Wastewater Treatment Tank Enclosure

Comprehensive Report on the 800m² Membrane Cover Project for Wastewater Tank in Inner Mongolia

Abstract: This report provides a detailed elaboration on an 800-square-meter wastewater tank cover project in Inner Mongolia. The project utilizes advanced “membrane structure cover” technology, specifically the “wastewater tank anti-hanging membrane” design. Based on the details visible in the provided project images, this report will comprehensively analyze and introduce this typical industrial environmental protection project from multiple perspectives. These include the project background and challenges, the core technical solution (anti-hanging membrane structure), material science (Q235 steel structure and PVDF membrane material), project implementation and seasonal challenges, project effectiveness and comprehensive value, and future prospects. The aim is to showcase its technical sophistication and environmental and social benefits.

1. Project Background and Challenges: Industrial Environmental Protection Meets Harsh Conditions

This project is located in the Inner Mongolia Autonomous Region of China, an area known for its concentrated industrial activity and unique continental climate—characterized by long, cold winters with strong winds and snow, and intense sunshine and sandstorms in summer. In such an environment, an open wastewater tank faces multiple severe challenges.

The primary issue is environmental pollution. During the treatment process, wastewater continuously releases malodorous and harmful gases such as hydrogen sulfide, ammonia, and volatile organic compounds. The unorganized emission of these gases seriously pollutes the local air quality, adversely affects the health and living conditions of plant workers and nearby residents, and contradicts the national policy of promoting ecological civilization.

Secondly, there are physical challenges posed by the climate. Frost, ice, and snow accumulation from severe cold impose significant static load pressure on any covering structure; strong winds test the structure’s stability and wind uplift resistance; intense ultraviolet radiation and significant temperature variations require the covering material to possess exceptional weather resistance. Furthermore, the interior of the wastewater tank is a highly corrosive environment, with hot, humid air containing various chemical substances that are extremely corrosive to any metal structure.

Therefore, covering this wastewater tank is not a simple matter of “putting a lid on it.” It requires an integrated technical solution that simultaneously addresses odor containment, structural safety, weather durability, corrosion resistance, and cost-effectiveness. Traditional solutions like concrete covers or color steel plates have drawbacks such as heavy weight, long construction periods, severe internal corrosion, and a tendency for condensation and dripping. It is precisely in this context that the membrane structure technology, known for being lightweight, high-strength, and corrosion-resistant, emerged as the optimal choice.

2. Core Technical Solution: Detailed Explanation of the Anti-Hanging Membrane Structure for Wastewater Tanks

The “anti-hanging membrane” method used in this project is a classic and mature solution for applying membrane structures to wastewater tank covers. Its technical principle is ingenious and efficient, fundamentally overturning the conventional thinking of cover structures.

2.1 Core Innovation: The “Anti-Hanging” Concept

The “anti-hanging” concept is the soul of this technology. As the name suggests, it involves “hanging” the high-strength, corrosion-resistant fluorocarbon fiber membrane material (such as the PVDF membrane used in this project) outsidethe supporting steel structure above the tank. The brilliance of this design lies in:

••Perfectly Solving Steel Corrosion: The corrosive gases inside the tank only contact the membrane material, while the supporting steel structure is completely isolated from the corrosive environment. The steel remains in a dry, well-ventilated environment, maximizing its designed service life and fundamentally eliminating the structural safety hazards and frequent anti-corrosion maintenance costs associated with steel corrosion.
••Rational Structural Mechanics: The membrane is tensioned into shape under prestress provided by the steel framework, forming a stable curved surface that efficiently transfers external loads (like snow and wind) to the supports, demonstrating high structural efficiency.

2.2 Structural System Composition

As can be seen clearly in the project images, the anti-hanging membrane system consists of three main parts:

••Supporting Steel Structure System: Constructed from Q235 steel, welded or bolted into a stable space frame (the dome shape in the image suggests a shell or arch system). This framework is the “skeleton” of the entire cover. Its design fully considers the local snow and wind loads in Inner Mongolia, ensuring absolute safety even in extreme weather.
••Covering Membrane System: The PVDF membrane material acts as the “skin” of the cover, responsible for sealing the tank. The membrane is cut into panels and fixed to the steel structure using specialized aluminum alloy clamps or stainless steel clamping plates, forming a complete, airtight cover.
••Ancillary Systems: These include necessary access doors, inspection windows, ventilation systems (such as pressure relief valves), and connections for odor gas extraction pipes. These facilities ensure the tank remains operable and maintainable after covering, and that the collected gases can be effectively conveyed to subsequent treatment equipment (like biofilters).

3. Material Science: The Excellent Properties of Q235 Steel and PVDF Membrane

The project’s success relies heavily on the correct selection of core materials.

3.1 Q235 Steel Structure: The Economical Strength Provider

Q235 is a common carbon structural steel with a yield strength of 235 MPa. It offers good strength, plasticity, toughness, excellent weldability, and high cost-effectiveness. In this project, because the “anti-hanging” design protects it from direct corrosion, the economic advantages of Q235 steel are fully realized. The steel components are fabricated standardized in a factory for precision and assembled efficiently on-site, significantly shortening the construction period. Its robust nature provides a reliable and unchanging boundary condition for the membrane, forming the foundation of the overall structural safety.

