Progressive Freezing Method for Concentrating Tetrahydrofuran (THF) Remained in Grignard Reagent Wastewater

Abstract

Progressive freezing technology was developed as a promising method to concentrate tetrahydrofuran (THF) remained in Grignard reagent wastewater. Effects of freezing temperature, ice formation rate, and seeding ice on ice purity were characterized. Results indicated the peak removal efficiency of chemical oxygen demand (COD) with the concentration of 3,050 mg⋅L−1 occurred at the lowest ice formation rate of 20% and −4.0°C. The minimal ice electrical conductivity happened at −6.0°C with the ice formation rate of 40%. Seeding ice improved ice purity in the range of −0.5 to −1.0°C. Subsequent test ran in plant revealed the potential application of this approach to concentrate THF from Grignard reagent wastewater. COD removal efficiency peaked at 98.09% at the stirring rate of 200 rpm and the cooling gear of 1 block. Moreover, the theoretical energy consumption was 38.26 kW⋅h per one ton of wastewater.

Sustainable nutrient recovery from animal manure: A review of current best practice technology and the potential for freeze concentration

“…As a solution, the authors suggested adding a sweating step to drain out the liquid trapped in the ice and to improve the resulting ice purity. PFC may also provide an effective, economical, and feasible alternative for recovering Tetrahydrofuran from Grignard reagent wastewater (Chen et al, 2019). Results obtained from pilot-scale tests showed an optimal COD removal efficiency of 98.1% and a COD as low as 680 mg L − 1 in the melted ice solution.…”

“…Freeze concentration (FC) has become a technology of interest due to the low temperature of the process (Sánchez et al, 2009). The use of FC has been reported by many sectors including: concentration of liquid foods, seawater desalination, purification of organic chemicals, and treatment of hazardous wastewater (Chen et al, 2019;Htira et al, 2018). Regardless of the application, the freezing temperature should be below the freezing point of the treated solution.…”

Application of Freeze Concentration Technologies to Valorize Nutrient-Rich Effluents Generated from the Anaerobic Digestion of Agro-Industrial Wastes

“…As an example, FC process has gained popularity at an industrial scale for the purpose of fruit juice concentration [17], sweetening solutions [18], dairy processing to improve milk quality [19], as a pre-step for ice-cream production [20] and wastewater treatment [21]. Chen et al (2019) [22] also reported a high separation efficiency of the FC process to treat seawater with 58% less energy consumption as a non-scaling and chemical-free process. Regarding valuable compounds preservation, FC technology has also been illustrated to be a highly effective process to concentrate juices [23], wine, beer, milk [19], coffee, and tea; with all flavor and aromatic components retained [16].…”