Denitrification potential enhancement by addition of external carbon sources in a pre-denitrification process

The aim of this study is to investigate the denitrification potential enhancement by addition of external carbon sources and to estimate the denitrification potential for the predenitrification system using nitrate utilization rate （NUR） batch tests. It is shown that the denitrification potential can be substantially increased with the addition of three external carbon sources, i.e. methanol, ethanol, and acetate, and the denitrification rates of ethanol, acetate, and methanol reached up to 9.6, 12, and 3.2 mgN/（g VSS.h）, respectively, while that of starch wastewater was only 0.74 mgN/（g VSS,h）. By comparison, ethanol was found to be the best external carbon source. NUR batch tests with starch wastewater and waste ethanol were carried out. The denitfification potential increased from 5.6 to 16.5 mg NO3-N/L owing to waste ethanol addition. By means of NUR tests, the wastewater characteristics and kinetic parameters can be estimated, which are used to determine the denitrification potential of wastewater, to calculate the denitrification potential of the plant and to predict the nitrate effluent quality, as well as provide information for developing carbon dosage control strategy.

Simultaneous nitrification and denitrification in step feeding biological nitrogen removal process

The simultaneous nitrification and denitrification in step-feeding biological nitrogen removal process were investigated under different influent substrate concentrations and aeration flow rates. Biological occurrence of simultaneous nitrification and denitrification was verified in the aspect of nitrogen mass balance and alkalinity. The experimental results also showed that there was a distinct linear relationship between simultaneous nitrification and denitrification and DO concentration under the conditions of low and high aeration flow rate. In each experimental run the floc sizes of activated sludge were also measured and the results showed that simultaneous nitrification and denitrification could occur with very small size of floc.

Nitrogen removal influence factors in A/O process and decision trees for nitrification/denitrification system

In order to improve nitrogen removal in anoxic/oxic(A/O) process effectively for treating domestic wastewaters, the influence factors, DO(dissolved oxygen), nitrate recirculation, sludge recycle, SRT(solids residence time), influent COD/TN and HRT(hydraulic retention time) were studied. Results indicated that it was possible to increase nitrogen removal by using corresponding control strategies, such as, adjusting the DO set point according to effluent ammonia concentration; manipulating nitrate recirculation flow according to nitrate concentration at the end of anoxic zone. Based on the experiments results, a knowledge-based approach for supervision of the nitrogen removal problems was considered, and decision trees for diagnosing nitrification and denitrification problems were built and successfully applied to A/O process.

Feasibility of an innovative integrated process of simultaneous desulfurization and denitrification for high strength wastewater

An anaerobic expanding-bed reactor was adopted to investigate the feasibility of an innovative integrated process of simultaneous desulfurization and denitrification （SDD） for high strength wastewater. In the reactor, heterotrophic bacteria （including sulfate reducing bacterium and denitrifying bacteria） and autotrophic bacteria （ including Thiobacillus denitrificans） cooperated together by incubating and enriching functional bac- teria on different carriers in the anaerobic activated sludge. Synthetic wastewater with high concentrations of sulfate and nitrate was employed. The experimental resuhs showed that the removal efficiency of sulfate and nitrate was above 85% , elemental sulfur was observed while nitrate was absent in effluent. The balance of sulfur, nitrogen and electron was discussed respectively, which indicated that the integrated SDD process could be actualized. These resuhs might provide a guidance to further investigate the key factors affecting the integrated SDD process and to improve the efficiency of desulfurization and denitrification in wastewater treatment.

Determination of respiration, gross nitrification and denitrification in soil profile using BaPS system

A facility of BaPS （Barometric Process Separation） was used to determine soil respiration, gross nitrification and denitrification in a winter wheat field with depths of 0-7, 7--14 and 14-21 cm. N2O production was determined by a gas chromatograph. Crop root mass and relevant soil parameters were measured. Results showed that soil respiration and gross nitrification decreased with the increase of soil depth, while denitrification did not change significantly. In comparison with no-plowing plot, soil respiration increased significantly in plowing plot, especially in the surface soil of 0-7 cm, while gross nitrification and denitrification rates were not affected by plowing. Cropping practice in previous season was found to affect soil gross nitrification in the following wheat-growing season. Higher gross nitrification rate occurred in the filed plot with preceding crop of rice compared with that of maize for all the three depths of 0-7, 7-14 and 14-21 cm. A further investigation indicated that the nitrification for all the cases accounted for about 76% of the total nitrogen transformation processes of nitrification and denitrification and the N2O production correlated with nitrification significantly, suggesting that nitrification is a key process of soil N2O production in the wheat field. In addition, the variations of soil respiration and gross nitrification were exponentially dependent on root mass （p〈0.00l）.

