Study On The Coking Wastewater Treatment By Using Combined Ferrate

STUDY ON THE COKING WASTEWATER TREATMENT BY USING COMBINED FERRATEABSTRACTIn this paper, the combined ferrate was used for the treatment of cocking wastewater as a flocculant and oxidant. The removal efficiency of CODcr, NHs-N, hydroxybenzene, chroma and turbidity were studied. Environmental conditions were investigated systematically, and all the effects on the contamination removal at different environmental conditions were analyzed. An improvement was adopted in the preparation of potassium ferrate and the combined ferrate was applied as a flocculant. The stability of the combined ferrate solution was analyzed by using the UV- Visible Spectrophotometer and the Cyclic Voltammograms. The experimental results showed that: (1) The cost of the treatment of cocking wastewater would decrease by use of the combined ferrate instead of the pure potassium ferrate as a flocculant, and the efficient concentration of Fe2O42" could also be kept at a certain degree more than that needed. (2) To the same initiative concentration of combined ferrate solutions, the stability of Fe2O42" could be improved at 50% level when a certain kind of additive (A) was added at the scale of 1 : 10 and the holding time of 200hr. And the oxidation and flocculation abilities of Fe2C>42" were not affected. (3) The CODcr removal rate could be reached to 58.54% when the CFeO42" = 5.68mg/L, pH=7, T=25.4*C and the initial CODcr = 159.85 mg/L. (4) The ammonia-nitrogen (NHs-N) removal rate could be reached to 98% when the initial NH3-N sS2.706mg/L, and the residual NH3-N was 0.0345mg/L . The results were better than that of other flocculants when they were used in the third-stage disposal. (5) When the combined ferrate was used in dealing with the high concentration of ammonia - nitrogen (NH3-N?2935.5mg/L), the removal rate could be reached to 56%. The residual NH3-N concentration could be met the microorganism need in A/O stages. This method was superior man the traditional technique, such as the investment of the equipment would be less. The feasibility would be realized easily when Ihe cost of the ferrate preparation was decreased and the stability would be better. (6) The chroma removal rate could be reached at 73.47% by 1.73mg/L ferrate when -the initial chroma was 250 and the pH=6.17, CODcr ? 150mg/L of the cocking wastewater. The disposed wastewater had no color and odor, having the characters as the clean water. Themicroorganism and the activejsludge. (7) The ferrate,was, a green flocculaht with moreoxidation, coagulation-flocculation and adsorption abilities compared with the other kinds oforganic or inorganic polymer flocculants.