| Chlortetracycline Hydrochloride wastewater is a kind of high density organicwastewater which has complex composition, especially the sulfate makes it muchmore difficult to achieve the desired treatment effect. In this paper, a two-phase upflow anaerobic sludge blanket (UASB) process was used to reduce the amount ofsulfate and COD respectively. The first stage UASB makes full use of sulfatededucting bacteria (SRB) to reduce the amount of sulfate as much as possible, reducethe sulfate reduction product impact to methanogens in the second stage UASB. Inthis way, the concentration of hydrogen sulfide will be reduced in methane, weakenthe corrosion influence to the pipeline and equipment, truly realize the economicvalue of methane.This paper analyses and summarizes the stable operating parameters of thetwo-stage UASB reactors in different environmental conditions. This study couldprovide some useful ideas for the actual anaerobic reactor engineering design,commissioning and operation. The key conclusions of the study are as follows:(1)When coagulation pretreatment to Chlortetracycline Hydrochloridewastewater, choosing50mg/L PAC and15mg/L PAM to be the coagulant. At theroom temperature stir3min at speed of130r/min, then stir20min at speed of30r/min, after15minutes’ standing, the outlet concentration of SS is1404mg/L, about78.4％SS removal,23.2％COD removal and9.2％SO42-removal, the results meetinfluent SS concentration requirement.(2) Using high SO42-loading to start-up of the first UASB reactor, the HRT is6h,the SO42-loading could touch about8.2kg/(m3d), the outlet SO42-concentrationis about250mg/L~400mg/L, COD concentration is about8000mg/L~10000mg/L,S2-concentration is about300mg/L, about82％SO42-removal and16.5％CODremoval. Results show that the system runs stably, and has great buffering capacity.(3) In the first UASB, through changing the ratio of carbon to sulfur (COD/SO42-)to study the effect of COD/SO42-on SO42-removal rate. The result shows that SO42-removal rate decrease with COD/SO42-decrease. When COD/SO42->3.5, more than85％SO42-is removed. When COD/SO42-<3.5, less than65％SO42-is removed.Therefore, after coagulation pretreatment to Chlortetracycline Hydrochloridewastewater, should guarantee the ratio of COD/SO42-is greater than3.5.(4) In the first UASB, through adding iron with different chemical balance to study the effect on SO42-removal rate. The result shows that, Fe3+is inhibitor of SRB,but the inhibition is not permanent; Fe2+and S2-will generate precipitation, reducingthe inhibition of S2-to SRB, as a whole to increase the SO42-removal rate; Fe0has noinfluence upon SO42-remove.(5)Air stripping experiment show that under the conditions of at roomtemperature, controlling pH6.2~6.5, keeping the gas flow rate at500ml/min, after20min the outlet concentration of S2-was60mg/L, about81％S2-was removed, at thesame time,the concentration of COD is also decreased. It says that if COD aremeasured using potassium dichromate method, a part of COD is offered by S2-.(6)In methanogenic-phase UASB, the temperature should be controlled strictly.In the experiment, the temperature control system was broken lead to acidification,but the response from pH behind the VFA. When recover the temperature controlsystem, wash the reactor by sodium hydrogen carbonate water and decrease ofinfluent load, the reactor will return to normality.(7) The study of the second UASB show that under the conditions of at35±2℃,controlling pH6.8~7.2, its COD load is9.0kg/（m3d）, outlet concentration ofCODwas1200~1400mg/L, about85.6％COD was removed.(8) In the second UASB, through changing the HRT to study the effect of HRTon COD removal rate. It shows that when the HRT decreased from24h to16h, theCOD load increased to13.52kg/（m3d）, the biogas yield increased to14.0L/d, butthe COD removal rate decreased to72％, the system is running stable. |
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