溶解氧对CASS工艺影响的研究

就曝气时间段DO的变化对处理效果的影响进行了实验,研究结果发现DO在3．0mg／L时COD去除率达90．7％;CASS工艺对NH3-N的去除效果随DO浓度降低而变坏;对TN的去除最佳点也是在130浓度为3．0mg／L时,去除率为73．3％;对TP的去除率在DO浓度为1．0～3．0时均能达到94％;CASS出水均能达标排放。     

CASS工艺处理高COD生活污水的优化运行研究

西南某市污水处理厂的进水为高COD生活污水,采用CASS工艺,在满负荷运行时出水水质难以稳定达标,针对此问题,通过正交试验和单因素试验优化运行参数,最终实现了出水水质的稳定达标。在满负荷运行条件下,当进水COD浓度高达500 mg/L左右时,控制CASS工艺的曝气时间为140 min、曝气时的DO浓度为3.5 mg/L、MLSS为4.5 g/L、污泥回流比为25%,可使出水水质稳定达到GB 18918—2002的一级B标准。     

颗粒污泥+好氧污泥处理焦化废水中氨氮的研究

采用好氧污泥协同微氧颗粒污泥技术对焦化废水中的氨氮进行处理,研究了其去除效果及影响因素,结果表明,微氧颗粒污泥+好氧污泥工艺对焦化废水中的氨氮有很好的去除效果,去除率可达80%以上;好氧阶段曝气时间和pH值对氨氮去除效果的影响较大,而整个系统运行稳定后停止运行1个月,对氨氮的去除效果无明显影响。     

有机负荷对好氧颗粒污泥反应器运行性能的影响

本试验研究了有机负荷对好氧颗粒污泥反应器运行性能的影响。试验结果表明:有机负荷控制在0.48～0.96kg/(m~3·d)运行时,颗粒污泥内微生物活跃度较高对废水中污染物降解效果较好,COD、NH_4~+-N、TN和TP平均去除率分别为97.16%、98.02%、86.82%和95.97%。有机负荷太高或太低都不能实现颗粒污泥对污染物的处理效果,只有合适的有机负荷范围能够有效维持好氧颗粒污泥反应器运行的稳定性,实现对COD、氨氮、TN和总磷的处理且具有较好的去除效果。     

双污泥反硝化除磷工艺处理生活污水的中试研究

为了探索双污泥反硝化除磷工艺(A2N工艺)的实际运行效果,采用好氧段为活性污泥法的A2N工艺处理无锡某污水处理厂的曝气沉砂池出水.中试结果表明:A2N工艺对COD、TP、磷酸盐、氨氮具有较好的去除效果,出水平均浓度分别为21.6、0.19、0.04和2.73 mg/L,对COD、TP和氨氮的平均去除率分别为80.8%、89.9%和89.3%;进水TN平均为28.8 mg/L,出水平均浓度为12.6 mg/L,平均去除率为55.95%;设置后曝气池确保了出水磷酸盐和氨氮的达标排放,而且通过吹脱氮气,还提高了反硝化聚磷污泥的沉降性能.     

间歇式循环上向流污泥床的同步脱氮除磷研究

为了提高对城市污水的处理能力,介绍一种新型高效生化反应工艺——间歇式循环上向流污泥床.采用其处理实际生活污水,研究了其同步脱氮除磷效果.在进水COD为240～330 mg/L、TN为50～70 mg/L、TP为4.0～6.5 mg/L、DO为0.4 mg/L的条件下,该反应器能同时实现对COD、氨氮、SS、TN和TP的去除,出水澄清,SS含量很低,对COD、氨氮、总磷的去除率分别在90％、90％、82％以上,COD、BOD5、氨氮、TN浓度等均能达到一级A标准,TP浓度能达到二级标准.     

