CAST工艺处理城市污水的强化脱氮研究

介绍了镇江征润州污水处理厂CAST工艺的运行情况，结合该厂实际运行状况开展了强化脱氮效果的生产性试验研究。结果表明，该工艺对COD、SS和TP的去除率均能维持在80％以上，但对氨氮的去除效果较差；在该厂运行模式下，控制进水／曝气前30min的DO〈0．5mg／L、进水／曝气后30min的DO浓度在1．0-3．0mg／L、纯曝气DO浓度在2．0-3．0mg／L，可以实现同步硝化反硝化和硝化／反硝化作用下的共同脱氮，使脱氮效率提高了57％左右；在控制进水／曝气后DO〈0．5mg／L、纯曝气DO浓度在1．0-3．0mg／L的条件下，可以实现同步硝化反硝化作用下的脱氮，但较难实现理想的脱氮效果。     

AVS系统在A~2/O工艺稳定运行及节能优化中的应用

北京清河污水处理厂采用优化曝气流量控制系统(AVS)对二期工程原有的曝气系统进行改造,包括生物反应池好氧段溶解氧分区与设备布局改造、曝气管路系统改造和鼓风机控制改造,实现了曝气环节的大闭环控制,于2010年1月底完成。截至目前,该工程已稳定运行超过一年半时间,实现了对于好氧段溶解氧的精细控制(好氧段的溶解氧浓度维持在设定值的±0.5 mg/L以内)。微生物生化环境的稳定帮助技术人员实现了更为精细的调控,提高了出水水质;同时处理单位污水鼓风机的耗电量却显著降低,创造了明显的经济效益。     

CAST工艺中曝气控制的研究

随着在线DO、ORP等仪表联合PLC控制技术的日趋成熟,CAST工艺的优越性充分体现。和其他生物处理技术一样,曝气控制是保证出水水质,节能降耗的关键所在。常见的曝气控制方式有时间控制,DO控制等。通过实验对DO控制法进行了检验,并对ORP控制模式作了探讨。     

纯氧曝气快速消除河流黑臭的工程性研究

研究了纯氧曝气对河流黑臭现象的工程控制效果,河流流量为4×104m3/d。结果表明,纯氧曝气工艺能够将河水的DO浓度从零迅速提高到20 mg/L,同时可将色度和嗅阈值分别控制在20倍和5倍以下,对COD也有一定的去除效果,但对NH3-N的去除效果不显著。河流流速和底泥都会明显影响DO浓度的分布和衰减,持续纯氧曝气对底泥具有原位钝化作用。纯氧曝气工艺对河水的处理费用约为0.05元/m3,氧利用效率为90%。     

模糊控制方法在污水处理厂曝气控制系统中的应用

生物池曝气系统的精细化控制对整个污水处理厂的运行具有重大意义。基于活性污泥法污水处理工艺技术原理,采用模糊控制方法,设计以DO目标值和实测值的偏差及偏差率为输入、以曝气量为输出的污水处理生物池曝气控制系统,并在上海某污水处理厂进行实例应用。结果表明,该控制系统具有较好的容错性和控制精度,可对污水处理生物池DO进行精细化控制,溶解氧目标值和实测值误差在±0.2 mg/L范围内波动,具有良好的控制效果;该控制系统能够为污水处理厂生物曝气过程高效、稳定运行提供指导。     

短程硝化反硝化快速启动及稳定运行研究

为了考察短程硝化反硝化的影响因素,对短程硝化反硝化快速启动和稳定运行的影响因素,采用实时控制手段研究.结果表明:通过DO和pH联合实时控制,低DO条件下可以实现短程硝化反硝化快速启动.启动成功的短程硝化污泥,过度曝气对NO2-N积累影响较大.合理控制曝气时间,应用实时控制策略,控制NH4+-N刚刚氧化完成时停止曝气,可保证NH4+-N完全氧化,防止NO2-N进一步氧化.实时控制可实现短程硝化,而且可以维持短程硝化稳定运行.     

低曝气量与实时控制下的常温短程硝化研究

为了使短程硝化反硝化技术应用于工程,采用SBR法处理实际的生活污水,考察了曝气量对亚硝酸氮积累的影响,以及实现短程硝化后,通过在线监测DO、pH实时控制曝气时间并逐渐提高曝气量,维持短程硝化的效果.结果表明,23℃下,当固定曝气时间为10 h、曝气量为40L/h时,DO平均为2 mg/L,未出现亚硝酸氮积累;当曝气量为32L/h时DO平均为0.5 mg/L,亚硝化率（NO2^-/NOx^-）平均达到了34%;当曝气量为28L/h时DO平均为0.3 mg/L,亚硝化率可达80%以上,实现了短程硝化.此后逐渐提高曝气量至40、48、56L/h,同时通过在线监测DO、pH实时控制曝气时间,不仅未破坏短程硝化,而且使硝化时间不断缩短,同时亚硝酸氮的积累率稳定维持在95%左右.     

