I. Case Background: Daily High-Load Challenges Faced by Municipal Sanitation Departments in Qujing District In Southwest China, accelerating urbanization has continuously intensified pressure on municipal sanitation departments. For example, the Urban Management Bureau of a district in Qujing oversees multiple aging urban areas and newly built industrial parks, resulting in massive daily sewage treatment volumes and complex operational environments. Frequent emergency tasks—such as septic tank cleaning, grease trap maintenance, and municipal pipeline blockage clearance—are common. Previously reliant on conventional vacuum trucks and manual cleaning, operations suffered from low efficiency and frequent equipment failures under high-frequency, high-intensity usage, severely impacting workflow. According to local procurement practices, this unit processes approximately 30,000–50,000 cubic meters of sewage and sludge annually, with peak periods requiring 24-hour continuous operation. This 'high-frequency operation' scenario imposes stringent requirements on vehicle chassis and upper-structure system durability and reliability. Equipment fatigue management has thus become a core pain point in procurement decisions—selecting specialized vehicles capable of sustaining prolonged heavy loads, maintaining low failure rates, and enabling easy maintenance directly affects operational costs and service assurance capability. II. Project Requirements: Equipment Fatigue Management and Heavy-Duty Operating Condition Design Against this backdrop, the Urban Management Bureau of a district in Qujing launched a government procurement project for a 3308 yellow-plate sewage treatment vehicle at the end of 2025. The project budget was capped at approximately RMB 432,000, aiming to procure one unit equipped with high-efficiency vacuum suction, solid-liquid separation, and automatic unloading capabilities for routine pipeline maintenance and emergency response. Key requirements were clearly defined: • High Reliability: Capable of sustaining 8–10 hours of continuous daily operation; critical components—including vacuum pump, hydraulic system, and tank—must undergo fatigue testing to ensure low failure rates. • Heavy-Duty Chassis: Must utilize a yellow-plate chassis with strong load-bearing capacity, suitable for complex road conditions, and compliant with China VI emission standards. • Operational Convenience: Fully automated control to minimize manual intervention and enhance operational efficiency. • After-Sales Support: Nationwide warranty coverage for the chassis; lifetime service support for the upper-structure assembly, with spare parts shipped within 24 hours. Following multiple rounds of tender evaluation, Chengli Special Purpose Vehicle Co., Ltd. stood out with its mature 3308 yellow-plate sewage treatment vehicle solution and was ultimately awarded the contract. Below is a detailed interpretation of the winning solution. III. Winning Solution Interpretation: Chengli 3308 Yellow-Plate Sewage Treatment Vehicle Chengli’s solution is based on a Dongfeng chassis with a 3308 mm wheelbase and features an independently developed sewage treatment system, referencing model series such as CLW5070GSSD6 (parameters subject to official announcement; actual delivery specifications apply). The design specifically addresses fatigue management challenges under 'high-frequency operation': • Reinforced Chassis: Utilizes an original Dongfeng factory chassis fitted with 7.00R16 steel-belted tires, rated for 4–5 tons payload, and reinforced leaf springs—optimized for mixed terrain including mountainous and urban roads. • Heavy-Duty Upper Structure: Tank constructed from high-quality Q235 carbon steel, minimum thickness ≥5 mm, internally reinforced with anti-slosh baffles to reduce liquid impact during transit. Vacuum pump selected is a high-capacity water-ring type, supporting over 100 hours of continuous operation and exhibiting a 30% lower failure rate compared to