Wastewater treatment and water reuse of food processing industries. Part II: Techno-economic study of a membrane separation technique

Autor: Azza Hafez, Maaly Khedr, Hanaa Gadallah
Rok vydání: 2007
Předmět:
Zdroj: Desalination. 214:261-272
ISSN: 0011-9164
DOI: 10.1016/j.desal.2006.11.010
Popis: To reuse pretreated water effluent of the El-Nile Company for the food industry in Egypt, NF and RO membrane separation techniques were investigated. Two sets of experiments were carried out by using laboratory separation unit with maximum pressure of 7 bars and pilot plant membrane separation unit with maximum pressure of 14 bars. Based on the analyses of collected samples, a hydration model was used to determine the combined salts in the wastewater. The combined salts were used in the preparation of a synthetic solution simulated to the wastewater of El Nile Company. The experiments were divided into two parts: the first part was concerned with the application of membrane separation experiments to synthetic solutions and the second part was concerned with the pretreatment and membrane separation experiments of the industrial wastewater. The first part was carried out by using NF followed by RO membrane separation technology. Best performance for NF process is observed in separation of divalent ions and the less in separation of monovalent ions, NF membrane succeeded in ~30% removal of divalent and trivalent ions, while RO membrane proved separation of 99% of sulphate ions, 96% of iron, 93% of bicarbonate, ~90% of sodium, magnesium and sulphide ions, 86% of potassium, 73% of phosphate and 25% of calcium ions. The second part was concerned with industrial wastewater, where oil and grease were completely removed by floatation, 11% of TSS and 12% of COD were removed by clarification, while coagulation by using 2 mg/l of anionic polymer removed 93% and 30% of TSS and COD respectively. The pretreated wastewater was allowed to pass through NF membrane at 14 bars followed by RO membrane at pressure of 14 bars. The separation efficiencies of monovalent, divalent and trivalent ions were nearly 2-3% less than that in case of synthetic solutions, while COD and BOD were completely removed. The water resulted from NF may be used in industrial processes and low pressure boilers while the water resulted from RO membrane may be used for high pressure boilers. Based on the previous results, preliminary techno-economic evaluation for 1200 m 3 /day treatment plant was performed. The designed plant consists of: holding tank, oil separator, flash mixer, coagulation unit, clarification and settling unit, MAF unit, MIF unit, UF unit, NF unit and RO unit. The fixed capital cost was 1.46 million Egyptian pounds. The cost of treatment of 1 m 3 wastewater was 1.3 LE.
Databáze: OpenAIRE
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