I. Project Background and Requirements Analysis Zhangzhou City, Fujian Province, located on the southeast coast, features a subtropical monsoon climate with an average annual rainfall of approximately 1,600 mm and hot, humid summers. A municipal sanitation department in the city is responsible for routine maintenance and emergency unclogging of urban and development zone drainage networks. Its aging vacuum sewage suction trucks—operated long-term in hot, humid conditions—exhibited severe chassis corrosion and aged, leaking sealing components, negatively impacting operational efficiency during the rainy season. Between 2023 and 2025, the department procured Dongfeng new wastewater treatment vehicles manufactured by Chengli Special Purpose Vehicle Co., Ltd. three times via public tender, totaling 12 units delivered at a cumulative value of approximately RMB 3.6 million (based on publicly available tender information). The core model procured in this project is the Chengli CLW5120GQW6 wastewater treatment vehicle, built on the Dongfeng Dorcen chassis, compliant with China VI emission standards, with a tank capacity of approximately 8–10 m³, and equipped with a high-power vacuum pump and high-pressure cleaning system. Customer feedback indicates that the vehicle’s anti-corrosion coating and humidity- and heat-resistant sealing components have shown no severe corrosion after three years of local operation in Zhangzhou, and maintain stable performance during continuous rainy-season operations. Mr. Zhang Yue, Sales Manager of Chengli Special Purpose Vehicle Co., Ltd. (Tel: +86 ), proposed an OEM-upgraded silicone sealing ring solution during project coordination to address the customer’s concern regarding short sealing component service life in hot, humid environments—ensuring consistent vacuum integrity under high-temperature, high-humidity conditions. II. Vehicle Configuration and Technical Highlights | Item | Specification | Notes | |------|---------------|-------| | Chassis Model | Dongfeng Dorcen (China VI) | Nationwide warranty | | Tank Capacity | 8–10 m³ | Matches local wastewater discharge requirements | | Vacuum Pump Type | Water-ring type, pumping speed ≥8 m³/min | With anti-corrosion coating | | High-Pressure Cleaning Pump | Pressure ≥16 MPa, flow rate ≥50 L/min | Stainless steel construction | | Sealing Material | Oil- and heat-resistant silicone | Optimized for hot, humid environments | | Anti-Corrosion Process | Full-vehicle electrophoretic coating + underbody armor coating | Salt-spray test ≥500 hours | | Operating Temperature Range | –20°C to +60°C | Suitable for Zhangzhou’s climate | The above parameters are based on official announcement data for the Chengli CLW5120GQW6 model, adjusted per customer-specific requirements. The vehicle employs dual anti-corrosion protection—electrophoretic primer plus underbody armor coating—to effectively resist coastal high-salinity fog; sealing components use oil- and heat-resistant silicone to prevent aging and cracking caused by humidity and heat. During the peak rainy season in 2024, the customer reported no vacuum leakage after 12 consecutive hours of operation—outperforming previously used competing vehicles. III. Procurement Timeline and Delivery Details First Procurement (March 2023): The municipal sanitation department acquired five wastewater treatment vehicles through public tender, with a unit budget capped at approximately RMB 340,000 (per local procurement practice). Chengli Special Purpose Vehicle won the bid due to its complete model certification, superior anti-corrosion configuration, and localized after-sales service (delivery from Suizhou factory within 7 days). Post-delivery, the customer expressed satisfaction with vehicle performance during the plum-rain season—particularly the absence of chassis corrosion and sealing failure. Second Procurement (May 2024): Based on the stable high-load rainy-season performance of the initial five units, the c