Case Study and Solution Analysis of the National VI Dongfeng 3308 mm Wheelbase Sewage Treatment Vehicle Procured by Nanning Municipal Government In the municipal sanitation sector, sudden equipment demands often test suppliers’ responsiveness and product reliability. During the summer of 2025, Nanning, Guangxi experienced continuous heavy rainfall. A municipal sanitation department’s existing sewage treatment vehicle—having operated for years under hot, humid, and high-load conditions—suffered from aging seals and severe corrosion, reducing treatment efficiency by approximately 30% and failing to meet emergency drainage requirements during the rainy season. Facing this urgent situation, the department promptly initiated an emergency procurement procedure and ultimately selected a National VI Dongfeng 3308 mm wheelbase sewage treatment vehicle supplied by Chengli Special Purpose Vehicle Co., Ltd. This article provides a comprehensive analysis of the case—from background and tender process to delivery plan and actual performance—based on publicly available tender information. I. Background of the Urgent Requirement: Equipment Limitations Under High-Load Rainy Season Conditions Nanning lies in a subtropical monsoon climate zone, characterized by high summer temperatures and abundant rainfall, with an annual average relative humidity exceeding 80%. The municipal sanitation department’s current sewage treatment vehicle had been in service for over five years, exhibiting the following key issues: 1. Failure of Anti-Corrosion Coating: Prolonged exposure to hot and humid environments caused large-scale peeling of the original coating on the tank body and pipelines, accelerating corrosion and compromising equipment service life. 2. Insufficient Seal Durability: Due to high operational frequency during the rainy season (averaging over 8 hours per day), rubber seals rapidly aged under alternating high-temperature and high-humidity conditions, increasing the risk of sewage leakage. 3. Inadequate Treatment Efficiency: The original vehicle was equipped only with a single-stage filtration system, which proved insufficient to handle the high-concentration sewage surges typical of the rainy season, failing to meet discharge standards. Based on internal assessment, the department urgently required a new National VI emission-compliant sewage treatment vehicle featuring superior corrosion resistance and higher treatment capacity to cope with the upcoming round of heavy rainfall. The procurement budget was capped at approximately RMB 513,000. Following local procurement conventions, the Dongfeng 3308 mm wheelbase chassis was selected for its optimal wheelbase, strong maneuverability, and suitability for narrow urban road operations. II. Emergency Tender Process: Tight Timeline and Stringent Requirements As an emergency procurement, the department adopted an ‘Urgent Procurement’ procedure, significantly shortening the tender cycle. From requirement announcement to bid opening, only 10 working days elapsed. Key technical and commercial requirements stipulated in the tender documents included: - Chassis Model: National VI Dongfeng 3308 mm wheelbase chassis (e.g., reference model CLW5070GSSD6 or equivalent configurations); - Upper-structure Key Specifications: Tank volume ≥ 5 m³; equipped with a high-efficiency solid-liquid separation system and automatic cleaning function; - Special Requirements: Full-vehicle anti-corrosion coating must comply with ISO 12944 C5 standard (for highly corrosive environments); sealing components must be high-temperature- and oil-resistant rubber; minimum warranty period: 2 years; - Delivery Deadline: Complete delivery within 15 days after contract signing. Leveraging its local manufacturing advantage in Suizhou, Chengli Special Purpose Vehicle submitted a detailed configuration proposal prior to bid opening: utilizing an original Dongfeng chassis, with upper-structure assembly completed at Chengli’s factory. To addr