湛江霞山污水处理厂CAST工艺的启动及调试

介绍了湛江市霞山污水处理厂CAST工艺的运行调试过程,针对采用南柳河河水作为原水进行试运行出现的进水水质波动较大以及COD,氨氮处理效果不佳等问题,通过合理调整CAST工艺的污泥龄、污泥负荷、曝气时间等工艺参数,使CAST工艺系统的出水水质达到了设计要求,为同类城市污水处理厂的试运行调试提供了参考.     

低DO浓度下氧化沟的除污及节能效果分析

以实际污水处理厂的沉砂池出水为研究对象,在微孔曝气氧化沟中试装置中进行了低溶解氧浓度和污泥微膨胀条件下去除污染物的试验并分析了节能效果。通过电动阀控制曝气量,使曝气区的DO维持在0.5～0.9 mg/L之间,SVI值为150～250 mL/g,即污泥处于丝状菌微膨胀状态,可以节省曝气量约50%,且对COD、NH3-N、TN和TP的平均去除率分别达到92.5%、99.1%、82.1%和96.2%,出水SS平均值小于10 mg/L,满足《城镇污水处理厂污染物排放标准》中一级A的要求,实现了低溶解氧浓度和污泥微膨胀状态下的运行与高效脱氮除磷。     

重力出流式DMBR处理生活污水的研究

采用重力出流式动态膜生物反应器(DMBR)处理生活污水,重点探讨了有机负荷、DO、pH等因素对污染物去除效果的影响及延缓膜污染的措施.结果表明:该系统对SS的去除效果很好,出水SS基本为零,但对TP的去除率仅为40%左右;耐冲击负荷性能良好,对COD、氨氮的去除效果均保持稳定;在DO、pH得到适当控制时,系统对COD、NH3-N的去除率分别可达94.2%、92.1%;沉淀区的污泥沉降作用和膜组件区的曝气作用可以有效减缓膜污染速度.     

好氧颗粒污泥处理综合城市污水的中试研究

采用好氧颗粒污泥技术对水质波动较大、含大量工业废水的城市污水开展了中试研究.研究发现采用该类污水可成功培养出好氧颗粒污泥,占COD总量60%的颗粒态COD是导致所形成的颗粒不规则、结构松散且颗粒化进程较慢的主要原因.运行期间系统对COD,NH4+-N、TP的平均去除率分别为(75.80±16.09)%、(52.85±33.65)%,(66.57±22.36)%.当进水COD浓度较低时,系统的去除效果受到严重的影响.进水氨氮浓度的大幅度变化对颗粒污泥沉速、粒径的影响不明显,但对颗粒污泥密度的影响显著.氨氮冲击负荷是导致颗粒污泥解体的主要原因.因此,建议在好氧颗粒污泥工艺的运行过程中设置厌氧搅拌阶段以加快颗粒化过程及保持颗粒的长期稳定,并应避免氨氮的冲击负荷.     

低DO下曝气方式对分段进水脱氮工艺的影响

采用分段进水生物脱氮工艺处理小区生活污水,考察了在低DO条件下,不同曝气方式对硝化率及污泥沉降性能的影响。结果表明,在曝气量为0．27m^3／h、MLSS平均为2700mg／L左右、好氧区的DO为0．26～2．5mg／L的条件下,当进水氨氮为44～55mg／L时,对氨氮的去除率保持在95％以上,对COD的去除率〉90％;当控制好氧区第1、2格室的DO分别为0．5～0．7和1．0～1．2mg／L时,系统的硝化率维持在90％以上,出水中的氨氮〈2mg／L;在恒定曝气量下,向进水中投加有机碳源,当水质改变较快时,容易引起丝状菌污泥膨胀,但通过恒DO曝气控制,可使污泥的沉降性能得到改善。     

低溶解氧下微膨胀污泥对污染物的去除性能

维持SBR反应器好氧段的平均DO为0.30 mg/L,采用好氧/缺氧的运行方式研究了微膨胀污泥在低溶解氧状态下去除污染物的效果.结果表明:在丝状菌污泥微膨胀状态下反应器的除污效果仍较好,出水SS含量很低,对COD、氨氮的去除率分别可达80%、90%以上,同时可以节省曝气量约25%.可见,在低溶解氧状态下采用微膨胀活性污泥处理生活污水是可行的.     

