Guiyang Dongfeng D6 Sewage Treatment Vehicle (Blue License Plate) Government Procurement Case: In-depth Analysis of Capacity Selection and Winning Bid Solution In Southwest China—especially in humid, rainy cities like Guiyang—the demand for sewage treatment vehicles among municipal sanitation departments is growing increasingly urgent. In 2026, the Urban Management Bureau of a district in Guiyang City publicly tendered for multiple blue license plate sewage treatment vehicles to support aging pipeline renovation and emergency rain-season drainage tasks. Chengli Special Purpose Vehicle Co., Ltd. delivered Dongfeng D6 chassis-based CLW5070GSSD6 model sewage treatment vehicles. Customers reported outstanding durability of sealing components and superior anti-corrosion performance under hot, humid conditions. This article uses this case as a starting point and provides procurement guidance across four dimensions: capacity selection, daily operational volume calculation, workload matching table, and FAQ. Capacity Selection: How to Choose Among 3 m³ / 5 m³ / 8 m³ / 12 m³? Blue license plate sewage treatment vehicles—drivable with a Class C1 driver’s license and subject to fewer urban traffic restrictions—are the preferred choice for street-level environmental maintenance units. However, tank capacity directly determines operational efficiency and cost-effectiveness. According to Chengli’s product database, the Dongfeng D6 chassis supports tanks ranging from 3 m³ to 5 m³; 8 m³ and 12 m³ tanks require upgraded yellow license plate chassis (e.g., Dongfeng Duolika or Sinotruk HOWO). In the Guiyang case, the district’s Urban Management Bureau primarily procured 5 m³ models, striking an optimal balance between maneuverability and per-trip capacity. Core Selection Principles: 3 m³ Tank: Suitable for narrow alleys and localized unclogging in old residential communities. Based on publicly available tender data, the unit price is approximately RMB 98,000—ideal for street-level units operating under tight budgets. 5 m³ Tank: Balances routine maintenance and emergency response needs. In the Guiyang case, this model achieves 6–8 trips per day. Equipped with Chengli’s proprietary anti-corrosion coating and durable sealing design, it reliably withstands high-humidity environments. 8 m³ Tank: Designed for continuous operations along major road networks (e.g., trunk pipeline systems). Local procurement practice indicates budget control within RMB 227,000–280,000. 12 m³ Tank: Intended for large industrial parks or municipal trunk lines; requires a Class B2 driver’s license and carries a unit price of approximately RMB 240,000–298,000. The Guiyang project placed special emphasis on anti-corrosion coating: Chengli applied an epoxy resin + polyurethane composite coating to the tank interior. Salt-spray testing confirmed a 30% service life extension under 90% relative humidity. Fluoroelastomer (FKM) seals were selected to prevent premature aging and leakage during frequent rainy-season operations. Customer feedback: “After six months of use, no corrosion observed on the tank body, and the vacuum pump seals remain fully intact.” Daily Operational Volume Calculation Formula: How to Assess Real-World Efficiency? Prior to procurement, precise calculation of daily operational volume is essential—to avoid either 'just sufficient but overloaded' or 'underutilized capacity.' General formula: Daily Operational Volume (m³/day) = Effective Single-Trip Capacity (m³) × Daily Trip Frequency × Effective Utilization Rate Parameter Definitions: Effective Single-Trip Capacity: The actual volume of wastewater that can be suctioned or transported—typically 85%–90% of the nominal tank capacity (accounting for vacuum reserve and foam space). Daily Trip Frequency: Constrained by driving time, suction/discharge duration, and maintenance intervals. Under normal conditions, a 5 m³ vehicle completes 6–8 trips per day; an 8 m³ vehicle—with longer loading/unloading c