分段进水A/O工艺流量分配方法与策略研究

分段进水缺氧/好氧(A/O)工艺是一种高效的污水生物脱氮工艺。但原水多点投配给该工艺带来诸多好处的同时, 也为其优化运行带来一定困难。其中,可行的流量分配方法的建立是分段进水工艺发挥其优势并高效运行的瓶颈问题。提出3种不同的流量分配方法并进行相应的理论分析: (1) 采用等负荷流量分配法,其遵循的原则是保证各段硝化菌负荷相同, 以利于硝化菌生长,优先满足系统硝化, 最大程度地降低出水氨氮浓度; (2)采用流量分配系数, 原则是各缺氧段进水有机物质恰好可以为上段好氧区产生的硝酸盐氮反硝化提供充足的电子供体。 利用该方法可以充分利用原水中碳源,发挥缺氧区反硝化潜力,并保证最后一段进水量最少, 降低出水硝酸盐氮含量; (3)末端集中进水,用于暴雨等产生洪峰流量时, 将进水点向系统末端移动, 并加大末端进水量, 以减小二沉池固体负荷, 避免污泥冲刷流失。3种流量分配方法的提出,可以应对水厂不同的进水水质和出水要求,增强分段进水A/O生物脱氮工艺的实际可操作性,提高处理效率,为目前采用分段进水A/O工艺的污水厂的优化运行管理提供可靠的理论借鉴。     

Investigation of OUR and NUR experiments for nitrogen and phosphorus removal with activated sludge: a lab-scale study

Activated sludge systems are widely used in wastewater treatment. Organic carbon removal and nutrient removal are important for stringent water discharge standards. Therefore, activated sludge systems are widely used to remove carbon, nitrogen and phosphorus in new wastewater treatment systems or upgrades of existing systems. The determination of system compounds and kinetic parameters for modelling of these systems are important. For this purpose, respirometric measurements are used to reveal the electron consumption rate of biomass. In order to determine OUR (oxygen uptake rate) and NUR (nitrate uptake rate) parameters, a laboratory scale activated sludge system, including anaerobic, anoxic and aerobic zones, was developed. The performance of the system was continuously controlled from influent and effluent samples. OUR and NUR measurements indicated the kind of nitrogen-phosphorus removal systems required. Moreover, phosphorus uptake in the anoxic zone was investigated. It was found that phosphorus uptake in the anaerobic zone was related to substrate type consumed biologically. The OUR and NUR were found to be lower than in continuous activated sludge measurements. This may be because the mixed culture of the system affected the system performance, owing to competition between denitrification bacteria and poly-P bacteria.     

深圳某水质净化厂A/A/O微曝氧化沟深度脱氮除磷工艺效果分析

为探究A/A/O微曝氧化沟深度脱氮除磷工艺的性能,根据深圳市某水质净化厂长期监测数据,分析了进水污染物浓度、生物池沿程脱氮除磷性能和微生物相。结果表明：进水可生化性一般,生物脱氮可行,但生物除磷效果有限,需借助化学除磷增强除磷效果,投药浓度与进水BOD₅/TP值变化趋势呈负相关;生物池好氧段微生物的氨氧化速率和亚硝酸盐氧化速率能满足硝化反应的正常进行;但缺氧段反硝化速率较低,是生物脱氮的限制因素,可通过降低内回流DO和增加缺氧段碱度来增强微生物的反硝化速率;生物池中有大量的累枝虫、钟虫、盾纤虫和轮虫,且成熟期菌胶团数量较多,结构紧密;深度处理对TP和SS的去除率分别为60.3%和33.71%。物料平衡分析结果显示,被同化的氮含量和反硝化的氮含量各占43%和57%,通过微生物合成和吸附被去除的磷含量和与除磷药剂形成化学沉淀的磷含量各占49.06%和50.94%。本研究结果为水质净化厂深度脱氮除磷提供了思路,可为提高出水水质标准提供参考。     

A-A2/O工艺脱氮实践运行效果及优化

A-A²/O工艺是预缺氧/厌氧/缺氧/好氧组成的生物脱氮除磷工艺,广州市某污水处理厂采用该工艺处理城市污水,具有同时去除有机物、脱氮除磷能力,但是TN去除率较低。分析了其TN去除率低的原因,并提出相应措施。该水厂针对本厂水质特征以及影响工艺脱氮性能的主要因素,优化了工艺控制参数,提高了TN去除率和TN达标保证率。     

