Vietnam possesses a coastline of over 3,200 km with many coastal urban areas, industrial zones, and tourist destinations rapidly developing. However, the rapid population growth and economic activities along the coast also bring about significant environmental pressure, particularly regarding coastal wastewater treatment. Seeking and applying appropriate treatment solutions not only contributes to the protection of marine resources but also ensures sustainable development for the coastal regions.
1. Challenges in Coastal Wastewater Treatment
Coastal wastewater typically includes domestic wastewater from residential areas, discharge from hotels and resorts, and especially from coastal industrial zones. According to the Ministry of Natural Resources and Environment, on average, about 70% of domestic wastewater in coastal urban areas is not treated to standard before being directly discharged into the environment. Additionally, coastal industrial zones—particularly seafood processing, shipbuilding, and chemical manufacturing—can discharge large volumes of wastewater, ranging from 2,000 to 5,000 m³/day depending on scale.
These wastewater sources contain high levels of organic compounds (BOD, COD), pathogenic microorganisms (Coliform, E.coli), heavy metals (lead, mercury, cadmium), and grease. According to the Institute of Marine Resources and Environment, the average COD concentration in wastewater in Vietnam's coastal areas can reach 250–400 mg/L, far exceeding the permitted limit under QCVN 14:2008/BTNMT (50 mg/L for Column A). If not thoroughly treated, these wastewater streams can flow directly into the sea, severely polluting the water environment, directly impacting marine ecosystems, fisheries, and the health of coastal communities.
Moreover, due to the low-lying terrain and frequent exposure to tides, waves, and sea winds, the design and operation of coastal wastewater treatment systems face many challenges. Specifically, the facilities must ensure corrosion resistance due to saline conditions, high durability against weather conditions, and careful consideration of fluctuating tidal levels, which can vary by 2–4 meters per day depending on the region.
*Coastal wastewater has more complex characteristics and is harder to treat than conventional wastewater.*
2. Coastal Wastewater Treatment Process
2.1 Collection Tank
All generated wastewater is directed through pipelines to the coastal wastewater treatment system. At the beginning of each pipeline, a bar screen or trash rack is installed to remove large-sized debris such as plastic bags, scrap paper, tree branches, spoiled vegetables, etc.
2.2 Grease Trap Tank
This tank plays the role of removing grease and oil present in the wastewater. Grease tends to adhere to pipes, pumps, and treatment equipment, which may lead to technical issues if not promptly removed. Due to its lighter density, grease floats on the surface and can be easily removed using a surface skimmer.
2.3 Equalization Tank
This is a key tank in coastal wastewater treatment, stabilizing the flow rate and pollutant concentration before moving to the next treatment steps. The tank is usually equipped with aeration devices at both ends to limit anaerobic conditions and prevent odor generation. Wastewater is typically retained in the tank for about 30–60 minutes before being pumped to the Anoxic tank via an automatic pump system.
**2.4 Anoxic Tank**
The Anoxic tank is where treatment occurs through anaerobic microorganisms such as *Nitrosomonas* and *Nitrobacter*. Here, denitrification and phosphate removal reactions take place, effectively reducing nitrogen and phosphorus compounds in the wastewater.
**2.5 Aerotank**
This is an aerobic biological tank where aerobic microorganisms break down organic matter. This process converts pollutants into simpler compounds such as water, nitrate, sulfate, etc. The tank is equipped with an air blower system to provide the necessary oxygen for microbial growth.
**2.6 Settling Tank**
After the Aerotank, the wastewater flows into the settling tank to separate the sludge generated during biological treatment. The sludge settles to the bottom, while the clarified water is directed to the disinfection stage.
The settled sludge is handled in two ways: one part is returned to the Anoxic tank to maintain the microbial population, while the remaining is transferred to the sludge holding tank for periodic collection and treatment.
**2.7 Disinfection Tank**
Before being discharged into the marine environment, the water must be disinfected to eliminate bacteria and pathogens. This process usually involves chlorination with an appropriate dosage to ensure the effluent meets biosafety and environmental standards.
*The coastal wastewater treatment process maximizes the removal of impurities, grease, and heavy metals.*
**3. Benefits of Coastal Wastewater Treatment**
Investing in coastal wastewater treatment systems offers several practical benefits:
* **Protecting the marine environment:** Prevents pollution and maintains biodiversity and coastal ecosystems.
* **Enhancing tourism image:** Tourists increasingly consider environmental factors when choosing destinations.
* **Legal compliance:** Meets government environmental protection regulations and avoids administrative penalties.
* **Sustainable economic development:** Efficient treatment systems reduce the cost of pollution remediation and maintain aquaculture productivity.
Coastal wastewater treatment is an urgent task, closely tied to environmental protection and sustainable development for coastal communities. Making the right investment in technology and choosing a reliable partner is key to solving long-term environmental challenges and building a green – clean – beautiful image for Vietnam’s coastal regions.
**Dai Nam Environmental Solutions** is a leading and reputable company specializing in the design, construction, and operation of coastal wastewater treatment systems. With a team of experienced engineers and advanced technologies, we are committed to delivering optimal, cost-effective solutions that meet environmental standards and ensure long-term operational sustainability.
**Choosing Dai Nam means choosing professionalism, efficiency, and responsibility toward Vietnam's marine environment.**
