Updated: July 2002

1. Abstract

This water treatment system is based on the distillation process for pure water production and waste water recovery.
Usually, pure water has been produced by the systems with ion exchange resins or membranes. In such systems, the resins and membranes require refreshing and/or cleaning periodically, which requires a significant volume of chemicals. And they are finally replaced and turned into industrial wastes.
While, our distilled pure water production & waste water recovery system requires only small amount of chemicals, and does not generate any industrial waste.
Furthermore, utilizing of surplus steam for co-generation units can improve the overall energy efficiency in the factory. Particularly, in precision electric/electronic devices manufacturing field, where significant amount of pure water and pure water is consumed and waste water containing obnoxious substance is discharged, this combined closed system of distilled pure water production system and water recovery system, will realize most suitable total system with a concept of zero emission target.

2. Principles

Main equipment's of the distilled pure water production system are deaerator(s) and evaporator. Deaerator(s) removes CO2 gas and dissolved oxygen (DO), etc., and evaporator with high efficiency mist-separator, removes foreign materials such as metal ion and silica, etc. This unit is able to produce the pure water with resistivity of 14 to 15 MΩcm. Furthermore, ultra-pure water with resistivity of over 18 MΩcm can be produced by addition of sub-system. The waste water recovery system also consists of deaerators and evaporator basically.
The evaporation technology applied to our systems is multiple effects evaporation method, in which our company has been experienced in the desalination plants for many years. Multiple effects evaporation, principle of which is shown in Fig.2, can utilize the heating steam effectively to produce pure water or to recover waste water. Stable evaporation operation can be maintained without any fluctuation of capability due to resins and/or membranes as well as raw water quality.
STEP 1: In No.1 effect, a portion of raw water is evaporated by heating steam to convert to pure steam. While, remaining portion is a little concentrated and transferred to No.2 effect.
STEP 2 : In No.2 effect, pure steam generated in No.1 effect is utilized as a heat source for evaporation of the raw water transferred from No.1 effect , and condensed into pure water.
STEP 3 : In the same manner as in STEP 2, pure water can be produced with high energy efficiency by utilizing generated pure steam as a heat source for the effect.

Fig.1 Total system of distilled pure water production/wastewater recovery

Fig.2 Principle of multiple effects evaporation

Fig.3 Distilled Pure Water Production Unit (Capacity: 3m³/h)