I. Tender Background: Practical Requirements of a Municipal Sanitation Department In Q3 2025, a municipal sanitation department in Liuzhou City, Guangxi Province, issued a public tender notice for 'Blue License Plate Sewage Treatment Vehicles.' This department is responsible for maintenance and emergency response of stormwater and sewage pipelines across the urban area and surrounding towns. Due to aging equipment and non-compliant emissions, it urgently needed to procure a batch of light-duty sewage treatment vehicles meeting China VI emission standards—capable of maneuvering flexibly through narrow urban alleys. According to the public tender information, the budget was capped at approximately RMB 316,000 per unit, with two units planned for procurement. The tender documents explicitly specified the following key requirements: Chassis Requirements: Blue license plate chassis from the Dongfeng series, with a gross vehicle weight not exceeding 4.5 tons—operable with a Class C1 driver’s license. Tank Body & Coating: The tank body must be fabricated from high-strength, corrosion-resistant material, featuring an anti-rust coating process specifically engineered for southern China’s hot, humid climate—ensuring no visible rust formation within five years under prolonged exposure to sewage and high humidity. Sealing Component Durability: Considering Liuzhou’s frequent rainy season and high ambient humidity, all pipeline connections and sealing components must maintain reliable performance for no less than three years in humid conditions, with easy replacement capability. Operational Capability: Must support sewage suction, solid-liquid separation, and wastewater recirculation/reuse functions; capable of continuous operation for over eight hours without failure during periods of high rainfall frequency. After-Sales Service: Chassis must be covered by nationwide warranty; superstructure must be supported by lifetime service, with spare parts shipped directly within 24 hours. II. Chengli’s Technical Response Proposal: Customized Design Based on CLW5070GSSD6 Announcement In response to the above tender requirements, Chengli Special Purpose Vehicle Co., Ltd. (hereinafter referred to as 'Chengli') developed a fully customized technical solution based on its Dongfeng D6 chassis and the CLW5070GSSD6 model announcement. 1. Chassis & Powertrain Configuration: Equipped with the Dongfeng D6 series blue license plate chassis, powered by a Quanchai Q23-115E60 engine (115 hp), mated to a 5-speed manual transmission—fully compliant with China VI emission standards. Overall vehicle dimensions strictly adhere to blue license plate specifications (L × W × H = 5995 mm × 2000 mm × 2650 mm); operable with a Class C1 driver’s license—ideal for narrow urban road operations. 2. Anti-Rust Coating & Tank Design: Tank constructed from Q235B carbon steel plate, internally coated with three layers of epoxy resin corrosion-resistant paint, and externally finished with polyurethane weather-resistant topcoat—implementing a 'three-coat-one-bake' process. This effectively resists acidic/alkaline corrosion from sewage and degradation caused by southern China’s high-humidity environment. According to Chengli’s technical documentation, this coating system extends corrosion resistance life by approximately 40% compared to standard coatings under humid conditions. 3. Sealing Component Durability Optimization: To address Liuzhou’s rainy-season characteristics, Chengli selected composite sealing components made of Nitrile Butadiene Rubber (NBR) and Fluoroelastomer (FKM) for all critical hydraulic lines, suction inlets, and discharge valves—and added protective dust covers. The manufacturer guarantees a service life of 3–4 years for these seals under normal operating conditions in humid environments, with rapid replacement capability. 4. High-Load Operational Performance: Fitted with a high-capacity vacuum pump (suction rate ≥120 m³/h) and an integrated solid-liquid separati