ENCON MVC Evaporator Used for Ion Exchange Resin Regenerate Wastewater in Food Processing Plant
Background
Client is located in the Middle East and operates a sugar processing facility. One of the process steps was removal of dissolved contaminants from the sugar prior to evaporation of the sugar using an ion exchange resin. The ion exchange resin would need to be regenerated with a sodium chloride salt brine that resulted in a waste stream that contained high levels of sodium chloride and mineral contaminants as well as high BOD/COD from residual sugar. Client had been disposing of this waste stream by trucking waste water to disposal firm where waste water was disposed of by direct discharge into the ocean via off shore deep water waste pipelines.
Client Needs
Changes in environmental regulations were made by the regulatory agencies that required the client to cease discharges to the ocean and find alternative means of disposal. Additionally, water was becoming a more scarce and expensive commodity due to population growth in the country. Client had identified use of this waste stream as a mineral/salt supplement in animal feed as a viable new means of waste disposal, however the waste stream as generated was too dilute for this use.
Options Investigated:
Biological Treatment- Biological treatment was investigated to reduce the COD/BOD of the waste stream. This option was not feasible due to the high salinity of the initial waste water preventing effective biological activity.
Reverse Osmosis - Reverse osmosis was investigated as a means to increase the concentration of the dissolved contaminants while producing water for re-use in the plant. Limitations of the reverse osmosis option was final concentration of waste stream was still too low resulting in need for additional treatment being required and fouling of membranes due to the contaminants was a significant concern.
Evaporation - Evaporation was investigated as a means to increase the concentration of the dissolved contaminants while producing clean water for re-use in the plant. Client was familiar with evaporation process due to evaporators being used in the their existing manufacturing process. Evaporator did not have limitations on final concentration of dissolved salts like the reverse osmosis option. Use of a forced circulation flash evaporator design would minimize deposition and fouling in the evaporator due to the high shear rate on the heat transfer surface and no phase change occurring in the heat exchangers.
Client Solution:Client selected ENCON to provide the Mechanical Vapor Compression (MVC) evaporator as the desired solution to their waste water treatment needs. ENCON's use of a custom design philosophy to ensure client system meets desired performance requirements and utilizes components appropriate for long service life in the application was a differentiating factor between ENCON and competitive evaporator suppliers.
Results:
- 80% reduction in volume of waste water
- Final wastewater residual:
- TDS - 250,000 mg/L
- COD - 40,000 to 65,000 mg/L
- BOD - 10,000 to 20,000 mg/L
- Chlorides - 100,000 mg/L
- Product suitable for use as animal feed salt supplement
- Distillate Quality:
- <50 mg/L of TDS
- Suitable for re-use in plant
- Energy Consumption <0.16 kW/gallon
Evaporator Specifics:
- Evaporator capacity - 450 gallons per hour of distillate
- Evaporator materials of construction - Titanium & Hastelloy C
- Electrical - 400V, 3 phase, 50 Hz
- Forced circulation, flash design
- Plate Heat exchangers with titanium plates