Optimization Design And Performance Research Of Novel Two-phase And Two-stage Anaerobic Reactor Treating Paper-making Wastewater

The characteristics of papermaking wastewater are high organic load, poor biodegradability, large amounts of refractory pollutants. Emission of papermaking wastewater account for 44% of industrial waste water, Its emission had a significant impact on the environment. Anaerobic technology can treat wasterwater which has high organic load.Aslo the anaerobic need low energy consumption and produce biogasenergy .So it is fit for treating papermaking wastewater, but the traditional anaerobic technology can not withstand the impact of mutative papermaking wastewater load which can cause the " acidification " phenomenon. If reactor arise acidification phemomenon, the reactor will have low treatment efficiency and poor stability, so the research of new high-rate anaerobic wastewater treatment technology is important. This paper studies include: the new anaerobic reactor research and development, improvement and optimization; then make comparison performance of new reactor between traditional anaerobic technology and analysis the performance of new anaerobic reactor,and last using the new reactor papermaking wastewater through ethanol acid desulfurization process which need go through domestication and startup of reactor ,then reaserching factors of startup and characteristics of the sludge.According analysis mathematical model called Monod equation which is related to the characteristics of anaerobic microorganisms and microbial metabolic characteristics, can definite the basic configuration of the circular cross-section of two-phase -two-phase upflow anaerobic reactor . Improve the key structures which are the anaerobic reactor water distribution, three-phase separator and the circulatory system, achieved these three goals through three ways, the frist is using the funnel-shaped spiral flow water distribution system to make water uniform distribution,it can reduce energy consumption; the scond is using the circulatory system which the air-lift coupled with multi-cyclemode, achived multi-level treatment, recycling nutrients and alkalinity, and through improving three-phase separator which set ramp to the bottom the three-phase separator , reduce sludge into the riser gas tank and cycle energy consumption, improve the adaptability and stability of the cycle system; finally throung increasing the channel-type -bio-spiral-phase separator, To achieve separation of the sludge which in the two phase. Through above improvement ,can form a new two-phase -two-stage anaerobic reactor,through optimizing the design of anaerobic reactor which through the mathematical modelto analysis of the structural design , then doing a small laboratory-scale test which do the comparison test between the anaerobic reactor and a new two-phase -two-stage anaerobic reactor,according to test results, the new reactor has better shock load capacity and faster boot.Using a new reactor for treating paper wastewater, establish ethanlo-based acid desulfurization process, the startup of system product intermediate products which mainly are formacetic acid and ethanol , establish food chain co-metabolism of biological communities between acidificationbacteria and sulfate-reducing bacteria which is "hydrolytic fermentativebacteriaâ†'ethanlo-producing bacteriaâ†'group of sulfate-reducing bacteriaâ†'methane-producing bacteria. Indifferent biologicalfunctional areas has a stable pH environment, in the stadge of startup the COD removal rate achived 91.6%, sulfate removal rate achived 95.77%, and the free H2S and sulfideconcentrations were lower than their suppression concentration , did not inhibit the anaerobicreaction.In the ethanol-based acid formation desulfurization process of new two-phase two-stage anaerobic reactor treating papermaking wastewater, affect factors, treatment performance and sludge characteristics were studied. Results showed that the treatment system had a certain resistance to the wastewater temperature and pH fluctuations. When the temperature was in the range of 22 to 45℃, COD removal efficiency in the methane-producing area varied from 83.2 to 94.1%. When pH of the effluent water stabilized at around 7.2, pH of the influent water fluctuated from 4.0 to 8.5. Also, COD and sulfate removal rates remained at 88 to 92% and 92 to 97% respectively. The system reflects the high environmental stability of internal pH. With the system volume load being 40 kg COD/(m3?d), COD removal efficiency still reached 84.1%. Moreover, COD removal efficiency didn't change a lot as volume load sharply increased. It can be concluded that the system has good capacity to fend against the attack. Sulfate-reducing reaction has not produced significant resistance to the anaerobic process. Sulfate reduction process mainly occurs in the acid formation desulfurization area and systematically solves the resistance by sulfate-reducing products to the reaction of producing methane.In the new reactor reflux ratio experimental study, the optimum reflux ratio had been determined,that is back to the bottom of the reactor water distribution device reflux ratio R1 = 2, back to the methane-producing area of the reflux ratio R2 = 0.5. Energy consumption was lower at this time , the water of sludge bed has been diluted , sludge bed has been expanded. Ensuring the water matrix was in full contact with the sludge, accelerated the biochemical reaction rate.In the reaserch of sludge characteristics study ,using new two-phase- two-stage anaerobic reactor which through ethanol-based aciddesulfurization process to treat papermaking wastewater, we found that in acid desulfurization phase,the sludge is form the loose dark black sludge to shallow blackgranular sludge which\size is 0.3mm ~1mm, color of the sludge changes to khaki, yellow, white and gray. Sludges has good hydrolytic acidification and sulfate-reducing features, shape is irregular oval,granular sludge has uneven surface, the granular sludge looks loose , the distribution of a large number of holes.In the methanogenic phase ,the granular sludge morphology has become more complete and full, sludge in the acid desulfurization phase and methanogenic phase show gradually increasing trend about particle size, size of sludge in acid desulfurization phase form 0.5mm increase to 0.5-1mm , the percentage of the primary sludge which size is 1-2mm become more and more.. At the same time , sludge methanogenic activity rate achive 422L/kgCOD, higher than the traditional single-phaseanaerobic reactor which methanogenic activity rate is 350L/kgCOD, has higher activity.