| For high emulsion stability, high oil and hard biodegradation as the maincharacteristics of water emulsion, high emulsion stability is the key to the treatment ofemulsion wastewater. Demulsification oil removal, COD reduction of dissolvingorganic matter in water is the two key problems of economic and effective treatment ofemulsion wastewater. The process object in this paper is emulsion wastewater of aChongqing engine manufacturers. The chemical demulsification-Fenton oxidation forthe treatment of emulsion wastewater was used in this paper. This paper studies somecharacteristics and laws about different kinds of demulsifier, dosageand pH ondemulsification of emulsion wastewater. Combined with the Zeta potential valuedetermination, related physical and chemical factors on the stability of the emulsionsystem mechanism were analyzed. The effect characteristics and laws of pH, dosage, n(H2O2)/(Fe2+) and reaction time on removal efficiency was studied in Fenton system,and the characteristics of H2O2, Fe2+of Fenton system were also examined.The results showed thatelectrostatic effect has a critical effectin the process of thedemulsification of emulsion wastewater with sulfuric acid. Low pH is advantageous tothe demulsification of emulsion. When the COD of emulsion wastewater was7500mg/L, and the pH of emulsion wastewater was adjusted to2, Zeta potential was-3.24mv and COD value fell to3080mg/L from initial7500mg/L.TheCODremoval of PFS,PAC was better than inorganic small molecule flocculant of sulfate, ferric chloride, andIron salts was better than aluminum salt. The oil droplets electrostatic repulsion changescaused bythe coagulant dosagehave a critical impact on demulsification of oil-waterdispersions. Increasing the dosing amount of coagulant contribute to reducing oilelectrostatic repulsion and strengthening the oil-water separation. The pHvalue ofwastewater effect has a great influence on COD removal. The appropriate pH valuecondition of oil droplets dispersed systemunstability should be smaller electrostaticrepulsion between oil droplets, and the existence of multi-core complexing ions whichhave large molecular weight and large specific surface area,and can be the role ofadsorption bridging, sweep volume to strengthen unstability of oil-water dispersions.In the Fenton system, the COD removal could have a certain improvement with theincrease of Fe2+dosage for a certain H2O2/Fe2+ratio. The COD removal increased to acertain limit as n (H2O2)/(Fe2+) increased to a certain degree for a certain Fe2+dosage. The COD of emulsion wastewater fell from1140mg/L to460mg/L with the increase ofH2O2/Fe2+ratio from1:2to20under the certain conditions:initialCOD1500mg/L, initialpH3, the Fe2+dosage of1500mg/L, reaction time of2hours.The COD removalefficiency of wastewater increased by50%.In the Fenton system of emulsionwastewater, H2O2concentration drastically decreased and then began to flatten. Fe2+concentration fell sharply in a very short time and gradually tend to be a balance. TheCOD removal rate increased with the increase of H2O2/Fe2+ratio for a certain Fe2+dosage，but the increase rate tends to be reduced. The time required to achieve stabilityof the COD removal, H2O2concentrationincreased with the increase of H2O2/Fe2+ratio,and Fe2+stable value sharply reduced to a low concentration level. Change ofCOD with time conform to the y=a+b·exp(-k·t) model. The change of H2O2, Fe2+withtimeconform to the first order reaction kinetics model.In pure water Fenton system,·OH generation increased to a certain limit asn(H2O2)/(Fe2+) increased to a certain degree for a certain Fe2+dosage,and correspond toCOD removal in the Fenton system of emulsion wastewater.Compared with pure watersystem, due to the existence of the wastewater pollutants and a variety ofsubstancesgenerated in the reaction,Fe2+conversion rate of emulsion wastewater Fentonsystemreduced and H2O2increased. |
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