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Magnetic wastewater treatment in the US chemical industry
NETICWASTEWATERTREATM
Magnetic wastewater treatment in the US chemical industry In this article Dr J L de Reuver of Dutchbased Envimag reports on a technical and economic description of a magnetic separation plant recently installed at a chemicals company in the United States.
agnetic wastewater treatment has been successfully introduced to the chemical industry in the United States. A plastics producing company has applied the Envimag magnetic wastewater treatment system for the removal of heavy metals from a 180 m3/hr wastewater stream. Because of strict end-of-pipe discharge limits set by the US Environmental Protection Agency and the large flow of wastewater, the Envimag system was chosen as the most suitable and costeffective system for the removal of metals. This article reports on a technical and economic description of a magnetic separation plant recently installed in the United States. As well as heavy metal removal, magnetic wastewater treatment can also be applied to the removal of colour, phosphates and oil at low concentrations. Small-scale units based on the magnetic separation principle are also available for lower flow rates.
M
The US market for magnetic wastewater treatment The American chemical industry is constantly actively searching for solutions to its problems with wastewater discharges. Companies find that the strict discharge limits imposed by the Environmental Protection Agency are rigorously enforced. The threat of huge tines and the closing of production plants is taken seriously. Because of the increasingly larger flow rates, the American chemical industry is facing the problem of finding a suitable treatment solution. The chemical company where Envimag’s wastewater treatment system is in operation, produces semi-manufactured plastic products. The production process requires copper as a catalyst during polymerisation. Small quantities of the copper catalyst dissolve in the process water, and emerge in a 180 m3/hr wastewater flow at concentrations between 1000 and 3000 parts per billion. The imposed EPA limit for copper discharge is 40 parts per billion. In order to minimise the possibility of exceeding the EPA limit, the company searched for a wastewater treatment facility with the potential to reduce the copper concentration below 20 parts per billion, and found Filtration & Separation
September/October
a suitable candidate in the Envimag process. The method of magnetic separation developed and applied by Envimag was shown to meet the imposed requirements. After a careful selection process based on both technical and economic evaluations, in which other systems such as hypertiltration were considered, magnetic separation proved to the most effective. The installation began in 1993, and is operating to the satisfaction of its owner. After its first year in use the system is to be evaluated, and it is anticipated that two additional installations may be ordered. Other American companies are interested in this newly installed system, and are keeping up-to-date with its progress. The useful combination of high wastewater flow rates and low discharge limits requires an innovative approach, and the Envimag wastewater treatment system is proving to be the key to the solution. Principle of the magnetic carrier method The Envimag system is based on the magnetic carrier principle. Fine magnetisable magnetite particles adhere to the pollutants, which are then removed from the wastewater stream using a magnet. The magnetite is recovered and recycled within the process. The magnetic force applied to remove the adhered pollutant is approximately 1000 times stronger than the force of gravity. A schematic diagram of the Envimag system is shown in Figure 1. Many practical applications require a pretreatment for the conditioning of the wastewater. Control of acidity and redox potential can be placed in-line with the magnetic separation unit.
Separation effectiveness of the Envimag system As a result of the very effective coprecipitation of poliutants with magnetite, and the large magnetic forces acting on the precipitate, magnetic separation has the potential to achieve large reductions in the pollutants. When compared with other conventional techniques, it is possible to obtain better separation efficiencies. This phenomenon makes the water clarification technique developed by Envimag particularly suitable for application in the US chemical industry. The stringent end-of-pipe limit of 40 parts per billion is easily achieved. The conditioning of the wastewater, partially performed by the client, consists of a pH correction with carbon dioxide gas, and dosing of a sulfide containing additive for the precipitation of the dissolved copper fraction. In order to improve the efficiency of the pollutant adherence onto the magnetic carrier, a polymer is dosed. When applying this procedure, copper concentrations of below 20 parts per billion have been achieved. Compact magnet installation A particular advantage of the relatively strong magnetic forces is the extremely low space requirements in comparison with competitive systems. The water velocity in the separation unit is considerably higher than is the case in other systems such as sedimentation and flotation. The magnetic separation installation exported to the US, which is suitable for flow rates up to 300 m3/hr, was transported across the Atlantic in a standard 20 ft container. The pretreatment unit for the adherence of the copper pollutant
@we 1. Schematic diagram of the Entimag magnetic wastewater treatment system.
