反硝化过程中亚硝酸盐积累特性分析

在分段进水工艺处理城市废水实现深度脱氮(TN＜5 mg·L-1)研究中,采用SBR反应器,分别以甲醇或葡萄糖为碳源研究了反硝化过程中亚硝酸盐(NO2--N)的积累情况、pH和ORP变化规律及动力学特性.结果表明,2种碳源系统、不同碳氮比(C/N)条件下反硝化过程均出现明显的NO2--N积累.相同C/N下,在NO2--N...     

SBR工艺中短程硝化反硝化的过程控制

以豆制品生产废水为对象,研究了在较高温度下[(31±1)℃]SBR工艺中短程硝化反硝化生物脱氮过程的实现,并在此基础上考察了应用ORP和pH值作为短程硝化反硝化过程控制参数的可行性。试验结果表明,该工艺对氨氮的去除率>95%,对亚硝酸盐的积累率(NO-2-N/NO-x-N)稳定在96%以上;同时发现反应过程中ORP和pH值的变化与有机物降解、氨氧化之间存在着很好的相关性,可以根据ORP和pH值变化曲线上的特征点来判断硝化和反硝化反应的终点,从而减少曝气和搅拌时间,达到节能的目的。     

DO对SBBR工艺亚硝酸型SND及过程控制的影响

在SBBR工艺亚硝酸型同步硝化反硝化过程中,DO是一个主要限制性因素,通过调节曝气量控制DO浓度在3.60～4.25 mg/L范围内可较好地实现亚硝酸型同步硝化反硝化。DO、pH值和ORP的变化规律与反应器内COD的降解和"三氮"的转化有良好的相关性。DO浓度的变化对DO、pH值和ORP曲线的变化规律影响较大,ORP曲线的特征点与COD的降解过程具有良好的相关性,可作为易降解有机物反应完毕的指示点。DO、pH值和ORP曲线的突跃特征点可以作为SBBR工艺亚硝酸型同步硝化反硝化反应结束的控制点。     

以DO、ORP、pH控制SBR法的脱氮过程

为实现SBR法脱氮在线模糊控制,以啤酒废水为研究对象,通过不同进水混合液氨氮浓度的试验,详细地研究了SBR法在去除有机物和硝化、反砂化过程中DO、ORP、pH的变化规律。试验表明,DO、ORP、pH的特征点和平台的重现性很好,可以作为SBR法去除有机物、砂化、反硝化的过程控制参数。     

以黄水为碳源的反硝化过程研究

针对南方城市污水厂生物脱氮过程中反硝化碳源不足的情况,以白酒生产过程中的副产物——黄水作为反硝化碳源,采用SBR反应器研究了碳氮比分别为7、6.5、6、5、4.5、4和3条件下的反硝化过程。研究结果表明:黄水驯化的反硝化菌以短杆菌属为主;黄水可以作为合适的反硝化碳源,如果以黄水作为反硝化碳源,C/N值为5时比较合适;不同C/N值下,在反应初期都存在NO-2-N积累现象,C/N值为4.5时积累量最大。     

反硝化生物滤池脱氮的中试研究

以某城市污水厂初沉池出水为原水,采用中试规模的移动床生物膜反应器/沉淀池/反硝化生物滤池工艺进行生物脱氮,重点考察了反硝化生物滤池的脱氮效果及C/N值对脱氮效率的影响,探讨了反硝化生物滤池再启动后的恢复情况,并构建了反硝化生物滤池脱氮动力学模型。结果表明,在稳定运行期间反硝化生物滤池对TN的去除率为86.4%~96.5%,当2.5C/N值5时,TN去除率与C/N值无相关性,平均去除率为93.3%,最佳C/N值为3.45。反硝化生物滤池经过3 d维护后再启动,运行12 h后即可恢复到滤池维护前的脱氮水平。在该中试条件下,反硝化遵循零级反应动力学,反应速率为174.4 mg/(L·h)。     

