Effect of recycle-to-influent ratio on activities of nitrifiers and denitrifiers in a combined UASB-activated sludge reactor system

A laboratory study using a combined upflow anaerobic sludge bed (UASB)-activated sludge (AS) reactor system was undertaken to explore the effect of recycle-to-influent ratio (R(e)=1, 2, and 3) on the activities of nitrifiers and denitrifiers. Suspended-solids pre-settled piggery wastewater was used as the substrate-feed wastewater. At the R(e) of 1-3, the combined reactor system achieved efficient removal of COD (96-97%), TKN (100%) and total nitrogen TN (54-77%). Methanogenesis occurred with nearly-complete denitrification in the UASB reactor, whereas complete nitrification took place in the AS reactor. A higher R(e) (i.e., accompanied with a shorter solids retention time) resulted in a larger amount of high-activity denitrifiers and thereby achieved a higher TN removal efficiency. Compact granules and a high biomass concentration in the UASB reactor were observed. At the R(e) of 1-3, the maximum specific reaction rate of nitrifiers (0.45-0.49 NH(4)(+)-NmgVSS(-1)d(-1)) and the specific nitrification rates of mixed culture (0.18-0.22mg NH(4)(+)-NmgVSS(-1)d(-1)) in the AS reactor varied slightly; whereas the maximum specific reaction rate of denitrifiers (0.18-0.27mg NO(x)(-)-NmgVSS(-1)d(-1)) and the specific denitrification and COD removal rates of mixed culture (0.025-0.050mg NO(x)(-)-NmgVSS(-1)d(-1); 0.24-0.31mgCODmgVSS(-1)d(-1)) in the UASB reactor increased with increasing R(e). The primary finding of the study is that the combined UASB-AS reactor system should be operated at a higher R(e) to maintain high-activity denitrifiers to remove organic materials and nitrogen from piggery wastewater.     

硫化物自养反硝化细菌颗粒污泥及其物化特征

采用上升流式缺氧颗粒污泥反应器成功驯化培养出了高性能的硫化物自养反硝化细菌颗粒污泥。反应器60 d完成污泥颗粒化,200 d后成熟的颗粒污泥平均粒径稳定在1 400 μm,SVI5和SVI30分别平均为（21.6±0.3）mL·g-1和（21.0±0.9）mL·g-1;系统稳定运行后,在污泥氮硫负荷分别为0.33 kg N·（m3·d）-1和0.62 kg S·（m3·d）-1,水力停留时间为5 h,脱氮效率保持在95%以上。与此同时,对接种污泥与颗粒污泥的物化特征进行对比分析发现,培养前后的污泥的无机组分与有机成分发生显著变化,Ca等元素参与并促进了颗粒污泥的形成,随着颗粒化的形成,蛋白质、多糖、脂质等物质均有不同程度的增长,使得颗粒污泥具有良好的脱氮性能,且结构和稳定性良好。     

不同乙酸钠浓度对UASB中颗粒污泥形成的影响

以污水处理厂厌氧消化池厌氧污泥作为接种物,采用上流式厌氧污泥床反应器(UASB),分别以不同配比的葡萄糖和乙酸钠为进水,考察厌氧颗粒污泥形成的特性。葡萄糖与乙酸钠进水COD浓度始终保持1:1所形成的颗粒污泥其沉降性、产甲烷活性等均明显优于乙酸钠进水浓度始终为500 mg COD/L的颗粒污泥。结果表明,不同碳源配比的进水条件下形成的颗粒污泥性能及对废水处理能力存在显著差异。     

