Oil And Water Separation Based On Coalescence Technology

Oily wastewater has a wide range of sources and serious hazardous. Oilywastewater treatment has important practical significances since it comes to energyrecovery and environmental protection. Among many treatment methods, coalescencetechnology has attracted increasing attention for its demulsification advantages,environment-friendly and low cost. A designed vertical sleeve separator and the glassmicrofiber selected as the main coalescence material were used in the research. Theeffects of the bed properties (porosity, length and arrangement) and flow conditions(flow rate, influent oil concentration) on the oil removal were revealed. Based on theexperimental results, the paper identified the interaction between bed porosity andheight, explained the mutual influences between the emulsion velocity andconcentration, and quantitatively derived the appropriate ranges of bed characteristicsand operating conditions. In addition, the subject revealed the entire process andconstructed a physical model of the oil removal by the coalescing bed.Porosity and length of the bed have a combined impact on oil removal. When thebed length was2mm, the effluent oil concentration increased by354.5%in theexponential form as the bed porosity increased from0.850to0.925; while the bedlength was4mm or8mm, the effluent oil concentration increased by44.9%and43.4%respectively in the liner form with the same porosity changes. The increase ofthe bed length increased the oil removal efficiencies from a macro perspective, but theforms and extents of the impactions were inconsistent in different bed sections. Inaddition, the investigation of the bed arrangement showed that the glass microfiberbed had the highest oil removal efficiency while the kapok bed efficiency was lowest,and the efficiencies of the composite bed and mixed bed were between the two purebeds.Compared to the influent oil concentration, the flow rate had a more crucialimpact on the coalescence function of the bed. When the flow rate was lower than thecritical velocity, the average effluent oil concentration was7.20mg/L. Once the flowrate exceeded the critical value, the effluent oil concentration increased dramatically.The increase of the influent oil concentration was beneficial to oil removal. When theinfluent oil concentration increased from200mg/L to1000mg/L, the oil removal efficiency of the three selected bed increased by2.90%,3.18%and4.77%,respectively. While the influent oil concentration exceeded1000mg/L, its impactswere reduced to a secondary position.In the mechanism analysis of the oil and water separation by the glass microfibercoalescing bed, the process of oil removal by coalescence was divided into threestages: accumulation stage, transition stage and equilibrium stage. The actual porosityof the coalescing bed was calculated according to Carman-Kozeny equation.Finally, the glass fiber bed was used in the treatment of the refinery oilwastewater, the oil and the suspended solids removal efficiency was beyond96.9%and86.5%, respectively.