Against the backdrop of rapid industrialization and urbanization, the discharge of industrial wastewater and domestic sewage continues to increase. Problems such as water eutrophication, heavy metal exceeding standards, and accumulation of organic pollutants have become increasingly prominent. These issues not only threaten the safety of the ecological environment but also restrict the sustainable development of the social economy. Developing scientific, efficient, and highly adaptable wastewater treatment solutions has become a core approach to solving water pollution dilemmas and realizing the synergistic development of "lucid waters and lush mountains" (ecological protection) and "gold and silver mountains" (economic development). Starting from the core needs of wastewater treatment, this article systematically analyzes the technical framework, application scenarios, and implementation key points of the solutions, providing professional references for enterprises, industrial parks, and local governments.

I. Core Objectives of Wastewater Treatment Solutions: From "Compliant Discharge" to "Resource Circulation"

Traditional wastewater treatment takes "compliant discharge" as its core objective, while modern wastewater treatment solutions have evolved into a multi-dimensional objective system of "purification + recovery + circulation", which can be specifically divided into three levels:

Basic Objective: Compliant Discharge

Strictly adhere to national and local standards such as the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants (GB 18918-2002) and the Technical Specification for Industrial Wastewater Treatment Engineering (HJ 2025-2013). Ensure that indicators such as COD (Chemical Oxygen Demand), BOD (Biochemical Oxygen Demand), SS (Suspended Solids), ammonia nitrogen, total phosphorus, and characteristic pollutants (e.g., heavy metals, volatile organic compounds) in the treated water fully meet the standards, so as to avoid secondary pollution to the receiving water bodies.

Advanced Objective: Resource Recovery

Realize the recycling and reuse of resources in wastewater through technological innovation. For example, use membrane separation technology to recover precious metals from wastewater (such as in the electronics industry wastewater), produce biogas through anaerobic fermentation (for energy supply), and use the treated reclaimed water for industrial cooling, municipal greening, or agricultural irrigation, thereby reducing reliance on fresh water resources.

Ultimate Objective: Circular Closed-Loop

Integrate the concepts of "sponge city" and "zero discharge" to build a circulation system of "sewage collection - treatment - recycling - reuse". For instance, realize "internal circulation of wastewater resource utilization" in industrial parks, and link municipal wastewater treatment plants with reclaimed water utilization pipe networks. Ultimately, achieve "zero waste" of water resources and "zero discharge" of pollutants.

II. Technical Framework of Wastewater Treatment Solutions: Customization by Scenario and Full-Process Coverage

Wastewater treatment solutions are not a one-size-fits-all fixed model. They need to be customized with a full-process technical scheme of "pretreatment - main treatment - advanced treatment - sludge disposal" based on the source of wastewater (industrial/domestic/municipal), type of pollutants (organic/inorganic/composite pollution), treatment scale (small-scale stations/medium-sized plants/large-scale parks), and reuse requirements. The following are the typical technical frameworks for three core scenarios:

1. Industrial Wastewater Treatment Solutions: Focus on "Targeted Removal of Characteristic Pollutants"

Industrial wastewater has complex pollutant components due to differences in industry attributes (e.g., chemical wastewater contains benzene series, pharmaceutical wastewater contains antibiotics, and electroplating wastewater contains heavy metals). Therefore, targeted technical routes need to be designed. The typical process is as follows:

