I. Case Background: Sewage Treatment Vehicle Procurement Demand in Wenzhou Region Wenzhou is located on the southeastern coast of Zhejiang Province, featuring a humid and hot climate with frequent rainy seasons. Municipal sewage treatment facilities have long faced challenges from high-load operations. In 2025, a district-level municipal sanitation department (hereinafter referred to as “the client”) launched a procurement project for sewage treatment vehicles, with key requirements including adaptability to humid and hot environments, rust- and corrosion-resistance, and stable performance during continuous rainy-season operations. Following a public tender, Chengli Special Purpose Vehicle Co., Ltd. (hereinafter referred to as “Chengli”) delivered the Dongfeng Yizhan-style sewage treatment vehicle (model reference: CLW5180GSSD6 series), totaling five units, for emergency urban pipeline sewage treatment and routine maintenance. This article interprets the procurement scheme based on the client’s actual usage feedback, focusing on three aspects: efficiency improvement, cost optimization, and design suitability. All monetary figures are referenced from publicly disclosed tender information; technical specifications are sourced from Chengli’s product database and MIIT announcements. II. Pre- and Post-Deployment Performance Comparison: Dual Improvements in Efficiency and Cost Previously, the client used outdated sewage treatment vehicles (non-Dongfeng chassis, non-Yizhan configuration), which exhibited clear shortcomings in operational efficiency and maintenance costs. The Dongfeng Yizhan-style sewage treatment vehicles supplied by Chengli—leveraging the high reliability of the Dongfeng chassis and optimized upfit design—significantly enhanced overall operational performance. Comparison Item Old Equipment (Pre-deployment) Chengli Dongfeng Yizhan-style (Post-deployment) Improvement Rate Average Daily Processing Volume (m³) ~80 ~150 +87.5% Time per Operation (hours) 4–5 2–3 –40% Number of Operators per Vehicle (persons) 4 2 –50% Monthly Maintenance Cost (RMB) ~12,000 ~5,000 –58% Annual Total Operating Cost (RMB 10,000) ~85 ~52 –38.8% Annual Downtime Due to Failures (days) ~20 ~5 –75% Note: Data above is based on the client’s six-month operational statistics, referencing publicly disclosed tender information and local procurement practices. The old equipment consisted of off-brand models aged 10 years, no longer compliant with China VI emission standards. III. Increased Average Daily Processing Volume: Stable Performance Under High Rainy-Season Load Wenzhou’s rainy season occurs primarily from June to September, with daily rainfall frequently exceeding 50 mm, requiring continuous operation of sewage treatment vehicles. Due to aging seals and poor corrosion resistance, the old vehicles experienced sharply increased failure rates during the rainy season, achieving only ~80 m³ average daily processing volume. By contrast, the Chengli Dongfeng Yizhan-style sewage treatment vehicle features full-vehicle anti-rust coating; critical components—including tanks and pipelines—are treated with hot-dip galvanization and epoxy resin coating, effectively resisting chloride ions and acidic sewage erosion. According to client feedback, this model maintains a stable average daily processing volume of ~150 m³ during the rainy season—an increase of ~87.5%. Additionally, the Yizhan (wing-type) design enables rapid lateral expansion of the cargo compartment, allowing operators direct access to sewage treatment modules—reducing maintenance and cleaning time and thereby indirectly improving single-operation efficiency. IV. Optimized Staffing: Intelligent Operation Reduces Labor Dependency Previously, the client assigned four operators per vehicle (one driver, two operators, one monitoring officer)