A-A~2/O工艺脱氮实践运行效果及优化

A-A2/O工艺是预缺氧/厌氧/缺氧/好氧组成的生物脱氮除磷工艺,广州市某污水处理厂采用该工艺处理城市污水,具有同时去除有机物、脱氮除磷能力,但是TN去除率较低。分析了其TN去除率低的原因,并提出相应措施。该水厂针对本厂水质特征以及影响工艺脱氮性能的主要因素,优化了工艺控制参数,提高了TN去除率和TN达标保证率。     

Predicted distributed state effects on enhanced biological phosphorus removal in a 5-stage Bardenpho wastewater treatment configuration.

Conventional wastewater treatment simulation programs use a "lumped" approach, where process rates are calculated using bulk concentrations of biomass and microbial storage products. A recently developed distributed, or agent-based, approach, where individual bacteria are modeled to account for their potentially variable hydraulic experiences, was applied to the 5-stage Bardenpho process, a type of enhanced biological phosphorus removal (EBPR) that includes internal recycle flows, which were hypothesized to affect distributed state development. Consistent with previous results, the EBPR predicted performance was worse according to the distributed approach than the lumped approach. In addition, increasing the internal recycle rate increased the anoxic reactor nitrate concentrations, tending to decrease EBPR performance. However, in the distributed approach, differences in the state distributions in internal recycle-linked reactors decreased with increasing recycle flow, tending to improve EBPR. These phenomena tend to have simultaneous and opposite effects on EBPR. The net effect will depend largely on the specific systems and the nitrate concentration in anoxic reactors.     

硝态氮为惟一氮源时异养微生物增长特性

采用SBR研究了缺氧条件下硝态氮为惟一氮源时异养微生物的增长特性。结果表明,异养微生物能利用硝态氮作为氮源进行增殖。当进水COD浓度为1 400 mg/L,硝态氮浓度为280 mg/L时,COD和硝态氮的去除率分别达到97%和99%;污泥中微生物的含氮量为8.8%,低于常规利用氨氮作为氮源的微生物;在实验条件下活性污泥的产率系数为0.30 g VSS/g COD。反硝化菌可利用硝态氮作为氮源进行细胞合成对含硝氮的废水处理具有重要意义。一方面由于无需投加氨氮降低了废水处理成本,另一方面由于污泥产率低,降低了污泥处理成本。     

分点进水A/O工艺处理低碳源生活污水的脱氮性能研究

针对低C/N比污水脱氮的难点问题,在缺氧段不同点设置进水口,采用分点进水A/O工艺处理校园生活污水.考察了在污泥回流比为100%,硝化液回流比为200%,分流比为1∶1,缺氧池水力停留时间(HRT)分别为2、2.4和3 h情况下,分点进水A/O工艺的反硝化性能,并与传统的A/O工艺进行比较.结果表明,当缺氧池的水力停留...     

Performance of a submerged membrane bioreactor system for biological nutrient removal.

A pilot submerged membrane bioreactor coupled with biological nutrient removal was used to treat the primary effluent at a municipal wastewater treatment plant. Long-term experiments were conducted by varying hydraulic retention time from 6 to 8 hours and solids retention time from 20 to 50 days, respectively. The performance was assessed by monitoring key wastewater parameters, including chemical oxygen demand (COD), nitrogen, and phosphorus concentration in individual anoxic, anaerobic, aerobic, and membrane separation zones. Results showed that the tested system can consistently achieve COD, nitrogen, and phosphorus removal efficiencies at 80 to 98%, 70 to 93%, and 89 to 98%, respectively. Effluent COD remained low as a result of efficient solid retention, even though there was great variation in influent quality. However, total nitrogen increased proportionally with influent concentration. At a 50-day solids retention time, higher COD and nitrogen oxides specific utilization rates in the anoxic zone resulted in a high production of nitrogen oxides in the subsequent aerobic zone.     

