Xi'an 3308 Yellow-Plate Sewage Treatment Truck Government Procurement Case and Bid-Winning Solution Analysis In autumn 2025, a municipal sanitation department issued a public tender notice for 3308 yellow-plate sewage treatment trucks to address sewage treatment requirements across Xi'an and its surrounding regions. This project aims to replace a batch of aging diesel special-purpose vehicles compliant with China's National III/National IV emission standards and meet increasingly stringent local environmental operation standards. After multiple rounds of technical evaluation and commercial negotiation, Chengli Special Purpose Vehicle Co., Ltd. (hereinafter referred to as "Chengli") was ultimately selected as the winning supplier, delivering the CLW5180GSSD6 model sewage treatment truck specifically adapted to local operating conditions. This article provides an in-depth analysis of the case from perspectives including policy background, technical solution, cost analysis, and regional adaptability. I. Policy Background: Transition to National VI Standards and Phased-Out Timeline for Older Vehicles Since 2021, China’s National VI emission standard has been fully implemented nationwide. As a key region, Xi’an has set clear requirements for phasing out and replacing in-use vehicles. According to publicly available information from local environmental authorities, diesel special-purpose vehicles meeting National III or lower emission standards must be retired by the end of 2024, while National IV vehicles are scheduled for gradual phase-out by 2026. The newly procured 3308 yellow-plate sewage treatment trucks are primarily intended for urban sewer network cleaning, septic tank suction, and emergency drainage operations. Many National IV chassis vehicles in the existing fleet are approaching restrictions on operation or mandatory scrapping. Consequently, the procurement authority required all newly purchased vehicles to comply with the National VIb emission standard and demonstrate high reliability and extended maintenance intervals to withstand the harsh, high-dust, high-sand conditions typical of desertified regions. According to the tender documents, the project budget was capped at approximately RMB 400,000, with plans to procure two units at an estimated unit price of RMB 170,000–180,000 (based on publicly disclosed tender information). In the technical evaluation criteria, "chassis emission standard" and "upper-structure sealing performance" each accounted for 15% weight, underscoring dual emphasis on environmental compliance and regional adaptability. II. Chengli’s Winning Solution: Detailed Overview of the CLW5180GSSD6 Model The CLW5180GSSD6 model delivered by Chengli is built upon the Dongfeng Tianjin chassis, powered by a Yuchai 180-horsepower National VI engine, and features a fully enclosed tank body with a dust-proof sealing system. This vehicle precisely matches Xi’an’s actual operational requirements across multiple dimensions. 1. Dust-Proof Sealing: Addressing High-Dust Environments in Desertified Regions Although Xi’an lies within the Guanzhong Plain, neighboring areas such as Weinan and Tongchuan experience persistent sandstorms and elevated airborne particulate concentrations. To counter this, Chengli added dual-layer sealing gaskets to both the tank top and side doors of the CLW5180GSSD6, and installed dust shields at the power take-off (PTO) and vacuum pump interfaces—effectively preventing external dust ingress into the hydraulic system during operation. Customer feedback indicates that, after one month of intensive daily use, no hydraulic valve jamming or seal failure attributable to dust contamination occurred. 2. Adaptability to Desertified Region Operations: Reinforced Chassis and Filtration System To cope with frequent sandstorms and high ambient temperatures common in desertified regions, Chengli equipped this model with a desert-grade air filtration system and optimized the cooling fan’s thermal di