Brackish / Sea Water Desalination

Featuring Automatic Permeate Flush

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Introduction

Desalination or desalting of water consists of a water treatment process by which sea or brackish water is converted into potable water for supplying communities that have the most difficulty accessing freshwater. The Reverse Osmosis System is currently the most common and economical way for desalinating water from brackish and seawater sources. energy recovery devices are also now mutual to reduce power consumption by 35-50% compared to none ERD equipped systems. However, its capital cost and operation are still considering on the high side compared to the accessible freshwater sources.

 

Brackish water sources (TDS ranging from 2,000-15,000 ppm) shall be considered to be treated 1st before considering desalination from seawater.
 

ROTEK has been supplying brackish water desalination systems to many countries for the past 2 decades. The most important feature of our brackish water RO systems is that it has included automatic permeate flush with adjustable flush frequencies in order to keep the system free from corrosion and membrane fouling against the high levels of chloride and hardness from the brackish water sources.

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WHY PERMEATE FLUSH IS SO IMPORTANT?

Prior to the shutdown of RO systems, a permeate water flush is recommended to avoid precipitation of salts and organics concentrated on the feed side of the element onto the membrane surface. Unfortunately, many RO systems do not incorporate a permeate flush and apply a feedwater flush instead. This accelerates all forms of membrane fouling (biofouling, colloidal fouling, scaling, organic fouling). ROTEK patented C-5TM RO controller is able to allow systems to perform automatic permeate flush at the lowest possible cost.

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Design Criteria

Based on the raw water quality analysis, we will provide our design suggestions follow by the 4 major treatment setup:

Filtration Systems
This section is basically responsible to filter out most of the fine particles, heavy metals, chlorine, organic matters, bacteria, color & odors. The filtration system usually consists of Clino-X Multimedia Sand Filter, Activated Carbon Filter, Water Softener, Ultra-Filtration System, Anti-Scale, and Chlorination Chemical Dosing Systems.

Purification Systems
Reverse osmosis (RO) is a water purification technology that ROTEK uses most of the time for many industries. RO can remove many types of molecules and ions from solutions and is used in both industrial processes and to produce potable water. Depending on the raw water quality, if raw water TDS is below 50ppm, then this section of the purification system may not be required as part of the design for bottled water production.

 

Remineralization Systems

Although RO removes everything from the water (including good and bad minerals),
however low mineralized water have few adverse effects:
- High corrosion potential
- Dietary deficiency causing risks of ischaemic heart and cerebrovascular disease (WHO, 2005a; WHO, 2006; Cotruvo, 2006)
The WHO recommends 10 mg/L of Magnesium and 30 mg/L of Calcium for drinking water. Therefore adding beneficial minerals to the product water is a process called demineralization. ROTEK uses natural minerals called "Camag" for adding pure Magnesium and Calcium to the product water with great improvement on the taste and pH level.

Disinfection Systems
The most common bacteria found in bottled water is Pseudomonas fluorescens, which is common in fresh-water springs. It is not considered to be a health threat until you leave the bottle open for extended periods of time and the bacteria begin to react with the carcinogens in the plastic. Reducing bacteria and microbial to the minimum is the most important issue in the bottled water production business. ROTEK disinfection system consists of UV sterilizer, Nanosilver Activated Carbon, 0.2-micron filter, and ozone disinfection. With four levels of protections, the ROTEK disinfection system will make sure the bacteria level is reduced to nil before filled to the bottle.