无泡曝气膜生物反应器去除高氨氮废水的试验研究

采用高浓度的氨氮人工污水对无泡曝气膜生物反应器(MABR)的硝化能力进行了研究,取得了良好的硝化效果,在进水氨氮浓度稳定在230mg/L左右时,获得了65%的氨氮去除率和0.377kg/(d.m3)的体积硝化速率。同时研究了影响硝化效果的各种参数如COD、曝气压强、DO、pH等,结果表明曝气压强和pH对硝化的影响很大。试验表明,随着氨氮负荷的提高,曝气压强为0.035~0.045MPa,进水pH为7.8~8.5时,处理效果最好。     

两种填料挂膜期间硝化反硝化强度对比试验

对河道污水在室内利用立体弹性填料和组合填料进行挂膜试验,对比不同水深处两种填料附着微生物的硝化强度与反硝化强度.结果表明:组合填料的硝化与反硝化强度整体高于立体弹性填料;距水面10 cm处两种填料的硝化作用最强,反硝化作用在不同水深处并无明显差别.     

预挂膜加速厌氧生物膜反应器启动的试验研究

对厌氧生物膜反应器的填料进行预挂膜处理 ,使其形成良好的丝状微生物结构 ,为厌氧微生物的附着和生长提供条件 ,试验结果表明预挂膜可以较大幅度地提高厌氧反应器的启动速率。并用生态学的观点对试验现象和结果进行了分析。     

预挂膜加速厌氧生物膜反应器启动的试验研究

对厌氧生物膜反应器的填料进行预挂膜处理，使其形成良好的丝状微生物结构，为厌氧微生物的附着和生长提供条件，试验结果表明预挂膜可以较大幅度地提高厌氧反应器的启动速率。并用生态学的观点对试验现象和结果进行了分析。     

膜生物反应器处理避孕药废水初探

采用A/O膜生物反应器处理高氨氮、高pH、难生物降解的避孕药废水。试验结果表明,此工艺处理该类废水可行,当水力停留时间为6h,系统对COD、氨氮和总氮的去除率分别为86%、73%和75%。好氧段的溶解氧维持在4mg/L可以同时实现对有机物和氮类的去除,对COD、氨氮和总氮去除率分别达到94%、63%和64%。通过控制A/O膜生物反应器的操作条件,可实现短程硝化和反硝化,提高总氮去除率。     

悬浮填料强化硝化及其工程应用效果研究

通过低温下的硝化速率试验并结合芦村污水处理厂升级改造实例,对新型SPR1悬浮填料的生产性强化硝化效果进行了分析。结果表明:在37%的填料填充率下,与不投加悬浮填料相比,系统硝化速率和硝化效果分别提高123%和99%,悬浮填料的投加强化了系统硝化;在填充率37%的悬浮填料—活性污泥复合系统中,悬浮填料表面上的附着硝化菌和混合液悬浮硝化菌对系统硝化速率的贡献分别为68.5%和31.5%;悬浮填料的工程应用效果良好,在47%的填料填充率下,低温季节系统的生产性硝化效果得到强化,平均提高60%。     

投料A2/O工艺的硝化特性

中试条件下,通过控制活性污泥的泥龄为4 d,观察了投料A2/O工艺的硝化特性.试验表明,该工艺表现出良好的硝化效果,在水温较高的条件下,出水氨氮低于GB18918-2002标准中8 mg/L的一级排放标准.通过改变好氧池中悬浮填料的投加位置与投配率,发现在较高的氨氮填料表面负荷条件下,出水氨氮仍可控制在较低水平.     

两种微污染原水生物预处理方法工艺性能比较

生物接触氧化池和生物陶粒滤池是对微污染原水进行预处理时两种常用的生物反应器。以天津引滦水为处理对象 ,从填料挂膜 ,污染物处理效果 ,以及运行维护管理等方面对两种反应器进行了试验研究。试验结果表明 ,生物陶粒滤池挂膜容易 ,对水中的主要污染物指标处理效率高 ,运行稳定 ,维护管理简单易行 ,比生物接触氧化池更适于处理污染程度较轻的微污染原水。     

微污染原水氨氮的硝化模式

受到污染的原水中氨氮的存在对给水处理及处理后水质都是不利的,生物预处理工艺可以有效地硝化原水中的氨氮.本文通过理论分析,结合实验结果,对影响原水氨氮生物硝化的各种因素进行了讨论,建立了原水氨氮生物硝化的数学模式.     

