaks: Bacteria in wastewater accumulate, increasing the risk of waterborne diseases like diarrhea, cholera, or skin infections.
• Unpleasant odors: Organic waste decomposition produces toxic gases like H2S, polluting the air and affecting residents' quality of life.
• Ecosystem destruction: Chemicals and heavy metals in wastewater kill plants and animals, disrupting the natural balance.
• Increased future treatment costs: To address severe pollution, authorities and residents will need to invest more resources to clean the environment.
• Economic and social impacts: A deteriorating living environment decreases property values, tourism, and public health.

3. Detailed Urban Wastewater Treatment Process

3.1 Collection and Trash Separation Tank

• Wastewater is filtered through a coarse mesh (5-10mm, SUS304) to remove large debris (10-20mm).
• Prevents blockages in pumps and pipes.
• Regular manual trash collection and disposal as per regulations.
• Wastewater is pumped to the grease separator tank.

3.2 Grease Separator Tank

• Wastewater is filtered through a fine mesh (3-5mm, SUS304) to remove small debris.
• Protects pumps and systems from clogging.
• Manual trash collection and proper disposal.
• Gravity-based oil separation (3 compartments), with floating oils being removed. Water then flows to the balancing tank.
• Meets QCVN 14:2008/BTNMT, Column A standards.

3.3 Balancing Tank

• Stabilizes flow rate and pollutant concentration with a long retention time.
• Stores wastewater during peak times for even distribution.
• Controls high-pollution wastewater flow to prevent overloads.
• Stores wastewater during system maintenance.
• Prepares solid waste for further treatment.

3.4 Anoxic Tank

• Nitrate and nitrite reduction, releasing N₂ gas.
• Combines wastewater with high nitrate from the biological tank and sludge from the settling tank.
• Adds alkaline chemicals and nutrients to adjust pH and support microbial growth.
• Submersible mixers enhance treatment efficiency.
• Water flows naturally to the aerobic MBBR tank.

3.5 MBBR Tank

• Biological treatment using aerobic sludge on suspended media.
• Large media surface area maintains high biomass, saving space.
• Three-layer microbial membranes (anaerobic, anoxic, aerobic) effectively treat N, P, and BOD.
• Aeration and oxygen distribution discs help decompose pollutants.

3.6 Aerotank

• Reduces organic material using self-nourishing aerobic microorganisms.
• Nitrate formation produces NO₃⁻ for the Anoxic tank.
• Aerators provide oxygen, breaking down organic material into CO₂ and H₂O.
• Floating sludge is recycled to the Anoxic tank, and the NO₃⁻-rich water circulates to reduce nitrogen.

3.7 Biological Settling Tank

• Gravity-based separation of microbial sludge: clean water flows above, sludge settles below.
• Water flows through overflow weirs into the disinfection tank.
• Sludge is collected centrally, with part recirculated to the Anoxic tank, the rest sent to the sludge storage tank.

3.8 Disinfection Tank

• Sodium hypochlorite (Javen) is added to eliminate pathogens.
• The process involves Javen diffusing through cell walls and disrupting metabolic enzymes.
• Water meets the standards before flowing into the monitoring canal.

3.9 Monitoring Canal

• Assesses wastewater compliance with QCVN 14:2008/BTNMT, Column A standards.
• Automatic monitoring station (pH, COD, TSS, flow rate) transmits data to the Ministry of Natural Resources and Environment.
• Equipped with cameras and automatic sampling for continuous monitoring.
• Water meeting the standards is then connected to the general drainage system.

3.10 Sludge Treatment

• Prevents environmental pollution, odors, and adverse impacts on ecosystems and health.
• Efficient sludge management ensures the sustainability of the wastewater treatment system.
• The wastewater treatment process at Đại Nam applies advanced technology and modern equipment.

4. Advantages of Building a Wastewater Treatment System at Đại Nam

• Optimized design tailored to specific treatment needs: Each wastewater treatment system at Đại Nam is designed based on input water characteristics, treatment requirements, and the customer's scale of operation for maximum efficiency.
• Underground design: Wastewater treatment systems are implemented underground to save space. Developers can utilize the surface area for public amenities like parks, parking lots, sports facilities, or green spaces, enhancing urban aesthetics.
• Application of advanced technology for high treatment efficiency: Đại Nam continuously updates and applies modern technologies like MBBR, MBR, and AAO to completely eliminate pollutants and meet strict environmental standards.
• Cost savings on operation and long-term maintenance: The systems are designed to optimize energy consumption, chemical use, and workforce, reducing operational costs. Durable materials and high-quality equipment minimize repair costs.
• Compliant with legal environmental standards: Đại Nam's wastewater treatment plants always meet Vietnam's environmental standards (QCVN), helping customers avoid legal risks and protect the environment.
• Professional construction process: Đại Nam’s technical team follows strict procedures, using modern equipment, ensuring safety, and committing to timely project completion.
• Experienced engineers and dedicated consultation: Đại Nam offers both technical solutions and operational advice with their team of engineers, supporting clients throughout the usage period.
• Stable operation and easy control: Đại Nam’s systems are equipped with monitoring and measurement devices, ensuring continuous and accurate water quality control, minimizing operational failures.
• Post-installation support and system upgrades: Đại Nam guarantees ongoing support after system commissioning, providing regular maintenance services and upgrading technologies when needed to keep the system running efficiently.