Engineering practice and economic analysis of ozone oxidation wet denitrification technology

SO_(2)and NO emitted from coal-fired power plants have caused serious air pollution in China.In this study,a test system for NO oxidation using O_(3)is established.The basic characteristics of NO oxidation and products forms are studied.A separate test system for the combined removal of SO_(2)and NO_(x)is also established,and the absorption characteristics of NO_(x)are studied.The characteristics of NO oxidation and NO_(x)absorption were verified in a 35 t·h^(-1)industrial boiler wet combined desulfurization and denitrification project.The operating economy of ozone oxidation wet denitrification technology is analyzed.The results show that O_(3)has a high rate and strong selectivity for NO oxidation.When O_(3)is insufficient,the primary oxidation product is NO_(2).When O_(3)is present in excess,NO_(2)continues to get oxidized to N_(2)O_(5)or NO_(3).The removal efficiency of NO_(2)in alkaline absorption system is low(only about 15%).NOx removal efficiency can be improved by oxidizing NO_(x)to N_(2)O_(5)or NO_(3)by increasing ozone ratio.When the molar ratio of O_(3)/NO is 1.77,the NOx removal efficiency reaches 90.3%,while the operating cost of removing NO_(x)per kilogram is 6.06 USD(NO_(2)).

Effects of antibiotics on corncob supported solid-phase denitrification: Denitrification and antibiotics removal performance, mechanism, and antibiotic resistance genes

Solid-phase denitrification(SPD)has been used in wastewater treatment plant effluent to enhance nitrate removal,and antibiotics co-existing in the effluent is a common environmental problem.In this study,it was systematically investigated the effect of single trace sulfamethoxazole(SMX)/trimethoprim(TMP)and theirmixture on microbial denitrification performance,the antibiotics removal,and antibiotics resistance genes(ARGs)in corncob supported SPD system.The average denitrification rate was improved by 46.90%or 61.09%with single 50μg/L SMX or TMP,while there was no significant inhibition with mixed SMX and TMP.The abundance of dominant denitrifiers(Comamonadaceae family and Azospia)and fermentation bacteria(Ancalomicrobium)were consistent with the denitrification performance of different antibiotics groups.Single SMX and TMP achieved relatively higher denitrification gene and enzyme abundance.Mixed SMX and TMP improved the denitrification gene copies,but they reduced the key denitrification enzymes except for EC 1.7.7.2.Additionally,the removal efficiency of TMP(56.70%±3.18%)was higher than that of SMX(25.44%±2.62%)in single antibiotic group,and the existence of other antibiotics(i.e.SMX or TMP)had no significant impact on the TMP or SMX removal performance.Biodegradation was the main removal mechanism of SMX and TMP,while sludge and corncob adsorption contributed a little to their removal.SMX had the risk of sulfanilamide resistance genes(SRGs)dissemination.Furthermore,network analysis indicated that Niveibacterium and Bradyrhizobium were the potential hosts of SRGs,which promoted the horizontal transmission of ARGs.

厌氧氨氧化工艺在主流污水处理中的应用及其调控研究进展

厌氧氨氧化工艺(Anammox)具有低能耗、低产泥量、高脱氮性能等特点,在处理垃圾渗滤液、污泥消化液等领域的应用与研究得到了广泛重视。尽管如此,受制于氨氮浓度低、有机物与水量波动大、低温等问题,影响了其在城市污水主流工艺的应用。本文在介绍厌氧氨氧化工艺的基础上,总结了以厌氧氨氧化为基础的组合工艺处理城市污水案例,分析了当前厌氧氨氧化工艺应用于城市污水处理的限制性因素以及新型调控手段与策略。进一步展望了厌氧氨氧化应用于城市污水主流工艺的发展方向,以期为厌氧氨氧化应用到主流污水提供理思路。