Microbial activity in a combined UASB-activated sludge reactor system

A combined upflow anaerobic sludge bed-activated sludge (UASB-AS) reactor system with consistently wasting of excess biomass was used to treat suspended-solids pre-settled piggery wastewater (COD=2000 mg l(-1), total Kjeldahl nitrogen TKN=400 mg l(-1), suspended solids=250-400 mg l(-1)). Thus, the activity of nitrogen-related microbial groups in each individual bioreactor was investigated. When the granules retention time (GRT) of 20-50 d in the UASB reactor, the solids retention time (SRT) of 10-25 d in the AS reactor and the recycle-to-influent ratio (Re) of 1 were maintained, the combined system removed 95-97% of chemical oxygen demand (COD), 100% of TKN and 54-55% of total nitrogen (TN). Denitrification and methanogenesis occurred in the UASB reactor so that both biochemical processes contributed to most of the COD removal and, complete nitrification (most of the TKN removal) occurred in the AS reactor. Compact granules with good settling abilities developed in the UASB reactor, and rapid rates of granulation of break-up granules in the UASB reactor were confirmed by experiments. The activity of nitrifiers and denitrifiers (an=0.68-0.87; adn=0.55-0.70) and the calculated specific nitrification and denitrification rates (qn=0.26-0.47 mg NH4+ -N mg VSS(-1)d(-1); qdn=0.046-0.076 mg NOx- -N mg VSS(-1)d(-1)) significantly increased with decreasing SRT and GRT, respectively. Accordingly, the combined UASB-AS reactor system should be regarded a promising alternative for the removal of organic carbon and nitrogen from piggery wastewater.     

UASB反应器处理PTA废水的启动及污泥特性分析

采用上流式厌氧污泥床（UASB）反应器,以精对苯二甲酸（PTA）废水为处理对象,研究了中温条件下反应器的启动、颗粒污泥的形态和产甲烷活性及微生物群落结构。实验结果表明：采用逐渐提高进水负荷和减少水力停留时间的运行方法,历时近200 d,可实现UASB 反应器的启动。此时,反应器对COD的去除率保持在80%以上,对应的容积负荷也达到4.0 kg·（m3·d）-1以上。反应器内污泥实现颗粒化,颗粒污泥的体积平均粒径为416.53 μm,产甲烷活性为121.2 mL·（g·d）-1 （以VSS计）。颗粒污泥表面存在大量菌胶团,杆菌和丝状菌镶嵌其中。菌胶团有助于微生物的聚集,加速污泥颗粒化过程。Syntrophorhabdus是降解PTA废水中苯类污染物的重要微生物,占细菌量的27.4%,而Methanosaeta则是主要的产甲烷菌,占古细菌总量的67.3%。该研究可为UASB 处理PTA废水的启动提供依据。     

上流式厌氧污泥床反应器处理饮料废水

通过监测西安可口可乐饮料有限公司污水处理站的上流式厌氧污泥床(UASB)反应器,探讨饮料废水厌氧处理过程中COD去除率、沼气组分、氢分压、出水挥发性脂肪酸、产甲烷活性以及污泥形态。结果表明,UASB反应器对饮料废水中的COD去除率达到84.55%,产生的沼气中甲烷组分含量高达74.5%。反应器内的氢分压仅2.5 Pa,为水解发酵和产氢产乙酸过程创造了良好的条件。UASB反应器中污泥具有较高的产甲烷活性,以乙酸、丙酸和丁酸为基质时,最大比产甲烷活性分别为407.14、331.74和241.27 mL CH4/(g VSS·d)。UASB反应器中的污泥形态主要为絮状,甲烷菌中的优势菌为甲烷丝菌,同时存在少量甲烷杆菌。针对该厂UASB反应器中污泥的现状,提出了影响颗粒化的因素和控制措施,为后期的运行和管理提供了参考依据。     

Phenol degradation and microbial characteristics in upflow anaerobic sludge blanket reactors at ambient and mesophilic temperatures

A synthetic wastewater containing phenol as sole substrate was respectively treated at temperatures of 26±1°C and 37±1°C in 2.8 litre upflow anaerobic sludge blanket (UASB) reactors. At the two temperatures, pH 7.0–7.5, with a 1:1 effluent recycle ratio, phenol in wastewater was efficiently degraded in a UASB reactor. Microbial community analysis using denaturing gradient gel electrophoresis (DGGE) showed that less shift in the microbial community occurred with the temperature changing. Phenol degradation in wastewater was recommended to select ambient temperature in UASB reactors. The optimal HRT was 12 to 16 hours corresponding to 6.0–4.5 g COD/(l.d) loading rate at ambient temperature in UASB reactors. The distribution of archaeal and bacterial populations in the UASB granular consortium was revealed using fluorescence in situ hybridisation (FISH) technique.     

Improvement of upflow anaerobic sludge bed performance using chitosan.