填料挂膜影响因素分析及阶段性工程改造方案优化研究

南区污水处理厂的出水TN难以稳定达到浙江省清洁排放标准,为提高生物脱氮效率,对现有AAO生反池进行了基于移动床生物膜工艺(MBBR)的升级改造。填料是MBBR的核心载体,结合MBBR工艺改造及其调试,研究了影响填料挂膜的因素,结果表明充足的碳源、适宜的曝气流化情况、较低的污泥浓度有利于填料挂膜。通过改造曝气系统优化了填料区整体流态,并通过综合分析表明南区污水处理厂冬季启动改造是最佳的选择。     

High nitrification rate at low pH in a fluidized bed reactor with chalk as the biofilm carrier.

A typical steady state bulk pH of about 5 was established in a nitrifying fluidized bed with chalk as the only buffer agent. In spite of the low pH, high rate nitrification was observed with the nitrification kinetic parameters in the chalk reactor similar to those of biological reactors operating at pH>7. Various methods were used to determine the reasons for high rate nitrification at such low pH including (i) determination of bacterial species, (ii) microsensor measurements in the biofilm, and (iii) comparison of nitrification performance at low pH with a non-chalk fluidized bed reactor. Fluorescence in situ hybridization (FISH) using existing 16S rRNA-targeted oligonucleotide probes showed common nitrifying bacteria in the low pH chalk reactor. The prevalent nitrifying bacteria were identified in the Nitrosomonas oligotropha, Nitrosomonas europeae/eutropha, Nitrosospira and Nitrospira related groups, all well known nitrifiers. Microelectrode measurements showed that the pH in the biofilm was low and similar to that of the bulk pH. Finally, reactor performance using a non-chalk biofilm carrier (sintered glass) with the same bacterial inoculum also showed high rate nitrification below pH 5. The results suggest that inhibition of nitrification at low pH is highly overestimated.     

Changes in ammonia oxidiser population during transition to low pH in a biofilm reactor starting with Nitrosomonas europaea.

Recent experiments in our laboratory using both biofilm and suspended biomass reactors have demonstrated high rate nitrification at low pH with known autotrophic nitrifying bacteria originating from wastewater treatment plants refuting previous assumptions that nitrification is significantly inhibited at low pH. Since much of the earlier microbiological work regarding ammonia oxidising bacteria (AOB) physiology was carried out using Nitrosomonas europaea, this model bacterium's capability for high rate nitrification at low pH in a continuous biofilm reactor was tested. A biofilm reactor filled with sintered glass particles was inoculated with a pure culture of N. europaea. The reactor was first operated to high nitrification rates under conditions favourable to N. europaea (pH > 7; high ammonium concentrations). To eliminate inhibitory concentrations of nitrite at low pH, an enriched culture of Nitrospira (a nitrite oxidising bacterium) was then added. The transition from neutral to acidic conditions was attempted by sharply lowering the nitrification rate and by using a feeding solution containing insufficient buffer for complete nitrification. As opposed to other successful transitions, the pH in the N. europaea/Nitrospira reactor initially dropped only slightly and maintained pH > 6 for over two weeks. The reactor reached pH 4.5 only after four weeks. FISH results showed that while the percent of AOB and Nitrospira to eubacteria remained relatively constant at 51.1 +/- 8.2% and 40.8 +/- 6.4%, respectively, the AOB community changed completely in 60 days from 100% N. europaea to 100% Nitrosomonas oligotropha. Even though N. oligotropha was not intentionally introduced into the reactor, it is apparently much better adapted to conditions of low pH.     

Inhibitory effect of the xenobiotic 1,2-dichloroethane in a nitrifying biofilm reactor.

The aim was to investigate the inhibitory effect of the xenobiotic 1,2-DCA on nitrification during the cometabolic degradation in a packed bed nitrifying biofilm reactor. This xenobiotic inhibited primarily the conversion of NH4-N to hydroxylamine by binding to the AMO enzyme. It had no inhibitory effect on the conversion of nitrite to nitrate. At high NH4-N loadings, the presence of 1,2-DCA inhibited NH4-N utilisation more severely than at low loadings. The suppressing effect of 1,2-DCA on NH4-N utilisation was found to be reversible due to the ability of cells to recover from inhibition. These results could fill a gap in the literature about the potential use of nitrifying biofilm systems for cometabolic treatment of 1,2-DCA and could be useful in the design of engineered 1,2-DCA remediation/treatment in biofilm reactors.     

