Case Background: In June 2025, a municipal sanitation department in a district of Shaoxing City launched a procurement project for a 3308-type sewage treatment vehicle, with a budget capped at approximately RMB 482,000. The tender required a vehicle integrating sewage suction, solid-liquid separation, and automatic discharge functions—intended for emergency dredging and routine maintenance of industrial park and urban sewage networks. Following a public tender, Chengli Special Purpose Vehicle Co., Ltd. delivered the EHY5045TWCE6 sewage treatment vehicle (chassis model: Dongfeng 3308 wheelbase). Customer feedback indicated stable performance under high-load operations during the rainy season, particularly praising the corrosion-resistant coating and durability of sealing components in humid, hot environments. This case study details the vehicle selection rationale and key configuration considerations for reference by similar procurement entities. Tank Capacity Selection: How to Choose Among 3 m³, 5 m³, 8 m³, and 12 m³ Models? Tank capacity directly determines daily operational efficiency and application scope. According to Chengli’s product database (CLW series official announcement parameters—e.g., analogous logic to CLW5070GSSD6 water-sprinkling vehicle models), mainstream sewage treatment vehicles on the market currently feature tank capacities ranging from 3 m³ to 12 m³. Considering Shaoxing’s rainy and humid climate, capacity selection must prioritize the following factors: 3 m³ (Blue License Plate): Suitable for small-scale operations such as streets and residential communities; daily processing capacity approx. 20–30 tons; ideal for budget-constrained or low-frequency operation units. Based on publicly available tender data, the landed price for blue-plate 3 m³ models ranges from RMB 103,000 to 138,000. 5 m³ (Yellow License Plate): Suitable for industrial parks or medium-scale pipeline maintenance; daily processing capacity approx. 40–60 tons; recommended for this case. Customers reported that this model strikes an optimal balance between maneuverability and efficiency, and remains less prone to operational bottlenecks during high-load rainy-season operations. 8 m³ (Yellow License Plate): Suitable for main urban roads or municipal emergency response; daily processing capacity approx. 70–100 tons; however, operators must hold a Class B2 driver’s license. Per local procurement practice, the budget for 8 m³ models is typically controlled within RMB 287,000–344,000. 12 m³ (Yellow License Plate): Suitable for large-scale wastewater treatment plants or centralized service areas; daily processing capacity exceeds 120 tons; however, it demands higher chassis specifications, and accelerated aging of sealing components under humid, hot conditions requires special attention. Selection Recommendation: The Shaoxing project ultimately selected the 5 m³ model, primarily based on alignment with operational demand (approx. 50 tons/day) and budget constraints (≤ RMB 482,000). Prior to bidding, Chengli Sales Manager Zhang Yue (Tel: +86 ) emphasized in the technical proposal that upgrading the vacuum pump and filtration system on the 5 m³ version could significantly enhance efficiency—eliminating the need for overinvestment in larger-capacity models. Daily Operational Volume Calculation Formula and Matching Workload Table To ensure precise vehicle selection, procuring entities should apply the following formula to estimate daily operational volume: Daily Operational Volume (tons/day) = Single-Operation Capacity (tons) × Daily Operation Frequency × Efficiency Factor (0.8–0.9, accounting for loading/unloading and transfer time) For example, a 5 m³ sewage treatment vehicle processes 5 tons per operation, performs 10 operations per day (including round-trip travel), and applies an efficiency factor of 0.85. Thus, daily processing volume = 5 × 10 × 0.85 = 42.5 tons.