Advanced Treatment Of Oily Wastewater By Technology Of Bacteriostatic Fly Ash Adsorption-Regeneration

For the present, the method of advanced treatment for oily wastewater includes adsorption,membrane technology, biological treatment and so on. The most common method was adsorption,and activated carbon was the most common adsorbing material. But the cost was high and theregeneration was very difficult, the applications were limited as well. Thus, fly ash was modifiedrationally which could applied to advanced treatment of oily wastewater and regenerationprocess was developed.Using acid to modify FA can increase the aperture of FA. The particle size of FA wasincreased from 4.98 nm to 11.32 nm. Using chemical graft method, quaternary ammonium saltgroups grafted to the fly ash surface. The highest bacteriostatic rate of modified FA was 96%above. When the dosage of quaternary ammonium salt was1 mL and reaction time was 6 h,quaternary ammonium salt of ethanol liquid repeated use four times later bacteriostatic rate stillcan reach 90%.In order to reduce the cost, silicone quaternary salts were prepared. 3-(Trimethoxysilyl)propyldimethyldodecyl ammonium chloride was synthesized by quaterisation reaction with3-chloropropyltrimethoxysilane and N, N-Dimethyldodecylamine. Some factors had beenstudied for the synthesis, such as the solvent and the reaction time. From these experiments, withalcohol as solvent, products in conversion and color was superior to other solvents. The optimalreaction conditions were found in the solvent of alcohol at 80℃for 24 h, and the yield of the product was 60.2%.Using the modified FA to treat oily wastewater, the adsorption properties were evaluated bydetermination of the oil removal rate through static adsorption. The result indicated, the optimumoperating conditions to static adsorption were the following: particle size of FA was 20 mesh,addition amount FA was, the temperature was 30℃, the initial pH was 10. The final oil removalrate was 90%. It is difficult to solve the question of regenerate the adsorbent, some methods hadbeen studied for the in situ regeneration, such as acid, alkali, biological. The feasibility ofregeneration and the influencing factors of percentage regeneration were studied in thisexperiment. The result indicated that three regeneration processes in effective and stable. After 4rounds of adsorption-biological regeneration cycles, the percentage efficiency can reach 72%.Biological regeneration was superior to acid and alkali regeneration in regenerative effect.Experimental water was the central sea asphalt with the light out, technology ofbacteriostatic fly ash adsorption-biological regeneration was in application.Adsorption-biological regeneration process water oil content < 1 mg/L, CODcr < 20 mg/L, canachieve reuse criteria.