Operation of a full-scale pumped flow biofilm reactor (PFBR) under two aeration regimes

A novel technology suitable for centralised and decentralised wastewater treatment has been developed, extensively tested at laboratory-scale, and trialled at a number of sites for populations ranging from 15 to 400 population equivalents (PE). The two-reactor-tank pumped flow biofilm reactor (PFBR) is characterised by: (i) its simple construction; (ii) its ease of operation and maintenance; (iii) low operating costs; (iv) low sludge production; and (v) comprising no moving parts or compressors, other than hydraulic pumps. By operating the system in a sequencing batch biofilm reactor (SBBR) mode, the following treatment can be achieved: 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD) and total suspended solids (TSS) reduction; nitrification and denitrification. During a 100-day full-scale plant study treating municipal wastewater and operating at 165 PE and 200 PE (Experiments 1 and 2, respectively), maximum average removals of 94% BOD5, 86% TSS and 80% ammonium-nitrogen (NH4-N) were achieved. During the latter part of Experiment 2, effluent concentrations averaged: 14 mg BOD5/l; 32 mg COD(filtered)/l; 14 mg TSS/l; 4.4 mg NH4-N/l; and 4.0 mg NO3-N/l (nitrate-nitrogen). The average energy consumption was 0.46-0.63 kWh/m3(treated) or 1.25-1.76 kWh/kg BOD5 removed. No maintenance was required during these experiments. The PFBR technology offers a low energy, minimal maintenance technology for the treatment of municipal wastewater.     

Nitrification in bulk water and biofilms of algae wastewater stabilization ponds.

Nitrogen removal in wastewater stabilization ponds is poorly understood and effluent monitoring data show a wide range of differences in ammonium. For effluent discharge into the environment, low levels of nitrogen are recommended. Nitrification is limiting in facultative wastewater stabilization ponds. The reason why nitrification is considered to be limiting is attributed to low growth rate and wash out of the nitrifiers. Therefore to maintain a population, attached growth is required. The aim of this research is to study the relative contribution of bulk water and biofilms with respect to nitrification. The hypothesis is that nitrification can be enhanced in stabilization ponds by increasing the surface area for nitrifier attachment. In order to achieve this, transparent pond reactors representing water columns in algae WSP have been used. To discriminate between bulk and biofilm activity, 5-day batch activity tests were carried out with bulk water and biofilm sampled. The observed value for Rnitrbulk was 2.7 x 10(-1) mg-N L(-1) d(-1) and for Rbiofilm was 1,495 mg-N m(-2) d(-1). During the 5 days of experiment with the biofilm, ammonia reduction was rapid on the first day. Therefore, a short-term biofilm activity test was performed to confirm this rapid decrease. Results revealed a nitrification rate, Rbiofilm, of 2,125 mg-N m(-2) d(-1) for the first 5 hours of the test, which is higher than the 1,495 mg-N m(-2) d(-1), observed on the first day of the 7-day biofilm activity test. Rbiofilm and Rnitrbulk values obtained in the batch activity tests were used as parameters in a mass balance model equation. The model was calibrated by adjusting the fraction of the pond volume and biofilm area that is active (i.e. aerobic). When assuming a depth of 0.08 m active upper layer, the model could describe well the measured effluent values for the pond reactors. The calibrated model was validated by predicting effluent Kjeldahl nitrogen of algae ponds in Palestine and Colombia. The model equation predicted well the effluent concentrations of ponds in Palestine.     

A new oxygen supply method for simultaneous organic carbon removal and nitrification by a one-stage biofilm process

A new oxygen supply method to biofilm is proposed for simultaneous organic carbon removal and nitrification. The main feature of the method is use of hydrophobic porous membrane or oxygen enrichment membrane as substratum of biofilm. In the biofilm formed on oxygen permeable membrane, oxygen is supplied from the bottom to the surface of the biofilm through the membrane while organic pollutants are supplied from the surface to the bottom of the biofilm. The oxygen supply method allows nitrifiers near the bottom region to grow with less competition from BOD oxidizers. The microbial population was investigated in the biofilm formed on hydrophobic microfilter. Nitrifiers grew mainly in the bottom region while denitrifiers grew in the middle region of the biofilm formed on the membrane. Simultaneous organic carbon removal and nitrification were carried out successfully by the biofilm. Furthermore, the potential of the new oxygen supply method was demonstrated with the biofilm formed on an oxygen enrichment-type biomass carrier in a single-stage treatment of domestic wastewater. The nitrification rate was about 1.9 g/m²d and was comparable to that in the conventional biofilm process designed especially for nitrification.     

