Effects of COD/N ratio and DO concentration on simultaneous nitrification and denitrification in an airlift internal circulation membrane bioreactor

The effects of chemical oxygen demand and nitrogen(COD/N)ratio and dissolved oxygen concentration(DO)on simultaneous nitrification and denitrification(SND)were investigated using an airlift internal circulation membrane bioreactor(AIC-MBR)with synthetic wastewater.The results showed that the COD efficiencies were consistently greater than 90% regardless of changes in the COD/N ratio.At the COD/N ratio of 4.77 and 10.04,the system nitrogen removal efficiency became higher than 70%.However,the nitrogen remova...

Simultaneous nitrogen and phosphor removal in an aerobic submerged membrane bioreactor

Simultaneous nitrification and denitrification （SND） effect and phosphor removal were investigated in a one-staged aerobic submerged membrane bioreactor on pilot-scale with mixed liquor suspended solids （MLSS） 19--20 g/L. The effects of DO concentration, sludge floc size distribution on SND were studied. Test results suggested that SND was successfully performed in the membrane bioreactor （MBR） and about 70% total nitrogen removal efficiency was achieved when DO concentration was set to 0.2-- 0.3 mg/L. The main mechanisms governing SND were the suitable sludge floc size and the low DO concentration which was caused by low oxygen transfer rate with such a high MLSS concentration in the MBR. In the meantime, phosphor removal was also studied with polymer ferric sulfate （PFS） addition and 14 mg/L dosage of PFS was proper for the MBR to remove phosphor. PFS addition also benefited the MBR operation owing to its reduction of extracellular polymer substances （EPS） of mixed liquor.

Simultaneous nitrification and denitrification in activated sludge system under low oxygen concentration

Simultaneous nitrification and denitrification(SND),which is more economical compared with the tradi-tional method for nitrogen removal,is studied in this paper.In order to find the suitable conditions of this process,a mixed flow activated sludge system under low oxygen concentration is investigated,and some key control parameters are exam-ined for nitrogen removal from synthetic wastewater.The results show that SND is accessible when oxygen concentra-tion is 0.3-0.8 mg/L.The nitrogen removal rate can be obtained up to 66.7%with solids retention time(SRT)of 45 d,C/N value of 10,and F/M ratio of 0.1 g COD/(g MLSS·d).Theoretical analysis indicates that SND is a physical phenomenon and governed by oxygen diffusion in flocs.

Simultaneous denitrification and denitrifying phosphorus removal in a full-scale anoxic–oxic process without internal recycle treating low strength wastewater

Performance of a full-scale anoxic-oxic activated sludge treatment plant（4.0×10-5 m-3/day for the first-stage project） was followed during a year.The plant performed well for the removal of carbon,nitrogen and phosphorus in the process of treating domestic wastewater within a temperature range of 10.8℃ to 30.5℃.Mass balance calculations indicated that COD utilization mainly occurred in the anoxic phase,accounting for 88.2% of total COD removal.Ammonia nitrogen removal occurred 13.71% in the anoxic zones and 78.77% in the aerobic zones.The contribution of anoxic zones to total nitrogen（TN） removal was 57.41%.Results indicated that nitrogen elimination in the oxic tanks was mainly contributed by simultaneous nitrification and denitrification（SND）.The reduction of phosphorus mainly took place in the oxic zones,51.45% of the total removal.Denitrifying phosphorus removal was achieved biologically by 11.29%.Practical experience proved that adaptability to gradually changing temperature of the microbial populations was important to maintain the plant overall stability.Sudden changes in temperature did not cause paralysis of the system just lower removal efficiency,which could be explained by functional redundancy of microorganisms that may compensate the adverse effects of temperature changes to a certain degree.Anoxic-oxic process without internal recycling has great potential to treat low strength wastewater（i.e.,TN 〈 35 mg/L） as well as reducing operation costs.

有机碳源对同时硝化/反硝化(SND)过程的影响

究了同时硝化 反硝化 (SimultaneousNitrificationandDenitrification ,SND)体系中有机碳源对氨氮去除的影响。实验结果表明 ,在氨氮初始浓度为 35mg L时 ,存在使氨氮降解率达到 99 5 %以上的有机碳源浓度区间 ,其CODCr浓度为40 0mg L～ 10 0 0mg L ;为保证反应后期体系中C N维持在微生物所需的水平 ,提出了补料的方式 ,使得氨氮降解不会出现停滞阶段 ,可以达到较好的去除效果 ;在周期为 8h的连续序批式 (SBR)操作中 ,采用较高的有机碳源初始进料值 ,并在反应过程中进行补料 ,可以很好的将出水氨氮的浓度维持在较低值 (<5mg L)