为置缺氧区的改良型Pasveer氧化沟工艺脱氮除磷性能研究

针对传统Pasveer氧化沟内缺氧段碳源难以被反硝化菌充分利用的问题,采用内置缺氧区的改良型Pasveer氧化沟工艺,并进行中试规模实验研究,考察了不同内回流比条件下系统的脱氮除磷效果。研究结果表明,在内回流比为200％的情况下,系统的脱氮除磷效果最好,出水TN和TP的浓度分别降至12．7mg／L和0．34mg／L,去除率分别达到61．9％和89．2％。内置缺氧区的设置一方面能使有限的碳源充分用于反硝化,另一方面,促使了反硝化吸磷现象的发生,这使得系统在进水碳源较低的情况下仍能够获得上佳的脱氮除磷效果。但是,过高的内回流比会导致好氧区亚硝酸盐的积累,这对生物除磷是不利的。     

内置缺氧区的改良型Pasveer氧化沟工艺脱氮除磷性能研究

针对传统Pasveer氧化沟内缺氧段碳源难以被反硝化菌充分利用的问题,采用内置缺氧区的改良型Pasveer氧化沟工艺,并进行中试规模实验研究,考察了不同内回流比条件下系统的脱氮除磷效果。研究结果表明,在内回流比为200%的情况下,系统的脱氮除磷效果最好,出水TN和TP的浓度分别降至12.7 mg/L和0.34 mg/L,去除率分别达到61.9%和89.2%。内置缺氧区的设置一方面能使有限的碳源充分用于反硝化,另一方面,促使了反硝化吸磷现象的发生,这使得系统在进水碳源较低的情况下仍能够获得上佳的脱氮除磷效果。但是,过高的内回流比会导致好氧区亚硝酸盐的积累,这对生物除磷是不利的。     

Biodegradation of triclosan and formation of methyl-triclosan in activated sludge under aerobic conditions

Triclosan is an antimicrobial agent which is widely used in household and personal care products. Widespread use of this compound has led to the elevated concentrations of triclosan in wastewater, wastewater treatment plants (WWTPs) and receiving waters. Removal of triclosan and formation of triclosan-methyl was investigated in activated sludge from a standard activated sludge WWTP equipped with enhanced biological phosphorus removal. The removal was found to occur mainly under aerobic conditions while under anoxic (nitrate reducing) and anaerobic conditions rather low removal rates were determined. In a laboratory-scale activated sludge reactor 75% of the triclosan was removed under aerobic conditions within 150 h, while no removal was observed under anaerobic or anoxic conditions. One percent of the triclosan was converted to triclosan-methyl under aerobic conditions, less under anoxic (nitrate reducing) and none under anaerobic conditions.     

改良A^2/O工艺的工程实践

城市污水处理厂采用多点进水的改良A^2/O生物脱氮除磷工艺,取得了较好的脱氮除磷效果.在工艺运行中,通过采取有效的调控措施,保证了生化池脱氮除磷各反应单元的溶解氧要求,得到了较佳的工艺运行参数控制范围.     

Maximum nitrogen removal in the step-feed activated sludge process.

This paper presents a mathematical framework that can be used to determine the flow distributions for a step-feed activated sludge process that result in maximum nitrogen removal. The model indicates that nitrogen removal efficiency in a step-feed activated sludge process is highly dependent on the ultimate biochemical oxygen demand (BOD(L))-to-total Kjeldahl nitrogen (TKN) ratio of the wastewater. For typical domestic wastewater, which has a relatively high BOD(L)-to-TKN ratio, the step-feed process will outperform the Modified Ludzack-Ettinger process for nitrogen removal, when the flow to each step is optimally distributed. Using plant-specific water quality data and operating conditions from a 1-year period, nitrogen removal performance for four step-feed activated sludge plants operated by the Sanitation Districts of Los Angeles County (California) was calculated using the developed model. The calculated nitrogen removal efficiencies match well with the actual plant performance data. These results validate the model as a useful tool for predicting nitrogen removal in a step-feed activated sludge process. Other analyses revealed that improvements in nitrogen removal at existing facilities are achievable by adjusting the split of primary effluent flow to each anoxic zone several times during the day. The timing of the adjustments and the optimal flow splits can be determined from data on diurnal fluctuations in BOD(L) and TKN concentrations. An example is provided to illustrate the application of such an operating strategy and the potential enhancement of nitrogen removal.     

改良A2/O工艺的工程实践

城市污水处理厂采用多点进水的改良A2/O生物脱氮除磷工艺,取得了较好的脱氮除磷效果.在工艺运行中,通过采取有效的调控措施,保证了生化池脱氮除磷各反应单元的溶解氧要求,得到了较佳的工艺运行参数控制范围.     