Population dynamics and biofilm composition in a new three-phase circulating bed reactor

The biofilm characteristics of a novel three-phase reactor, the circulating bed reactor (CBR), were studied using industrial prototype fed with primary and secondary settled effluent in conditions of tertiary N and secondary C+N nitrification. The results showed a high nitrification rate close to the intrinsic values for N and C+N conditions: up to 2 and 0.6 kgN-NH₄ m^-3 d^-1, or 1.88±0.26 and 0.22±0.07 gN g^-1 PR d^-1, respectively. The application of an integrated approach for biofilm analysis enabled the better understanding of biofihn dynamics. The biofilm remained relatively thin, below 100 μm, indicating an effective control of the biofilm development. Protein, measured by the conventional colometric method and pyrolysis-GCMS, was the major fraction accounting for up to 35% of the biomass dry weight and 58% of the biopolymer content. The polysaccharide's fraction remained very low (<3%). The ribosomal RNA probes analysis confirmed the predominance of bacterial cells in the CBR biofilm (80–86% of bacteria versus the universal probe) showing a high proportion of nitrifying bacteria accounting for up to 50% and 27% in the N and C+N removal respectively. Nitrosomonas predominated in tertiary nitrification whereas carbon input led to the appearance of other ammonia oxidizers. This particular composition was characterized by a high state of oxidation of the biomass, expressed by the low COD/DW ratio of about 0.85. In conclusion, it can be stated that this new three-phase bioreactor ensures a high nitrification rate through an effective biofilm control promoting the development of bacterial cells, especially nitrifying bacteria, and minimizing exopolysaccharides production.     

Water reuse for irrigation from waste water treatment plants with seasonal varied operation modes.

Irrigation periods are usually limited to vegetation periods. The quality requirements for treated wastewater for disposal and for reuse are different. The reuse of water for irrigation allows partly the reuse of the wastewater's nutrients (N and P). Outside the irrigation period the water must be treated for disposal, thus nutrient removal is often required in order to avoid detrimental effects on the receiving surface water body. Only wastewater treatment plants with different operation modes for different seasons can realise these requirements. The nitrification is the most sensitive biological process in the aerobic wastewater treatment process. At low water temperatures the nitrifying bacteria need several weeks to re-start full nitrification after periods without NH4-removal. Therefore it is necessary to develop options for waste water treatment plants which allow a fast re-start of the nitrification process. Based on theoretical considerations and computer simulations of the activated sludge treatment process, one possibility for implementing a wastewater treatment plant with different seasonal operation modes is evaluated.     

Innovations in wastewater treatment: the moving bed biofilm process.

This paper describes the moving bed biofilm reactor (MBBR) and presents applications of wastewater treatment processes in which this reactor is used. The MBBR processes have been extensively used for BOD/COD-removal, as well as for nitrification and denitrification in municipal and industrial wastewater treatment. This paper focuses on the municipal applications. The most frequent process combinations are presented and discussed. Basic design data obtained through research, as well as data from practical operation of various plants, are presented. It is demonstrated that the MBBR may be used in an extremely compact high-rate process (<1 h total HRT) for secondary treatment. Most European plants require P-removal and performance data from plants combining MBBR and chemical precipitation is presented. Likewise, data from plants in Italy and Switzerland that are implementing nitrification in addition to secondary treatment are presented. The results from three Norwegian plants that are using the so-called combined denitrification MBBR process are discussed. Nitrification rates as high as 1.2 g NH4-N/m2 d at complete nitrification were demonstrated in practical operation at low temperatures (11 degrees C), while denitrification rates were as high as 3.5g NO3-Nequiv./m2.d. Depending on the extent of pretreatment, the total HRT of the MBBR for N-removal will be in the range of 3 to 5 h.     

The effect of temperature and sludge age on COD removal and nitrification in a moving bed sequencing batch biofilm reactor.

This study investigates the effect of temperature and the sludge age on the performance of a moving bed sequencing batch biofilm reactor (MBSBBR) for COD removal and nitrification. The experiments are conducted in a lab-scale MBSBBR operated at three different temperatures (20, 15 and 10 degrees C) with a synthetic feed simulating domestic sewage characteristics. Evaluation of the results revealed that removal of organic matter at high rates and with efficiencies over 90% was secured at all operation conditions applied. The nitrification rate was significantly influenced by changes in temperature but complete nitrification occurred at each temperature. The nitrification rates observed at 20 and 15 degrees C were very close (0.241 mg NO(x)-N/m2d, 0.252 mg NO(x)-N/m2 d, respectively), but at 10 degrees C, it decreased to 0.178 mg NO(x)-N/m2d. On the other hand, the biomass concentration and sludge age increased while the VSS/TSS ratios that can be accepted as an indicator of active biomass fraction decreased with time. It is considered that, increasing biofilm thickness and diffusion limitation affected the treatment efficiency, especially nitrification rate, negatively.