surface water treatment plant

Gravity valveless filter is a commonly used filtration equipment in water treatment systems, mainly used to remove suspended solids, particles, microorganisms and other impurities in water. Its working principle is based on the action of gravity and the filtration effect of the filter medium.

 

 

 

1、 Working conditions

Operating at room temperature and pressure, power supply voltage: AC220V.

 

2、 Equipment composition

Gravity valveless filters are typically composed of the following components:

Filter material layer: The filter material layer is a key part of the filter tank, usually using multi-layer filter materials such as sand, quartz sand, activated carbon, etc. These filter media can effectively filter suspended and particulate matter in water, while providing sufficient surface area for microbial attachment and degradation of organic matter.

 

Water inlet: Water enters the filter through the inlet, which is usually located at the top of the filter.

 

Water outlet pipe: The water filtered by the filter material layer is discharged from the outlet pipe, which is usually located at the bottom of the filter tank and is discharged by gravity.

 

Gravity valveless filters do not have control valves, and their operation relies on gravity flow. Water enters the filter tank from the inlet and passes through the filter material layer under the action of gravity. The filter material intercepts impurities in the water, and purified water flows out from the outlet pipe. When the accumulation of impurities in the filter material layer reaches a certain level, it is necessary to clean or replace the filter material.

 

It has the advantages of simple structure and low maintenance cost, and is suitable for small and medium-sized water treatment systems, such as household tap water filters, agricultural irrigation systems, pre-treatment in industrial production processes, etc.

 

3、 Working principle

The structure of a valveless filter is shown in the following figure. Like a regular filter, its operation can be divided into two processes: filtration and flushing. During the filtration process, due to the blockage of the filter layer, the water flow resistance continues to increase, causing the water level above the filter to increase. After reaching a fixed value, the filter tank is siphoned and backwashed using the principle of water falling and air extraction on the filter, and the intake is used to break the siphon, thus terminating the backwashing process.

 

When the resistance of the filter layer has not reached the maximum allowable value and needs to be manually flushed, forced backwashing can be carried out. The principle is to connect a pressure water pipe to the upper part of the tee connected to the auxiliary pipe and the exhaust pipe, and use the pressure water to form a high vacuum and high flow rate to quickly form the siphon phenomenon required for backwashing. There is a conical shape at the outlet of the lower end of the siphon, and the backwashing intensity is controlled by adjusting the height of the conical shape.

 

After entering the water distribution tank, the raw water enters the siphon riser through the inlet pipe, and is evenly distributed on the filter material layer through the baffle under the top cover. The filtered water rises to the flushing water tank through the connecting channel and flows into the clean water tank through the overflow weir. As the filtration time increases, the head loss of the filter material layer gradually increases, and the water level in the siphon rising pipe correspondingly increases. When the water level rises to the mouth of the siphon auxiliary pipe, water flows down from the auxiliary pipe, and the vacuum formed in the pipe drives the water flow in the descending pipe together, causing a sharp increase in vacuum in the pipe and forming a backwash. When the water level in the water tank drops to the siphon breaking bucket, the flushing ends and the filtration starts again.