Springfield, Massachusetts (413)

Transcription

1 Waste Reduction and Minimization by COLD VAPORIZATION by Val Partyka CALFRAN International Inc. Springfield, Massachusetts (413) Topic No. 100 or 600

2 Introduction CALFRAN'S approach to waste reduction and minimization is to separate aqueous wastes into recyclable pure product water while concentrating the waste or raw material into potentially reclaimable residues. The CALFRAN Process can be applied for 1.) Wastewater Treatment and 2.) Waste Reduction. Process applications result in the following options. 1.) Recovery/Recycle Product Water 2.) Recycle/Reclaim Concentrate and 3.) Selectively recover product water and concentrate from segregated wastestreams. It has long been the objective to achieve zero discharge. The CALFRAN Process is being applied to realize this goal. Not only is water being recycled - in addition, high purity concentrates are being reclaimed, thus eliminating hazardous waste disposal liabilities. The CALFRAN Process offers a means of achieving both waste minimization and advanced treatment through the use of one technology. The CALFRAN Process The CALFRAN Process is a physical process of wastewater purification consisting of: 1.) COLD VAPORIZATION which is low temperature evaporation conducted at 50 degrees to 70 degrees F. under a vacuum of approximately 10 mm of Hg and 2.) FREEZE VAPORIZATION which is ultra low temperature evaporation conducted at 32 degrees to 35 degrees F. under a vacuum of approximately 4 mm of Hg. Presently all Wastewater Treatment and Waste Reduction Applications have been handled through the COLD VAPORIZATION mode. Water vapor is formed in the reaction vessel and condensed to pure product water. The contaminants remain behind in the reaction vessel where they can be eventually concentrated to a liquid or solid form. Liquid concentrates are removed through a concentrate pump while dry residues are manually removed. Basic units consist of a vacuum pump/s, refrigeration compressor/s, circulation pump/s, product water pump/s and heat exchangers. The heat given up in the refrigeration circuit is reclaimed back into the reaction resulting in no external heat source. Therefore, no compressed air, steam, or water supply is necessary when installing the units. All systems come skid mounted with smaller capacity units being portable. Units have auto fill and auto product water removal. Basic systems consist of stainless steel reaction vessels and condensing coils with schedule 40/80 PVC shells and frame. Routine maintenance involves vacuum pump oil changes once a week or once every two weeks. The CALFRAN Process offers an effective and efficient means of removing and concentrating hazardous materials in an aqueous solution without the use of chemicals, membranes, filters or exchange media.

3 Advantages Insensitivity to Concentration Fluctuations in concentration do not affect process performance efficiencies. As the feed concentration increases, the brine solution concentration will increase but the product water purity will remain the same. This makes the process particularly attractive for those applications where the wastestream concentration varies widely.. HIGH RELIABILITY Since the system does not use filters, employs compatible alloy heat exchanger at operating temperatures below 100 degrees F., is insensitive to feedwater or concentration or the accidental introduction of vagrant pollutants, the process is less susceptable to upsets, resulting in costly and lengthy down times. One need only to flush the system with water if contamination should occur, start feeding the wastestream again and the system is back on line. Because it is a physical process, product water contamination can only occur by one of the following: 1. In a few feedwaters, excessive foaming can cause carryover into the condensing area. Wastestreams which have a tendency to foam are metered in at a controlled rate under vacuum. In this manner, solutions such as electro-cleaners, soap-cleaners and phosphates are successfully processed. 2. Carryover can also occur if droplets of concentrate reach the condensing area. This is controlled by proper mist elimination in the form of large diameter extended vapor tubes. NO PRETREATMENT Pretreatment is not required; most wastestreams are processed directly without chemically altering their characteristics. However, some customers have requested ph adjustment before processing, which usually is performed on very low ph solutions where special alloy heat exchangers are not used. SIZE AND EASE OF OPERATION Units are compact with all components mounted on a single frame. Basic units consist of an air cooled compressor, a vacuum pump, and specially designed condensers. These are the major components with larger systems consisting of two or more of each. The units are simple to operate. Once the vacuum pump is on and the vacuum reading on the gauge begins to drop, one has only to open the chiller valve and the system is up and running with no further process changes necessary. The process can be stopped or interrupted at any time and restarted without causing damage to the equipment or effecting treatment and product water quality. This has been a very welcome experience to all who are accustomed to complicated systems where severe damage can be done or system upset can occur if operational procedures IY I-

4 are not strictly followed or when chemical additions are not properly monitored. No water, steam, or air supply is necessary. Wastestreams can be hard piped for continuous large volume operations or units can be batch run for small volumes. Wastewaters are fed to individual reaction vessels through level controls, solid state tined feed, and appropriate feed valves depending upon the type of waste being processed. ENERGY REQUIREMENTS Though process time varies depending on the specific gravity of the feed solution, typically electrical costs are $0.06/ gallon. WASTE REDUCTION The CALFRAN Process is capable of concentrating a solution to saturation, and has been applied for waste reduction. Aqueous Solutions can be reduced by as much as 99% with significant savings in disposal costs. Example 1 - One customer who is generating one drum per day (210 kg/day) of a hazardous waste which contains a high concentration of Selenium (up to 1,000 ppm) has utilized a CALFRAN 100 gal/day PTU (Portable Treatment Unit) to reduce the volume down to 8.0 kg/day. The material comprising the 8.0 kg is 96% solids. Where the customer was generating one drpm/day of hazardous waste, he is presently generating one drum every 10 days. With this reduction the amount of waste disposed of has dropped from approximately 250 drums/year to 25 drums/year. At $ disposal cost per drum, the savings is in excess of $50,00O/year. This customer has seen a payback on the unit of approximately six months. The unit utilizes approximately 0.44 KWH/gal for electricity. A typical days' operation involves 1.5 hour per day of operator's time which includes startup and shut down with manual concentrate removal. Test data on the product water indicate Selenium levels were reduced to 0.0 ppm or nondetectable. Once the unit has been started, the wastestream is automatically fed until the 55 gal/drum is empty. At this point in the process run, the unit will begin to take the concentrate to its final concentration. This is accomplished automatically by high and low pressure controls within the unit. The operator simply allows the unit run unattended until the process concentrates the waste. When the wastestream has reached its maximum concentration either as a liquid or dry material which depends on the type of waste being processed, the compressor will shut down, leaving the unit in a standby mode. In this way an operator need not monitor the process other than to occasionally visually inspect the reaction chamber. Example I1 - Involves a 50 gal/day CALFRAN Unit which is being applied for the reduction of Nickel Chloride solution and Electroless Nickel. The.unit has been set up with its own feed