• Pretreatment Stage: Adopt the process of "grille + regulating tank + demulsification/air flotation" to remove suspended solids, oil, and some refractory organic matter in the water, and reduce the subsequent treatment load. For example, the pretreatment of electroplating wastewater needs to add a "neutralization reaction tank" to adjust the pH value and precipitate some heavy metal ions.
• Main Treatment Stage: Select appropriate technologies according to the type of pollutants:
  • For high-concentration organic wastewater (such as in the food and printing and dyeing industries): Adopt "anaerobic biological treatment (UASB/IC reactor) + aerobic biological treatment (MBR/AAO)" to degrade organic matter through microorganisms.
  • For heavy metal wastewater (such as in the electroplating and metallurgical industries): Adopt "chemical precipitation (adding alkali/sulfide) + membrane separation (NF/RO)" or "ion exchange resin" to realize the interception and recovery of heavy metals.
  • For high-salt wastewater (such as in the chemical and coal chemical industries): Adopt "evaporative crystallization (MVR) + advanced oxidation (Fenton/O₃)" to treat high salt content while degrading refractory organic matter.
• Advanced Treatment Stage: Use "activated carbon adsorption + ultraviolet disinfection" or "advanced oxidation" to further reduce COD, chroma, and odor, ensuring that the effluent meets the reuse or discharge standards.
• Sludge Disposal Stage: Adopt "concentration + dehydration + drying" to reduce the volume of sludge. If the sludge contains heavy metals, it needs to be treated by "solidification and stabilization" before safe disposal to avoid secondary pollution.

2. Urban Domestic Sewage Treatment Solutions: Balancing "Efficiency and Energy Conservation"

Urban domestic sewage is mainly composed of organic matter, suspended solids, nitrogen, and phosphorus. It has a large treatment scale and high stability requirements. The solution needs to balance treatment efficiency and operation costs. The mainstream technical route is as follows:

• Pretreatment: "Coarse grille (removing large particles of impurities) + fine grille + grit chamber (removing sand particles)" to avoid equipment blockage.
• Main Treatment: Prioritize the adoption of the "AAO process (anaerobic - anoxic - aerobic)" or "MBR process (membrane bioreactor)":
  • The AAO process realizes nitrogen and phosphorus removal through microorganisms. It has low cost and simple operation and maintenance, and is suitable for medium and large-sized wastewater treatment plants.
  • The MBR process combines biological treatment and membrane separation. It occupies a small area and has good effluent quality (which can be directly reused), and is suitable for cities with tight land use or scenarios with reclaimed water demand.
• Advanced Treatment: "High-efficiency sedimentation tank + filter (quartz sand/anthracite) + disinfection (sodium hypochlorite/ultraviolet)" to ensure that the effluent COD is ≤50mg/L and ammonia nitrogen is ≤5mg/L, meeting the Class A standard of GB 18918-2002.
• Reclaimed Water Reuse System: Further treat the qualified effluent with "ultrafiltration (UF) + reverse osmosis (RO)". The produced reclaimed water is used for municipal road flushing, park greening, and non-drinking water in residential communities, alleviating the pressure on urban water resources.

3. Industrial Park Wastewater Treatment Solutions: Building a System of "Centralized Treatment + Classified Reuse"

Wastewater in industrial parks (such as chemical parks and high-tech industrial parks) has the characteristics of "multi-source mixing and complex composition". The solution needs to integrate "centralized treatment plants + enterprise pretreatment stations" to form a hierarchical management and control system:

• Enterprise-Side Pretreatment: Each enterprise builds pretreatment facilities according to its own type of wastewater (e.g., chemical enterprises build acid-base neutralization tanks, and electronic enterprises build heavy metal pretreatment stations). Ensure that the wastewater meets the "pipe network access standards" (such as COD ≤500mg/L, pH 6-9) before being connected to the park's pipe network.
• Park Centralized Treatment Plant: Adopt a combined process of "pretreatment + multi-stage biological treatment + advanced treatment", such as "hydrolytic acidification tank + MBR + NF/RO". On the one hand, the treated water meets the standards and is discharged to the municipal pipe network or receiving water bodies. On the other hand, through the classified reuse system, reclaimed water of different water qualities is distributed to enterprises in the park (such as cooling water and cleaning water).
• Intelligent Management and Control System: Introduce the Internet of Things (IoT) technology to real-time monitor the wastewater discharge volume of each enterprise, pollutant concentration, and operating parameters of the treatment plant (such as DO, pH, and sludge concentration). Realize early warning of abnormal situations and precise regulation, and reduce operational risks.

III. Implementation Key Points of Wastewater Treatment Solutions: Full-Cycle Management from Technology to Implementation

A high-quality wastewater treatment solution not only requires advanced technical support but also needs to ensure the implementation effect through full-cycle management of "preliminary research - scheme design - project construction - operation and maintenance management".