Process performance and polyphosphate-accumulating organism-glycogen-accumulating organism communities in an anaerobic/anoxic/oxic system operated with different carbon sources

A pilot plant anaerobic/anoxic/oxic (A2/O) system fed with domestic wastewater was operated to examine the effect of varying different types of carbon source (acetic acid, propionic acid, and glucose), added as a complement to the wastewater, on the (1) process performance and (2) microbial population. The operational condition that lead to a significant removal of total nitrogen (82%) was achieved with acetic acid. When the complementary carbon source was propionic acid, an improved removal efficiency of orthophosphate (97%) was observed. Because this finding was concurrent with higher polyphosphate-accumulating organism (PAO) population fractions detected using fluorescent in situ hybridization analysis (41.9 +/- 3.0%), it suggests that members of PAO populations that were able to reduce nitrate gained importance over PAO members that could not, thus improving the denitrifying phosphorus removal.     

CAST工艺处理低C/N生活污水的强化脱氮性能

研究了不同运行条件对CAST工艺处理低C/N实际生活污水脱氮性能的影响,并对pH值和ORP的变化规律进行了分析。结果表明,传统4 h运行模式下,提高原水C/N比,TN去除效果并无显著提高;对于低C/N生活污水,降低充水比有利于提高出水TN去除率,然而,充水比降至16%时,系统因低负荷运行发生污泥膨胀。在不投加外碳源的情况下,采用分段进水交替A/O运行模式可大幅改善系统脱氮性能,且TN去除率随着交替次数的增多而提高,交替4次平均去除率达87.23%。系统采用实时控制方式运行时,可根据有机物降解、氨氧化及反硝化时pH值和ORP曲线上是否出现拐点,来判断反应系统的曝气以及搅拌时间是否过长、适当或不足。     

某污水处理厂CAST工艺的脱氮性能评价

通过对某污水处理厂循环活性污泥法工艺(cyclic activated sludge technology, CAST)中选择池、缺氧池和好氧池中氮组分和污泥浓度进行测定,结合污泥活性、同步硝化-反硝化(simultaneous nitrification and denitrification, SND)速率及饱食-饥饿(feast-famine)批次实验,评价该处理工艺的脱氮性能。结果表明,好氧池内同步硝化-反硝化和沉淀过程中的内源反硝化(endogenous denitrification, ED)脱氮对总氮去除的贡献占据主导,分别为(35.50±4.15)%和(62.86±4.13)%,而缺氧池反硝化(DEN)脱氮贡献仅为(1.64±0.05)%;溶解氧(dissolved oxygen, DO)浓度对CAST工艺脱氮性能有极大影响,控制好氧池中DO浓度为1~1.5 mg·L⁻¹时可获得最佳脱氮效果,CAST工艺的TN去除率可达84.51%;饱食-饥饿批次实验证明,饥饿时长为36 h时对乙酸(HAc)的吸收能力最强,可达每1 g VSS消耗0.173 g HAc,依此可推算出CAST工艺的最佳回流比为45%。     

交替缺氧/好氧CAST工艺污染物去除特性

以模拟城市污水为处理对象,采用循环式活性污泥法(CAST)反应器,对交替缺氧/好氧模式下系统去除污染物的性能进行了研究。结果表明,运行期间系统内有机物的去除率稳定,出水COD小于40 mg/L,COD平均去除率为91.7%;NH4+-N、TN的平均去除率分别为83.9%、72.4%,出水TN以NO3--N为主;系统的除磷性能良好,磷酸盐的平均去除率为90.6%。此外,出水COD、TN和TP均达到《城镇污水处理厂污染物排放标准》(GB-18918-2002)的一级A要求。     

人工神经网络在强化一级处理系统过程模拟与优化中的应用

针对化学强化一级处理系统(CEPT)处理废水时影响因素多,难以进行适当的控制和处理效果的预测等问题,建立起基于BP人工神经网络的CEPT法处理猪场稳定塘废水预测模型,并应用该模型对烧杯试验进行了模拟.结果表明,预测值和实测值吻合较好,模型对COD、总磷、浊度去除率预测的平均相对误差分别为7.5%、4.8%和4.9%.通过对pH值和絮凝剂投药量等可控参数进行优化计算,得到CEPT系统的最佳操作条件和最合理操作条件.该模型的建立为CEPT法处理废水工艺系统实现自动化控制提供了一条简便实用的途径.