SBR短程同步硝化反硝化耦合除磷的研究

在序批式活性污泥反应器(SBR)中,以模拟城市污水为处理对象,考察了在稳定运行期间的典型周期里COD、TP、TN、DO、pH以及ORP的变化规律。试验表明,在SBR反应器中实现短程同步硝化反硝化耦合除磷是完全可行的,在温度为20～25℃、pH值为7.12～7.43的条件下,系统对COD的去除率达到95.6%,对TP和TN的去除率分别为88.8%和87%,实现了短程同步硝化反硝化与反硝化除磷的统一。     

无外加碳源SBBR脱氮工艺及其控制方法研究

为提高脱氮效果并实现利用内碳源进行反硝化,开展了SBBR（以好氧-缺氧方式运行）处理生活污水的脱氮研究.在好氧阶段,SBBR中的生物膜能创造缺氧微环境并吸收、储存碳,实现了同步硝化反硝化,降低了硝态氮的浓度;在缺氧阶段,可利用内碳源实现剩余硝态氮的反硝化.溶解氧浓度的大小对好氧时间、好氧剩余硝态氮浓度和缺氧反应时间有较大影响,因而可以利用在线检测的DO作为曝气量控制参数.DO、pH和ORP值的变化具有规律性,反映了生物脱氮过程中耗氧和供氧、产酸和产碱、氧化和还原过程的变化.为准确判断好氧和缺氧反应过程的终点,并减少控制的滞后时间,建议以pH值的＂氨谷＂和ORP的＂硝酸盐膝＂作为主控制特征点分别指示硝化和反硝化的终点,而以ORP的＂氨肘＂和pH值的＂硝酸盐峰＂作为参考或辅助控制特征点.     

晚期渗滤液短程生物脱氮的实现

在SBR反应器中利用游离氨(free ammonia, FA)、游离亚硝酸(free nitrous acid, FNA)对NOB(nitrite oxidizing bacteria, NOB)选择性抑制并耦合实时控制策略处理晚期垃圾渗滤液,成功实现持久稳定的短程生物脱氮,并研究了不同碳氮比及初始pH值对短程生物脱氮的影响。结果表明：通过FA和FNA对NOB的选择性抑制,在线检测反应中pH、DO和ORP数值,利用出现的“氨谷”、“ORP平台”“亚硝酸盐膝”等特征点作为运行操作控制时间点,准确得知反应进程,及时开始下一步操作,获得稳定短程生物脱氮。进水NH4 +-N浓度为108~177.3 mg/L(平均值为138.7 mg/L)时,亚硝积累率一直稳定达90%左右,乙酸钠为碳源时最佳C、N质量比为3,相对于混合液悬浮固体浓度的反硝化速率的平均值达到19.8 mg·g -1·h -1 NOx --N,出水NH4 +-N、NO2 --N、NO3 --N、TN分别小于6、2、1和30 mg/L;初始pH值为8.5时,反硝化速率最大,pH介于7.5~8.5间,反硝化速率差异小于7.3%.     

阶段时间对CMICAO工艺低温运行特性的影响

研究了低温下多点交替进水阶式A2/O(CMICAO)工艺阶段运行时间对污染物去除率的影响,探讨了DO、ORP以及pH状态参数与污染物去除率之间的关系。结果表明,水温8~10 ℃,泥龄13 d,水力停留时间16 h,污泥浓度2 680~3 560 mg/L,污泥回流比30%,阶段1至6的运行时间为3、2.5、2、3、2.5、2 h时,工艺出水TN、氨氮、NO3--N和TP浓度的平均值分别为10.1、1.1、7.4和0.8 mg/L。硝化反应结束时,pH由下降转为上升,ORP上升趋于平缓,DO上升趋缓;反硝化结束时,ORP曲线明显跌落,pH由上升趋于平缓并略有下降;释磷结束后ORP曲线由下降趋于平缓。降低前好氧池DO浓度,有助于同步硝化反硝化作用的发生,从而提高脱氮效率,节省能耗。     

SBR工艺对低碳量城市污水的反硝化除磷研究

广州地区的城市污水含碳量低，碳、氮、磷浓度比例失调，采用传统工艺处理很难达到理想的脱氮除磷效果，为此采用SBR工艺对其进行处理，考察了该工艺的反硝化除磷效果。结果表明，在厌氧／缺氧／好氧的运行模式下，采用逐步增加缺氧段运行时间的方法可有效提高污泥的反硝化除磷性能；在试验进水水质条件下，反应器厌氧运行30min、缺氧运行3h、好氧运行1h可保证对磷的稳定高效去除，出水TP〈1mg／L；ORP值无法指示缺氧反硝化与吸磷过程，pH值可作为缺氧吸磷结束的指示参数，而ORP和pH值均可作为好氧吸磷结束的控制参数。     

