Sludge fermentation liquid addition attained advanced nitrogen removal in low C/N ratio municipal wastewater through short-cut nitrification-denitrification and partial anammox

Biological nitrogen removal of wastewater with low COD/N ratio could be enhanced by the addition of wasted sludge fermentation liquid(SFL),but the performance is usually limited by the introducing ammonium.In this study,the process of using SFL was successfully improved by involving anammox process.Real municipal wastewater with a low C/N ratio of 2.8–3.4 was treated in a sequencing batch reactor(SBR).The SBR was operated under anaerobic-aerobic-anoxic(AOA)mode and excess SFL was added into the anoxic phase.Stable short-cut nitrification was achieved after 46d and then anammox sludge was inoculated.In the stable period,effluent total inorganic nitrogen(TIN)was less than 4.3 mg/L with removal efficiency of 92.3%.Further analysis suggests that anammox bacteria,mainly affiliated with Candidatus_Kuenenia,successfully reduced the external ammonia from the SFL and contributed approximately 28%–43%to TIN removal.Overall,this study suggests anammox could be combined with SFL addition,resulting in a stable enhanced nitrogen biological removal.

Alternating shortcut nitrification-denitrification for nitrogen removal from soybean wastewater by SBR with real-time control

A novel treating technology for nitrogen removal from soybean wastewater was studied. The process for nitrogen removal was achieved by alternating aeration and mixing, combined with real\|time control strategies. Results showed that the COD and total nitrogen removal rates are more than 90% and 92% at COD and total nitrogen loads of 1\^0-1\^2 kg COD/(kgMLSS·d) and 0\^20-0\^27 kg TN/(kgMLSS·d), respectively. In addition, it could improve sludge settling property. SVI value is less than 70 g/ml during the whole cycles. The method not only may be adapted to treat soybean wastewater with high nitrogen, but also may be applied to treat other high nitrogen wastewater.

An innovative membrane bioreactor and packed-bed biofilm reactor combined system for shortcut nitrification-denitrification

An innovative shortcut biological nitrogen removal system, consisting of an aerobic submerged membrane bioreactor （MBR） and an anaerobic packed-bed biofilm reactor （PBBR）, was evaluated for treating high strength ammonium-bearing wastewater. The system was seeded with enriched ammonia-oxidizing bacteria （AOB） and operated without sludge purge with a decreased hydraulic retention time （HRT） through three phases. MBR was successful in both maintaining nitrite ratio over 0.95 and nitrification efficiency higher than 98% at HRT of 24 h, and PBBR showed satisfactory denitrification efficiency with very low effluent nitrite and nitrate concentration （both below 3 mg/L）. By examining the nitrification activity of microorganism, it was found that the specifc ammonium oxidization rate （SAOR） increased from 0.17 to 0.51 g N/（g VSS.d） and then decreased to 0.22 g N/（g VSS.d） at the last phase, which resulted from the accumulation of extracellular polymers substances （EPS） and inert matters enwrapping around the zoogloea. In contrast, the average specific nitrite oxidization rate （SNOR） is 0.002 g N/（g VSS.d）, only 1% of SAOR. Because very little Nitrobactor has been detected by fluorescence in situ hybridization （FISH）, it is confirmed that the stability of high nitrite accumulation in MBR is caused by a large amount of AOB.

An autotrophic nitrogen removal process:Short-cut nitrification combined with ANAMMOX for treating diluted effluent from an UASB reactor fed by landfill leachate