Chitosan, with a degree of deacetylation of 85% and a molecular weight of 2.5 x 10(5) Da, yielding high flocculation efficiency (85 to 100% flocculation) and a broad flocculation region (2 to 45 mg/g suspended solids), was selected for accelerating granulation in a 30-L upflow anaerobic sludge bed (UASB) used to treat wastewater from a tropical fruit-processing industry. Compared with other studies, smaller amounts of chitosan were applied (two injections with 2 mg chitosan/g suspended solids in the reactor at each injection). Comparison with the UASB without chitosan addition, the UASB had a 24 to 37% larger particle size and a 6 to 41% longer solids retention time. In addition, the reactor performances were also enhanced. The UASB with chitosan addition had a 9 to 59% lower effluent chemical oxygen demand (COD), 4 to 10% higher COD removal, up to 35% higher biogas production rate, and a 16 to 68% lower biomass washout. The paired t-test analysis indicated that these performance parameters were significantly different (P < 0.05).     

硝酸盐反硝化颗粒污泥的快速培养与理化特性

以甲醇为碳源,在USB反应器内接种活性污泥,50 d内培养出优质的反硝化颗粒污泥。颗粒污泥的形成历经3个阶段:启动运行期,颗粒污泥出现期以及颗粒污泥成熟期。颗粒污泥床底层反硝化效率最高可达总量的78%,中部颗粒污泥湿密度与沉降速率较大,分别为1.077 g/mL和194 m/h。成熟的颗粒污泥具有湿密度大,沉降速率高等特点,颗粒表面丝状体互相缠绕,有明显的孔隙结构。     

The inhibitory effects of lindane in batch and upflow anaerobic sludge blanket reactors

In this study, the inhibitory effects of lindane (LIN) on originally unacclimated mixed anaerobic cultures were investigated by anaerobic toxicity assay (ATA) experiments. ATA experiments revealed that 10 mg/l LIN exerted inhibitory effects on anaerobic cultures, which was recoverable. Continuous reactor experiments conducted to determine the inhibitory effects of LIN and the maximum LIN loading rate achievable in two-stage upflow anaerobic sludge blanket (UASB) reactors indicated that anaerobic granular cultures were successfully acclimated to 30 mg/l LIN. The maximum LIN loading rate and minimum hydraulic retention time (HRT) possible for the UASB system were 10 mg/l day and 18 h, respectively, which resulted in the overall chemical oxygen demand (COD) removal efficiency of 89%.     

高盐废水体系运行模式对活性污泥颗粒化过程的影响

好氧颗粒污泥(AGS)技术在高盐废水处理领域具有广阔应用潜力,高盐胁迫条件下运行模式对造粒过程影响尚不清晰。采用3个序批式反应器(SBR),探究好氧模式(R1)、厌氧/好氧模式(R2为厌氧推流进水30 min;R3为厌氧推流进水120 min)对活性污泥颗粒化过程及高盐废水处理效能的影响。结果发现,R1、R2和R3造粒时间无显著差异(分别在第13、13、10 d实现完全颗粒化),而R3培养的颗粒结构更致密、胞外蛋白/胞外多糖(PN/PS)含量较高。3个SBR均可在高盐废水体系实现高TOC去除率(>97%);R1和R2的NH₄⁺-N去除率大于96%,而R3在50%~70%波动,可能是硫酸盐还原菌(Desulfovibrio和Fusibacter)在长厌氧推流进水过程产生的S^2-抑制了硝化反应。本研究结果可为高盐废水体系活性污泥造粒过程提供参考。     

连续流反应器中培养好氧颗粒污泥的运行效能研究

在连续流完全混合反应器(CSTR)中,采用不同进水方式,以乙酸钠作为碳源配制的人工配水作为原水,对好氧颗粒污泥的运行效能进行了试验研究。研究表明,采用不同进水方式运行的2个反应器在颗粒污泥出现后,运行效能差别不大;好氧颗粒污泥反应器运行高效稳定,在水力停留时间为1.5h、COD容积负荷为1.0kg/(m3·d)的条件下,对COD、TP、NH4+-N和TN的去除率分别为90%、85%、95%和60%,并具有明显的脱氮除磷效果;反应器中存在同步硝化反硝化现象。     

Comparative granule characteristics and biokinetics of sucrose-fed and phenol-fed UASB reactors