接触氧化过滤一体化生物反应器处理城市污水研究

针对一种采用组合填料的接触氧化过滤一体化生物反应器(CFBR),进行了处理城市污水的效能及其影响因素的研究.结果表明,CFBR能在一个反应器内同时实现对COD、NH_4~+-N、浊度的有效去除,同时还去除了大部分的TN和TP.CFBR处理城市污水的最佳工艺参数:曝气时间为60 min,DO为2～3 mg/L,水温为22～25℃,下部滤层的初始滤速为5 m/h.在一定的进水容积负荷下,高底物负荷可产生高有机物去除率;DO为1～4 mg/L时,增加DO会提高对COD和NH_4~+-N的去除率,但对TN、TP和浊度的去除率会减小;水温在13～25℃变化时,水温的升高有利于对NH4+-N的去除;当滤速<8 m/h时,增大滤速会使对COD的去除率下降.     

非丝状菌污泥膨胀对无排泥MBR的影响

在无排泥条件下,通过对MBR系统中发生的非丝状菌污泥膨胀现象的研究发现:污泥膨胀导致污泥沉降性变差,系统污泥量上升,对TN的去除率较低且不稳定,但对COD和氨氮的去除效果影响不大,去除率分别能达到80%和90%以上;在初期对TP的去除率较高,随着污泥停留时间的延长,对TP的去除率逐渐下降。通过减少曝气量、降低进水COD和TN浓度、增加进水TP浓度,能有效解决MBR中发生的非丝状菌污泥膨胀现象,同时能降低污泥产率。     

Nitrification with high nitrite accumulation for the treatment of wastewater with high ammonia concentration

The objective of this paper was to determine the best conditions for partial nitrification with nitrite accumulation of simulated industrial wastewater with high ammonia concentration, lowering the total oxygen needed in the nitrification step, which may mean great saving in aeration. Dissolved oxygen (DO) concentration and pH were selected as operational parameters to study the possibility of nitrite accumulation not affecting overall ammonia removal. A 2.5L activated sludge reactor was operated in nitrification mode, feeding a synthetic wastewater simulating an industrial wastewater with high ammonia concentration. During the start-up a pH of 7.85 and a DO of 5.5mg/L were used. The reactor was operated until stable operation was achieved at final nitrogen loading rate (NLR) of 3.3kgN- NH(4)(+)/m(3)d with an influent ammonia concentration of 610mg N-NH(4)(+)/L.The influence of pH was studied in continuous operation in the range of 6.15-9.05, changing the reactor pH in steps until ammonia accumulation (complete nitrification inhibition) took place. The influence of DO was studied in the same mode, changing the DO in steps from 5.5 to 0.5mg/L.The pH was not a useful operational parameter in order to accumulate nitrite, because in the range of pH 6.45-8.95 complete nitrification to nitrate occurs. At pH lower than 6.45 and higher than 8.95 complete inhibition of nitrification takes place. Setting DO concentration in the reactor at 0.7mg/L, it was possible to accumulate more than 65% of the loaded ammonia nitrogen as nitrite with a 98% ammonia conversion. Below 0.5mg/L of DO ammonia was accumulated and over a DO of 1.7mg/L complete nitrification to nitrate was achieved.In conclusion, it is possible under the conditions of this study, to treat high ammonia synthetic wastewater achieving an accumulation of at least 65% of the loaded nitrogen as nitrite, operating at a DO around 0.7mg/L. This represents a reduction close to 20% in the oxygen necessary, and therefore a considerable saving in aeration.     

