Government Procurement Case and Bid-Winning Solution Analysis for the Dongfeng D6 Blue License Plate Sewage Treatment Vehicle in Guangzhou This spring, a municipal sanitation department in a district of Guangzhou faced an urgent challenge: low sewage pumping efficiency at multiple flood-prone locations within its jurisdiction, coupled with frequent failures of aging equipment—necessitating the acquisition of highly maneuverable sewage treatment vehicles suitable for narrow urban roads. Following preliminary research, the department focused on blue license plate sewage treatment vehicles built on the Dongfeng D6 chassis and adopted a 'trial-use-before-bulk-procurement' model. This article fully documents the procurement decision-making process for reference by sanitation authorities nationwide. I. Project Background: Why Choose a Blue License Plate Sewage Treatment Vehicle? Guangzhou is located in South China, where the rainy season is long and precipitation is highly concentrated; urban flooding and sewage pumping constitute an annual operational challenge. Most of the department’s existing equipment consisted of yellow license plate large-scale vacuum trucks exceeding 8 meters in length—making them difficult to maneuver through narrow streets in old residential communities, urban villages, and commercial districts, while also facing license plate restrictions. In contrast, blue license plate sewage treatment vehicles (gross vehicle weight ≤ 4.5 tons) can be operated with a Class C1 driver’s license, are exempt from traffic restrictions, and offer superior agility across the urban core. After initial screening, the department selected Chengli special-purpose vehicles—modified on the Dongfeng D6 chassis—for trial use. II. Trial Phase: Real-World Performance of One Unit Under Humid, Hot Conditions In June 2025, the department purchased one Dongfeng D6 blue license plate sewage treatment vehicle (model series referenced from CLW5070GSSD6 technical platform, tank capacity approx. 3–4 m³) from Chengli Special-Purpose Vehicle Co., Ltd. (No. 1 Chengli Avenue, Economic Development Zone, Suizhou City, Hubei Province), deploying it for routine inspection and emergency pumping operations. The trial period lasted three months, focusing on evaluation of the following three key performance indicators: 1. Anti-Corrosion Coating: Resistance to High Humidity and Salt Fog Guangzhou’s relative humidity consistently exceeds 80%, and its proximity to the coast poses significant salt fog corrosion risks. The vehicle’s tank features a reinforced epoxy resin anti-rust coating, with an additional polyurethane topcoat applied externally. During the trial, the vehicle underwent only basic post-operation cleaning using a high-pressure water jet—no special maintenance was performed. After three months, inspections revealed no visible rust spots at weld seams, flange connections, chassis frame rails, or rear axle components; paint adhesion remained excellent. By comparison, a previously used vacuum truck from another brand (lacking specialized coating) developed localized rust spots after just two months under identical environmental conditions. 2. Sealing Component Durability: Rubber Aging Test Under Humid-Hot Conditions Reliable sealing of pipelines and valves is critical for sewage treatment vehicles. This unit employs fluorocarbon rubber (FKM) O-rings—resistant to oil and acidic/alkaline media—supplemented with dust covers. Throughout the trial, the vehicle operated continuously for 10 days during heavy rainfall, averaging over six hours of daily operation while handling sludge-laden, oily, and chemically contaminated wastewater. No leakage, hardening, or swelling-induced failure occurred in any sealing components; vacuum pump air extraction rates remained consistently above standard specifications. The driver reported: “With our previous vehicle, we had to replace seals weekly during the rainy season—but this one hasn’t required any seal repl