Government Procurement Case and Bid-Winning Solution Analysis of the CN6 Dongfeng Sewage Treatment Vehicle with 3308 mm Wheelbase in Lanzhou. In Northwest China—especially around Lanzhou—urban drainage network maintenance and sewage treatment tasks are heavy, while the region faces unique climatic challenges including strong sandstorms, dry air, and large day-night temperature fluctuations. Under such operating conditions, selection of sanitation vehicles affects not only operational efficiency but also long-term equipment reliability and maintenance costs. This article analyzes, based on actual procurement records over the past two years from a municipal sanitation department in Lanzhou (hereinafter referred to as 'the Municipal Sanitation Department'), why it has selected the same supplier—Chengli Special Purpose Vehicle Co., Ltd.—for three consecutive procurements, and focuses on dust-proof design and filter system maintenance solutions for operations in desertified areas. I. Procurement Background and Project Overview The Municipal Sanitation Department of Lanzhou is responsible for urban drainage network maintenance, sewage lift station operation, and emergency flood control within its jurisdiction. As urban infrastructure ages, frequent siltation and leakage issues occur in aging pipelines. Conventional vacuum trucks can only handle simple liquid sewage suction and cannot cope with complex working conditions involving high sludge content, high sand content, or even solid impurities. After preliminary research and technical evaluation, the department decided to procure integrated sewage treatment vehicles capable of 'vacuuming, separation, dewatering, and transportation' to achieve volume reduction and harmless treatment of sewage. Between 2023 and 2025, the department procured the CN6 Dongfeng sewage treatment vehicle with 3308 mm wheelbase, manufactured by Chengli Special Purpose Vehicle Co., Ltd., on three separate occasions, with a total delivery of six units and a cumulative contract value of approximately RMB 2.3 million (based on publicly available tender information). Specific procurement batches are as follows: Procurement Batch | Procurement Date | Quantity | Budget Control (Reference) | User Feedback ---|---|---|---|--- First Batch | June 2023 | 2 units | ~RMB 360,000/unit | After six months of initial operation, users reported high separation efficiency but requested enhanced dust sealing. Second Batch | March 2024 | 2 units | ~RMB 370,000/unit | Based on feedback from the first batch, Chengli provided free upgrades to dust-sealing components and the air filtration system. Third Batch | October 2025 | 2 units | ~RMB 380,000/unit | Directly specified the improved configuration from the second batch and proceeded with additional procurement. As shown in the table above, the department’s procurement budget remained stable at approximately RMB 400,000–423,000 per unit, with consistent order volumes year-on-year. Notably, the third batch directly adopted the upgraded configuration introduced in the second batch—clear evidence of the client’s strong confidence in Chengli’s products and services. II. Special Operational Challenges in Desertified Areas and Chengli’s Solutions Lanzhou lies at the transitional zone between the Loess Plateau and the Qinghai-Tibet Plateau and features a typical temperate continental climate, characterized by frequent sandstorms in spring and dry, cold winters. Such environmental conditions impose stringent requirements on sewage treatment vehicles’ dust-proof sealing, filtration systems, and cold-weather engine starting performance. 1. Dust-Proof Sealing: From 'Prone to Dust Ingress' to 'Fully Sealed' During the first post-delivery follow-up visit, operators from the Municipal Sanitation Department of Lanzhou reported that, during nighttime or sandstorm operations, dust accumulation occurred at locations including pipeline joints between chassis and upper structure, hydraulic oil ta