A combined process consisting of a short-cut nitrification （SN） reactor and an anaerobic ammonium oxidation upflow anaerobic sludge bed （ANAMMOX） reactor was developed to treat the diluted effluent from an upflow anaerobic sludge bed （UASB） reactor treating high ammonium municipal landfill leachate.The SN process was performed in an aerated upflow sludge bed （AUSB） reactor （working volume 3.05 L）,treating about 50% of the diluted raw wastewater.The ammonium removal efficiency and the ratio of NO 2 N to NOx-N in the effluent were both higher than 80%,at a maximum nitrogen loading rate of 1.47 kg/（m 3 ·day）.The ANAMMOX process was performed in an UASB reactor （working volume 8.5 L）,using the mix of SN reactor effluent and diluted raw wastewater at a ratio of 1：1.The ammonium and nitrite removal efficiency reached over 93% and 95%,respectively,after 70-day continuous operation,at a maximum total nitrogen loading rate of 0.91 kg/（m 3 ·day）,suggesting a successful operation of the combined process.The average nitrogen loading rate of the combined system was 0.56 kg/（m 3 ·day）,with an average total inorganic nitrogen removal efficiency 87%.The nitrogen in the effluent was mostly nitrate.The results provided important evidence for the possibility of applying SN-ANAMMOX after UASB reactor to treat municipal landfill leachate.

Identification and Metabolic Mechanism of Non-fermentative Short-cut Denitrifying Phosphorus-removing Bacteria

To investigate the characteristics and metabolic mechanism of short-cut denitrifying phospho- rus-removing bacteria （SDPB） that are capable of enhanced biological phosphorus removal （EBPR） using nitrite as an electron acceptor, an aerobic/anoxic sequencing batch reactor was operated under three phases. An SDPB-strain YC was screened after the sludge enrichment and was identified by morphological, physiological, biochemical properties and 16S rDNA gene sequence analysis. Denitrifying phosphorus-removing experiments were conducted to study anaerobic and anoxic metabolic mechanisms by analyzing the changes of chemical oxygen demand （COD）, phosphate, nitrite, poly-fl-hydroxybutyrate （PHB）, and glycogen. The results show that strain YC is a non-fermentative SDPB similar to Paracoccus denitrificans. As a kind of non-fermentative bacteria, the energy of strain YC was mainly generated from phosphorus release （96.2%） under anaerobic conditions with 0.32 mg P per mg synthesized PHB. Under anoxic conditions, strain YC accumulated 0.45 mg P per mg degraded PHB, which produced most of energy for phosphate accumulation （91.3%） and a little for glycogen synthesis （8.7%）. This metabolic mechanism of strain YC is different from that of traditional phosphorus-accumulating organisms （PAOs）. It is also found that PHB, a kind of intracellular polymer, plays a very important role in denitrifying and accumulating phosphorus by supplying sufficient energy for phosphorous accumulation and carbon sources for denitrification. Therefore, monitoring AP/APHB and ANO2 -N/APHB is more necessary than monitoring AP/ACOD, ANO2 -N/ACOD, or AP / ANO2 -N.

Effects of Short-cut Flowering Branches on Harvest Time,Yield and Quality of Guire No.82 Mango

[Objectives]To further study the technology of short-cut flowering branches for Guire No.82 Mango,adjust its harvest time,increase yield and improve fruit quality,and increase the economic benefits of mango production.[Methods]The experiment of short-cut flowering branches was carried out for Guire No.82 Mango.[Results]At the initial flowering stage and full flowering stage of the primary inflorescence,with short-cut flowering branches and corresponding cultivation techniques,Guire No.82 Mango was easy to extract regenerated inflorescences.Compared with the control group,the flowering period of the regenerated inflorescences was delayed by 30-35 d and 40-50 d,respectively;the harvest time was delayed by 30 and 40 d,respectively;the yield significantly increased by 1.63 times and 2.25 times,respectively;compared with the control group,the number of fruits with embryo increased significantly,which were 1.39 and 2.25 times of the control,respectively;there was no significant difference in the fruit quality at the harvest time.[Conclusions]Short-cut flowering branches at the initial flowering stage and full flowering stage of the primary inflorescence is an effective measure to delay the marketing time of Guire No.82 Mango.