5 tank and product water holding tank. The operator need only start up the unit, activate the auto feed and the vacuum from the system will draw the wastestream to the reaction chamber to a present level. Once all of the solution has been processed, the unit will then take the concentrate to dryness. The unit has reduced approximately 1600 gallons of Nickel Chloride solution down to 5.0 gal or - 50 lbs. of dry Nickel Chloride salt. In this application, the dry Nickel Chloride is periodically added back to the plating bath and any excess is easily stored as a dry material. The pure product water is recycled back into the process thereby completely closing the loop with no regulatory permit or monitoring required. Example I11 - Spent Nitric, Sulfuric and Sodium Hydroxide etchants are combined, ph adjusted to 3 and processed in a PTU rated at 150 gal/day. Three 300 gallon etchant tanks containing 5% solution are processed every three weeks from a wire drawing operation. The three solutions are mixed together in a 1,000 gallon waste holding tank where the ph is brought from 1 to 3. The waste is then processed at a rate of approximately 100 gal/day. Clear product water is held in a 1,000 gallon holding tank, where it is ultimately reused to make up the new etchant solutions. The concentrate or residue remaining after each run is held in a 55 gallon drum for disposal. 1,000 gallons of etchant are reduced to one 55 gallon drum of waste. The system, since it is closed looped with zero discharge, requires no regulatory permitting: Example IV - An aluminum anodizing operation generates six different wastewaters, all of which are being successfully processed through a CALFRAN HSTU-1000 rated at 1000 gal/day. Product water is low in TDS and conductivity and therefore is recycled back to the static rinse tanks. Six 2500 gallon rinse tanks are processed every month resulting in 200 gallons of liquid concentrate. Once again, since the process is completely self-contained and closed looped, no regulatory permit is required. Example V - A wetting agent used in offset printing consisting of a mixture of alcohol and water is being processed through CALFRAN'S COLD VAPORIZATION Process. The wastestream consists of the following ratio per bath. 2 gal water and 1 gal Isopropyl Alcohol oz. gum arabic oz. Fountain Concentrate (Red Etch). The customer is able to process the alcohol and water mixture by first evaporating the alcohol and then the water. The alcohol is reused to make up fresh wetting agent and the water is discharged. The customer has seen a savings of $4,000 per year on Isopropyl Alcohol and $30,000 per year on hazardous waste disposal costs based on disposing 250 drums/ year at a cost of $125/drum.

6 Example VI - Spent Electroless Nickel from the manufacturing of computer disk drives is being reduced by 75%. The Electroless Nickel consists of: Constituent Nickel Sulfate Sodium Hypophosphate Organic Acid Orthophosphite Concentration 6 g/l 30 g/l 50 g/l 100 g/l Approximately 550 gallons per day of spent Electroless Nickel Solution is processed through a CALFRAN PTU Wastewater Treatment/Waste Reduction Unit. The 550 gallons is reduced to 110 gallons of concentrated liquid slurry..product water quality is exceptional. Nickel values are as low as 0.01 ppm in the product water, with Total Dissolved Solids (TDS) less than 10 ppm. The customer has experienced significant savings. Example VI1 - CALFRAN is presently conducting a Waste Reduction and minimization evaluation in cooperation with Margaret Harris, Environmental Engineer for Robins Air Force Base. The application involves reducing spent Chromic Acid and a Cadmium stripping solution containing Cyanide. Preliminary studies have indicated an 80% volume reduction is possible. The following table represents the concentrations of the waste solutions and CALFRAN'S purified product waters. Chrome Solution Cyanide Solution Untreated Treated Cd Cr 69, Cu Pb Ni Zn Untreated Treated Cd 3, Cr Cu Pb Ni Zn Cn 12, CALFRAN has achieved exceptional product water quality. Metals are reduced consistantly below 0.1 ppm. These metal concentrations are on average 200 times lower than present EPA Limits. CALFRAN has also successfully treated and reduced numerous industrial wastestreams from the following categories. Electroplating Operations Printed Circuit Board Coatings Etchants Leachates Semiconductors Grinding and Mill Operations Quenching

7 Enameling Phosphate Precoats Printing Galvanizing Anodizing Developing Paint Spray Booths Tubbing Operations Hot Dip Soldering Boiler Blowdown Cooling Tower Recovery Precious Metals Lubricants These categories include such solutions as spent pickling and plating baths and their rinsewaters, dyes, inks, emulsified oils, aqueous coatings, soap cleaners and electrocleaners. These applications can be handled by the PTU (Portable Treatment Unit) Line of Waste Reduction Units rated from 20 gal/day to 750 gal/day. CONCLUSIONS With the future on water reuse, resource recovery, and waste reduction, the CALFRAN Process OFFERS A MEANS OF ATTAINING ALL THREE. The inherent advantage of the CALFRAN Process over existing technologies has been established.