Influence of mixed liquor recycle ratio and dissolved oxygen on performance of pre-denitrification submerged membrane bioreactors

The conflicting influence of mixed liquor recycle ratio and dissolved oxygen on nitrogen removal and membrane fouling of a pre-denitrification submerged MBR was investigated in this study. It was found that a high aeration rate of 10 L air/min was able to minimize membrane fouling as compared with lower aeration rates of 5 and 2.5L air/min in this study. Faster fouling at lower aeration rate was due to the decrease in cross-flow velocity across the membrane surface. However, high DO concentration (average of 5.1+/-0.5mg O2/L) present in the recycle mixed liquor at an aeration rate of 10 L air/min deteriorated the TN removal efficiency when operating at a recycle ratio of more than 3. A lower aeration rate of 5L air/min, resulting in an average DO concentration of 3.4+/-0.7 mg O2/L in the recycle mixed liquor, led to an improvement in TN removal efficiency: 63%, 80%, 84% and 89% for mixed liquor recycle ratio of 1, 3, 5 and 10, respectively. Further decrease in aeration rate to 2.5L air/min, resulting in an average DO concentration of 1.9+/-0.8 mg O2/L, did not improve the TN removal efficiency. Using a newly developed simplified nitrification-denitrification model, it was calculated that the COD/NO3(-)-N required for denitrification at 10 L air/min aeration rate was higher than those associated with 5 and 2.5L air/min aeration rates. The model also revealed that denitrification at an aeration rate of 10 L air/min was limited by COD concentration present in the wastewater when operating at a mixed liquor recycle ratio of 3 and higher.     

Oxygen transfer and uptake, nutrient removal, and energy footprint of parallel full-scale IFAS and activated sludge processes

Integrated fixed-film activated sludge (IFAS) processes are becoming more popular for both secondary and sidestream treatment in wastewater facilities. These processes are a combination of biofilm reactors and activated sludge processes, achieved by introducing and retaining biofilm carrier media in activated sludge reactors. A full-scale train of three IFAS reactors equipped with AnoxKaldnes media and coarse-bubble aeration was tested using off-gas analysis. This was operated independently in parallel to an existing full-scale activated sludge process. Both processes achieved the same percent removal of COD and ammonia, despite the double oxygen demand on the IFAS reactors. In order to prevent kinetic limitations associated with DO diffusional gradients through the IFAS biofilm, this systems was operated at an elevated dissolved oxygen concentration, in line with the manufacturer’s recommendation. Also, to avoid media coalescence on the reactor surface and promote biofilm contact with the substrate, high mixing requirements are specified. Therefore, the air flux in the IFAS reactors was much higher than that of the parallel activated sludge reactors. However, the standardized oxygen transfer efficiency in process water was almost same for both processes. In theory, when the oxygen transfer efficiency is the same, the air used per unit load removed should be the same. However, due to the high DO and mixing requirements, the IFAS reactors were characterized by elevated air flux and air use per unit load treated. This directly reflected in the relative energy footprint for aeration, which in this case was much higher for the IFAS system than activated sludge.     

DAT-IAT改进工艺对生活污水中氨氮的去除

以需氧池-间歇曝气池（DAT-IAT）工艺为基础，在其后设置一生物接触氧化反应器，考察了该组合工艺对生活污水中氨氮的去除效果。结果表明，在IAT池以曝气2h、沉淀1h、出水1h的工况运行及生物接触氧化反应器的HRT为3h的条件下，系统对氨氮的平均去除率为81．1％，出水氨氮平均浓度为7．0mg／L，满足《城市污水再生利用城市杂用水水质》（GB／T 18920-2002）的要求。系统对氨氮的去除率随着进水COD浓度的提高而下降，当进水COD为815．3mg／L时，出水氨氮浓度仍可满足GB／T 18920-2002的要求；随着进水氨氮浓度的提高，系统对氨氮的去除率先略有上升后明显下降，为保证出水氨氮浓度达到回用标准，应将进水氨氮浓度控制在50mg／L以下；系统适宜的pH值范围为7～8，pH值过高或过低都会造成系统对氨氮去除率的显著下降。