1994
00151882/94/118$7.00
0
1994 Elsevier Science
Ltd
606
NETICWASTEWATERTREATM onto the magnetic carrier consists of a reactor/flocculation tube with a retention time of 1 minute. The unit for the recovery of the magnetic carrier is designed for a flow rate of 5 m3/hr - only a small fraction of the total water flow. The main components of the recovery unit are a centrifugal disrupter for the decoupling of the copper pollutant and the carrier, and a magnetic drum separator for the recovery of the magnetic carrier from the slurry. The system was delivered skidmounted, completely assembled and tested. On arrival it was ready for connection and operation. Advantages of magnetic treatment
wastewater
major advantages of the magnetic carrier principle are the high separation efficiencies and the relatively small space requirements. The space requirements enable the system to be skid-mounted. After connection on-site the unit is a reliable lock for pollutants in wastewater. Because of the open structure inside the magnet, the problems of blockage and clogging - which frequently occur in conventional systems - have been eliminated. The
separation apparatus suitable for flow rates below 40 m3/hr. The apparatus consists of a rotating disc with permanent magnets. A pilot unit with a capacity of 1 m3/hr has been successfully operated in the electroplating industry and in several textile factories. For use with even lower flow rates, the company offers compact systems without magnets. These systems are based on gravity separation of the carrier and the adhered pollutants. The magnetic carrier is then recovered and reused. The surface of the applied settler is approximately six times smaller than that of conventional equipment. Complete magnetic wastewater treatment installations are available for various industries including, but not limited to. the chemical and textile industries.
A common misunderstanding, that electromagnets consume considerable amounts of energy, can be easily dismissed by the following example. An Envimag electromagnet suitable for a flow rate of 300 m /hr consumes only 3.5 kW. The magnet, specially designed for application to wastewater treatment, has been patented in Europe and in the US. The cost of the skid-mounted installation is approximately Us$450,000, while the costs of chemical and energy demand per m3 of wastewater are US.SO.08and 0.1 kWh, respectively. Future
prospects
in the US and Europe
Corporations continue to show interest in this American installation. It is expected that several other companies worldwide will order installations in 1994. In the EC, the German market looks suitable for application of the system. The discharge limits in Germany are strict, and because of the high flow rates especially those occurring in steelworks - magnetic separation is an attractive alternative to conventional approaches. Most wastewater flow rates in the Netherlands are lower than those in the US. Anticipating these lower flow rates, the company has developed a magnetic
THE NORITAKE NR RANGE OF AUTOMATIC FILTER PRESSES Unique in the World Specially
Designed
for Solid-Liquid
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and for Dehatering
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l Realizing unmanned full automation of filtration, cake cleaning, cake compressing,
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0 Extremely simple mechanism of automated equipment 0 Extremely easy maintenance and inspection
l A variety of filter plate dimensions available, 850mm to 1500mm Model and Type:
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September/October
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Bottom feed Cake compressing type (High compressing 20kgicm’)
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NORITAKE Izuo, Taisho-Ku, 1994
PP, FC, FCD, SUS, RL, etc I
IRON WORKS CO, LTD
Osaka, Japan Tel: (06) 552-l 431 607
Magnetic wastewater treatment in the US chemical industry In this article Dr J L de Reuver of Dutchbased Envimag reports on a technical and economic description of a magnetic separation plant recently installed at a chemicals company in the United States.
agnetic wastewater treatment has been successfully introduced to the chemical industry in the United States. A plastics producing company has applied the Envimag magnetic wastewater treatment system for the removal of heavy metals from a 180 m3/hr wastewater stream. Because of strict end-of-pipe discharge limits set by the US Environmental Protection Agency and the large flow of wastewater, the Envimag system was chosen as the most suitable and costeffective system for the removal of metals. This article reports on a technical and economic description of a magnetic separation plant recently installed in the United States. As well as heavy metal removal, magnetic wastewater treatment can also be applied to the removal of colour, phosphates and oil at low concentrations. Small-scale units based on the magnetic separation principle are also available for lower flow rates.
M
The US market for magnetic wastewater treatment The American chemical industry is constantly actively searching for solutions to its problems with wastewater discharges. Companies find that the strict discharge limits imposed by the Environmental Protection Agency are rigorously enforced. The threat of huge tines and the closing of production plants is taken seriously. Because of the increasingly larger flow rates, the American chemical industry is facing the problem of finding a suitable treatment solution. The chemical company where Envimag’s wastewater treatment system is in operation, produces semi-manufactured plastic products. The production process requires copper as a catalyst during polymerisation. Small quantities of the copper catalyst dissolve in the process water, and emerge in a 180 m3/hr wastewater flow at concentrations between 1000 and 3000 parts per billion. The imposed EPA limit for copper discharge is 40 parts per billion. In order to minimise the possibility of exceeding the EPA limit, the company searched for a wastewater treatment facility with the potential to reduce the copper concentration below 20 parts per billion, and found Filtration & Separation
September/October
a suitable candidate in the Envimag process. The method of magnetic separation developed and applied by Envimag was shown to meet the imposed requirements. After a careful selection process based on both technical and economic evaluations, in which other systems such as hypertiltration were considered, magnetic separation proved to the most effective. The installation began in 1993, and is operating to the satisfaction of its owner. After its first year in use the system is to be evaluated, and it is anticipated that two additional installations may be ordered. Other American companies are interested in this newly installed system, and are keeping up-to-date with its progress. The useful combination of high wastewater flow rates and low discharge limits requires an innovative approach, and the Envimag wastewater treatment system is proving to be the key to the solution. Principle of the magnetic carrier method The Envimag system is based on the magnetic carrier principle. Fine magnetisable magnetite particles adhere to the pollutants, which are then removed from the wastewater stream using a magnet. The magnetite is recovered and recycled within the process. The magnetic force applied to remove the adhered pollutant is approximately 1000 times stronger than the force of gravity. A schematic diagram of the Envimag system is shown in Figure 1. Many practical applications require a pretreatment for the conditioning of the wastewater. Control of acidity and redox potential can be placed in-line with the magnetic separation unit.