不同碳氮比下后置反硝化工艺中溶解性有机质的分子特征及其转化机理

污水处理厂后置反硝化工艺中外加碳源的投加量会影响出水溶解性有机质(DOM)的特性,从而影响后置反硝化的处理效率和出水水质.本研究以实际污水中DOM为研究对象,利用傅里叶变换离子回旋共振质谱(FT ICR-MS)开展了不同碳氮比(C/N=3、4、5、6)下后置反硝化工艺中DOM的分子特征及其转化机理研究.结果表明,在4种C/N下,C/N=5的反应器出水芳香性DOM分子(AImod>0.5)和不饱和程度高的分子(DBE≥4)占比最高,分别为24.72%和97.6%,说明C/N=5时,出水难生物降解程度较高.通过分子转化分析可知,C/N=5的反应器产生的DOM分子占比(58.35%)最高且不饱和程度较高,去除的分子占比(2.80%)低且不饱和程度较低,再次证实C/N=5的反应器出水相较于C/N=3、4、6的反应器出水DOM分子惰性高,排放至受纳水体环境风险较低.此外,微生物群落结构及其与DOM的关联分析可知,Proteobacteria在C/N=5的反应器中相对丰度最高,其主导后置反硝化工艺中DOM分子的产生,Planctomycetota、Nitrospirota、Chloroflexi和Gemmatimonadota对DOM分子的去除和产生也具有重要作用.综上所述,推荐C/N比为5作为后置反硝化工艺中外加碳源的适宜C/N比.

污水处理系统中厌氧氨氧化细菌的富集策略

厌氧氨氧化(Anammox)工艺有利于实现可持续的污水生物处理,自发现以来就引起了人们的极大兴趣,与传统的生物脱氮技术相比,其优势在于节约充氧电耗与外加碳源所需的运行费用,以及较低的剩余污泥产量。然而,厌氧氨氧化细菌(AnAOB)的生长速率极其缓慢,限制了Anammox工艺的大规模应用。综述了以往富集AnAOB的研究,主要介绍了以下3个方面:接种污泥选择、载体与反应器设计以及外加化学物质。该文将有助于研究人员规划和设计一个合适的AnAOB富集策略,有利于拓宽Anammox工艺在污水生物处理中的应用。

硫化物对厌氧氨氧化耦合自养脱硫反硝化工艺脱氮除硫效能的影响

以成熟Anammox颗粒污泥与产甲烷颗粒污泥作为接种物实现了硫自养反硝化耦合厌氧氨氧化(SADA)工艺快速启动,探究了不同硫化物负荷对SADA工艺脱氮效能的影响及其脱硫机理.结果表明:较高硫化物负荷(>1.50g S/(L·d))对耦合系统中An AOB无显著抑制作用,相应的系统脱氮效率连续运行1.5个月后趋于稳定.当将硫化物浓度降为零,耦合系统的总氮去除率(TNRE)仍能达到88.1%,相应的化学计量比R_(s)(1.23±0.13)与R_(p)(0.33±0.08)亦与Anammox理论值近似,表明解除高硫化物负荷胁迫条件后SADA系统中Anammox颗粒污泥仍能实现生物脱氮过程.当解除高硫化物负荷胁迫1.5个月后,在较低硫化物负荷条件下(0.30g S/(L·d))恢复硫化物胁迫,耦合系统出水NO_(3)^(-)降低,相应的R_(p)降至0.21,表明SADA系统仍能较好地实现同步脱氮除硫,兼具硫自养反硝化和厌氧氨氧化的双重功效.系统存在的产甲烷颗粒污泥降低硫化物对An AOB抑制,缩短了SADA工艺启动时间,且能在重新引入硫化物后快速激活脱硫反硝化过程.通过颗粒污泥形态分析和高通量测序菌群解析可知:不同硫化物胁迫条件下,SADA系统中仍能实现An AOB(如Candidatus Kuenenia,16.9%)和硫氧化菌(如Thiobacillus,31.6%)的共存富集,且能实现高硫化物负荷条件下较高的TNRE(>60%)和硫单质产率(95.2%).

异养/硫自养集成短程反硝化工艺影响因素研究

为保证厌氧氨氧化(Anammox)过程的亚硝态氮(NO2--N)稳定来源,提升自养脱氮系统的运行效能。本研究采用上流式厌氧污泥床(UASB)反应器,构建异养/硫自养集成短程反硝化系统,探究碳源浓度、pH、水力停留时间(HRT)、温度对系统的影响。结果表明,碳源浓度与系统短程反硝化效能成反比。碳源浓度为200 mg/L时NO2--N积累率(NAR)最高,此时NO_(2)^(-)-N平均积累率及其速率分别为76.99%和1.63 mg/(L·h),异养反硝化功能菌属Thauera丰度由3.26%升至19.73%。系统短程反硝化效能随pH的升高先升后降,pH为8.0±0.5时NAR最高,此时NO2--N平均积累率及其速率分别为79.46%和1.90 mg/(L·h);HRT与系统短程反硝化效能成反比。当HRT=9.7左右时NAR最高,此时NO2--N平均积累率及其速率分别为77.35%和1.68 mg/(L·h)。温度与系统短程反硝化效能成正比,与Thauera、Terrimonas等反硝化功能菌属丰度成反比。当温度在35℃左右时NAR最高,此时NO_(2)^(-)-N平均积累率及其速率分别为71.21%和1.68 mg/(L·h)。集成短程反硝化为自养脱氮工艺提供NO2--N的过程具有NAR高且运行稳定性强等优点,更适用于自养脱氮工艺稳定高效运行,为该领域提供更多思考。

