| By extensively reviewing relevant literature and data, combined with production practice, andadopting feasible pre-processing, research and design of resource scheme was conducted for thethermoplastic phenolic wastewater, which phenol concentration was about4.4%, formaldehydecontent was about0.09%, COD was more than130,000mg·L-1, in order to achieve the purposeof realize the resource, reduce the toxicity of phenol wastewater, cut the cost, and don’t affect thesubsequent processing of biochemical system, two schemes was formulated as follows.Plan A: Firstly pretreated with adsorption method, then SBR process for advanced treatment.The research was carried out on the pre-processing feasibility of6kinds of adsorbent, includingsoft polyurethane foam (SPF), activated carbon fiber and so on. The results showed that SPF hadthe highest adsorption capacity on phenol. The static adsorption, dynamic adsorption,regeneration properties and service life of SPF were discussed for the purpose of study theadsorption characteristics of SPF on phenol; And the tolerance and stability of the activatedsludge on phenol were tested within24hours in SBR process.The main results are as follows:（1）Static experiments were carried out to study the effects of pH, temperature,and time onthe adsorption capacity of SPF on phenol. The adsorption isotherms were drawed, and fittedwith Freundlich and Langmuir isotherm equation. The results showed that the static maximumadsorption capacity of SPF was emerged30minutes later under the normal temperature and pHbetween2to4. Meanwhile, its adsorption isotherm was according with Langmuir model.（2）Dynamic experiments were carried out to study the effects of wastewater velocity onthe adsorption capacity of SPF on phenol. The breakthrough curves were drawed, and theoptimum mass of SPF was determined. The saturated SPF was desorbed and regenerated byalkali washing and the beet concentration of NaOH was determined. The results indicated that the breakthrough volume was75mL, the breakthrough concentration was0.3108%, and theadsorption capacity of SPF on phenol was607.27mg·g-1when the mass of SPF was5.2782g, andthe wastewater velocity was100mL/h. Furthermore, the optimum mass of SPF for dynamicadsorption was3.8990g under the condition of60ml phenolic wastewater, and the adsorptioncapacity was661.49mg·g-1. The desorption efficiency was up to93.53%when the saturated SPFwas desorbed and regenerated by6%NaOH solution at room temperature.（3）In order to study The regenerability and service life of SPF,84times fatigue tests with3.8990g SPF under the condition of60ml phenolic wastewater were carried out totally.Meanwhile, the SEM images of SPF surface in different stages were got by means of scanningtunneling electron microscopy to analyze the adsorption and desorption mechanism. The resultsturned out to be good. The best effect was emerged in the fifth time of fatigue tests which theremoval rate of phenol reached98.76%. After80times fatigue tests, the removal rate of phenolwas over94%, and COD was over90%, and the effluent qualities were stable. it showed soexcellent mechanical strength and adsorption-regeneration properties that could be used as anadsorbent for pretreating wastewater of high concentration phenol.（4）After primarily adsorped by SPF, the concentration of phenol was reduced to about0.1%. The tolerance and stability of the activated sludge on phenol within24hours in SBRprocess were studied. The results pointed out that when gradually increased the concentration ofphenol to about50mg·L-1, the removal rate of phenol was up to93.51%after24hours. Theactivated sludge disintegration occured when the concentration of phenol increased to100.8mg·L-1. The SBR process showed good stability when the influent concentration of phenolwas kept at50mg·L-1, and added some acclimated activated sludge, continuously running for6days, the removal rate of phenol was more than92%after24hours, and the removal rate ofCOD was more than72%.Plan B: To remove phenol and salt, it was formulated to used the organic acids as catalystsinstead of concentrated sulfuric acid to catalyze the second Condensation of phenol andformaldehyde, which could recover some low-grade phenolic resin at the same time. The Phenolic wastewater, which used concentrated sulfuric acid as catalyst, had suchcharacteristics as high salinity and non biodegradable when neutralized. To solving theseproblems, it was planed to used the three kinds of organic acids as catalysts, including salicylicacid, oxalic acid and acetic acid,whose feasibility and the best dosage were studied. The resultsshowed that, only oxalic acid could play a catalytic role. It received better effect when addded3gpolycondensation formaldehyde(mass concentration is37%) and6g oxalic acid into every100mL wastewater. At this time, the removal rate of phenol was90.31%, the removal rate ofCOD was70.01%. Althought this method could recover some low-grade phenolic resin, however,the utilization rate of formaldehyde was merely48.37%. Further, the concentration offormaldehyde was more than6000mg·L-1. Therefore, this method was infeasible. |
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