Specific Examples

Repeated Reuse of Wastewater in Thailand

Headquartered in Thailand, Mitsubishi Elevator Asia Co., Ltd. (A-MEC) manufactures passenger elevators, escalators, and moving walkways. Beginning around 2000, its production volume began to rise and so too the volume of wastewater treated at its factory. In response, the company decided to introduce a system for recycling and reusing water.

One of the company's production lines, that for polishing coatings, requires water that has low electrical conductivity, hinders the formation of rust, and is largely free of impurities. An expensive reverse osmosis (RO) system*, therefore, is used to produce the required water.

Improvement Overview

Equipment for processing wastewater for reuse

The following measures are used to treat wastewater from the polishing process.

1) The electrical conductivity of wastewater from the polishing process is automatically measured. Water falling below the required threshold is sent back for reuse in the polishing process.

2) When electrical conductivity is above the required threshold, an alarm sounds and a valve is switched to send the water to the wastewater processing facility.

Impact

Over 60% reductions were achieved in both usage of RO-treated water and wastewater discharges. Going forward, the Company will seek to reuse water on an even greater scale within its factory.

* Reverse osmosis systems force water through a filter that removes ions, salts, and other impurities. They are used, for example, to produce drinking water from seawater.