Experimental Study On Coking Residual Ammonia Wastewatr Treatment By Enhanced Fenton Reagent Combined With Coagulation

The treatment of coking wastewater has been a severe problem all over the world due to its complexity,intractableness and inhibitory characters. The traditional technology treating coking wastewater couldn't meet the current requirements. By comparing some common Fenton - like reagents, the paper chose Fenton /UV combined with coagulation system as the scheme to treat the residual ammonia effluent which had strong biologic inhibition.Firstly the paper established the main influencing factors in Fenton /UV system, L₉(3⁴)table was designed to do the orthogonal experiments, Composite score method was used for the statistics of the data . The results showed the sequence of importance among these factors are the dosage of H₂O₂ >reaction time>dosage of FeSO₄ > pH value, prime combination of these parameters were ascertained.According to the results, single factor Rota tests were carried out to study the impact and correlations between removal rates and those main influencing factors, respectively, the optimized running parameters were confirmed.Taking both the treatment effect and cost into consideration, the optimum condition of Fenton / UV system was obtained under the following condition: H 2O2concentration 5.9g/L, FeSO4 2.5g/L, reaction time 75 min, pH value 7. the optimization studies showed that the COD concentration of effluence was 410.48mg/L ,with a removal rate 85.14% and chroma was about 16 and pH 2.2, the volatile phenol was nearly wiped off completely.Coagulation tests took the oxidation effluence as the objective, the following conclusions could be drawn: Fe³⁺ alone couldn't achieve a favorable effect, the existence of PAM would remarkably enhanced this process, the flocs were more bulkier and denser, and had a bigger sedimentation rate, it also had preferable effects on the COD and chroma removal rate; The forms of hydrolyzed polymer of Fe³⁺ were strongly linked with pH value, when pH =7, Fe³⁺ and Fe²⁺ would fully settled, COD removal efficiency could reach 85.88%, further increase of pH value would bring in lower removal rate.The overall performance results of this study for the Fenton /UV reagent combined with coagulation of coking wastewater obtained maximum overall efficiencies of 97.51% forCOD , 80% for chroma and 94.82% for NH₃-N. The main parameters of the effluent were COD 68.74mg/L, chroma 16, NH₃-N 97mg/L, pH value was maintained between 6 and 7, each index could meet the standard except NH₃-N.