Removal Efficiency Of Nitrogen And Phenol By Process Of Fluid Bed With Mesoporous Biological Carriers And Coagulation Adsorption Of Montmorillonite

Coking wastewater is a kind of typical trouble industrial wastewater with high concentration of phenols and NH₄⁺-N, which could pollute environment seriously and do harm to human health heavily. Though the effect there was on the treatment of phenol, cyanogens and BOD5 in this wastewater by the existent treatment methods, the effluent COD, NH₄⁺-N and colority couldn't meet the discharge standard, which has been one of the main pollution sources of river in our country. In this paper, according to the research situation of treatment process of coking wastewater, the combination process of biological fluid-bed packed with new mesoporous biological carriers and adsorption coagulation with modification montmorillonite was proposed. Organic compound and nitrogen removal performance of mesoporous biological carriers and modification montmorillonite were investigated in the treatment of simulated wastewater and coking wastewater, and both lab-scale and practical application studies were conducted. This combination process will be a feasible scheme to solve the problem of the coking wastewater pollution.High concentration phenol and coking wastewater was regarded as research object, and the organic compound and nitrogen removal performance of fluid-bed packed with mesoporous biological carriers were researched. The results showed that there were good effect on the phenol solution of 1000¹500mg/L and coking wastewater with COD of 1700⁴200mg/L in this fluid-bed reactor, the removal efficiency of phenol, COD and NH₄⁺-N was above 99.9%, 80% and 70%, respectively, when HRT was 20 h, pH was 6.6⁸.1 and DO was 1.8³.7 mg/L. And this fluid-bed reactor packed with mesoporous biological carriers had the stronger impact resistance and self recovery capability. And it also was found that there was phenomenon of simultaneous nitrification and denitrification (SND) in the reactor. Orthogonal experiment results indicated that the importance of influence factors on treatment effect of this fluid-bed reactor was HRT > DO >influent COD concentration > pH. Furthermore, combination of two stage fluid-bed reactor could evidently improve the loading of influent NH₄⁺-N and obtain good treatment effect, effluent COD and NH₄⁺-N had been close to the discharge standard. When the ratio of COD/NH₄⁺-N was above 10, the removal efficiency of COD, NH₄⁺-N and TN was above 95%, 90% and 80%, respectively.Because the effluent quality of biological fluid-bed reactor to coking wastewater couldn't completely meet discharge standard, organic modification montmorillonite and Na-montmorillonite were prepared by common heating method and microwave irradiation using cetyltrimethyl ammonium bromide(CTAB) as organic modifier and Na2CO3 as sodium agent, and the adsorption of simulation phenol and NH4Cl wastewater on these materials was investigated. The results indicated that the adsorption effect of phenol on organic modification montmorillonite by microwave irradiation (M-OMt) was the best, the removal efficiency was 80.7%, when the dosage of this montmorillonite was 20 g/L, adsorption time was 30 min, pH was lower than 10. And the adsorption effect of NH₄⁺-N on Na-montmorillonite (Mt(Na)) was the best, the removal efficiency was above 60%, when the dosage of this montmorillonite was 10 g/L, adsorption time was 30 min, pH was 7⁹. The adsorption processes of the two montmorillonite materials both were in conformity with Freundlich isothermal adsorption equation. According to the analysis of adsorption thermodynamics and dynamics, it was preliminarily ascertained that the main mechanism of phenoladsorption was physical sorption for M-OMt, and the main mechanism of NH₄⁺-N adsorption was chemical sorption for Mt (Na). The adsorption kinetics for two montmorillonite materials could be well described by the pseudo-second order kinetics model, and the adsorption activity energy was 2.589 and 1.613 kJ/mol, respectively. The composite adsorption coagulants prepared with M-OMt : Mt (Na) : polyaluminum chloride = 20 : 20 : 1 (mass ratio) was used to deeply treat coking wastewater, and the treatment effect was also investigation. The results showed that the removal efficiency of COD, NH₄⁺-N and colority was 84.8%, 78.2% and 96%, respectively, when the dosage was 30 g/L, adsorption time was 30min.Physical and chemical performance of new mesoporous biological carrierswere investigated, the results showed that there were lots of negative charges on the surface of mesoporous biological carriers that was mainly composed oforganic substance with about 81.6% amount. The existence of this biological carrier in the fluid-bed reactor accelerated the process of oxygen transfer, which could improve the oxygen transfer coefficient to about 10%. And the adsorption of phenol on this biological carrier was very low, which indicated that the removal efficiency of phenol in the fluid-bed reactor mainly caused by the degradation of microorganism, not by the adsorption of biological carriers. The change of appearance and structure of montmorillonite before and after modification was also characterized. The results showed that comparison with raw montmorillonite, the interlayer spacing of M-OMt was increased and the specific surface area was decreased; the interlayer spacing and specific surface area of Mt (Na) were all decreased. And the basic raw structure of montmorillonite wasn't changed after modification. The characteristic results also indicated that the arrangement of CTAB cations in OMt was the close M-type lateral-monolayer combined with the monolayer adsorbed water molecule, however, CTAB in M-OMt was arranged in the form of the orderly and loose inclination angle of 34.1o.The practical application was carried out to verify the operation efficiency of this combination process. The results indicated that this combination process could completely meet the treatment requirement of high concentration coking wastewater, the effluent of COD, NH₄⁺-N and total phenol was 20.56, 9.55 and 0.12 mg/L, respectively, which was lower than the GradeΙof Wastewater Discharge Standard. According to the analysis of water quality, it was found that there were excellent removal effect of nondigradation heterocyclic compounds in coking wastewater on the combination process, and the main residual organic compounds were alkanes in the effluent of this combination process. And the treatment efficiency of the process was stable, and the combination process could tolerate the bigger organic loading and hydraulic impact. Work of this dissertation has great theoretical and practical value as it provided a feasible technology and enough data basis to solve the problem of the gasification wastewater contamination.