Extract From

AUSTRALIAN WATER & WASTEWATER

ASSOCIATION INC(Victorian Branch)

&

INSTITUTE OF WATER ADMINISTRATION

RECOVERABLE RESOURCES

May 1998

Peter L Voigt

Clean TeQ

ABSTRACT



Synthetic ion exchange media have been used in the resource recovery industry for many years. From a background of materials recovery, the ion exchange process has been extended to purification processes involving both wastewater and water. Continuous Ion Exchange (Clean-iX) technology has the potential to provide a cost effective solution for the provision of potable water and as a technology for the tertiary treatment of wastewater and to provide valuable products from waste streams from a variety of industrial sources. The Clean-iX process has advantages in terms of capital and running costs as well as simplicity in operation and control

KEYWORDS
Continuous Ion Exchange, Clean-iX, ion exchange, potable water, wastewater, metal recovery, nutrient removal, applications.

INTRODUCTION
The development of Clean-iX technology was pioneered in the Chemical Institute of Technology in Moscow in the 1950's. Primarily the research was directed towards the extraction and purification of uranium as a source of energy. The developments included the synthesis of innovative resins with either broad or narrow specificity along with excellent mechanical strength. With the development of the resins came the opportunity of revolutionising the processing system to enable the system to be operated in a continuous rather than batch fashion.The development of the Clean-iX system was in response to the needs of industry for a cost- effective alternative to the batch-wise processes. The system needed to address the problems associated with the current technology in regards to plant cost, size and operation. The new Clean-iX technology addresses these issues and offers a quantum step in processing technology for water, wastewater and resource recovery.
 


DISCUSSION
Ion exchange Systems are used extensively for water deminerialisation, resource recovery and purification. In general, the systems and resins have been developed to be used in a batch mode in the majority of applications. The development of the Continuous Ion Exchange (Clean-iX) technology now offers the opportunity of extending the technology in many different industries as the regulatory requirements are tightened and customer demands increase in respect of quality. The Clean TeQ Continuous Ion Exchange (Clean-iX) system allows for simultaneous exchange and absorption, regeneration and washing procedures. The operation is continuous except for a short intermediate process whereby an airlift system move the resins between columns. A schematic is shown in Figure 1.
 

The Clean-iX system as shown in Figure I is a single ion system. The number of columns is doubled if both anionic and cationic species are to be removed. The ratio of time for exchange absorption versus the resin transport is dependent on the concentration of components to be removed. The regeneration chemicals are also dependent on the compounds removed and resin type.

The Clean-iX has several advantages over traditional methods of water and waste treatment. The advantages as summarised in Table 1.

Table 1- Advantages of Clean-iX Technology


ADVANTAGE
HOW
Simple, automatic operation Normal continuous mode or via a plant PLC or SCADA system
Reduced operating costs Very effective use of chemicals and minimum use of was water
Reduced capital and resin costs The amount of resin required is generally 70% less than batch mode operations. Capital equipment is less and so capital costs are significantly reduced
Samaller footprint for equipment The column dimensions are also 50 to70% less than batch operations and so less space is required
High liquid flow rates The specific velocity through the plant can be high, with low pressure drops through the bed
Slurries and solids handling The system can handle suspended solids up to 10% without clogging
Was reuse Acid washes can be reused and neuralisation chemicals can be reduced

 

 
 
 

The use of the Clean-iX process in conjunction with the R-Tec resins allows the system to be used in a variety
of applications as shown in Table 2
Table 2 - Applications of Clean-iX Technology

