Experimental Study On The Removal Of Ammonia-nitrogen In Coking Wastewater

Coking wastewater which contains not only high concentrations of ammonia-nitrogen, phenol, cyanide, and also contains indole, naphthalene, pyridine, phenanthrene anthracene, benzopyrene and other aromatic compounds is difficult to be treated. Huge amounts of ammonia-nitrogen pollution has been discharged to our water resources from coke plant every year, bringing great harm to our environment. Forced by the pressure of energy-saving and ejection-decreasing, many coke plants have to modification the water treatment system. Much research shows that high concentration of ammonia-nitrogen in coking wastewater can not be effectively removed by traditional biodenitrification as the bacteria performs low activity.The subject put forward a new way to reduce the concentration of ammonia-nitrogen to a low level allowed by biological treatment. A new craft combination of chemical precipitation and ceramic membrane technology is researched in this paper.Through simulation of struvite formation reaction, probably estimates the optimal pH and ways of drug dosing information. Then coking wastewater from Ningbo Steal Co., Ltd. was tested. Based on a amount of experiments, the paper sutdied several parameters and summarized the relationship among PH value, reaction ratio etc. Through single factor and orthogonal experiments, the paper drew an optimal reaction condition. The research result shows that optimal PH is 9.5, Mg:N is 1.2:1.0, P:N is 1.3:1.0. This paper also discussed the kinetic parameters of struvite formation reaction and calculated Ea=13.5KJ·mol-1.Especially, the subject focuses on the design and operation parameters of ceramic membrane filter. Through practical application, the optimal inlet pressure is 0.6MPa, backwashing pressure is 0.6MPa, backwashing period is 10h, backwashing time is 25min. As the shortcomings inherent in ceramic membrane limited, it need be cleaned with 1.0% HCl and 2.0% NaOH solution each month. After 10 minutes cleaning, it can get very good restoration.The integrative craft combination of MAP precipitation and ceramic membrane technology provides a good reference to many of the older coke plants. This study shows that the craft is feasible and stable. Just adding some equipments, the system can reach the ejection-decreasing standard.