一体式短程反硝化-厌氧氨氧化工艺研究进展

短程反硝化具有稳定的亚硝态氮积累能力,这为厌氧氨氧化的应用带来曙光。相对于分段式短程反硝化-厌氧氨氧化(PD-A),一体式PD-A布局更紧凑、操作更方便。首先介绍了短程反硝化与厌氧氨氧化的脱氮机理;接着从悬浮污泥、生物膜、颗粒污泥、细胞固定系统下阐述一体式PD-A的启动方式和工艺形式,发现一体式PD-A中的空间结构不仅利于功能菌的保留还有利于衍生工艺的开发;随后从碳源、进水基质、pH等方面总结PD-A的影响因素,并介绍强化PD-A的方法;最后概括PD-A及其衍生工艺的应用进展、并探讨发展方向,发现一体式PD-A在城市污水脱氮处理以及资源化利用方面具有广阔的前景,符合我国“双碳”目标发展要求。

预处理-厌氧处理-MAP-生物脱氮组合工艺高效处理餐厨垃圾渗滤液工程

上海某区产生的餐厨垃圾渗滤液油分、固体悬浮物含量大,同时有机物、氨氮和总磷浓度高,属于难处理有机废水。本工程采用预处理-厌氧反应器-磷酸铵镁(magnesium ammonium phosphate,MAP)反应器-生物脱氮组合工艺处理餐厨垃圾渗滤液,处理能力达到100 m^(3)/d。预处理采用三相分离机分离浮渣油脂等物质。厌氧处理阶段通过两级厌氧处理工艺强化废水有机质降解去除。组合工艺系统对水量水质变化有较强抗冲击负荷能力。工程运行表明,组合处理工艺出水平均COD_(Cr)质量浓度为245 mg/L,氨氮质量浓度为6 mg/L,总氮质量浓度为40 mg/L,总磷质量浓度为4 mg/L,出水水质达到了上海市《污水综合排放标准》(DB 31/199—2018)的三级纳管标准。工程吨水处理成本为134.57元,进一步表明预处理-厌氧反应器-MAP-生物脱氮组合工艺是处理餐厨垃圾渗滤液的有效方法。

膜曝气生物膜反应器脱氮性能研究

膜曝气生物膜反应器(MABR)有效地将生物膜法技术和膜分离技术结合在一起,在污水脱氮方面潜力巨大。以MABR处理模拟生活污水和豆制品加工废水,着重考察了MABR的稳定性及脱氮性能。结果表明,在HRT=12 h、曝气压力=10 kPa和C/N=5时,MABR对模拟生活污水处理效果最佳,COD、氨氮、TN的平均去除率分别为92.0%、86.5%、83.3%。而在HRT=8 h和曝气压力=10 kPa时,MABR对豆制品加工废水处理效果最佳,COD、氨氮、TN的容积负荷分别为1320、125.5、184 g(/m^(3)·d),平均去除率分别可达到84.2%、81.5%、79.7%,优于传统生物膜法脱氮。

污水生化处理工艺发展阶段化技术特征及未来趋势

百余年来,伴随人类社会和科技日新月异,污水生化处理技术也在实现快速发展与不断迭代,新工艺与新反应器、新功能微生物与新生化代谢途径不断被提出、发现和解析,并进一步推动了污水处理技术的进步与升级。回顾了过去百余年污水生化处理技术发展历程,就典型污水生化工艺,结合技术研发进展、技术成熟度及案例应用情况,给出了不同生化处理工艺代际划分与技术发展期“S曲线”,分析了近些年来新涌现出的一些革新性污水生化处理工艺的技术原理、技术特征,结合实际案例分析了工艺技术特征、技术优势与总体效能,从工艺强化、绿色低碳与集约高效等方面总结了未来污水处理发展的技术趋势,以期为“双碳背景”下排水系统提质增效工作、未来国内前瞻性污水厂工艺设计与运行提供参考和借鉴。