INDUSTRY
APPLICATION
Municipal Water Treatment Deminerialisation 
Colour and Turbidity Reduction 
Toxin Removal 
Nitrate Removal 
Waste Water Treatment Ammonia and Nitrate Removal 
Toxic and Heavy Metals Removed
By-Products Metals Removed 
Mining and Metallurgical Selective Metal Extraction 
Selective Metal Recovery 
Acid Recovery from Electrolytes 
Fertiliser Ammonium Nitrate Removal 
Phosphoric Acid Defluorination 
Phosphoric Acid Cadmium Recovery 
Plating and Pickling Acid and Metal Recovery
Site Remediation Acid Mine Drainage Remediation 
Retention Pondage Remediation 
Refineries and Petrochemical Organic Catalyst Removal 
Organic Acid Metal Recovery 
Phenol Removal and Recovery 
Radiactive Waste Treatment Strontium-90, Ceasium-137, Uranium-235 and Radium Extraction 
Rare Earth Extraction 
Food Industry Specific Sugar from Whey By-Products 
Deashing and Decolourisation 
Sugar Fractionating 

 

The application of Clean-iX to the water treatment industry is shown in the following example. The treatment of a feed water stream containing up to 2,000 mg/l dissolved solids and at a flow rate of 3 Ml per day by the Clean-iX system would require the following plant:

  • Sorption Columns (x2); volume -Up to 6m3 (Ø 1 .65m, h = 2 - 2.25 m)
  • Regeneration Columns (x2); volume 3m3 (Ø = 0.75m and h = 4.5 - 5 m)
  • Wash Columns (x2); volume 3m3 (Ø = 0.75- 0.9m and h = 4.5 - 5 m)
The ratio of purified water to pregnant resin would be 1:100 or 1:200, depending on the actual anions, cations and turbidity of the incoming water. The ratio of clean water to wash water production would be approximately 1:200. Table 3 below shows the results from the purification of water in one particular area of Australia. The results were independently confirmed by an outside laboratory and clearly show the success of Clean-iX technology.

Table 3 - Results of Clean-iX Process for Potable Water


ITEM
PRODUCT IN WATER
RAW WATER
CLEAN WATER
1
 Colour (Pt/co units)
10
<5
2
 Turbidity (N, T, U)
11
<2
3
 Chloride*
370
58
4
 Sulphate
26
<1
5
 Manganese
0.02
<0.01
6
 Iron
0.65
0.27
7
 Copper
0.73
<0.01
8
 Lead
0.03
<0.01
9
 Zinc
0.10
<0.02
10
 Hardness (as CaCO3)
160
1.6
11
 Calcium
23
0.27
12
 Potassium
3.7
0.21
13
 Magnesium 
27
0.25
14
 Sodium 
150
60

*Concentration of cations and anions is in mg/l.

 

If cleaner water is required, it can be done by applying one more stage of purification which will allow a further 10-fold purification step.
One of the most common ways of purification of sewage and wastewater from toxic metal is through the use of floculants. The production of hydroxide flocs and their removal is a problem as the physical nature of these hydroxides make them hard to handle. Typically, the equipment used for separation processes is mechanically complex and there is a requirement for over-dosing of chemicals to ensure compliance.
Ion exchange technology is a more selective and cost-effective method of dealing with ionic species present in wastewater. The ion-exchanging process takes place in an counter-current process where the resin moves against the effluent flow. The equipment used in the process is simple in construction, has a relatively small footprint and a high production capacity. The system is also effective in treating solutions containing small solid particles and can be automatically operated, being relatively simple in procedure and highly reliable.
Ion-exchanging method can be used for cleaning different solutions apart from sewage waters, such as extraction of toxic and admixtures in the production of the pharmaceutical, biochemical and food products. In the food industry, Clean-iX can be for the purification of milk, whey and other dairy products by extracting sugars, metals and salts.
The use of ion-exchange for the purification of washing water from chemical plants (those that use galvanic processes) has large potential. This water can be cleared of chromium(VI), one of the most toxic elements through the use of resin which is specifically treated for chromium which has a high capacity of absorption.

CONCLUSIONS
The Continuous Ion Exchange (Clean-iX) Process will allow many industries a process for recovery, recycling and treatment. The outputs from the process can be channeled into added-value goods providing the client with a cost equalisation potential. The use of the technology in providing potable water supply and wastewater treatment to small to medium towns and industry is also a major market for this new and novel technology.

ACKNOWLEDGMENTS
The assistance of Dr Nikolai Zontov, R-Tec Inc. is acknowledged in the preparation of this paper.