1. Preliminary Research: Accurately Locating Needs and Pain Points

• Water Quality and Quantity Analysis: Continuously monitor the wastewater discharge volume and water quality indicators (COD, BOD, ammonia nitrogen, characteristic pollutants, etc.) for 7-15 days. Clarify the fluctuation range of pollutant concentrations to avoid redundant or insufficient scheme design due to "data deviation".
• Scenario Demand Confirmation: Clearly define the core needs with the customer - whether it is "emergency treatment" (such as sudden pollution incidents), "long-term operation" (such as newly built plants), or "upgrading and reconstruction" (such as substandard discharge of existing facilities). At the same time, confirm whether additional functions such as reclaimed water reuse and sludge resource utilization are needed.
• Policy and Cost Assessment: Investigate the environmental protection policies of the project location (such as discharge standards and pollutant discharge permit requirements). Combine with the customer's budget to balance "technical advancement" and "economic feasibility", and avoid over-design or cost overruns.

2. Scheme Design: Focusing on "Adaptability" and "Forward-Looking"

• Adaptability of Technology Selection: For example, in cold regions in northern China, it is necessary to consider the thermal insulation design of the biological treatment system (such as adopting buried MBR tanks). In high-altitude areas, it is necessary to adjust the parameters of the aeration system (to adapt to the low-pressure environment).
• Reserved Expansion Space: Reserve 20%-30% of the treatment capacity during scheme design to cope with the future growth of wastewater volume (such as the increase of urban population and the expansion of enterprises in the park).
• Integration of Low-Carbon Concepts: Adopt technologies such as "solar aeration system" and "biogas recovery and power generation" to reduce the energy consumption and carbon emissions of the solution, in line with the requirements of the "double carbon" goal.

3. Operation and Maintenance Management: Ensuring Long-Term Stable Operation

• Personnel Training: Provide operation and maintenance personnel training for the customer, covering equipment operation (such as membrane module cleaning and pump valve regulation), water quality monitoring (such as rapid detection of COD and ammonia nitrogen), and emergency treatment (such as process adjustment when the inlet water exceeds the standard).
• Intelligent Operation and Maintenance: Build a "remote monitoring platform" to collect real-time operation data of the treatment system (such as flow rate, pH, and dissolved oxygen) through sensors. The platform automatically generates operation reports, and abnormal situations are warned through SMS/APP, reducing labor costs.
• Regular Maintenance: Formulate an equipment maintenance plan (such as checking the grille monthly, cleaning the membrane module quarterly, and replacing activated carbon annually) to avoid the shutdown of the treatment system due to equipment failure.

IV. Conclusion: Future Trends of Wastewater Treatment Solutions - Greenization, Intelligence, and Resource Utilization

With the tightening of environmental protection policies, the intensification of water resource shortages, and the advancement of the "double carbon" goal, wastewater treatment solutions are upgrading in three directions:

• Greenization: More adoption of "low-energy biological treatment technologies" and "natural adsorption materials (such as straw and activated carbon)" to reduce the use of chemical agents and the secondary impact on the environment.
• Intelligence: Combine AI (Artificial Intelligence) technology to realize the automatic optimization of process parameters (such as adjusting aeration time and sludge return ratio according to the inlet water quality). Combine big data analysis to predict changes in wastewater volume and water quality, and improve treatment efficiency.
• Resource Utilization: Shift from "passive treatment" to "active recovery". For example, convert sludge into organic fertilizers (for agriculture) and convert organic matter in wastewater into bio-natural gas (for energy supply), realizing the value upgrade of "wastewater turning into resources".

Choosing a scientific and suitable wastewater treatment solution is not only an inevitable requirement for enterprises and local governments to fulfill their environmental protection responsibilities but also a key measure to realize the recycling of water resources and promote green and low-carbon development. In the future, with technological innovation and industrial synergy, wastewater treatment will become an important link connecting "ecological protection" and "economic development", providing solid support for the construction of a "Beautiful China".

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