Nitrogen removal via nitrite from municipal landfill leachate

A system consisting of a two-stage up-flow anaerobic sludge blanket （UASB）, an anoxic/aerobic （A/O） reactor and a sequencing batch reactor （SBR）, was used to treat landfill leachate. During operation, denitrification and methanogenesis took place simultaneously in the first stage UASB, and the effluent chemical oxygen demand （COD） was further removed in the second stage UASB. Then the denitrification of nitrite and nitrate in the returned sludge by using the residual COD was accomplished in the A/O reactor, and ammonia was removed via nitrite in it. Last but not least, the residual ammonia was removed in SBR as well as nitrite and nitrate which were produced by nitrification. The results over 120 d （60 d for phase I and 60 d for phase II） were as follows： when the total nitrogen （TN） concentration of influent leachate was about 2500 mg/L and the ammonia nitrogen concentration was about 2000 mg/L, the shortcut nitrification with 85%-90% nitrite accumulation was achieved stably in the A/O reactor. The TN and ammonia nitrogen removal efficiencies of the system were 98% and 97%, respectively. The residual ammonia, nitrite and nitrate produced during nitrification in the A/O reactor could be washed out almost completely in SBR. The TN and ammonia nitrogen concentrations of final effluent were about 39 mg/L and 12 mg/L, respectively.

Taxonomic and functional variations in the microbial community during the upgrade process of a full-scale landfill leachate treatment plant-from conventional to partial nitrification-denitrification

Because of the low access to biodegradable organic substances used for denitrification,the partial nitrification-denitrification process has been considered as a low-cost,sustainable alternative for landfill leachate treatment.In this study,the process upgrade from conventional to partial nitrificationdenitrification was comprehensively investigated in a full-scale landfill leachate treatment plant(LLTP).The partial nitrification-denitrification system was successfully achieved through the optimizing dissolved oxygen and the external carbon source,with effluent nitrogen concentrations lower than 150 mg/L.Moreover,the upgrading process facilitated the enrichment of Nitrosomonas(abundance increased from 0.4%to 3.3%),which was also evidenced by increased abundance of amoA/B/C genes carried by Nitrosomonas.Although Nitrospira(accounting for 0.1%-0.6%)was found to stably exist in the reactor tank,considerable nitrite accumulation occurred in the reactor(reaching 98.8 mg/L),indicating high-efficiency of the partial nitrification process.Moreover,the abundance of Thauera,the dominant denitrifying bacteria responsible for nitrite reduction,gradually increased from 0.60%to 5.52%during the upgrade process.This process caused great changes in the microbial community,inducing continuous succession of heterotrophic bacteria accompanied by enhanced metabolic potentials toward organic substances.The results obtained in this study advanced our understanding of the operation of a partial nitrification-denitrification system and provided a technical case for the upgrade of currently existing full-scale LLTPs.

基于卷积神经网络的小目标检测改进算法

针对基于卷积神经网络(CNN)的目标检测算法因未对高层特征语义信息和低层特征细节信息之间的关系进行充分利用而导致的小目标检测率低的问题,提出一种基于卷积神经网络的小目标检测改进算法。通过对稠密连接块进行全连接,将多层特征图的特征语义信息进行融合,在候选区域添加一个具有短捷径连接的卷积与反卷积网络,以加快收敛速度。在PASCAL VOC数据集上的实验结果表明,与目前最好的算法相比,小目标的检测率从78.4%、80.5%提高到了81.6%。

Evaluation of the stability of shortcut nitrification-denitrification process based on online specific oxygen uptake rate monitoring

Shortcut nitrification-denitrification(SCND)is widely concerned because of its low energy consumption and high nitrogen removal efficiency.However,the current difficulty lies in the stable maintenance of SCND performance,which leads to the challenge of large-scale application of this new denitrification technology.In this study,the nitrogen removal pathway from complete nitrification-denitrification(CND)to SCND was rapidly realized under high free ammonia(FA),high pH and low dissolved oxygen(DO)conditions.The variations of specific oxygen uptake rate(SOUR)of activated sludge in both processes were investigated by an online SOUR monitoring device.Different curves of SOUR from CND to SCND process were observed,and the ammonia peak obtained based on SOUR monitoring could be used to control aeration time accurately in SCND process.Accordingly,the SOUR ratio of ammonia oxidizing bacteria(AOB)to nitrite oxidizing bacteria(NOB)(SOURAOB/SOURNOB)was increased from 1.40 to 2.93.16S rRNA Miseq high throughput sequencing revealed the dynamics of AOB and NOB,and the ratio of relative abundance(AOB/NOB)was increased from 1.03 to 3.12.Besides,SOURAOB/SOURNOB displayed significant correlations to ammonia removal rate(P<0.05),ammonia oxidation rate/nitrite oxidation rate(P<0.05),nitrite accumulation rate(P<0.05)and the relative abundance of AOB/NOB(P<0.05).Thus,a strategy for evaluation the SCND process stability based on online SOUR monitoring is proposed,which provides a theoretical basis for optimizing the SCND performance.