Two upflow anaerobic sludge bed (UASB) reactors were fed with a non-inhibitory substrate sucrose and an inhibitory substrate phenol, respectively, to compare granule characteristics and biokinetics. The average size of biomass granules in the sucrose-fed UASB reactor was slightly larger than that of the phenol-fed reactor. The average microbial density was significantly higher in the phenol-fed reactor. The intrinsic biokinetics of sucrose-acidogenesis and phenol-acidogenesis followed Monod and Haldane kinetics, respectively. By comparing half-saturation constants for sucrose and phenol (Ks1,s; Ks1,p), the affinity of phenol to the granule should be much higher. The mass fraction of methanogens (f) in the sucrose-fed reactor decreased with increasing volumetric loading rate (VLR) because of the accumulation of volatile fatty acids (VFAs); the f of the phenol-fed reactor decreased with increasing VLR because acidogenesis was the rate-limiting step. The mass transfer resistance in overall substrate removal in the sucrose-fed reactor was greater than that in the phenol-fed reactor.     

Treatment of carbofuran-bearing synthetic wastewater using UASB process

In the present study, fate of carbofuran in anaerobic environments and the adverse effects of carbofuran on conventional anaerobic systems were evaluated. Carbofuran degradation studies were carried out in batch reactors with varying carbofuran concentrations of 0 to 270.73 mg/L corresponding to a sludge-loading rate (SLR) of 2.12 x 10(-6) to 3.83 x 10(-3) g of carbofuran/g of volatile suspended solids (VSS)/d. Carbofuran concentration was reduced to undetectable levels at the end of 8 and 13 days in the batch reactors operated with a SLR of 2.12 x 10(-6) and 3.33 x 10(-5) g of carbofuran/g of VSS/d, respectively. Performances of two anaerobic reactors i.e. upflow anaerobic sludge blanket (UASB) and modified UASB (with tube settlers) were evaluated in the presence and absence of carbofuran using synthetic wastewater. In the absence of carbofuran, the soluble chemical oxygen demand (COD) removal efficiency in the conventional UASB reactor at 8 h and 6 h hydraulic retention time (HRT) was nearly 88% and 76%, respectively, whereas in modified UASB reactor it was increased to 90% at 8 h HRT and 78% at 6 h HRT. When 28 mg/L (SLR of 1.19 x 10(-2) g of carbofuran/g of VSS/d) of carbofuran was introduced in the reactors, the COD removal efficiency was reduced to 41% and 44% in conventional and modified UASB reactors respectively. However, the reactor could maintain around 80% COD removal efficiency at a carbofuran concentration of 7.84 mg/L (SLR of 3.64 x 10(-3) g of carbofuran/g of VSS/d). The reactor efficiency was also measured in terms of specific acetoclastic methanogenic activity (SMA). The toxic effect of carbofuran was reversible to a certain extent. Carbofuran removal efficiency in the conventional UASB reactor at carbofuran concentrations of 7, 13 and 28 mg/L were 40 +/- 3%, 27 +/- 3%, and 11 +/- 3%, respectively. In modified UASB reactor, carbofuran removal efficiency was almost uniform at 7 and 13 mg/L but it was reduced nearly by 56% at 28 mg/L. The major metabolite of carbofuran i.e. 3-keto carbofuran was found in all the reactors.     

絮凝剂对高速厌氧反应器污泥颗粒化的强化作用

以考察絮凝剂对厌氧反应器中活性污泥性能的影响为目的,将聚合氯化铝(PAC)、聚丙稀酰胺(PAM)、聚季铵盐3种不同类型絮凝剂以不同投加量添加到反应器中,采用生物化学甲烷势(BMP)和厌氧毒性测定(ATA)分析方法,评价了3种絮凝剂的厌氧生物可降解性以及3种絮凝剂对厌氧污泥产甲烷活性、沉降性能等方面的促进或抑制作用。确定以聚季铵盐作为厌氧污泥颗粒化促进剂,建议采用多次投加方式,反应器中聚季铵盐质量浓度以10-50mg／L为宜。     

An observation on sludge granulation in an enhanced biological phosphorus removal process

A sequencing batch reactor (SBR) seeded with flocculated sludge and fed with synthetic wastewater was operated for an enhanced biological phosphorus removal (EBPR) process. Eight weeks after reactor startup, sludge granules were observed. The granules had a diameter of 0.5 to 3.0 mm and were brownish in color and spherical or ellipsoidal in shape. No significant change was observed in sludge granule size when operational pH was changed from 7 to 8. The 208-day continuous operation of the SBR showed that sludge granules were stably maintained with a sludge volume index (SVI) between 30 to 55 mL/g while securing a removal efficiency of 83% for carbon and 97% for phosphorus. Fluorescent in situ hybridization (FISH) confirmed the enrichment of polyphosphate accumulating organisms (PAOs) in the SBR. The observations of sludge granulation in this study encourage further studies in the development of granules-based EBPR process.     

