Solutions for Industrial Field
Water scarcity and pollution are persistent global issues. The most prudent solution is to recycle and reuse wastewater. Therefore, environmental authorities all over the world introduce ZLD(*1) systems to industrial processes.
We, Toshiba, have a state of the art ZLD system based on HERO™(*2) technology, which offers more efficient and superior treatment at lower life cycle cost than conventional systems.
(*1) ZLD: Zero Liquid Discharge
(*2) HERO™ is a trademark, a technology protected by a patent, and a proven technology with 150+ reference installations worldwide. Toshiba Water Solutions Private Limited as one of our group companies is a licensee of HERO™.
The ZLD system can be introduced in cases where water resources are limited and environmental sustainability is prioritized.
The recycling system with RO(*3) membrane generates reject water containing highly concentrated wastewater with TDS(*4). In most cases, reject water cannot be discharged, thus an evaporator is installed after RO, to evaporate reject water and concentrate salts to dryness. Also due to the high cost of evaporators, it is a prerequisite to integrate a high efficiency RO system in the ZLD process so as to minimize the RO reject volume and optimize the size of the evaporator to be installed. This can be achieved by increasing the recovery across the RO system in the ZLD system based on HERO™ technology.
(*3) RO: Reverse Osmosis
(*4) TDS: Total Dissolved Solids
There are scaling and fouling problems in the ZLD system with conventional RO, causing an increase in feed pressure, a decrease in permeate flow, lower permeate quality, frequent RO cleaning, longer downtime, and eventually frequent replacement of RO membranes.
For a conventional RO system, pH of feed water is lowered and antiscalant is dosed to prevent hardness scaling. But it does not work for higher recovery rates. In addition, lower pH decreases silica solubility, resulting in silica scaling. Some of the COD(*5) remain in industrial wastewater even after biological treatment. In many cases, the conventional RO fails to operate in a sustainable manner at 80%+ recovery due to silica and residual COD in the feed water.
(*5) COD: Chemical Oxygen Demand
HERO™ is a technology to eliminate all scaling and fouling factors (hardness, alkalinity, silica precipitation, organic fouling and bio-fouling) by ion exchange, degassing and RO system operation at high pH by maximizing recovery through the RO system.
In the HERO™ system, scaling and fouling are eliminated; therefore, the system can increase the RO water recovery rate to the maximum extent possible.
|Lime/caustic clarifier and/or ion exchange system||Degassing tower or membrane||High pH RO operation|
|Hardness removal (Softening)||Alkalinity removal||Prevention of RO filter fouling
Increase in water recovery rate
|To remove Ca, Mg and other heavy metals, which can potentially cause scaling in RO||To remove carbonic acid, which can cause carbonate scaling in RO||To improve silica solubility, prevent the adsorption of organic matter by RO, inactivate bacteria, and enhance the zeta potential between membrane and particles|
1. Hardness scaling
1. Hardness scaling
2. Silica scaling
3. Organic fouling
By virtue of high efficiency, low generation of reject and downsizing of the evaporator, the HERO™ system can reduce operation costs, compared to conventional RO systems.
|ZLD with conventional RO||ZLD with HERO™|
-rateCompared to conventional RO,
(*6) CIP: Clean in Place
HERO™ is used in regions where Toshiba Water Solutions promotes sales except for the following industries.
The recovery rate of conventional RO systems is limited to 70% to 80% depending on inlet water quality.
We offer the HERO™ system for ZLD, which can operate at a recovery rate of more than 95% in most cases.
Compared to conventional RO systems, the HERO™-based RO system can reduce the volume of reject water to 1/4 and provide significant operational savings.
Scaling and fouling factors are eliminated, leading to an extension of the RO membrane life, a reduction of the system shutdown time, and eventually a significant reduction in the life cycle cost of the system.
|Project Description||Wastewater treatment plant for automotive industry was built. ZLD was adopted in order to meet strict wastewater treatment requirements in India.|
|Scope||Design, engineering, supply, erection, installation, testing and commissioning|
|Solutions||We constructed ETP - ZLD system. The system consists of pre-treatment, anoxic - aerobic - MBR(*7) based treatment, HERO™ thermal based evaporator to provide treated water suitable for reuse in the production plant. The HERO™ evaporator is less than 1/4 of the conventional RO system in size. Accordingly, steam consumption can be saved by 75% and water recovery can reach 95%.|
(*7) MBR: Membrane Bioreactor
Please download the leaflet of ZLD with HERO™.
ZLD with HERO™ (PDF: 547 KB)
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