Design Scheme of Water Purification Vehicle

The existing urban water plants generally use advanced treatment techniques such as sand filtration and membrane separation. All designs and constructions are based on qualified water sources or slightly polluted water sources.
Sudden pollution in water sources is generally not taken into account. Therefore, emergency water supply is a prominent issue that urgently needs to be solved in the field of water supply in China. Therefore, specific requirements have been put forward for the zoning, layout, and design of emergency water purification vehicles. Overall planning of the layout of emergency rescue water supply centers at the national level, filling the gap in China’s water supply emergency rescue capabilities.

This article covers aspects such as process flow, applicable conditions, process design, vehicle layout, and operational data. Introduced an emergency water purification vehicle with ultrafiltration and reverse osmosis as the core technologies. The water purification vehicle system adopts a water treatment process of “pretreatment+ultrafiltration+reverse osmosis” and a disinfection process of “ultraviolet disinfection+chlorine disinfection”. Has strong adaptability to raw water quality and can be directly consumed.

The process flow adopted by the emergency water purification vehicle

The basic process of the water treatment system in this project adopts “pretreatment+ultrafiltration+reverse osmosis”. The disinfection process adopts “ultraviolet disinfection+chlorine disinfection”, and the process flow is shown in Figure 1.

Pre treatment of raw water by emergency water purification equipment can reduce the turbidity of raw water, remove some suspended solids, and remove sand. Reduce the burden of subsequent processing technology.The pre-treatment part of this project adopts the process of “dosing flocculation (tubular mixer)+two-stage cyclone sand remover+self-cleaning filter“.

Pre treated water enters the ultrafiltration section. It can effectively remove impurities such as suspended solids, colloidal particles, and bacteria from water. It is a pre-treatment process for reverse osmosis technology.

The reverse osmosis unit is the core of the emergency water purification device. Further deep desalination treatment of ultrafiltration produced water.The production water adopts the process of “ultraviolet disinfection+chlorine disinfection”. The ultraviolet disinfection time is short, and the produced water may be contaminated again by microorganisms. Not conducive to water storage. Therefore, chlorine disinfection is also required for water production.

Applicable conditions for emergency water purification vehicles

The post disaster water source has great uncertainty. The emergency water purification device has strong adaptability to the quality of raw water.
Not limited to surface water or groundwater. Can handle high turbidity, slightly polluted water, brackish water, low-temperature low turbidity water, high algae water and other raw water. The specific water quality requirements for adapting to raw water are as follows.

  • High algae water: The total number of algae cells in the original water is ≤ 10 million per L.
  • Bitter and saline water: Total dissolved solids ≤ 10000 mg/L.
  • High turbidity water: sand content ≤ 100 kg/m3.
  • Low temperature and low turbidity water: The water temperature is (4 ± 2) ℃, and the turbidity is ≤ 10 NTU.
  • Micro polluted surface water: CODMn ≤ 10 mg/L, odor and odor ≤ level 5.

The water quality of the produced water meets the “Hygienic Standards for Drinking Water” (GB 5749-2006) and can be directly consumed. Water production capacity: The water purification vehicle has sufficient emergency water supply capacity, and each device has a water production capacity of ≥ 5m3/h (water temperature ≥ 4 ℃).

Emergency water purification vehicle process design

The pre-treatment section mainly includes the raw water tank, booster pump, chemical dosing system, tubular mixer, secondary cyclone sand remover, and self-cleaning filter. The main design parameters are as follows.

Tubular mixer. Main function: Fully mix the flocculant with water. Design parameters: DN80, L=700 mm.

Secondary cyclone sand remover. Main function: As a pre-treatment part for treating high turbidity raw water, the secondary cyclone sand removal has two cyclone sand removal devices. Through secondary swirling flow, the sand removal rate can reach 80%. Design parameters: The designed processing capacity is 15.4m3/h, and the inlet pressure is 220 kPa. The single-stage pressure loss is 10 kPa, and the recovery rate is 90%. For high turbidity raw water, ensure that the effluent is less than 100 NTU.

Self cleaning filter. Main function: to intercept small particles in the raw water. Design parameters: The designed processing capacity is 13.86m3/h, and the filtration accuracy is 200 μ m. The inlet pressure is 200 kPa, and the pressure loss is 50 Kpa. The turbidity removal rate is 80%, and the recovery rate is 99%.

Other parts

  • System UF unit. Main function: pre-treatment process for reverse osmosis process. Effectively remove impurities such as suspended solids, colloidal particles, and bacteria from water.
  • Design parameters: The number of membrane columns is 3, and the designed water production is 11.09m3/h. The designed membrane flux is 52.91 L/(m2 ∙ h), and the membrane material is PVDF. The average membrane pore size is 0.02 μ m, and the membrane form is a hollow fiber membrane. The designed blowing air volume is 12m3/(branch ∙ h) and can withstand a pH value of 2-12. The applicable water temperature is 4~40 ℃, and the filtration method is cross flow filtration. The effluent turbidity is 0.1 NTU, and the recovery rate is ≥ 90%.
  • Reverse osmosis unit. The reverse osmosis part mainly includes high-pressure pump, reverse osmosis unit, and intermediate water tank.
  • High pressure pump. Main function: The main function of the high-pressure pump is to pressurize the water in the intermediate water tank to the pressure required by the reverse osmosis process and send it to the subsequent treatment process. Design parameter: Q=12m3/h, H=150 m,N=11 kw。 The pump body material is 304 stainless steel.
  • Reverse osmosis membrane assembly. Main function: This section performs desalination treatment on ultrafiltration produced water to ensure clean water quality. The reverse osmosis device meets the drinking water quality standards, as shown in Figure 2.

Design parameters: The designed water yield is 5m3/h, and the desalination rate is>99%. The recovery rate is 45-75%, and the design flux is 18.38 L/(m2 ∙ h). The reverse osmosis level is first level reverse osmosis, equipped with a maintenance cleaning system. The water temperature is between 4 ℃ and 40 ℃, and the membrane form is a coiled membrane. The tolerance pH value is 2-12, with 4 pressure vessels and 2 components per container.

Vehicle layout and functional division

The overall size of the water purification vehicle is: 10000 mm x 2500 mm x 3 980 mm (L x W x H). The maximum size inside the compartment is: 7 590 mm x 2 390 mm x 2 400 mm (the height inside the equipment area is 2 300 mm).
The functional areas for compartment space design (Figure 3) include: cockpit, generator compartment, control equipment compartment, water purification equipment compartment, portable equipment storage compartment, spare parts storage area, and roof platform area.