I. Policy Context: Transition to National VI Emission Standards and Phasing-Out Timeline for Older Vehicles In recent years, with the State’s continuous intensification of atmospheric pollution prevention and control efforts, the National VI emission standards for heavy-duty diesel vehicles have been fully implemented nationwide. According to the ‘Notice on Implementation of National VI Emission Standards for Heavy-Duty Diesel Vehicles’, jointly issued by the Ministry of Ecology and Environment and other departments, the National VI emission standards for heavy-duty diesel vehicles took full effect across China starting July 1, 2021. This means that previously widely deployed sanitation vehicles meeting National V or lower emission standards are now under increasing pressure to be gradually phased out or upgraded. Specifically in Yueyang City, the local Urban Management Bureau and sanitation departments actively responded to this policy and formulated a phased-out timeline for older vehicles: all National III-emission sanitation vehicles must be retired by the end of 2023; National IV vehicles must be replaced or retrofitted by the end of 2025; and early replacement of National V vehicles is encouraged, with eligibility for local fiscal subsidies. This timeline directly prompted a municipal sanitation department in Yueyang to launch its 2024 sanitation vehicle procurement plan, which included one National VI Dongfeng sewage treatment vehicle with a 3308-mm wheelbase for river dredging and sewage treatment operations. II. Project Background and Procurement Requirements A municipal sanitation department in Yueyang (hereinafter referred to as the ‘Procuring Entity’) faced challenges including sediment accumulation and sewage treatment issues in multiple rivers and stormwater pipelines within its jurisdiction, necessitating procurement of a specialized vehicle capable of high-efficiency sludge suction, solid-liquid separation, and sewage purification. Following preliminary research, the Procuring Entity specified the following requirements: – Chassis must be based on the Dongfeng 3308-mm wheelbase and comply with National VI emission standards to ensure regulatory compliance for road operation and long-term use; – Sewage treatment capacity must be no less than 30 m³/hour, with automatic unloading functionality; – Tank volume must be no less than 8 m³, fabricated from high-strength steel plate; – The complete vehicle must be listed in the MIIT’s Announcement of Road Motor Vehicle Manufacturers and Products, enabling normal registration, annual inspection, and commercial operation licensing. The project budget was capped at approximately RMB 497,000 (based on publicly available tender information), with procurement conducted via open tender. After multiple rounds of evaluation, Chengli Special Purpose Vehicle Co., Ltd. was selected to deliver the solution. The vehicle is now operational at a sewage treatment facility in Yueyang. III. Chengli’s National VI Solution: Dongfeng 3308-mm Wheelbase Sewage Treatment Vehicle – Detailed Overview To meet this project’s requirements, Chengli Special Purpose Vehicle developed the CLW5070GSSD6 sewage treatment vehicle, built upon the Dongfeng 3308-mm wheelbase chassis (note: this model number is covered under the MIIT Announcement and reflects the configured chassis; the delivered unit is a customized version). Key specifications include: – Chassis: Dongfeng Dorica D6 series, 3308-mm wheelbase, equipped with a Yuchai 140-hp National VI diesel engine, fully compliant with emission regulations; – Superstructure: 8-m³ tank (high-strength steel plate), fitted with vacuum pump, high-pressure cleaning pump, solid-liquid separator, and sewage purification system; – Functions: Capable of sludge suction, discharge, high-pressure cleaning, and sewage filtration/purification—ensuring high operational efficiency; – Warranty & Support: Dongfeng chassis covered by nationwide joint warranty; Chengli superstru