Analysis On The Characteristics Of A1 - A2 / O Process Emission From Black Cat Coking Wastewater And Experimental Study On Dehydration Of Coke Powder

Coking wastewater is a kind of waste water with high concentration organic, it was produced in the process of high temperaturedry distillation, coarse gas purification and deep processing of chemical products. Its composition is very complicated, containing polycyclic, hetercyclic aromatic compounds and toxic and refractory organic compounds. In this paper, the A1-A2/0 treatment process of Heimao company was selected as the research object, through continuous testing of each unit of water quality index, the discharge emission characteristics of this treatment process was obtained by using UV and GC-MS methods. In order to deepen the treat of biochemical effluent, the pulverized coke was used in biochemical effluent. The results are as follows:According to the national discharge of waste water, the final plant effluent indexes for Heimao company are:COD meets the national secondary standard, ammonia nitrogen is slightly higher than the first national standard, cyanide and sulfide are both higher than the first and secondary standard, the removal of volatile phenol is almost 100%. In the A1-A2/O each unit effluent, the most remarkable degradation of COD, ammonia nitrogen, volatile phenol, cyanide and sulfide index is in anoxic tank stage, and the removal rates are 64%, 57.4%,69.6%,41.6%,58.6%. The respectively pHs in each process unit are stable between 8-9, which could provide the stability of the breeding environment for microorganisms metabolism.As can be seen from the UV chromatography, in addition to the aerobic tank, adjustable tank to secondary sedimentation tank, each unit effluent decreased gradually in the peak area of 200-400nm interval, that indicat each stage has different levels of degradation of organic matter. Contracting two adjacent unit effluent drop size in the peak area of 200-400 nm interval, draw the degradation degree of each unit of organic matter as:anoxic tank> aerobic tank> anaerobic pool. At a wavelength of 300 nm has been the existence of an absorption peak, its absorption is the peak of naphthalene by subsequent GC-MS analysis.More than 60 kinds of organic compounds were delected from the waste water by GC-MS, mainly divided into these categories:phenol, ammonia nitrogen, alkanes, alcohols, acid and salts. The phenol compounds occupie 45% of the total organic matter, ammonia nitrogen compounds accounte for 17%, alkanes accounte for 18%, the three above compounds are the most of the organic components in the coking wastewater. Analyzing the chromatogram and mass spectrometry data, the degradation of organic matter in each reaction pool could be affected by organic molecule struclres, microbial population and biological enzyme system factors. A sharply decrease of organic matter was observed in the anoxic pond water, and it was presumed that:a large number of phenol and ammonia nitrogen were cleavaged under the action of PAH dioxygenase, which could provide carbon source for denitrification. In secondary sedimentation tank effluent, only detected low concentration of 2,2-methylene -4- methyl phenol, naphthalene, and long chain alkane. Naphthalene makes up 91.7% of the total phenolic content system. It has more stable Ï€â†'Ï€ conjugated system than single ring phenol,which results in the low degradation.Pulverized coke was used as adsorbent in the depth of processing effluent, through single factor experiment, investigat four factors of pulverized coke adsorption properties:the dosage of pulverized coke(30-180 g/L), particle size(0.5-6.0 mm), adsorption time(1-5 h), pH(2-10), achieve the adsorption process conditions of single factor. Based on the results above, Design Expert software was used for optimizing the single factor process conditions, the optimized conditions are:133 g/L dosage,3.5 h adsorption time, particle size of 1-2.5 mm and pH 3.5-4. Five validation experiments were carried out under the best process conditions, the average removal rate of COD is 70.5%, which coincides with the prediction value 71.4%. Further more, it indicats that the pulverized coke could be applied in the deep treat of coke effluent. The experiment data will provide theoretical guidance and data support for advanced treatment of biochemical effluent.