I. Case Background: Procurement Requirements of a Municipal Sanitation Department in Zhangzhou In spring 2025, a municipal sanitation department in Zhangzhou planned to procure a batch of National VI emission-standard sewage treatment vehicles to address urban sewer network maintenance and emergency rain-season support needs. Previously, the department had procured water-sprinkling trucks and vacuum suction trucks from Chengli Special Purpose Vehicles through public tendering. Based on its recognition of the vehicles’ anti-corrosion coating performance and durability of sealing components under humid-heat conditions, the department prioritized evaluating sewage treatment vehicle models built on the Dongfeng 3308 mm wheelbase chassis for this procurement. According to publicly released tender information, the project budget was capped at approximately RMB 510,000, with requirements that the vehicles must integrate suction, separation, and transportation functions, and be suitable for high-humidity, rainy operational environments typical of southern China. Ultimately, Chengli Special Purpose Vehicle Co., Ltd. delivered two units of the CLW5070GSSD6 model (based on the Dongfeng 3308 mm wheelbase chassis), which met the official announcement parameters and customized solution requirements, and the vehicles entered service in June 2025. II. Vehicle Configuration and Bid-winning Solution Analysis The delivered model is the Chengli CLW5070GSSD6, built on the Dongfeng EQ1075SJ3CDF chassis with a 3308 mm wheelbase, equipped with a National VI-compliant Yuchai or Quanchai engine (selected per local procurement practice). Key configurations include: Tank Material: High-strength carbon steel, with interior and exterior surfaces coated with anti-corrosion paint (coating thickness ≥120 μm) to withstand Zhangzhou’s humid-heat environment; customer feedback confirms no visible corrosion after six months of operation. Sealing Components: Silicone rubber O-rings—oil-resistant and corrosion-resistant—demonstrated zero leakage during high-frequency rainy-season operations (average 6–8 hours per day); passed durability testing. Suction System: Equipped with a water-ring vacuum pump, achieving a maximum suction depth of 7 meters and suction rate ≥10 m³/hour—meeting rapid response requirements for pipeline blockages. Separation System: Hydraulically driven screw-type separator, capable of separating solid waste (e.g., silt, debris) from wastewater into a dedicated compartment while enabling liquid recirculation, thereby reducing transport frequency. Solution Analysis: In its bid-winning proposal, the department specifically emphasized three criteria: “National VI emission compliance,” “anti-corrosion treatment,” and “sealing component warranty.” Chengli’s proposal featured an original Dongfeng chassis (nationwide warranty), lifetime after-sales service for the superstructure, 24-hour direct shipment of spare parts, and full regulatory compliance (CLW5070GSSD6 is listed in the MIIT Announcement), ensuring nationwide registration and annual inspection eligibility. Key Parameter Comparison (Based on Public Tender Information and Chengli Product Database) Chengli CLW5070GSSD6 vs. Comparable Market Models Item Chengli CLW5070GSSD6 Comparable Market Models Chassis Wheelbase 3308 mm 3300–3360 mm Emission Standard National VI National VI Tank Capacity Approx. 5 m³ 4–5.5 m³ Anti-Corrosion Coating Thickness ≥120 μm 80–100 μm (typical) Sealing Material Silicone (oil- and corrosion-resistant) Nitrile rubber (typical) Suction Depth 7 meters 6–8 meters Superstructure After-Sales Service Lifetime service 1–2 years warranty (typical) Vehicle Unit Price (approx.) Approx. RMB 220,000