MBBR耦合多段AO工艺在大型市政污水处理厂的运行初探和实践成效

新建城市污水处理厂或提标改造老旧污水处理厂普遍存在出水水质差、污染物负荷与占地面积等不可调和的矛盾,基于纵向扩大池容会增加建设成本、高负荷运行具有超标风险,因此,急需一种污泥/容积负荷高、运行稳定、操作简单的污水处理新技术。对此,某大型市政污水处理厂利用移动床生物膜反应器(MBBR)泥膜共混技术提高生化池有效污泥浓度、实现功能微生物的强化和富集,耦合多段AO工艺,经历雨/旱、夏/冬季,已稳定运行227 d,当进水COD_(Cr)、氨氮、TN质量浓度分别为277.97、34.92、45.95 mg/L,对应出水质量浓度分别降低至12.68、0.33、7.55 mg/L,MBBR挂膜前后的氨氮污泥负荷为0.011、0.015 g氨氮/(g MLSS·d)、TN污泥负荷为0.014、0.020 g TN/(g MLSS·d)。系统稳定运行期间,好氧Ⅰ段氨氮硝化速率为7.27 mg/(L·h)、缺氧Ⅰ段NO-3-N还原速率为3.48 mg/(L·h)。结果表明,通过负载微生物和游离污泥的交互作用,寻求复杂微生物群落功能的强化和调控,可以设计出更加合理、高效的污水处理新工艺。

知识和数据驱动的污水处理反硝化脱氮过程协同优化控制

为有效提升城市污水处理过程的脱氮效果,提出一种知识和数据驱动的反硝化脱氮过程协同优化控制(Knowledge-data-driven cooperative optimal control,KDDCOC).所提方法主要有以下两个方面:首先,建立一种基于自适应知识核函数的协同优化控制目标模型,动态描述出水水质(Effluent quality,EQ)以及泵送能耗(Pumping energy consumption,PE)、关键变量的协同关系;其次,提出一种知识引导的协同优化算法(Knowledge guide-based cooperative optimization algorithm,KGCO),快速准确求解硝态氮(Nitrate nitrogen,SNO)优化设定值,提高KDDCOC的响应速度.KDDCOC利用比例−积分−微分(Proportional-integral-derivative,PID)控制器对硝态氮优化设定值进行跟踪,将提出的KDDCOC应用于城市污水处理过程基准仿真模型1号(Benchmark simulation model No.1,BSM1),实验结果表明,该方法能够提高出水水质,降低运行能耗,有效改善脱氮效果.

渣油加氢装置催化剂全蜡油硫化技术应用总结

分析了固定床渣油加氢装置开工全部使用蜡油硫化方案的可行性。某公司首次采用全蜡油硫化对新鲜催化剂进行预硫化,全蜡油硫化可节省装置开工时间16 h,减少装置开工柴油使用量,减少产生不合格蜡油720 t,在低温硫化阶段蜡油硫化的上硫率更高,硫化更均匀。对比分析了全蜡油硫化与分阶段硫化的催化剂性能,在工艺条件、原料性质基本相同的条件下,两种不同方式硫化后的催化剂杂质脱除率同样高,活性相当。使用全蜡油硫化的催化剂运行周期相对较长,说明全蜡油硫化催化剂的稳定性较高。全蜡油硫化具有操作简单、节约资源、还原活性好等优点,对于其他同类装置具有借鉴意义,为今后同类装置开工优化预硫化操作提供了宝贵经验。

秸秆-钢渣混合填料对低C/N比污水脱氮研究

为探讨作物秸秆和钢渣对低C/N比污水脱氮的影响,本研究分别以空白(CK)、小麦秸秆(W组)、水稻秸秆(R组)、小麦秸秆+钢渣(WF组)、水稻秸秆+钢渣(RF组)、钢渣(F)为填料,在厌氧循环系统中对C/N比为0.23~0.93的污水进行处理,探究6种不同的填料-系统对NO3-N的去除效果。结果表明:W组、R组、WF组和RF组的NO_(3)^(-)-N去除率分别为94.99%、86.70%、98.75%和94.70%;相比于WF组和RF组填料系统,纯秸秆填料系统(W组和R组)对污水中NO_(3)^(-)-N的去除速度更快,但在处理过程中的可溶性有机碳(DOC)浓度更高;WF组和RF组钢渣中含铁化合物的释放及转化会消耗有机质,因此其DOC浓度保持在较低水平,避免了因DOC浓度过高而引起的二次污染问题。综合考虑,小麦秸秆+钢渣混合填料在脱氮过程中能够在保持高效脱氮的同时避免出水二次污染问题,更适用于低C/N比污水的脱氮。