Separation effectiveness of the Envimag system As a result of the very effective coprecipitation of poliutants with magnetite, and the large magnetic forces acting on the precipitate, magnetic separation has the potential to achieve large reductions in the pollutants. When compared with other conventional techniques, it is possible to obtain better separation efficiencies. This phenomenon makes the water clarification technique developed by Envimag particularly suitable for application in the US chemical industry. The stringent end-of-pipe limit of 40 parts per billion is easily achieved. The conditioning of the wastewater, partially performed by the client, consists of a pH correction with carbon dioxide gas, and dosing of a sulfide containing additive for the precipitation of the dissolved copper fraction. In order to improve the efficiency of the pollutant adherence onto the magnetic carrier, a polymer is dosed. When applying this procedure, copper concentrations of below 20 parts per billion have been achieved. Compact magnet installation A particular advantage of the relatively strong magnetic forces is the extremely low space requirements in comparison with competitive systems. The water velocity in the separation unit is considerably higher than is the case in other systems such as sedimentation and flotation. The magnetic separation installation exported to the US, which is suitable for flow rates up to 300 m3/hr, was transported across the Atlantic in a standard 20 ft container. The pretreatment unit for the adherence of the copper pollutant
@we 1. Schematic diagram of the Entimag magnetic wastewater treatment system.
1994
00151882/94/118$7.00
0
1994 Elsevier Science
Ltd
606
NETICWASTEWATERTREATM onto the magnetic carrier consists of a reactor/flocculation tube with a retention time of 1 minute. The unit for the recovery of the magnetic carrier is designed for a flow rate of 5 m3/hr - only a small fraction of the total water flow. The main components of the recovery unit are a centrifugal disrupter for the decoupling of the copper pollutant and the carrier, and a magnetic drum separator for the recovery of the magnetic carrier from the slurry. The system was delivered skidmounted, completely assembled and tested. On arrival it was ready for connection and operation. Advantages of magnetic treatment
wastewater
major advantages of the magnetic carrier principle are the high separation efficiencies and the relatively small space requirements. The space requirements enable the system to be skid-mounted. After connection on-site the unit is a reliable lock for pollutants in wastewater. Because of the open structure inside the magnet, the problems of blockage and clogging - which frequently occur in conventional systems - have been eliminated. The
separation apparatus suitable for flow rates below 40 m3/hr. The apparatus consists of a rotating disc with permanent magnets. A pilot unit with a capacity of 1 m3/hr has been successfully operated in the electroplating industry and in several textile factories. For use with even lower flow rates, the company offers compact systems without magnets. These systems are based on gravity separation of the carrier and the adhered pollutants. The magnetic carrier is then recovered and reused. The surface of the applied settler is approximately six times smaller than that of conventional equipment. Complete magnetic wastewater treatment installations are available for various industries including, but not limited to. the chemical and textile industries.
A common misunderstanding, that electromagnets consume considerable amounts of energy, can be easily dismissed by the following example. An Envimag electromagnet suitable for a flow rate of 300 m /hr consumes only 3.5 kW. The magnet, specially designed for application to wastewater treatment, has been patented in Europe and in the US. The cost of the skid-mounted installation is approximately Us$450,000, while the costs of chemical and energy demand per m3 of wastewater are US.SO.08and 0.1 kWh, respectively. Future
prospects
in the US and Europe
Corporations continue to show interest in this American installation. It is expected that several other companies worldwide will order installations in 1994. In the EC, the German market looks suitable for application of the system. The discharge limits in Germany are strict, and because of the high flow rates especially those occurring in steelworks - magnetic separation is an attractive alternative to conventional approaches. Most wastewater flow rates in the Netherlands are lower than those in the US. Anticipating these lower flow rates, the company has developed a magnetic
THE NORITAKE NR RANGE OF AUTOMATIC FILTER PRESSES Unique in the World Specially
Designed
for Solid-Liquid
Separations
and for Dehatering
Features:
l Realizing unmanned full automation of filtration, cake cleaning, cake compressing,
blow and cake discharge
0 Extremely simple mechanism of automated equipment 0 Extremely easy maintenance and inspection
l A variety of filter plate dimensions available, 850mm to 1500mm Model and Type:
WlORjtAKE 56,6-chome, Filtration & Separation
September/October
NR type
Non cake compressing type
NR-PF-L type
Cake compressing type (Low compressing 7kg/cm*)
NR-PF-SH type
Bottom feed Cake compressing type (High compressing 20kgicm’)
1 Materials of filter plate
1
I
I
NORITAKE Izuo, Taisho-Ku, 1994
PP, FC, FCD, SUS, RL, etc I
IRON WORKS CO, LTD
Osaka, Japan Tel: (06) 552-l 431 607