Government Procurement Case and Winning Bid Solution Analysis of the Dongfeng Yizhan-Style Sewage Treatment Vehicle in Chongqing. In this mountain-and-river city, municipal sanitation departments have long faced a thorny issue: aging sewage treatment equipment suffers severe rusting and rapid sealing component degradation under hot, humid, and rainy conditions—leading to frequent failures during high-load operations in the rainy season. In 2025, a district urban management bureau conducted an equipment upgrade via public tender and ultimately accepted the Dongfeng Yizhan-style sewage treatment vehicle supplied by Chengli Special Purpose Vehicle Co., Ltd. This article uses this government procurement case as a benchmark to interpret the end-to-end process—from pain-point identification to solution implementation—to provide reference for similar organizations. Pain Points of Aging Equipment: 'Incompatibility with Local Conditions' in a Humid, Hot Environment The bureau’s existing sewage treatment vehicles—some in service for over eight years—exhibited three primary issues: 1. Failure of Anti-Rust Coating: Chongqing’s annual average relative humidity is approximately 80%, with a rainy season lasting five months. The original vehicle frames and tank coatings began peeling extensively within three years, compromising structural integrity. 2. Poor Durability of Sealing Components: Hot, humid conditions accelerated rubber seal aging; frequent leaks occurred at drain valves and pipe joints, increasing maintenance frequency from once per quarter to once per month. 3. Suboptimal Performance Under High-Load Rainy-Season Operations: During prolonged overcast and rainy weather, equipment was required to operate continuously for over 12 hours. However, the original engine and hydraulic systems overheated and shut down due to insufficient heat dissipation, undermining emergency response efficiency. According to local procurement practice, these aging units incurred approximately RMB 50,000 in annual maintenance costs—and, due to frequent breakdowns, actual operational time fell below 70% of the designed standard. New Requirements Survey: Transitioning from 'Functional' to 'Durable' In early 2025, the bureau launched a new procurement initiative, with a budget capped at approximately RMB 1.323 million, targeting two sewage treatment vehicles—each with a minimum processing capacity of 20 m³/hour. The evaluation team prioritized the following technical criteria: • Chassis and upper-structure anti-corrosion processes: Mandated electrophoretic coating for the chassis frame and weather-resistant polyurethane coating for the tank. • Sealing component material: Required fluorocarbon rubber (FKM) or silicone rubber, rated for operating temperatures from −20°C to 120°C. • Continuous operation capability: Must maintain stable performance for 10 hours under ambient conditions of 35°C and 90% relative humidity. • Regulatory compliance: Must meet China VI emission standards and be eligible for nationwide registration and annual inspection. After visiting multiple suppliers, the Dongfeng Yizhan-style proposal from Chengli Special Purpose Vehicle Co., Ltd. attracted strong interest from the procurement team. Based on a Dongfeng chassis, the proposed vehicle model falls under the CLW5180GSSD6 series (officially certified), featuring a wheelbase of 4,500 mm, kerb weight of approx. 7.8 tons, rated payload of approx. 10.2 tons, and powered by a Dongfeng Cummins B6.2NS6B210 engine delivering 154 kW nominal power—fully compliant with China VI emission standards. Chengli’s Solution Match: Targeted Optimizations for Corrosion Resistance and Sealing Reliability To address Chongqing’s humid, hot environment, Chengli’s engineering team proposed three targeted improvements: 1. Upgraded Anti-Rust Coating System: Chassis employs a three-layer coating process—cathodic electrophoretic primer + epoxy intermediate coat + polyurethane topcoat; internal tank surfaces are co