在SBBR中接种硝化菌时SND特性及机理

通过加硝化菌与未加硝化菌的对比试验,对序批式生物膜法(SB BR)中所表现出来的脱氮特性进行了试验分析,研究探讨生物膜法SN D脱氮的机理:好氧情况下生物膜的吸附作用为反硝化菌提供碳源和能源;SN D反应主要发生在好氧生物膜层和兼性生物膜分界内;在深层的反硝化菌利用生物膜中储存的有机物作为有机碳源,将好氧生物膜中产生的N O3--N转化为N2。同时加入一定量的硝化菌能较好地提高硝化、脱氮率。

A/O生物脱氮工艺处理生活污水中试(二)系统性能和SND现象的研究

应用A/O中试装置处理实际生活污水,研究了低DO浓度下系统对有机物、氨氮和总氮的去除效果.研究结果表明,低DO浓度下COD和氨氮的平均去除率分别为85%和92%.由于进水C/N比仅为2.93,总氮平均去除率仅为64%,但提高亚硝酸氮积累率可以提高总氮去除率,当亚硝化率从15%增加到85%,总氮去除率将增加12%.氨氮去除率和硝化速率、总氮去除率具有较好的相关性.维持低DO浓度可以实现亚硝酸型同步硝化反硝化反应,基于氮的物料平衡可知它占系统总氮去除率的5%～12%,增加DO浓度将破坏同步硝化反硝化（SND）现象.

DO对亚硝酸型SND的影响

采用序批式生物膜反应器(Sequencing batch biofilm reactor,SBBR)处理南方地区城市污水,应用亚硝酸型同步硝化反硝化(SND)技术进行强化生物脱氮。在进水TN30mg·L-1、COD150～250mg·L-1、pH值7.20～7.60及常温(24～29℃)等条件下,研究了DO与TN去除率和亚硝酸盐氮积累率的关系。试验结果表明,在40～100L·h-1曝气量下均会得到稳定的亚硝酸型SND,当曝气量增加到120L·h-1时,会向全程硝化转化。曝气量60L·h-1时为SBBR反应器的最佳曝气条件,脱氮效果更好,亚硝酸盐氮积累率可达89.7%,TN去除率最高可达87.8%。

过量储存-SND作用脱氮特性及机理研究

对序批式生物膜法工艺中所表现出来的脱氮特性进行了探讨,并提出了过量储存-SND脱氮作用机理,厌氧段脱氮主要靠生物膜对含碳氮有机物的过量储存作用;好氧段脱氮主要靠生物膜的SND作用,反硝化的有机碳源主要为生物膜中在厌氧段过量储存的有机碳源.

C/N和曝气时间对固体碳源SND处理低碳污水的影响

在SBBR反应器中以丝瓜络作为固体碳源和填料,采用同步硝化反硝化(SND)技术形成膜-SND系统处理城市低碳污水。试验研究了C/N(COD/TN)和曝气时间对处理效果的影响,并对系统生物相和挂膜前后丝瓜络表面形态进行分析。结果表明:C/N在10以内,反应周期内前4 h,COD可降解至30 mg/L以下,在C/N为2.5时,TN平均去除率可达79.1%,之后随C/N增加脱氮效果少量提高;最佳曝气时间为9 h,出水NH4+-N、TN分别为3.91、5.35 mg/L。

SBBR反应器SND脱氮的影响因素分析及响应曲面优化

采用活性炭涂层改性悬浮填料,在连续曝气的条件下,考察了SBBR反应器脱氮性能。结果表明,SBBR反应器表现出良好的同步硝化反硝化(SND)脱氮性能,对NH3-N和TN的去除率分别为80.7%和63.1%。典型周期内反应器同步硝化反硝化率可达82.7%。单因素试验发现,脱氮率随着曝气时间t的增加而增加,随着溶解氧质量浓度ρDO和填料投加量δ增大而先增大后减小。同时,以溶解氧质量浓度、填料投加量和曝气时间为考察因素,脱氮率为评价指标,采用响应曲面法建立了二次多元回归模型。通过模型求解得出最佳工况:溶解氧浓度为2.37mg/L,填料投加量为40.10%,曝气时间为5.17h,此时,脱氮率得到最大值为69.28%。验证试验表明,回归模型的预测值与实测值偏差率为1.57%。

