During the Tết holiday period, production activities at many factories and industrial facilities are typically suspended for 7–10 days. This leads to sharp variations in influent flow rates and substantial changes in wastewater composition, particularly a significant reduction in flow, along with fluctuations in organic matter concentration, oil and grease, and other key pollution parameters.
Such variations pose considerable challenges for the operation of wastewater treatment systems, especially biological treatment systems. Without appropriate operational strategies during the shutdown period, systems may become unstable, increasing the risk that effluent quality fails to meet discharge standards when production resumes after the holiday.
From a technical perspective, when influent wastewater is significantly reduced or nearly absent, microorganisms in biological treatment tanks lack sufficient substrate to maintain metabolic activity. If the system remains idle for an extended period, microbial populations may decline severely or even die off, resulting in prolonged and difficult system restart after the Tết holiday, potentially taking weeks or even months.
Related article: How to ensure effluent meets discharge standards when influent wastewater fluctuates continuously
Meanwhile, under the National Technical Regulations on Industrial Wastewater (QCVN), treated wastewater must still fully comply with permissible discharge limits before being released into the environment. This means enterprises must not only restart the system after the holiday, but also ensure stable performance and treatment efficiency from the very beginning of post-holiday operations.
Related regulation: QCVN 40:2025/BTNMT – National Technical Regulation on Industrial Wastewater
Operational Measures to Maintain System Stability During Tết
To minimize risks and maintain microbial activity during the Tết holiday, enterprises may consider implementing the following measures:
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Supplementing carbon sources (e.g. molasses, methanol), nitrogen, and phosphorus
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Maintaining aeration and submerged mixing
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Operating the system under a controlled low-load mode
These measures help prevent severe microbial deterioration and ensure the system is ready to receive wastewater immediately when production resumes.
Pre-Holiday Checklist for Wastewater Treatment System Operators
Based on practical operational experience, to reduce the risk of system instability during and after the Tết holiday, wastewater treatment system operators should proactively review and prepare the following tasks:
Equipment Inspection
Check the operating capacity of machinery and equipment
(Source: Images from Nanoen's actual projects)
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Capacity check of mechanical equipment
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Maintenance of blowers and pumps:
Prior to the holiday, inspect lubricant oil levels, belt tension, and clean air filters of blowers. Ensure wastewater pumps are free from debris clogging the impellers. -
Sensor cleaning:
pH and DO probes should be cleaned to remove biofilm buildup and prevent false readings that may cause incorrect operation of automatic control systems. -
Electrical safety:
Tighten electrical connections inside control panels to prevent short circuits caused by humidity or insect intrusion during the holiday period.
Biological System Assessment
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For systems that must be completely shut down: A thorough, detailed, and professional technical assessment of system conditions is required.
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For systems maintained in operation to preserve biomass (aeration, submerged mixing): Check sludge concentration in biological tanks and gradually increase influent flow on a daily basis, allowing microorganisms to adapt while rebuilding biomass density.
Chemical Dosing System Inspection
Check the chemical system
(Source: Images from Nanoen's actual projects)
Some chemicals may cause pipeline clogging after prolonged stagnation (e.g. coagulants, sodium hydroxide (NaOH), lime). Therefore:
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Flush chemical pipelines with clean water before restarting the dosing system
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Inspect dosing pump flow rates and operational performance
Post-Holiday System Restart Planning
Enterprises should establish a post-Tết system restart plan, including:
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A projected load ramp-up schedule
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Monitoring and control of influent and effluent parameters
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Contingency measures for handling potential operational incidents during the early restart phase
Related article: Common issues encountered during wastewater treatment system operation
Conclusion
In practice, the Tết holiday period is a high-risk phase for operational incidents if wastewater treatment systems are not properly monitored and prepared. Accurately assessing load fluctuations, influent wastewater characteristics, and system response capacity is critical to ensuring effluent compliance after the holiday.
With extensive experience in consulting and operating wastewater treatment systems across various industrial sectors, Nanoen focuses on supporting enterprises through technical reviews, operational risk assessments, and tailored maintenance and operation solutions that comply with current environmental regulations—particularly during sensitive periods such as before and after the Tết holiday.
Contact Nanoen for professional consultation on wastewater treatment system operation solutions tailored to your specific wastewater characteristics.
Professional and Reliable Environmental Consulting Services in the Mekong Delta
Nano Environment Technology – Construction Limited Liability Company (Nanoen) is a trusted and professional provider of environmental consulting and environmental services in the Mekong Delta region. Throughout our years of operation, Nanoen has earned the confidence of clients through our integrity, dedication, and strong sense of responsibility toward customers as well as the quality of our products and services.
With a team of highly experienced professionals, we offer comprehensive environmental solutions, ranging from environmental documentation consulting to design, construction, and operation of environmental treatment systems. Our services also include wastewater treatment system operation training, environmental system operation support, and the supply of biological treatment products.
We are committed to delivering optimal and practical solutions that fully meet the diverse needs of enterprises, while ensuring compliance with current environmental regulations.
Contact Nanoen today for FREE consultation
Hotline: 0941.777.519 - 0907.803.678 - 0901.229.798
Nanoen
NANO ENVIRONMENT TECHNOLOGY - CONSTRUCTION LIMITED LIABILITY COMPANY
Address: 661E/29 Vo Van Kiet, Long Tuyen Ward, Can Tho City
Hotline: 0941.777.519 - 0907.803.678 - 0901.229.798
Email: nanoentech@gmail.com
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