Biological nitrogen removal with a real-time control strategy using moving slope changes of pH(mV)- and ORP-time profiles

A new real-time control strategy using moving slope changes of oxidation-reduction potential (ORP)- and pH(mV)-time profiles was designed. Its effectiveness was evaluated by operating a farm-scale sequencing batch reactor (SBR) process using the strategy. The working volume of the SBR was 18 m³, and the volumetric loading rate of influent was 1 m³ cycle⁻¹. The SBR process comprised six phases: feeding → anoxic → anaerobic → aerobic → settle → discharge. The anoxic and aerobic phases were controlled by the developed real-time control strategy. The nitrogen break point (NBP) in the pH(mV)-time profile and the nitrate knee point (NKP) in the ORP-time profile were designated as real-time control points for the aerobic and anoxic phases, respectively. Through successful real-time control, the duration of the aerobic and anoxic phases could be optimized and this resulted in very high N removal and a flexible hydraulic retention time. Despite the large variation in the loading rate (0.5-1.8 kg NH₄-N m⁻³ cycle⁻¹) due to influent strength fluctuation, complete removal of NH₄-N (100%) was always achieved. The removal efficiencies of soluble nitrogen (NH₄-N plus NO_x-N), soluble total organic carbon, and soluble chemical oxygen demand were 98%, 90%, and 82%, respectively. Monitoring the ORP and pH(mV) revealed that pH(mV) is a more reliable control parameter than ORP for the real-time control of the oxic phase. In some cases, a false NBP momentarily appeared in the ORP-time profile but was not observed in the pH(mV)-time profile. In contrast, ORP was more the reliable control parameter for NKP detection in the anoxic phase, since the appearance of NKP in the pH(mV)-time profile was sometimes vague.     

Integrated real-time control strategy for nitrogen removal in swine wastewater treatment using sequencing batch reactors

A new integrated real-time control system was designed and operated with fluctuating influent loads for swine wastewater treatment. The system was operated with automatic addition control of an external carbon source, using real-time control technology, which utilized the oxidation-reduction potential (ORP) and the pH as parameters to control the anoxic phase and oxic phase, respectively. The fluctuations in swine wastewater concentration are extreme; an influent with a low C/N ratio is deficient in organic carbon, and a low carbon source level can limit the overall biological denitrification process. Consequently, a sufficient organic source must be provided for proper denitrification. The feasibility of using swine waste as an external carbon source for enhanced biological nitrogen removal was investigated. The real-time control made it possible to optimize the quantity of swine waste added as the load fluctuated from cycle to cycle. The average removal efficiencies achieved for TOC and nitrogen were over 94% and 96%, respectively, using the integrated real-time control strategy.     

饮用水ORP的健康意义及影响因素探讨

从人体的氧化还原平衡角度,分析了饮用水的氧化还原电位(ORP)对人体健康可能产生的作用,提出在不含任何有毒、有害物质的条件下,可将ORP作为健康饮用水的标准之一,其数值可确定在200 mV以下。通过试验研究了热处理、pH值、碱度、硬度以及茶水对饮用水ORP的影响,结果表明,对饮用水进行热处理或提高饮用水的pH值、碱度、硬度均可明显降低饮用水ORP值,茶叶可大幅度降低饮用水的ORP值。     

Effects of peat and water quality parameters on groundwater arsenic contamination in Bangladesh

To clarify the effect of peat and groundwater quality parameters on groundwater arsenic (As) contamination, As concentrations and the source of nitrogen (N) in groundwater and peat, and oxidation‐reduction potential (ORP) and ammonium‐N concentration of groundwater were compared between As‐contaminated and uncontaminated areas in Bangladesh. Groundwater in the contaminated area had a reducing ORP with a high ammonium‐N concentration, whereas groundwater in the uncontaminated area had a non‐reducing ORP with a low ammonium‐N concentration. Peat was present only in the contaminated area, whose As concentration was very high, indicating the critical role of peat in groundwater As contamination. The source of N in peat and groundwater was identified as chemical N fertilizer. N present in peat and groundwater served as a nutrient, enhancing microbial activity. In the reducing ORP condition, As was thought to be released intensively to groundwater by the mechanism of reductive release.     

