All the equipment AWT proposes for our customers are products with the best cost performances created by considering all factors for reducing costs, such as the non-chemical dosing method, implementing power recovery devices, and analyzing the qualities of various raw water sources.



Cost variances between non-chemical dosing equipment and chemical-dosing equipment
The chemical-dosing method requires the injection and refilling of chemicals. Injection costs are 40 - 60 yen/m³, which would accumulate to approximately the same amount as replacing the RO membrane in 2 years. On the other hand, the non-chemical dosing method is easy to operate, and maintenance management work can be implemented without requiring any dedicated engineer, which therefore enables reduced running costs. The unit cost for producing water for 1 m³ would be less than 100 Yen.

Comparison of cost required between chemical-dosing method and non-chemical dosing method when desalinating seawater of 1,000 m³/d
Item Chemical dosing method Non-chemical dosing method
Pre-chlorination ￥9.8 ￥0.0
Flocculating agent ￥1.8 ￥0.0
Neutralizing agent ￥5.8 ￥0.0
Scale inhibitor ￥25.5 ￥0.0
pH conditioning agent ￥1.8 ￥0.0
Treated water chlorine sterilizing agent ￥1.4 ￥1.4
  ￥46.1 ￥1.4



Reducing energy costs by
using energy saving devices
AWT’s equipment is equipped with energy-saving pumps with a device that generates powerful exhaust pressure that can reduce energy consumption by 35–50% compared with conventional equipment. Additionally, the new superior recovery system can reduce energy consumption by as much as 60%.

Electricity cost for the energy- saving system per 1 m³ (Unit: kWH/m³)
Treated water volume No energy-saving Energy-saving pump New energy recovery system
50m³/d 6.63 4.41 -
100m³/d 6.47 4.11 2.55
200m³/d - 4.38 2.43
300m³/d - 4.34 2.37
500m³/d - 4.27 2.29
1,000m³/d - 4.14 2.21
2,000m³/d - 4.08 2.13


*1The figures shown above show the electricity cost for the main body of the seawater desalination plant only.
*2There are no non-energy-saving models with a capacity above 200 m³/day.
*3The new system cannot be applied for the models with a capacity below 50 m³/day.


Cost variance due to
the quality of the raw water
For cases where the raw water is well water or river water, the running costs may vary significantly due to the water quality. Running costs may increase due to the following five factors.


   
  The density of the total dissolved solid (TDS)  
  When the TDS of the raw water is small, the motor can be small-sized
When the TDS of the raw water is high, the motor needs to be large-sized

  
  Recovery rate (the ratio between the raw water volume and the treated water volume)  
  If the recovery is set to a low rate, electricity costs rise.
If the recovery is set to a high rate, electricity costs fall.
If the recovery is set to too high a rate, electricity costs rise significantly.

  
  Interfering minerals in the raw water  
  Depending on the ratio (ingredient composition) of calcium, magnesium, bicarbonates,
and sulfates, a scale inhibitor will be required, and costs may rise.

  
  Total iron and manganese content  
  These substances need to be removed before being fed into the reverse osmosis membranes,
requiring pre-treatment units.

  
  Silica content  
  Silica is removed (concentrated) by the reverse osmosis membranes.
It adheres to the RO membrane surface as an ingredient for glass, and cannot be washed away.
As a general rule, silica content in raw water needs to be below 50 PPM.