Treatment To Organic Pollutant In The Municipal Landfill Leachate By The Submerged Ultrafiltration Membrane Bioreactor

According to the state of our country, the landfilling method is still the main andthe final treatment for the municipal household refuse. And along with the incrementof the population quantity and social production, the research on the way oflandfilling and the treatment of byproduct will also become the environmentalworker's important topic in the new century. Nowadays, the increment of thelandfilling quantity and the limit of method make the pollution of the landfillleachate serious increasingly. However, there is not a practically feasible andtechnically reliable technique for the leachate treatment. As the national standard ofthe wastewater discharge tends to be stricter, it is significative to some degree todevelop polishing technology so as to make the effluent meet the discharge standard.At the same time, the hard-degradation organic pollutant is the most difficultproblems in the leachate treatment.1. Research purpose and contentThe thesis is established in the status quo of municipal household refuse handledand the quality characteristics of the leachate at ChangChun city, combiningbiological and physical technics, deflecting the membrane bioreactor into thetechnics of leachate treatment, to study the polishing technology for the landfillleachate.The municipal household refuse of ChangChun city is mainly concentrated inthe ChangChun PeiJia sanitary landfill and the ChangChun SanDao sanitary landfill.Leachate fetched from the PeiJia sanitary landfill is typically the old leachate. Themost easily degradable organics in the leachate had been purified by the naturaldegradation, while the leachate has high ammonium and low BOD5/COD ratio.The leachate fetched from the SanDao sanitary landfill had suffered the leachaterecycle, and so it has low COD value and ammonium concentration. But the CODand ammonium value is still very high compared tu the national discharge standard,and also, the most part of organics left is difficult to be degraded. So, to some degree,the leachate treatment is the continuation and intensification of the purification inlandfills.Taking the two kinds of leachate as the subject investigated, removing the mostorganic pollutants by the aerobic degradation in bioreactor, and utilizing thecharacteristic that the membrane separation can intercept macromolecules, bacteriaand microorganisms in the reactor, I am able to carry on my study that are theremoval of COD and hard-degradation organics and the degradation regulation in theMembrane BioReactor (call the MBR), and the harmless discharge of the leachatewill be realized.The thesis mainly includes there stages. The first stage is a combining processthat the anaerobic pretreatment connects the aerobic treatment. In this stage, thetreated leachate fetched successively from the SanDao sanitary landfill has the twokinds of quality characteristics. In the experiment, by the contrast with theintermittent Sequencing Batch Reactor(call the SBR) easily used in the wastewatertreatment, we can observe the result difference between two crafts. At the early daysof the experiment, considering the low COD value of the leachate, the anaerobicpretreatment is not added. But because of the ideal results, the anaerobicpretreatment is added to increase the degraded capability at the last of the stage, andthe results are meliorated. The second stage is the confirmation of the best conditionsof MBR. In condition of changing the complication influenced MBR, I want toconfirm the best conditions of MBR in order to provide the basis for its futureutilization. In this stage, the SBR is also the contrast. The third stage is the appliedtreatment to the typical old leachate. In the experiment, the leachate of PeiJia sanitarylandfill with high-concentration organic pollutants as the treated object is used tovalidate the utilized effect of MBR. Then, I use the humic acid as a representation toobserve the removal of hard-degradation organics.The two concrete group technology processes operated simultaneously are asfollow, and at the whole experiment period, two processes is completely similar tothe treated water and the operation condition.Process 1: Leachate Anaerobic reactor Aerobic membranebioreactor(MBR)Process 2: Leachate Anaerobic reactor Aerobic sequencingbatch reactor(SBR)2. The main results2.1 Results obtained from the first stageThe contrast experiment is used to observe the effect that COD of the leachateare degraded by MBR and SBRIn process 1, the leachate effluent COD value is 71.547mg/L(the influent valueis 465.498 mg/L),BOD5 is 5 mg/L(the influent value is 120 mg/L), but in process 2,the leachate effluent COD value is 252.974 mg/L, the removal ratio is 33.33% whichthe values are clearly lower than those of MBR. The value of BOD5,SS in theleachate effluent meets to the discharge standard of GB-16889-1997.2.2 Results obtained from the second stageIn this stage, the best condition of MBR or SBR is confirmed (the main indexobserved is the organic pollutants ). The factors, such as temperature,pH,DO andHRT, influenced MBR or SBR are discussed.The results are as follow: the aerated quantity is 0.14m3/h in order to keep theDO ≥4.0 mg/L in the reactor; the pH value is 7.58～7.71; the temperature is 28±1℃;the HRT is 23h.2.3 Results obtained from the third stageIn the best conditions, I contrast the degraded effect that the organic pollutantsof the leachate are treated by MBR or SBR, and the degraded effect of thehard-degradation organics is investigated which the humic acid and TOC are materialindexes.In process 1, the leachate effluent COD value is 531.892 mg/L(the influentvalue is 2610.457 mg/L), BOD5 is 20 mg/L (the influent value is 680 mg/L), theremoval ratio of TOC is 74.63%, the removal ratio of the humic acids is 94.8%. Inprocess 2, the effluent COD value is 1264.285 mg/L, the removal ratio is only34.56%. The process we choose is of strong anti-ability to various pollutants loading,and of stable running state. When the influent organics loading is increased from0.13 to 0.65 kgBOD5/m3·d, increasing 5 times, the total removal fraction of organicsstill keeps more than 95%.By the test of three-kind condition and two-kind technics process, we canconclude that the process "anaerobic pretreatment connected aerobic MBR or SBR"is used to treated the typically old leachate and the recycled leachate is technicallyfeasible. The thesis investigated the degradation condition of the humic acids onbehalf of the hard-degradation organics. The removal ratio of the humic acids is83.15% and 94.8%. The results testify that the treated capability of hard-degradationorganics by the MBR really exist.