单级A/O程序HSMBR系统性能和亚硝酸型SND

采用单级A／O程序复合膜生物反应器（HSMBR）处理高氨氮废水，研究了在低DO浓度下系统对有机物、氨氮和总氮的去除效率。研究结果表明：在低DO浓度下，COD，氨氮的平均去除率分别为94．4％和92．8％。由于进水COD／TN比仅为2．01，则使得总氮平均去除率仅为69．4％，但是当系统亚硝化累积率从60．5％～67．1％提高到83．5％。86．4％时，系统总氮去除率提高了17．7％。另外，DO在0．5—1．0mg·L^-1时，TN去除率为69．4％，亚硝酸盐氮累积率在60．5％-89．5％之间，可见维持低DO浓度可以实现亚硝酸型同时硝化反硝化。

DO对生物膜SND脱氮及N_2O产量的影响

采用连续流生物膜反应器,通过控制进水DO浓度在2.0 mg·L-1、2.5 mg·L-1、3.0 mg·L-1、3.5 mg·L-1、4.0 mg·L-1、4.5 mg·L-1左右,考察DO浓度对生物膜SND脱氮效果和N2O产量的影响.结果发现,当DO浓度为3.5 mg·L-1时,NH+4-N去除率在90%以上,TN去除率达到74.32%,生物膜SND效果最佳.DO浓度为3.0 mg·L-1时,系统N2O产量最大,转化率也最高,约为3.40%左右.从SND脱氮效果、节能降耗和控制N2O产量3方面考虑,将进水DO控制在3.5 mg·L-1左右比较合理,既可以达到良好的脱氮效果,又可以减少N2O的产量.

气水比对曝气生物滤池SND的影响

采用两段BAF处理城市污水,探讨了气水比对反应器处理效果的影响。在A段水力负荷为0.81 m/h、气水比为3：1时,分析了B段气水比分别为3：1、2：1和1：1时反应器的运行情况。结果表明：A段反应器对TN基本上没有去除效果,因NH4＋-N的部分氧化使得出水中NO2^--N质量浓度介于0.45-0.70 mg/L之间,NO3^--N质量浓度则介于26.09～41.04 mg/L;B段反应器气水比为2：1时,TN的去除效果最好,平均去除率为50.02%,出水中硝酸盐含量达到最小值。

同时硝化反硝化(SND)脱氮技术

结合近年来国内外脱氮的最新研究成果,从宏观环境理论、微环境理论和微生物学理论方面对同步硝化反硝化的产生机理进行了综述,并对SND的控制因素作了介绍。

MUCT工艺亚硝酸型SND途径对污染物的去除

采用MUCT工艺处理低ρ(C)/ρ(N)比实际城市生活污水,研究在短程硝化稳定运行的基础上实现亚硝酸型同步硝化反硝化(simultaneous nitrification and denitrification,SND).反应器在(28±2)℃下运行177 d,试验结果表明:通过控制溶解氧(DO)质量浓度为0.3～0.6 mg/L、水力停留时间(HRT)为6 h实现了短程硝化,亚硝酸盐积累率(nitrite accumulation rate,NAR)达到90%以上,短程硝化反硝化稳定运行118 d.在短程硝化的基础上,好氧区低氧运行实现了亚硝酸型SND,通过亚硝酸型SND途径的总氮去除率平均33%,最高达到56%.亚硝酸型SND途径下氨氮、总氮、磷的去除率明显提高,无外加碳源时分别达到99%、83%和96%.因此,MUCT工艺实现亚硝酸型SND是低碳源污水处理的一种有效的运行方式,能充分利用原水中的有机碳源,总氮去除率的提高和碳源的节省保证了磷的去除效果.

Isolation and characterization of heterotrophic nitrifying bacteria in MBR

The study presented the method for isolating the heterotrophic nitrifiers and the characterization of heterotrophic nitrification. Continuous tests via a membrane bioreactor (MBR) were operated under the controlled conditions to proliferate the nitrifiers. Heterotrophic nitrifying bacteria were isolated from the system in which the efficiency of total nitrogen(TN) removal was up to 80%. Since no autotrophic ammonium and nitrite oxidizers could be detected by fluorescence in situ hybridization(FISH), oxidized-N production was unlikely to be catalyzed by autotrophic nitrifiers during the heterotrophic nitrifiers' isolation in this study. The batch test results indicate that the isolated heterotrophic bacteria were able to nitrify. After 3 weeks incubation, the efficiencies of the COD removal by the three isolated bacterial strains B1, B2, and B3 were 52 6%, 71 7%, and 77 7%, respectively. The efficiencies of the TN removal by B1, B2, and B3 were 35 6%, 61 2% and 68 7%, respectively.

