Study On Demulsification-coagulation-adsorbent Process For The Treatment Of Oil-bearing And Emulsifying Wastewater Containing Fluorescent Permeating Agent

Fluorescent penetrant is used for the cleaning process of precision machine parts in non-destructive testing?NDT?.There will be produced wastewater with fluorescent permeating agent with high chemical oxygen demand?COD??1000¹5000 mg/L?,high mineral oil?300³000 mg/L?and high chroma?600²000?.This liquid waste has seriously influence to environment for its' stronger biological toxicity and higher virulent.How to treat them is a difficult task in sewage treatment.In view of the characteristics of wastewater with no destructive testing of precision parts in this mechanical company in Hengyang,this research has compared demulsification effects between the nonionic surfactant demulsifier of AR and the eletrolyte demulsifier of CaCl₂ and MgCl₂,the coagulation performance between the polymeric aluminum chloride?PAC?and the polyaluminium chloride sulfate?PACS?.Effects of the types of demulsifier and coagulant,dosage,pH,static duration,absorbing time and other process parameters have been investigated.Based on that,the process parameters have been optimized.The main conclusions are as follows:?1?Comparing AR demulsifier with the traditional demulsifier CaCl₂and MgCl₂,AR demulsifier has better COD removal efficiency.The best pH is 7⁹,adding 4 mL/L in wastewater,sat at 100 r/min for 3 min,and settling for 1.5 h.?2?The experimental results of PAC and PACS show that PACS has a better coagulation property than PAC in the treatment of wastewater with fluorescent permeating agent.Using a PACS coagulant dose of 3mL/L,the pH was optimised at 7⁹ to attain minimum COD,using a PAM dose of 4 mL/L as coagulant aid and laying-aside for 15 min.?3?The result of kinetic study of COD on the vermiculite can be described by the pseudo-second-order kinetics model.?4?The wastewater was treated with vermiculite as adsorbent with the best dosage of 5 mg/L for 30 min adsorption time.The equilibrium adsorption capacity of the pseudo-second-order kinetics model is up to11.455 mg/g and the equilibrium adsorption capacity of the test is 10.899mg/g.?5?After treated by the integration method,which brings high quality and efficiency in removal of 97.87%COD,99.62%oil and99.22%colority.This can meet the first grade standard of integrated wastewater discharge standard?GB8978-1996?.Thus,the integration method of demulsification-coagulation-adsorbtion is a practicable way to solve this kind of sewage.