Case Background: Procurement Requirement of a Municipal Sanitation Department in Yancheng — In 2025, a municipal sanitation department in Yancheng issued a public tender to procure a batch of sewage treatment vehicles targeting urban drainage network and river remediation needs. The project budget was capped at approximately RMB 4.221 million (per publicly available tender information), primarily intended for three typical operating conditions: light-duty municipal (e.g., cleaning sewage wells in residential communities and streets), heavy-duty industrial (e.g., bypass treatment at industrial parks and wastewater treatment plants), and special operations (e.g., river sediment removal and emergency rescue). Ultimately, Chengli Special Purpose Vehicle Co., Ltd. delivered five Dongfeng Yizhan-style sewage treatment vehicles, configured with varying specifications to ensure stable performance under complex operating conditions. Customer feedback indicated excellent real-world performance, particularly regarding upper-structure durability and chassis off-road capability. Analysis of Application-Matched Solutions 1. Light-Duty Municipal Operating Condition: Flexible, Efficient, and Cost-Effective Applicable Scenarios: Cleaning of sewage wells and septic tanks in urban streets, residential communities, and commercial districts—requiring superior vehicle maneuverability, ease of operation, and environmentally compliant emissions. Recommended Specifications: Based on Chengli’s product database and MIIT announcement parameters (e.g., model CLW5070GSSD6), the light-duty municipal condition recommends the Dongfeng DOLICA chassis, with an engine displacement of 3.8–4.0 L, China VI emission compliance, water tank capacity of 5–8 m³, sewage tank capacity of 3–5 m³, equipped with a high-pressure cleaning pump (pressure ≥ 200 bar) and vacuum suction system (suction lift ≥ 8 m). Chengli’s Tailored Solution: To address Yancheng’s narrow streets and height/width restrictions, Chengli selected the Dongfeng Yizhan cab configuration, with a wheelbase of 3,308 mm and overall vehicle height ≤ 2.8 m, enabling easy access into residential communities and alleyways. The upper structure features a stainless-steel tank offering strong corrosion resistance, plus automatic discharge valves and overflow alarm systems to enhance operational safety. The budget was controlled within approximately RMB 1.055 million (unit price ~RMB 190,000, per publicly available tender data), aligning with standard procurement practices for light-duty municipal applications. Additionally, Chengli provides lifetime maintenance support, nationwide Dongfeng chassis warranty coverage, and 24-hour direct shipment of upper-structure spare parts—significantly reducing long-term operational and maintenance costs. 2. Heavy-Duty Industrial Operating Condition: High Capacity, High Strength, and Continuous Operation Applicable Scenarios: Industrial parks, wastewater treatment plants, chemical enterprises, etc.—requiring high processing capacity, extended continuous operation time, and capability to handle highly concentrated wastewater. Recommended Specifications: Per Chengli’s product database, heavy-duty applications recommend the Dongfeng Tianjin or Sinotruk HOWO chassis, with engine displacement of 6.0–6.7 L, China VI emission compliance, water tank capacity of 12–15 m³, sewage tank capacity of 8–12 m³, equipped with a high-power vacuum pump (air extraction rate ≥ 80 m³/h) and high-pressure cleaning system (pressure ≥ 250 bar); optional solid-liquid separation unit. Chengli’s Tailored Solution: For an industrial park in a district of Yancheng, Chengli delivered two heavy-duty sewage treatment vehicles based on the Dongfeng Tianjin chassis (wheelbase 4,700 mm), conforming to the announced CLW5180GSSD6 specification: 15 m³ water tank, 10 m³ sewage tank, total capacity of 25 m³—enabling single-trip treatment of large-volume wastewater. The upper structure includes hydraulic lid-flip and