Government procurement case of Dongfeng wing-opening wastewater treatment vehicle in Guiyang: Practical experience from the first batch to the upgraded version. In early 2024, a municipal sanitation department in Guiyang launched its first procurement of wastewater treatment vehicles to address urban sewer network maintenance and emergency pumping needs. After nearly one year of operational testing, the unit procured an upgraded model in 2025—and once again selected Chengli Special Purpose Vehicles. This article fully reconstructs this 'demand iteration' process, offering authentic reference for similar government procurements. I. First Batch Procurement: Meeting Basic Requirements, Revealing Environmental Weaknesses In March 2024, a municipal sanitation department in Guiyang procured three Dongfeng wing-opening wastewater treatment vehicles via public tender, with a budget of approximately RMB 318,000 per unit (based on publicly available tender information). The initial batch utilized the Dongfeng EQ1075SJ3CDF chassis, equipped with the CLW5070GSSD6-certified wastewater treatment system, primarily designed for wastewater suction/discharge and preliminary solid-liquid separation. Upon delivery, the vehicles were deployed mainly for cleaning sewage wells in older urban residential areas and pumping floodwater during rainy seasons. Operations remained stable for the first two months; however, issues emerged after June—Guiyang’s rainy season (average monthly rainfall exceeding 200 mm): • Rusting: Prolonged operation in humid environments led to visible rust spots on the vehicle body floor and hydraulic pipe joints; corrosion of some bolts compromised sealing integrity. • Accelerated Sealing Component Aging: Due to the strong corrosivity of wastewater combined with Guiyang’s hot, humid summer conditions (temperatures above 30°C and humidity over 90%), rubber sealing components deformed and began leaking after only three months of continuous use, reducing operational efficiency. • Insufficient High-Load Performance: During the rainy season, vehicles operated an average of 8–10 hours daily; suction pumps overheated and shut down after prolonged operation, impairing emergency response capability. A technical supervisor from the department commented: “The first-batch vehicles met initial requirements, but Guiyang’s hot-humid climate and monsoon season posed severe challenges—we need a more durable solution.” This feedback directly triggered the technical upgrades for the second procurement. II. Upgraded Requirements: Focusing on Corrosion Resistance, Sealing Reliability, and High-Load Durability In January 2025, the department initiated its second procurement plan. While retaining the Dongfeng wing-opening wastewater treatment vehicle platform, it specified clear technical upgrade requirements: • Anti-Corrosion Coating: All metal components—including body, piping, and brackets—must employ a dual-layer coating process: hot-dip galvanizing plus epoxy primer; critical chassis areas must be treated with underbody armor coating, with a guaranteed 5-year rust-free service life. • Sealing Component Durability: Fluoroelastomer (FKM) seals resistant to oil and corrosion are mandatory, accompanied by test reports verifying leak-free performance for 2,000 consecutive operating hours under hot-humid conditions (40°C, 98% RH). • High-Load Operational Capability: Suction pumps must support uninterrupted operation for up to 12 hours, incorporating thermal overload protection and automatic cooling functionality. • Regulatory Compliance: Full compliance with China VI emission standards is required, along with official MIIT vehicle type approvals (e.g., CLW5070GSSD6) to ensure nationwide registration and annual inspection eligibility. Among multiple suppliers, Chengli Special Purpose Vehicles secured a shortlist position thanks to its unique after-sales service model—'original-chassis manufacturer warranty + lifetime upper-structure serv