3.2 PVDF Membrane Material: The Corrosion and Weather Resistant Guardian

The PVDF (Polyvinylidene Fluoride) membrane is the key material for blocking pollution in this project. Its outstanding properties include:

••Excellent Corrosion Resistance: Highly resistant to chemicals like hydrogen sulfide, ammonia, and organic solvents, making it ideal for harsh wastewater treatment plant environments.
••Superior Weather Resistance: A surface coating of PVDF resin effectively resists UV degradation, providing strong anti-aging properties and a service life of 15 years or more. This is evident in the membrane’s bright, white appearance under strong sunlight in the image.
••High Self-Cleaning Property: The PVDF coating exhibits a “lotus effect,” meaning dirt and pollutants do not easily adhere. Rainwater is sufficient to clean the surface, reducing maintenance efforts.
••Good Flame Retardancy: Typically meets the B1 flame-retardant standard, enhancing fire safety.
••Light Transmittance and Aesthetics: The membrane has a certain degree of light transmittance (usually 5%-20%), providing natural diffused light inside the tank during the day, reducing lighting energy consumption. Its clean white color and smooth, curved shape also enhance the visual environment of the industrial plant.

4. Project Implementation and Coping with Seasonal Challenges

The winter scene in the project image indicates successful management of Inner Mongolia’s harsh conditions, particularly winter challenges, during implementation or after completion.

4.1 Evidence of Snow Load Design: The snow accumulation on the dome is visible. The dome shape is not arbitrary; it is a precisely calculated curved surface (like a hyperbolic paraboloid or spherical approximation). This streamlined design significantly reduces snow accumulation by allowing snow to slide off or distribute evenly, preventing localized stress concentrations. The structural design undoubtedly incorporated local snow load data for 50-year or even 100-year return periods, ensuring safety during heavy snowfalls.

4.2 Construction Organization and Seasonal Scheduling: Outdoor construction in cold regions requires overcoming challenges like low temperatures affecting welding. The project team likely scheduled major steel erection and welding for milder seasons and implemented detailed winter construction plans, such as pre-heating and post-heat treatment for welds to ensure quality. Membrane tensioning also requires specific temperature ranges to apply prestress accurately.

4.3 Landscape Integration: The image shows the white membrane structure harmoniously set against a backdrop of blue sky, white clouds, and trees. This demonstrates that industrial environmental facilities need not be unsightly; with careful design, they can integrate well with the natural landscape, even becoming a distinctive feature, reflecting modern industry’s pursuit of aesthetics and environmental friendliness.

5. Project Effectiveness and Comprehensive Value Analysis

The successful implementation of this 800m² membrane cover project delivers significant multi-dimensional value.

5.1 Environmental Benefits (Core Value)

••Effective Odor Gas Containment: The sealed membrane structure contains the pollution source with high efficiency (>95%). Collected gases are treated centrally before emission, drastically improving air quality on-site and in surrounding areas.
••Fulfilling Environmental Responsibilities: Helps the enterprise comply with increasingly stringent environmental regulations and build a responsible social image.

5.2 Economic Benefits

••Low Long-Term Maintenance Costs: The anti-hanging design protects the steel, and the PVDF membrane’s self-cleaning property significantly reduces lifecycle maintenance and anti-corrosion costs.
••Energy Savings: The membrane’s light transmittance reduces daytime lighting electricity consumption for the tank area.
••Rapid Construction, Minimal Footprint: Prefabricated components allow quick on-site installation, minimizing disruption to the plant’s normal operations.

5.3 Safety and Social Benefits

••Enhanced Operational Safety: Reduces worker exposure to hazardous gases.
••Improved Community Relations: Effectively resolves odor nuisance issues, promoting harmony between the enterprise and the community.

6. Conclusion and Outlook

The 800m² membrane cover project in Inner Mongolia is a exemplary application of “anti-hanging membrane” technology in the harsh, cold climate of Northern China. It is more than just an engineering project; it is a systematic solution integrating advanced material science, innovative structural design, and precise environmental adaptation.

The project images vividly demonstrate the structure’s excellent performance in real-world conditions: the snow-dusted dome under the winter sun, set against the blue sky and environment, creates a picture of quiet yet powerful efficiency, silently speaking to the harmony between industry and environmental protection, and humans and nature. It proves that through technological innovation, facilities once associated with waste and odor can be transformed into safe, efficient, and aesthetically pleasing components of a modern plant.

Looking ahead, with the continuous emergence of new materials and processes—such as smarter sensor systems for monitoring membrane stress and integrity, and the integration of photovoltaic technology with membrane structures (BIPV) to provide green energy for the plant—the application of membrane structures in industrial environmental protection will become more intelligent, integrated, and sustainable. This project provides valuable practical experience and a clear success case for the promotion of such technologies, contributing positively to the advancement of industrial environmental pollution control both in China and globally.