As an ancient capital with thirteen dynasties, Xi'an boasts profound historical and cultural heritage. Meanwhile, it is confronted with major tasks including water resource protection and sewage treatment amid modernization. Driven by the 14th Five-Year Plan for Water Ecological Environmental Protection of Xi'an, the city's sewage discharge volume keeps rising. Diversified pollution sources such as industrial wastewater, domestic sewage and sewage from urban villages pose threats to the ecological environment of the Weihe River, Chanba River and other basins. Against this backdrop, sewage treatment equipment tailored to local conditions has become core infrastructure to tackle water ecological problems and advance the city's green development.
I. Core Demands of Sewage Treatment in Xi'an: Why Professional Equipment Is Indispensable?
      Sewage treatment projects in Xi'an feature prominent regional characteristics, which rule out one-size-fits-all equipment and call for targeted solutions:
      Complex Water Quality: Xi'an has a complete industrial system covering equipment manufacturing, electronic information, food processing and other sectors. Industrial wastewater contains heavy metals, organics, suspended solids and multiple other pollutants. In addition, aging sewer pipelines in old urban areas lead to serious combined sewage and rainwater overflow. The concentration of COD and ammonia nitrogen fluctuates sharply, requiring equipment with strong anti-shock load capacity.
      High Climate Adaptability: Xi'an has a temperate monsoon climate with minimum temperatures below -10℃ in winter. Traditional equipment without thermal insulation tends to suffer cracked pipelines and reduced microbial activity, lowering treatment efficiency. In hot summer, the equipment must be anti-corrosive and heat-resistant to prevent breakdowns.
      Land Restrictions: The densely built old town suffers from land shortage, leaving little space for new sewage facilities. Integrated and modular sewage treatment units stand out for their small footprint and flexible installation, making them the top choice for urban renewal. For suburban counties, easy maintenance and low operating costs are major priorities.

II. Mainstream Sewage Treatment Equipment Suitable for Xi'an and Their Technical Advantages

      Three types of equipment are widely adopted in Xi'an to match local treatment demands, each with defined application scenarios and technical strengths:
(1) Integrated Domestic Sewage Treatment Equipment: Ideal for Renewal of Old Urban Districts and Urban Villages
      The biggest obstacles for sewage renovation in Beilin District, Lianhu District and urban villages are difficult pipeline laying and limited land approval. Integrated equipment with modular assembly perfectly solves these problems:
      Technical Principle: It adopts the process of pre-treatment + biological contact oxidation + MBR membrane separation + disinfection. Bar screens and sedimentation tanks remove large impurities in the pre-treatment stage. Highly efficient microorganisms degrade organics in the biological contact oxidation tank, and MBR membranes trap suspended solids and microbes. The effluent meets Grade A standard of GB18918-2002 Pollutant Discharge Standard for Urban Sewage Treatment Plants, which can be directly used for green irrigation or discharged into natural water bodies.
      Adaptation Merits: The whole unit can be buried underground with only operating shafts above ground, saving surface land for narrow lots in old towns. Underground thermal insulation layers or electric heat tracing maintain proper temperature in winter to avoid low-temperature failures. Single sets range from 5m³/d to 500m³/d to match population sizes of urban villages. Only regular membrane inspection is needed, cutting labor costs greatly.
(2) Specialized Industrial Wastewater Treatment Equipment: Customized Solutions for High-Pollution Industries
      Enterprises in Xi'an Economic and Technological Development Zone and High-tech Zone, especially machinery manufacturing, electroplating and food fermentation factories, discharge wastewater containing heavy metals such as chromium and nickel or high-concentration organics, which need targeted treatment units:
      Heavy Metal Wastewater Treatment Equipment: It follows the process of chemical precipitation + chelating resin adsorption. Chemical agents including calcium hydroxide and sodium sulfide turn heavy metal ions into precipitates, and chelating resins perform deep purification to keep heavy metal concentration below 0.1mg/L, complying with GB8978-1996 Comprehensive Wastewater Discharge Standard. Automatic chemical dosing systems and online monitors adjust dosage in real time to adapt to fluctuating pollutant concentrations.