SBR法短程硝化及过程控制研究

考察了采用SBR法处理氨氮浓度较高的化工废水时供氧方式对硝化过程中DO、ORP和pH值变化规律的影响。试验结果表明，在曝气量恒定的条件下，可以硝化过程中DO和pH值升高速率的不同表征反应的进程程序，即当氨氮浓度接近零时，DO和pH值升高速率或变化幅度加大，二者可以作为SBR硝化反应时间的控制参数，而ORP值对SBR硝化反应结束的批示作用不是很明显；在DO量恒定的情况下，pH值在整个硝化反应过程中都是缓慢下降或趋于稳定的，当硝化反应结束时突然升高，因此pH值也可作为SBR硝化反应时间较好的控制参数，而ORP值在硝化反应的初期快速升高，之后升高的速度越来越慢直至趋于平稳，它对SBR硝化反应结束的指标作用同样不是很明显。     

应用DO、pH和ORP在线控制A/O硝化过程

开展了应用DO、pH和ORP传感器在线控制A/O工艺硝化过程的试验研究,结果表明,好氧区第1格室的DO浓度可以指示进水氨氮浓度高低;好氧区首、末端pH差值与进水氨氮浓度具有较好的相关性;好氧区pH曲线可以指示系统硝化进行的程度及曝气量和碱度是否充足;好氧区末端ORP值与出水氨氮、硝酸氮浓度具有很好的相关性;好氧区最后格室的DO浓度和ORP值呈对数相关性。基于上述在线信息建立的A/O工艺硝化过程控制策略,不但能提高出水水质,而且降低了运行能耗。     

Improved bioproduction of short-chain fatty acids from waste activated sludge by perennial ryegrass addition

To improve short-chain fatty acids (SCFAs) production from waste activated sludge (WAS), studies that focus on pre-treatment methods, pH control or adding extra carbon like rice were reported. In this study, a kind of green waste (perennial ryegrass) was used as carbon source to adjust carbon to nitrogen ratio (C/N) in WAS to enhance SCFAs production. The effects of different C/N ratio ranging from 26/1 to 7/1 on SCFAs production and cellulose, hemicellulose, and lignin consumption were investigated in detail. It was observed that the maximal SCFAs yield was 368.71 g COD per kilogram of total solids (TS) at C/N 20/1 with fermentation time of 12 d, which was, respectively, over 4 and 12 times than that at C/N 26/1 (sole perennial ryegrass) and C/N 7/1 (sole WAS). Meanwhile, cellulose, hemicellulose and lignin consumptions were 109.12, 148.74, 20.90 g COD/kg TS, respectively, at C/N 20/1 with fermentation time of 12 d. The analysis of the composition of SCFAs showed that acetic acid ranked the first among other acids from C/N ratio of 26/1 to 18/1, whereas propionic acid was the dominant product from C/N ratio of 16/1 to 7/1. Because the results of this study were different from previous studies of SCFAs generation, the mechanism of improved SCFAs at C/N ratio of 20/1 by perennial ryegrass addition was investigated. Results showed that as soluble COD, soluble protein and soluble carbohydrate increased, more substrates were available for SCFAs production at C/N ratio of 20/1. In addition, with the drop of pH to 4.82, methane generating was inhabitant and the SCFAs production was therefore significantly enhanced. Additionally, the mechanism of improved SCFAs generation was analyzed from the view of enzyme activities and microbial community. The experiments revealed that at C/N ratio of 20/1 the activities of enzymes were the highest comparing with other C/N ratios and lignin was the rate-limiting steps in WAS anaerobic digestion by perennial ryegrass addition. The 16S rRNA gene clone library demonstrated that Clostridia, Spirochaetes, and Bacteroidetes were the dominant microbial community at C/N ratio of 20/1.