Improving Rule Base Quality to Enhance Production Systems Performance

Production systems have a special value since they are used in state-space searching algorithms and expert systems in addition to their use as a model for problem solving in artificial intelligence. Therefore, it is of high importance to consider different techniques to improve their performance. In this research, rule base is the component of the production system that we aim to focus on. This work therefore seeks to investigate this component and its relationship with other components and demonstrate how the improvement of its quality has a great impact on the performance of the production system as a whole. In this paper, the improvement of rule base quality is accomplished in two steps. The first step involves re-writing the rules having conjunctions of literals and producing a new set of equivalent rules in which long inference chains can be obtained easily. The second step involves augmenting the rule base with inference short-cut rules devised from the long inference chains. These inference short-cut rules have a great impact on the performance of the production system. Finally, simulations are performed on randomly generated rule bases with different sizes and goals to be proved. The simulations demonstrate that the suggested enhancements are very beneficial in improving the performance of production systems.

Effects of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as end product

The effect of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as the end product was studied by using a SBR. Experimental results indicated that the growth of nitrobacteria was inhibited and very high levels of nitrite accumulation at different salinities were achieved under the conditions of 25—28℃, pH 7.5? ?.0 , and the influent ammonia nitrogen of 40—70 mg/L when seawater flow used to flush toilet was less than 35%(salinity 12393 mg/L, Cl - 6778 mg/L) of total domestic wastewater flow, which is mainly ascribed to much high chlorine concentration of seawater. Results showed that high seawater salinity is available for short-range nitrification to nitrite as the end product. When the seawater flow used to flush toilet accounting for above 70% of the total domestic wastewater flow, the removal efficiency of ammonia was still above 80% despite the removal of organics declined obviously(less than 60%). It was found that the effect of seawater salinity on the removal of organics was negative rather than positive one as shown for ammonia removal.

Validity of Amontons's law for run-in short-cut aramid fiber reinforced elastomers:The effect of epoxy coated fibers

Friction between two contacting surfaces is studied extensively.One of the k n o w n friction theories is Amontons,law which states that the friction force is proportional to the normal force.However,Amontons7 law has been found to be invalid for elastomers.In the present study,the validity of Amontons7 law for short-cut aramid fiber reinforced elastomers is studied.Two types of fillers are used to reinforce the elastomers,namely highly dispersible silica and short-cut aramid fibers.Short-cut aramid fibers with two different surface treatments are used,namely non-reactive fibers with standard oily finish(SF-fibers)and fibers treated with an epoxy coating(EF-fibers).A pin-on-disc tribometer is used to investigate the frictional behavior of the composites in sliding contact with a granite counter surface.The results show that,after the run-in phase,Amontons,law is valid for those composites that are reinforced by short-cut aramid fibers(without reinforcing filler,i.e.,silica)if the contact pressure is below a threshold value.However,once the contact pressure exceeds this threshold value,Amontons'law will be invalid.The threshold contact pressure of the composites containing EF-fibers is higher than of the composites containing SF-fibers.The composites that are reinforced by silica and short-cut aramid fibers do not follow Amontons7 law.

