I. Project Background and Requirements Identification In Q3 2025, a municipal sanitation department in a district of Yueyang City discovered during routine inspections that complaints regarding sewer blockages and septic tank overflows in aging residential communities had increased significantly. Existing vacuum suction trucks demonstrated low single-operation efficiency and were incapable of treating sewage containing solid impurities. Senior management explicitly stated at the meeting: “We require an integrated vehicle capable of simultaneous vacuum suction, solid-liquid separation, and wastewater purification—reducing secondary transportation costs, and ideally enabling direct discharge to regulatory standards or water reuse.” Preliminary market research revealed that common vacuum suction trucks (e.g., Chengli CLW5070GSSD6) only perform suction and transport, lacking on-site treatment capability; while cleaning-suction trucks offer high-pressure flushing, they also lack purification functionality. Ultimately, the Dongfeng Yizhan-style sewage treatment vehicle emerged as a strong candidate—featuring integrated vacuum suction, solid-liquid separation, flocculation sedimentation, and reclaimed water reuse, precisely matching the requirements. II. Internal Vehicle Selection: Multi-Dimensional Comparison The procurement team conducted comparative analysis across three mainstream models: | Evaluation Criteria | Dongfeng Yizhan-Style Sewage Treatment Vehicle | Conventional Vacuum Suction Truck (e.g., Chengli CLW5070GSSD6) | Cleaning-Suction Truck | |---------------------|--------------------------------------------------|----------------------------------------------------------------|-------------------------| | Functional Integration | Vacuum suction + solid-liquid separation + purification | Vacuum suction and transport only | Vacuum suction + high-pressure cleaning | | Daily Wastewater Treatment Capacity | Approx. 50–80 m³ | ~5–8 m³ per operation | ~8–12 m³ per operation | | Discharge Standard Compliance | Meets Grade III discharge standards or enables water reuse | Requires transport to wastewater treatment plant | Requires transport to wastewater treatment plant | | Unit Price (Reference Public Data) | ~¥400,000–¥550,000 | ~¥98,000–¥178,000 | ~¥150,000–¥250,000 | | Applicable Scenarios | Septic tanks, sewer blockages, emergency response | Routine suction and transport | Sewer cleaning + suction | | Upper-Structure After-Sales Service | Chengli lifetime service | Chengli lifetime service | Chengli lifetime service | After two rounds of discussion, the team reached consensus: although the Dongfeng Yizhan model carries a higher upfront cost, it reduces secondary transportation costs by approximately 60% per operation and lessens dependence on municipal wastewater treatment plants—delivering superior long-term comprehensive cost-effectiveness. This model was therefore selected as the preferred tender option. III. On-Site Inspection at Chengli Factory In mid-October 2025, a four-member procurement team led by the department head visited Chengli Automobile Industrial Park in Suizhou, Hubei Province. Chengli Sales Manager Zhang Yue (Tel: +86 ) provided full accompaniment throughout the visit. Key inspection items included: • Production Workshop: Tour of the Dongfeng Yizhan-style sewage treatment vehicle assembly line confirmed OEM Dongfeng chassis, 304 stainless steel tank body, and German-imported diaphragm pump for the upper structure; core components carry a 3-year warranty. • Live Demonstration: Simulated septic tank operation on-site completed full suction, separation, and purification within 15 minutes; effluent was clear and odorless, meeting Grade B requirements of the “Standards for Wastewater Discharged into Urban Sewer Systems” (GB/T 31962–2015). • Regulatory Compliance Documentation: Verified inclusion in the MIIT Announcement and the Tax Exemption Catalogue—exempting the vehicle from purchase tax and