CAST工艺运行优化和控制研究

根据扬州市汤汪污水处理厂CAST工艺的设计参数及运行情况,利用活性污泥模型ASM2D建立了符合该污水厂实际运行状况的水质模型,分别对不同水温、曝气时间、DO浓度等控制参数下的模拟结果进行定量预测。结果表明,当水温较低时,需确保曝气阶段的DO达到2mg/L或增加曝气时间,以弥补低温对微生物活性的不利影响;当水温较高时,应根据进水水质、水量及模拟结果选择最佳调控参数,以提高出水水质和避免能源浪费。另外,根据CAST工艺优化诊断结果建立了生物工艺智能优化控制系统,使优化成果得以执行实施,从而实现了污水处理厂自动化控制下的节能减排目标。     

基于在线营养盐控制的污水处理曝气优化及应用

曝气过程占污水处理过程总能耗的50%~75%,优化曝气过程控制、探索新的运行控制模式是节能降耗及改善出水水质的关键。传统的污水处理生化曝气过程是以DO为基础的PID控制,实践证明这种控制模式存在诸多缺欠。欧美等发达国家近些年开始采用基于营养盐信号的后馈或前馈/后馈闭环控制,在改善出水水质的同时,运行能耗可以降低15%~30%。介绍了以在线NH_4~+-N/NO_3~--N控制信号为基础的曝气过程高级控制系统(AOC)的类型、技术优势及实现方式,并结合实际案例介绍了AOC系统实施的方法及效果。     

基于OUR曝气控制系统在污水厂中的应用

将基于耗氧速率(OUR)气量计算模型和基于进水氨氮负荷DO预测模型相结合的曝气控制系统应用于武汉某污水厂,通过现场应用考察了曝气控制系统运行的稳定性和节能效果。实际运行结果表明,曝气控制系统可以根据进水氨氮负荷合理设定DO值,并根据OUR和DO值计算好氧池的最佳需氧量,将实际DO值控制在设定值±0.315mg/L范围内;同时曝气控制系统可以保证出水COD和NH_3-N满足《城镇污水处理厂污染物排放标准》一级A要求;曝气控制系统可以将鼓风机处理单位体积水的电耗降低21.9%。     

Control of the aeration volume in an activated sludge process using supervisory control strategies

In this paper, a simulation benchmark of a pre-denitrifying activated sludge process is utilized in order to evaluate a supervisory aeration volume control strategy. The aeration volume control strategy has also been evaluated in a pilot plant at Hammarby Sj?stad in Stockholm, Sweden. The main idea has been to let the dissolved oxygen (DO) concentration in some of the aerated compartments be determined by a higher level controller driven by the DO concentration in other compartments. In this way, only sensors for measuring the DO concentrations are needed for the decision of time varying DO set-points. The high reliability of such sensors implies robust input values for the proposed control strategy. Moreover, it is known that the respiration rate is affected by the content of substrate and nitrogen in the compartments; therefore, the suggested manipulations of the DO set-points are indirectly determined by the current load into the plant. Compared to constant DO control and a supervisory DO set-point control strategy based on ammonium measurements in the last aerobic compartment, the suggested aeration volume control strategy could reduce the effluent nitrate and ammonium concentrations significantly without increasing the aeration energy.     

扬州六圩污水厂智能优化控制系统调试与运行

针对扬州六圩污水处理厂进水中工业废水所占比例较大,且存在较多难降解物质和毒性物质的情况,为确保工艺正常运行和出水水质的稳定达标,在生物池中安装在线监测仪表实时反映进水污染物负荷的变化和工艺的运行状况。在保证出水水质稳定达标的前提下,通过生物智能优化控制系统(BIOS)计算出内回流比和各廊道所需溶解氧,曝气控制系统(BACS)根据生物智能优化控制系统得出的溶解氧设定值,对鼓风机、空气阀门等设备进行调整,使曝气量既能满足生物池的溶解氧需要,又不浪费能源。BACS将追踪溶解氧的响应时间控制在30 min以内;在48 h连续控制周期内,西池第一和第二廊道溶解氧实时值与设定值的偏差在±0.5 mg/L之内的时间分别占88.40%、98.99%。通过两套系统的联动运行,在保证出水水质稳定的前提下为六圩污水处理厂降低了约19.4%的鼓风系统能耗。     

