Government Procurement Case and Bid-Winning Solution Analysis for the Dongfeng Yizhan-Style Sewage Treatment Vehicle in Ningbo In 2022, a municipal sanitation department in Ningbo (hereinafter referred to as 'the Ningbo entity') launched its first public tender to procure a batch of sewage treatment vehicles, aiming to enhance urban sewage treatment efficiency and performance. Following multiple rounds of technical evaluation and cost-effectiveness comparison, Chengli Special Purpose Vehicle Co., Ltd. was awarded the contract to supply the Dongfeng Yizhan-style sewage treatment vehicle (chassis model reference: CLW5070GSSD6). Over more than two years of actual operation—particularly under Ningbo’s typical high-temperature, high-humidity, and rainy environmental conditions—these vehicles have demonstrated stable and reliable performance. Based on high user satisfaction, the entity initiated a follow-up procurement in early 2024, expanding the order volume. This article analyzes the vehicle selection rationale and operational performance based on this real-world government procurement case. Case Background: Initial Procurement and Operational Experience in 2022 Ningbo is located along China’s coast, experiencing hot, humid summers and prolonged rainy seasons. Sewage treatment vehicles must frequently operate on flooded roads and in damp working environments. In 2022, the Ningbo entity procured five Dongfeng Yizhan-style sewage treatment vehicles for the first time, with a budget cap of approximately RMB 503,000 per unit (per publicly available tender information), and an actual purchase price of around RMB 450,000 per unit. Upon delivery, the vehicles were immediately deployed for tasks including urban drainage pipe cleaning and emergency sewage treatment at wastewater treatment plants. During actual use, the vehicles faced three core challenges: 1. Corrosion Resistance Testing of Anti-Rust Coating: Ningbo’s humid coastal climate poses a high risk of metal component rusting. Chengli implemented full-vehicle anti-corrosion treatment on the Dongfeng Yizhan chassis, applying a composite coating system—epoxy zinc-rich primer plus polyurethane topcoat—to critical welded areas, effectively resisting salt fog corrosion. Customer feedback indicates no visible rusting occurred within two years. 2. Durability of Sealing Components Under Hot-Humid Conditions: Sewage treatment vehicles involve sewage tanks, piping systems, and hydraulic systems; sealing component reliability directly impacts operational safety. Chengli selected high-performance fluororubber O-rings with excellent oil resistance and weather resistance, and added anti-aging treatments to sealing components. No leakage failures occurred during continuous high-temperature, high-humidity operations. 3. High-Load Performance During Rainy-Season Operations: With an average annual rainfall of approximately 1,400 mm, vehicles in Ningbo often operate over 10 hours per day during the rainy season. Equipped with a Dongfeng engine (China VI emission standard) and a robust hydraulic system, the vehicles maintained stable performance under sustained high-load conditions. Single-operation cycles were reduced to within 30 minutes, improving efficiency by approximately 20% compared to conventional solutions. According to internal reports from the user entity, the initial batch of vehicles processed over 15,000 cubic meters of sewage within two years, maintaining an equipment serviceability rate above 98%, while maintenance costs remained below projected levels. Follow-Up Procurement in 2024: Expanded Volume and Configuration Upgrades Based on the outstanding performance of the initial batch, the Ningbo entity launched a follow-up procurement in 2024, increasing the order quantity from five to eight units, with a total budget of approximately RMB 4.024 million (per local procurement conventions). While retaining the Dongfeng Yizhan chassis, the newly ordered vehicles feature the follo