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# Common terminology in water treatment

Sep 23, 2017

1, expansion rate:

The swelling rate of the filter layer refers to the volume expansion of the filter layer under certain backwashing strength. After the volume expansion increases the volume and volume ratio before expansion, the general expansion rate of the filter layer is 40% -50% When the viscosity of the filter medium decreases and the density decreases, a larger backwash strength must be used to achieve the same expansion rate.

2, backwash intensity:

Backwash strength refers to the amount per liter of medium (usually water or compressed air) used per unit hour of filtration per unit of time. The unit is L / m2 · S.

3, interception capacity:

Filtration capacity of the filter layer, also known as sludge capacity. Refers to the unit volume filter layer can remove the amount of suspended solids.

4, the recovery rate:

The amount of water that can be recycled is the percentage of water that is taken into the reverse osmosis unit. The recovery is calculated using the following formula:

Recovery rate (%) = product water flow / raw water flow × 100

Note: raw water flow is equal to the product flow with waste water (concentrated water) flow, both easy to measure. For example,

Fruit product flow is 0.4 gallons per minute, concentrated water flow is 3.60Gpm, should be calculated:

Recovery (%) = 100 = 10%

The denitrification amount of the reverse osmosis membrane is proportional to the TDS concentration of the raw water, irrespective of the use pressure. However, pure water production is proportional to the pressure used by the membrane. Increasing the operating pressure increases the production of water without affecting the amount of salt removed. Therefore, the higher the use of pressure means that the better the water quality, the more water production. You can consider the use of high recovery operation to reduce the operating costs of the system.

5, desalination rate:

The amount of TDS removed by the coating is called the desalination rate, expressed as a percentage, and 99% of the desalination rate means that the 99% of the soluble solids in the water are removed. Use the following formula to calculate the desalination rate:

Desalination rate (%) = TDS of raw water (TDS of product water) / TDS × 100 for raw water

The raw water TDS refers to the water content of the total dissolved solids in the water entering the filter cartridge. The product water TDS refers to the water content of the total dissolved solids of the clean water. For example, the raw water TDS is 35000 ppm and the product water TDS is 350 ppm

Desalination rate (%) = (35000-350) / 35000 × 100 = 99%