I. Case Background: Municipal Wastewater Treatment Requirements in a Humid and Hot Environment In 2025, the Urban Management Bureau of a district in Chengdu issued a public tender to procure one 3308 wastewater treatment vehicle (model EHY5045TWCE6) to address insufficient supporting wastewater treatment facilities in aging urban residential communities and industrial parks. This vehicle is primarily used for emergency domestic wastewater treatment during high-load rainy seasons, septic tank cleaning, and purification of river discharge outlets. According to publicly available tender information, the project budget was capped at approximately RMB 512,000, and Chengli Special Purpose Vehicle Co., Ltd. was awarded the contract. Customer feedback indicates that Chengdu experiences high summer temperatures and abundant rainfall, with relative humidity consistently exceeding 80%. This poses severe challenges to the anti-corrosion performance and sealing component durability of wastewater treatment vehicles. Conventional models tend to suffer from tank and pipeline rusting, as well as accelerated aging of hydraulic seals, resulting in persistently high maintenance costs. Consequently, the procurement specifications explicitly emphasized requirements such as “anti-corrosion coating process” and “reliability for continuous operation under humid and hot conditions.” II. Vehicle Specifications and Configuration Overview The delivered EHY5045TWCE6 wastewater treatment vehicle is built upon Chengli’s mature special-purpose vehicle modification platform. Its chassis adopts a Dongfeng series (referencing technical parameters from announcement models such as CLW5070GSSD6), equipped with a China VI-compliant engine. Key configurations include: • Tank Capacity: Approximately 3.3 m³; double-layer anti-corrosion coating—epoxy resin lining on the interior surface and hot-dip galvanizing on the exterior—to withstand high-humidity environments. • Sealing System: Oil- and hydrolysis-resistant fluororubber O-rings, offering ~40% longer service life than standard rubber seals, capable of continuous 8-hour operation in environments with >90% humidity. • Operational Efficiency: Equipped with a self-priming sewage pump, achieving a maximum suction depth of 6 meters; average single-operation cycle time is ~20 minutes—suitable for small-to-medium-scale emergency treatment tasks. • Announcement Model: EHY5045TWCE6, China VI emission standard, nationally registerable. Per local procurement practice, the unit price of this vehicle is approximately RMB 420,000 (tax-inclusive landed cost), covering the superstructure, chassis, and first-year insurance. As a direct manufacturer, Chengli provides after-sales commitments including “original-chassis nationwide warranty” and “lifetime service for the superstructure”—particularly critical in humid regions. In cases of seal aging or localized coating damage, replacement parts can be shipped directly within 24 hours, minimizing downtime. III. Total Cost of Ownership (TCO) Analysis: 5-Year / 8-Year / 10-Year The following TCO estimates are based on real-world data from Chengli’s proprietary knowledge base (e.g., fuel consumption and maintenance intervals for models such as CLW5070GSSD6), combined with typical operational frequency in Chengdu. Assumptions: average annual operating days = 200; average daily diesel consumption ≈ 18 L (diesel price = RMB 10/L). Cost Item 5 Years (RMB 10,000) 8 Years (RMB 10,000) 10 Years (RMB 10,000) Acquisition Cost (Tax-Inclusive Landed Price) 42 42 42 Fuel Cost (Avg. ~RMB 27,000/Year) 13.5 21.6 27 Scheduled Maintenance (Every 5,000 km; Avg. ~RMB 3,000/Year) 1.5 2.4 3 Major Overhaul Costs (Year 5 / Year 8 /