Nitrogen removal from coal gasification wastewater by activated carbon technologies combined with short-cut nitrogen removal process

A system combining granular activated carbon and powdered activated carbon technologies along with shortcut biological nitrogen removal （GAC-PACT-SBNR） was developed to enhance total nitrogen （TN） removal for anaerobically treated coal gasification wastewater with less need for external carbon resources. The TN removal efficiency in SBNR was significantly improved by introducing the effluent from the GAC process into SBNR during the anoxic stage, with removal percentage increasing from 43.8%49.6% to 68.8%-75.8%. However, the TN removal rate decreased with the progressive deterioration of GAC adsorption. After adding activated sludge to the GAG compartment, the granular carbon had a longer service-life and the demand for external carbon resources became lower. Eventually, the TN removal rate in SBNR was almost constant at approx. 43.3%, as compared to approx. 20.0% before seeding with sludge. In addition, the production of some alkalinity during the denitrification resulted in a net savings in alkalinity requirements for the nitrification reaction and refractory chemical oxygen demand （COD） degradation by autotrophic bacteria in SBNR under oxic conditions. PACT showed excellent resilience to increasing organic loadings. The microbial community analysis revealed that the PACT had a greater variety of bacterial taxons and the dominant species associated with the three compartments were in good agreement with the removal of typical pollutants. The study demonstrated that pre-adsorption by the GAC-sludge process could be a technically and economically feasible method to enhance TN removal in coal gasification wastewater （CGW）.

Ecological filter walls for efficient pollutant removal from urban surface water

Urban surface water pollution poses significant threats to aquatic ecosystems and human health.Conventional nitrogen removal technologies used in urban surface water exhibit drawbacks such as high consumption of carbon sources,high sludge production,and focus on dissolved oxygen(DO)concentration while neglecting the impact of DO gradients.Here,we show an ecological filter walls(EFW)that removes pollutants from urban surface water.We utilized a polymer-based three-dimensional matrix to enhance water permeability,and emergent plants were integrated into the EFW to facilitate biofilm formation.We observed that varying aeration intensities within the EFW's aerobic zone resulted in distinct DO gradients,with an optimal DO control at 3.19±0.2 mg L^(-1) achieving superior nitrogen removal efficiencies.Specifically,the removal efficiencies of total organic carbon,total nitrogen,ammonia,and nitrate were 79.4%,81.3%,99.6%,and 79.1%,respectively.Microbial community analysis under a 3 mg L^(-1) DO condition revealed a shift in microbial composition and abundance,with genera such as Dechloromonas,Acinetobacter,unclassified_f__Comamonadaceae,SM1A02 and Pseudomonas playing pivotal roles in carbon and nitrogen elimination.Notably,the EFW facilitated shortcut nitrification-denitrification processes,predominantly contributing to nitrogen removal.Considering low manufacturing cost,flexible application,small artificial trace,and good pollutant removal ability,EFW has promising potential as an innovative approach to urban surface water treatment.

单质硫自养短程反硝化耦合厌氧氨氧化强化脱氮

通过在厌氧氨氧化(ANAMMOX)连续流反应器中添加单质硫,试图引入单质硫自养短程反硝化(short-cut S0-SADN)来强化ANAMMOX过程中NO^-3-N的去除.在温度为(33±2)℃,pH为7.8~8.2条件下,探讨不同的进水NH^+4-N/NO^-2-N比对耦合系统中氮素转化以及NO^-2-N竞争特性的影响.结果表明,在不同的进水NH^+4-N/NO^-2-N比(1∶1.3、1∶1.5、1∶1和1∶1.1)下,耦合系统的TN平均去除率分别达到了96.78%、97.21%、94.68%和97.72%,均远远大于ANAMMOX理论TN最高去除率89%.其中,在进水NH^+4-N/NO^-2-N比为1∶1或1∶1.1条件下,耦合系统能够实现单质硫自养短程反硝化耦合ANAMMOX深度脱氮的稳定运行.在最佳进水NH^+4-N/NO^-2-N比1∶1.1、NH^+4-N和NO^-2-N浓度分别为240mg·L^-1和265mg·L^-1条件下,TN去除速率达到1.50kg·(m^3·d)^-1,ANAMMOX和S0-SADN途径的TN去除率分别稳定在(95.68±1.22)%和(2.04±0.77)%.在整个运行过程中,ANAMMOX在底物NO^-2-N的竞争过程中一直占据着绝对的优势,ANAMMOX菌的活性(以NH^+4-N/VSS计)稳定在(0.166±0.008)kg·(kg·d)^-1.