厌氧序批式反应器中丝状颗粒污泥的形成

以葡萄糖为基质,研究浮动盖式ASBR中颗粒污泥的形成。实验结果表明,污泥在120 d时完全颗粒化,颗粒污泥具有良好的沉降性能(25 m/h)及良好的产甲烷活性,甲酸、乙酸、丙酸及丁酸最大代谢活性分别达到0.216、0.825、0.237和0.796 g COD/(g VSS.d)。电镜扫描(SEM)发现,整个污泥结构均一,均由丝状菌构成。     

UASB反应器处理链霉素废水启动及运行性能

采用上流式厌氧污泥床(UASB)反应器处理链霉素生产废水,研究了中温条件下反应器启动和稳定运行中废水处理性能及厌氧污泥颗粒化过程。结果表明,通过逐步提高链霉素废水进水比例和负荷,可以实现UASB反应器的启动和稳定运行,并对高浓度链霉素实际废水具有良好的处理性能,COD去除率稳定在80%以上,COD去除负荷达7.2 kg/(m3·d),CH4产生量达到6.2 L/d。UASB反应器启动运行过程中,链霉素废水对污泥活性具有抑制影响,造成短期反应器运行性能明显下降,而后很快恢复。同时高负荷链霉素废水造成甲烷产率降低。污泥性状变化显著,污泥形态逐渐转变为颗粒态,污泥粒径增大,出现大量0.5~1.0 mm颗粒污泥,污泥VSS/SS比值升高,污泥沉降性明显增强,比产甲烷活性显著升高,表明污泥开始实现颗粒化。     

Anammox-HAP颗粒污泥型膨胀床反应器的氮磷同步去除能力及污泥特性

为实现集成、高效的氮磷处理,提高厌氧氨氧化工艺的运行稳定性及功能集成性,搭建了一种新型的anammox-HAP颗粒污泥型膨胀床反应器。设置了3个不同温度条件下的反应器,通过控制进入反应器中的钙、磷元素,以及调控反应器pH,探究了膨胀床反应器对氮、磷的同步去除能力,并对污泥特性进行了分析。结果表明：anammox-HAP颗粒污泥型膨胀床反应器在35、25、15℃条件下均可稳定运行,并能分别实现(44.90±0.32)、(17.12±0.97)、(8.79±0.14 ) g·(L·d)⁻¹的氮去除速率,且总氮去除率稳定维持在85%以上;磷元素以HAP核的形式聚集在anammox颗粒内部,可在随剩余污泥排出的同时进行回收;anammox-HAP反应器中颗粒污泥的沉降性能明显高于一般厌氧或anammox工艺中的颗粒污泥,并与颗粒中的磷含量正相关。本研究阐释了anammox-HAP颗粒污泥型膨胀床反应器的特点,可为废水中氮磷的处理提供参考。     

原位臭氧氧化污泥减量工艺的运行效能

采用ASBR/SBR原位臭氧污泥减量工艺,重点研究了原位臭氧氧化对SBR段污泥产率和出水水质的影响。两个相同的ASBR/SBR组合工艺同时运行,每隔3个周期向臭氧投加组SBR的曝气阶段原位间歇投加臭氧,臭氧投加量为0.027 g O3/g MLSS,连续运行40 d;对照组不投加臭氧作为对比。结果表明,原位臭氧氧化实现污泥减量约43.9%,臭氧投加组SBR段平均污泥产率系数为0.1447 g SS/g SCOD,而对照组为0.2580 g SS/g SCOD,投加组没有惰性污泥的累积,并且污泥沉淀性能得到改善。原位臭氧氧化对出水水质影响不大,投加组与对照组相比,臭氧投加3周期后的出水COD、NH4+-N、TN和TP平均值分别为47.8、0.76、14.1和6.4 mg/L,去除率分别下降了4%、2%、3%和7.7%,其中COD、NH4+-N和TN均能达到《城镇污水处理厂污染物排放标准》(GB18918-2002)一级A标准。