      High-Concentration Organic Wastewater Treatment Equipment: For food processing and brewing wastewater, the combined UASB anaerobic reactor + aerobic biological process is applied. Macromolecular organics are decomposed into small-molecule organic acids in the anaerobic tank, and biogas can be recycled as boiler fuel. The aerobic stage further degrades pollutants with a COD removal rate over 90%. The equipment is made of corrosion-resistant 316L stainless steel to withstand high-strength wastewater.
(3) Intelligent Sewage Lifting Equipment: Solve Collection Difficulties at the End of Pipe Networks
      Townships in suburban districts such as Lintong and Yanliang lack complete sewer networks, so scattered rural sewage cannot be connected to municipal pipelines. Intelligent lifting equipment realizes efficient collection and transportation via negative pressure collection and intelligent delivery:
      Core Functions: The sealed negative pressure system collects decentralized sewage through buried collecting wells and transports sewage to distant sewage plants with negative pressure pumps without large lifting pump stations. Equipped with IoT modules, the equipment transmits real-time data on flow, pressure and fault alarms. Operators conduct remote monitoring via mobile APP and reduce on-site inspections. The unit only occupies 2-3 square meters, fitting scattered rural layout.
III. Application Cases in Xi'an: From Pilot Projects to Citywide Popularization
      Specialized sewage treatment equipment has delivered remarkable water ecological improvements across multiple regions. Typical cases are as follows:
      Case 1: Old Town Renovation Project in Beilin District. In 2023, 20 sets of buried integrated sewage equipment (50m³/d per set) were deployed to treat domestic sewage from 12,000 households along East Guannan Street. The mixed rainwater and sewage problem was completely solved. The COD concentration in tributaries of the moat dropped from 80mg/L to below 30mg/L, and water transparency increased by 50%, setting a model for old-town sewage governance.
      Case 2: Electroplating Wastewater Project for High-tech Zone Enterprises. An electronics manufacturer in the high-tech zone adopted heavy metal treatment equipment with a capacity of 200m³/d. Chromium ion content in effluent fell from 5mg/L to 0.05mg/L. Annual heavy metal discharge was cut by 36kg. Treated water was recycled for workshop cleaning, saving 12,000 tons of fresh water per year. The enterprise was awarded the title of Xi'an Green Factory.
IV. Key Principles for Enterprises and Institutions When Purchasing Sewage Treatment Equipment in Xi'an
      Buyers shall select equipment according to treatment scale, water quality and site conditions instead of blind procurement. Four major factors should be prioritized:
      Prioritize Adaptability: Choose integrated units for domestic sewage treatment. Industrial buyers shall provide water quality test reports for customized processes: chelating resin equipment for heavy metal pollution, anaerobic-aerobic combined units for high COD wastewater. Make sure the equipment has thermal insulation structures for cold winters.
      Ensure Compliance: Require manufacturers to provide CCEP environmental product certification to guarantee effluent meets local standards (Grade A standard for water discharged into the Weihe River). The equipment must also comply with CJJ60-2011 Technical Specifications for Operation, Maintenance and Safety of Urban Sewage Treatment Plants to avoid operational violations.
      Value Intelligent Functions: Prefer units with online monitoring and remote maintenance, especially for remote township projects to cut labor costs. The fault alarm function of intelligent lifting equipment effectively prevents overflow pollution caused by unexpected shutdowns.
      Choose Local After-sales Service: Select manufacturers with service outlets in Xi'an to guarantee on-site maintenance within 24 hours. Local environmental equipment suppliers offer faster response and avoid non-compliance risks caused by long-term equipment downtime.
V. Conclusion: Sewage Treatment Equipment Boosts Coexistence of Lucid Waters, Green Mountains and Ancient City Culture
      As Xi'an advances construction as a national central city, sewage treatment is not merely an environmental task but a necessity for high-quality urban development. Professional and customized equipment addresses differentiated pollution problems in old towns, industrial parks and rural townships, and safeguards water quality for the Weihe River Ecological Belt and Chanba National Wetland Park. In the future, with technological upgrades including membrane separation, intelligent monitoring and resource recycling, sewage treatment facilities will evolve from standard discharge to full water resource circulation, providing lasting support for ecological protection and cultural inheritance of the ancient capital.