Treatment of coking wastewater using oxic-anoxic-oxic process followed by coagulation and ozonation

An oxic-anoxic-oxic(O-A-O)system followed by coagulation and ozonation processes was used to study the treatment of coking wastewater.In the O-A-O process,the removals of NH4+-N,total nitrogen and COD were 91.5-93.3%,91.3-92.6%and 89.1-93.8%,respectively when employing hydraulic residence times of 60 h for the biochemical system.High removal of NH4+-N was obtained due to the placement of an aerobic tank in front of A-O system which can mitigate the inhibitory effect of toxic compounds in coking wastewater on nitrifying bacteria.Addition of methanol into the anoxic reactor greatly increased the removal of total nitrogen,indicating that denitrifiers can hardly use organic compounds in coking wastewater as carbon source for denitrification.COD values of the effluent from the O-A-O system were still higher than 260 mg/L even with a prolonged time of 160 h mainly due to the high refractory properties of residual compounds in the effluent.The subsequent coagulation and ozonation processes resulted in the COD removal of 91.5%-93.3%and reduced the relative abundance of large molecular weight(MW)organics(>1 kDa)from 55.8%to 20.93%with the ozone,PAC and PAM dosages of 100,150 and 4 mg/L respectively.Under these conditions,the COD value and concentration of polycyclic aromatic hydrocarbons in the final effluent were less than 80 and 0.05 mg/L,respectively,which meet the requirement of the Chinese emission standard.These results indicate that the combined technology of O-A-O process,coagulation and ozonation is a reliable way for the treatment of coking wastewater.

Influence of influent on anaerobic ammonium oxidation in an Expanded Granular Sludge Bed-Biological Aerated Filter integrated system

Shortcut nitrification-denitrification,anaerobic ammonium oxidation(ANAMMOX),and methanogenesis have been successfully coupled in an Expanded Granular Sludge Bed-Biological Aerated Filter(EGSB-BAF)integrated system.As fed different synthetic wastewater with chemical oxygen demand(COD)of 300-1200 mg·L^(-1)and NH_(4)^(+)-N of 30-120 mg·L^(-1)at the outer recycle ratio of 200%,the influence of influent on ANAMMOX in the integrated system was investigated in this paper.The experimental results showed that higher COD concentration caused an increase in denitrification and methanogenesis but a decrease in ANAMMOX;however,when an influent with the low concentration of COD was used,the opposite changes could be observed.Higher influent NH_(4)^(+)-N concentration favored ANAMMOX when the COD concentration of influent was fixed.Therefore,low COD=NH_(4)^(+)-N ratio would decrease competition for nitrite between ANAMMOX and denitrification,which was favorable for reducing the negative effect of organic COD on ANAMMOX.The good performance of the integrated system indicated that the bacterial community of denitrification,ANAMMOX,and methanogenesis could be dynamically maintained in the sludge of EGSB reactor for a certain range of influent.

Enhancing nitrogen removal from low carbon to nitrogen ratio wastewater by using a novel sequencing batch biofilm reactor

Removing nitrogen from wastewater with low chemical oxygen demand/total nitrogen （COD/TN） ratio is a difficult task due to the insufficient carbon source available for denitrification. Therefore, in the present work, a novel sequencing batch biofilm reactor （NSBBR） was developed to enhance the nitrogen removal from wastewater with low COD/ TN ratio. The NSBBR was divided into two units separated by a vertical clapboard. Alternate feeding and aeration was performed in the two units, which created an anoxie unit with rich substrate content and an aeration unit deficient in substrate simultaneously. Therefore, the utilization of the influent carbon source for denitrification was increased, leading to higher TN removal compared to conventional SBBR （CSBBR） operation. The results show that the CSBBR removed up to 76.8%, 44.5% and 10.4% of TN, respectively, at three tested COD/TN ratios （9.0, 4.8 and 2.5）. In contrast, the TN removal of the NSBBR could reach 81.9%, 60.5% and 26.6%, respectively, at the corresponding COD/TN ratios. Therefore, better TN removal performance could be achieved in the NSBBR, especially at low CODfrN ratios （4.8 and 2.5）. Furthermore, it is easy to upgrade a CSBBR into an NSBBR in practice.