Studies On The Performance Of An Anaerobic Baffled Reactor For Desizing Wastewater

The anaerobic baffled reactor (ABR) consists of a series of vertical baffles to force the wastewater to flow under and over them as it passes from the inlet to the outlet, and ABR may be classified as a series of compartment. It is simple in design and improved biomass retention within reactor. This reactor system has been reported to have many advantages over other well established reactor systems; therefore ABR is one of the many types of high-rate anaerobic reactors presently attracting growing interests. Desizing wastewater which containing polyvinyl alcohol(PVA) is one kind of Printing and Dying wastewater ,and with the characteristics of high concentration,fluctuates fiercely,high pH and hard to decompose by biodegradation to, it had been a difficulty problem for engineers.The paper design an ABR to decompose the desiring wastewater under long hydraulic retention time (HRT) 7d on the basic of small-scale Printing and Dying plant. On the purpose of increased the biodegradation to make a preparation for the next oxidation treatment step. This paper studied the following contents: the start-up of ABR and through contrast test, studied the effect of effluent recycle on the performance of Barthes effect of recycle rate and HRT on the performance of ABR,monitor pH,COD,VFA, analysis of purify function of the each compartment of anaerobic baffled reactor, put forward controlling measure. Pilot study on characteristics of anaerobic biological of PVA, and several key parameter was acquired, hence it has an important scientific value. Result of the study indicated:(1) Study on ABR treating desizing wastewater, the stable COD removal rate is above 50% at medium temperature(32～34℃),the up-flow velocity is 5m/h,the HRT is 7d and volume load is 1.80 kgCOD/(m~3·d). Low OLR is the key to start-up successful and the influent pH,alkalinity also take a part role to succeed.(2) The effect of effluent recycle by contrast test on ABR start-up has beed studied, the result revealed: with the high influent substance concention, the recycle could not increased the COD removal rate,but could change the contribution rate of each compartment. The reactor buffering ability was reinforced by recycle and the pH,ALK,VFA of each compartment is approach nearly. The VFA is significantly increased than the VFA of ABR without recycle and apparently, the acidogenic bacterium was predominating in the front compartments.(3) The paper studied the effect of hydrolysis loading range which changed by HRT and recycle velocity on the performance of ABR.The result revealed that the long HRT had a positive effect to increase the removal rate.At the HRT of 7d ,the total removal rate and front compartment contribution rate were 56.5% and 77%.The recycle velocity test result showed that with the appropriate up-flow velocity assured,the recycle velocity has little effect on ABR performance, the effluent COD removal rate fluctuated faintly.(4) The experiment results showed that average removal efficiency of PVA,COD were 40% and 55% after adaptability.PVA were decomposed under four compartment coaction; acidification of PVA in front compartment improved the biological characteristics of wastewater, which was key stage of PVA decomposed, COD concentration decreased along with compartment, sludge characteristcs of decompose PVA were mainly acidogenic bacterium in 1#/,2#compartment, methanothrix in other compartment. The key fact was the amount of acidogenic bacterium. The amylum goes against the breaking down of PVA. While pH is between 5.5～8.0, the removal ratio of PVA is become up first and down then.The best removal ratio is 58.4% when pH is 6.5. When the alkalinity is between 500 to 2000mg/L, it's infection for removal efficiency of PVA is imperceptibly.(5) The test of inhibition by PVA concentration on PVA decomposed showed that: at the early stage,high PVA concentration has a positive effect for adsorption,but 10 days later,high PVA have a serious inhibition.The highest removal rate appeared when the PVA is 3g/L～6g/L, which is the cultivated contentaition by ABR.when the PVA concentration is similar to that of sludge , the sludge cultivated by PVA would be better adapted ;otherwise ,when the influent concentation is different from that of sludge , it would inhibit anaerobic microorganisms biodegradation , and the greater the PVA difference the more obvious the inhibition.