CASS工艺处理造纸中段废水的应用研究

选取石家庄市鹿泉造纸厂污水处理站运行的一套CASS系统进行研究，中段废水是造纸工业的主要污染源之一。采用CASS工艺处理造纸废水运行结果表明：废水中的有机污染物得到高效降解，COD的去除率达90％以上；易降解和难降解的有机废水应分别采用限制曝气和非限制曝气的进水方式为宜；DO可以作为CASS系统去除COD情况的一个指标，易于实现自动化控制。     

CASS工艺处理高校生活污水的试验研究

为了优化CASS工艺的运行参数,通过正交试验重点研究了污泥负荷、污泥沉降比(SV)、DO浓度、曝气时间等对COD、氨氮和TP去除效果的影响。结果表明,CASS工艺对有机物的去除效果较好,且抗冲击负荷能力较强;污泥负荷和SV值对COD、氨氮和TP去除效果的影响较大,而曝气时间和DO浓度的影响相对较小;试验条件下,CASS工艺的最佳运行参数如下:污泥负荷为0.50 kgCOD/(kgMLSS·d)、SV值为32%、曝气时间为2.5～3.0 h、DO为2.0～2.5 mg/L。     

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。     

Studies on dissolved oxygen concentration and sludge retention time affecting the full-scale activated sludge process

We have made a series of experiments on dissolved oxygen (DO) concentration and sludge retention time (SRT) to affect the full-scale activated sludge process.

For DO control, a better effluent water quality and a reduced current consumption have been achieved as compared with those in a constant air flow operation. The best control point for the DO control operation is at the outlet side of the aeration tank.

For SRT control, effluent COD seems to fluctuate slightly, and is favorably stable when SRT is between 10 and 20 days. It takes about twice as many days as SRT value set up for the total mass of sludge in the process (M) to be stabilized in case of making set value change as a result of simulation using mathematical models.     

An improved system for the control of dissolved oxygen in freshwater aquaria

A system for the removal and control of dissolved oxygen (DO) from freshwater was designed and constructed with aquarium-type fish studies in mind. Degassed water was obtained using a partial vacuum of −14 psi, and DO regulated at an aquarium scale using electronically controlled aeration with timed partial water renewal. The degassing system was capable of producing water with ∼1.7 mg L⁻¹ DO within 10 min of operation, and 0.55 mg L⁻¹ after 2 h. The control system was capable of maintaining DO levels of ca 0.8 mg L⁻¹ over 48 h in the absence of aeration and further capable of precisely controlling DO levels as low as 1.16±0.002 mg L⁻¹ (mean±SEM) with aeration over a 48 h period.     

Sludge settling and online NAD(P)H fluorescence profiles in wastewater treatment bioreactors operated at low dissolved oxygen concentrations

Biological nitrogen removal via simultaneous nitrification and denitrification (SND) may be achieved in the single-tank bioreactors operated at low dissolved oxygen concentrations (DO). The continuous-stirred tank reactor (CSTR) configuration and the low DO environments employed are; however, more conducive to growth of filamentous bacteria and, thus, poor sludge settling in clarifiers. In this work, a synthetic wastewater was treated in bench-scale (approximately 6L) bioreactors under either cyclic or constant-rate aeration, at various sludge retention times (SRT) and DO. The objective was to evaluate the effects of these factors on the sludge settling indicated by sludge volume index. The cyclic aeration was carried out by alternating the aeration between a higher rate for 1h and a lower (or zero) rate for 30 min. In different experiments, the DO during the period of higher aeration (HDO) was 0.4, 0.6, 0.8, or 2.0 mg/L and the DO during lower aeration (LDO) was 0.0 or 0.2mg/L. The sludge established under the cyclic aeration was found to settle better than that under constant-rate aeration. Shortening SRT also improved the sludge settling significantly. NAD(P)H fluorescence profiles in these bioreactors were monitored using an online fluorometer. A procedure was developed to quantitatively describe the metabolic state of sludge's heterotrophic population on a 0-1 scale using the fluorescence profile, with "0" corresponding to the fully anoxic-denitrifying state and "1" to the fully aerobic state.     

改良氧化沟工艺处理城市污水的优化控制

邯郸市西污水处理厂采用厌氧选择池/改良氧化沟工艺处理城市污水,但由于实际进水水质与设计值有偏差,造成运行管理困难且费用较高.针对该厂的实际运行情况,探讨了曝气系统的DO、MISS、泥龄等运行参数的控制问题,并对各参数进行分析、优化调整,最终使该工艺具有较好的脱氮除磷效果.