Traditional Nitrogen Removal Coupled with SND to Meet Advanced WWTP Standards at a Full Scale SBR Wastewater Treatment Facility

A Florida wastewater treatment facility studied how Simultaneous Nitrification Denitrification (SND) coupled with traditional nitrogen removal would be used to meet the state’s current advanced wastewater treatment nutrient criterion. This study examined the effect of these combined processes on the fate and transport of the nitrogen species during the treatment process. The effectiveness of nitrogen removal within the full scale sequential batch reactor system (SBR) and the extent of SND compared to nitrification and denitrification in the nitrogen removal process was also evaluated. Finally, the overall performance of the municipal wastewater treatment facility utilizing these combined processes was evaluated. Overall, this application reduced the total nitrogen to almost 6% of the permitted concentration of 3.0 mg/L. The combination of both processes also resulted in an actual ?concentration 93.7% lower than the acceptable theoretical ?concentration, which also resulted in effluent Total Inorganic Nitrogen nearly 80% lower than the permitted 3.0 mg/L effluent concentration. Further, the process produced a composite Total Nitrogen concentration that was 74% lower than the permitted concentration. This coupling of SND with traditional nitrogen removal resulted in a highly effective process to reduce nitrogen in the municipal wastewater effluent which is also attractive for potential implementation due to the low cost expenditure incurred in its utilization.

调控内生正磷酸盐强化好氧颗粒污泥脱氮除磷

采用絮状活性污泥为接种污泥,以人工配水为进水,分别以不同的内生正磷酸盐调节方式运行4组活性污泥序批式反应器(SBR),探究不同内生正磷酸盐调节方式对于富集反硝化聚磷菌(DPAOs)和造粒等方面的影响.结果表明,以内生正磷酸盐排出液回流方式运行的颗粒污泥脱氮除磷效果更好,DPAOs活性更高,并且颗粒沉降性能良好.其中,相较于以微好氧模式运行的颗粒污泥系统,以厌氧/微好氧(AO)模式运行的颗粒污泥系统的污染物处理污染物性能更优,其化学需氧量(COD)、总氮(TN)和总磷(TP)的去除效率可分别达到92.57%、94.7%和97.62%.这主要是由内生正磷酸盐刺激、DPAOs和反硝化聚糖菌(DGAOs)的协同作用等多种因素共同影响的结果,在周期性调控系统中内生正磷酸盐后,系统中污泥的内碳源转化率明显提高,DPAOs和DGAOs的活性得到增强,异养反硝化菌(DOHOs)活性被抑制,这也是在进水水质不变的情况下系统脱氮除磷效果得到明显提高的原因,而在较长的周期运行模式下,氨氧化菌(AOB)与DPAOs形成互生作用的同时也抑制其他异养微生物的生长.本研究结果可为同步短程硝化反硝化除磷(SPNDPR)工艺的实际工程化应用提供理论支持.

ASBR联合SBBR工艺同步硝化反硝化处理垃圾渗滤液深度脱氮效能

为了提高垃圾渗滤液生化处理的TN去除率,采用厌氧序批式反应器(ASBR)串联序批式生物膜反应器(SBBR)处理化学需氧量(COD)为(5700±500)mg/L、TN浓度为(210±50)mg/L的实际垃圾渗滤液。结果表明:ASBR的出水进入SBBR反应器进行深度脱氮,主要作用是调节后续SBBR进水的碳氮比(C/N),ASBR对渗滤液COD的去除率为90%。C/N是决定SBBR脱氮效率的关键,进水C/N调至4.8,在生物膜的作用下,SBBR仅通过厌氧搅拌和好氧阶段的同步硝化反硝化(SND)便可以实现对垃圾渗滤液的深度脱氮,出水TN浓度低于10 mg/L,周期运行时长也由第54天的24 h缩短至5.6 h。整个串联系统经过103 d的驯化和启动可以达到最佳的处理效果,出水COD、氨氮(NH4+-N)、TN浓度分别为(380±10)、(1.0±0.5)、(5±5)mg/L,去除率分别达到93%、99%和95%。通过高通量测序分析可知,系统中变形菌门(Proteobacteria)和拟杆菌门(Bacteroidetes)相对丰度较高,分别为55.11%、21.32%。系统中具有反硝化作用的厚壁菌门(Firmicutes)相对丰度占比为2.81%,这可能是SBBR取得优秀脱氮效果的关键。在属水平下,系统中具有反硝化功能的菌种主要为Thauera和Limnobacter,在系统中占比分别为15.22%和2.84%,它们的存在可能是系统SND效果好的主要原因之一。