Influence of earthworm Eisenia fetida on removal efficiency of N and P in vertical flow constructed wetland

This study investigates biomass, density, photosynthetic activity, and accumulation of nitrogen (N) and phosphorus (P) in three wetland plants (Canna indica, Typha augustifolia, and Phragmites austrail) in response to the introduction of the earthworm Eisenia fetida into a constructed wetland. The removal efficiency of N and P in constructed wetlands were also investigated. Results showed that the photosynthetic rate (P _n), transpiration rate (T _r), and stomatal conductance (S _cond) of C. indica and P. austrail were (p?<?0.05) significantly higher when earthworms were present. The addition of E. fetida increased the N uptake value by above-ground of C. indica, T. augustifolia, and P. australis by 185, 216, and 108 %, respectively; and its P uptake value increased by 300, 355, and 211 %, respectively. Earthworms could enhance photosynthetic activity, density, and biomass of wetland plants in constructed wetland, resulting in the higher N and P uptake. The addition of E. fetida into constructed wetland increased the removal efficiency of TN and TP by 10 and 7 %, respectively. The addition of earthworms into vertical flow constructed wetland increased the removal efficiency of TN and TP, which was related to higher photosynthetic activity and N and P uptake. The addition of earthworms into vertical flow constructed wetland and plant harvests could be the significantly sustainable N and P removal strategy.     

8种植物床人工湿地脱氮除磷的研究

分别以水葫芦、西洋芹、空心菜、水芹、混合种(黄菖蒲、千屈菜、再力花)、千屈菜、再力花、黄菖蒲等植物床构建潜流人工湿地,研究其对生活污水氮、磷的净化功能及其去除率与水力停留时间(HRT)的变化规律。结果表明,各种植物床对TN、TP的去除率随HRT的延长而增加,不同植物床的脱氮除磷效果是不同的。千屈菜植物床对TN的去除效果最好,HRT为3d时,TN去除率为56%;HRT为6d时,TN去除率达77%。再力花植物床对TP的去除效果最好,HRT为3d时,TP去除率达78%;HRT为6d时,TP去除率达96%。其他植物床也有较好的脱氮除磷效果。各种植物床处理后出水TN、TP均较低,HRT为3d时,出水TN均低于《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级A标准规定的限值(15mg/L),出水TP均低于GB 18918—2002二级标准规定的限值(3mg/L);7种植物床构建的潜流人工湿地(水葫芦的数据丢失)对TN、TP的去除均满足一级反应动力学方程,且相关性显著。     

复合人工湿地去除生活污水中的有机物和氮

为提高人工湿地对生活污水的处理能力,对传统的单一垂直流湿地进行改进和优化。采用2个垂直流人工湿地串联,并在好氧湿地内增加曝气供氧,使好氧湿地内溶解氧保持在2～2.5 mg/L范围内,而后增加出水回流。结果表明,增加曝气显著提高了出水的COD、NH3-N去除率,但TN去除效果仍不达标;当随着回流比的增加,NH3-N的去除率略有提高,而后趋于稳定,TN去除率提高显著,但回流比过大时,TN去除率则有所下降。     

间歇曝气潜流人工湿地的污水脱氮效果

采用间歇曝气运行方式,提升潜流人工湿地生活污水处理系统中的溶解氧浓度,强化脱氮效果。结果表明,间歇曝气运行方式有效提高了湿地内部溶解氧水平,曝气时溶解氧浓度可达6~9 mg/L,停止曝气后,溶解氧浓度迅速下降至0.5 mg/L以下,在湿地内部营造了一种交替的好氧和缺氧环境,分别促进好氧硝化和缺氧反硝化作用。在水力停留时间为3 d的情况下,间歇曝气潜流人工湿地系统对氨氮、总氮和COD的去除率分别可达到98.0%、87.6%和96.3%,较常规潜流人工湿地系统分别提高了74.1%、56.4%和18.1%,实现了氨氮、总氮和COD的同步高效去除。     

2种人工湿地的水力停留时间及净化效果

以复合垂直流人工湿地(IVCW)和水平潜流人工湿地(HSCW)为研究对象,研究了2种湿地运行的季节性最佳水力停留时间(HRT)参数,并监测了2种湿地在最佳HRT参数下运行时对污水的净化效果。结果显示:(1)在IVCW中,最佳HRT在春、秋季为8～10 h;夏季为6 h;冬季为12 h。在HSCW中,最佳HRT在春、秋季为10～12 h;夏季为6～8h;冬季为24～36 h。(2)2种湿地对COD的去除率均无显著的季节性差异;湿地进水中NH4+-N/TN比值与TN去除率显著负相关;不同季节下IVCW对TN的去除效果均高于HSCW。(3)水温对TN、TP去除率的影响在IVCW中比HSCW中的明显;水温高时,2种湿地中的TN去除率较高,IVCW中的TP去除率也较高,但HSCW中的TP去除率则较低,它们间均未达到显著的相关性。     

Nitrogen transformations and balance in constructed wetlands for slightly polluted river water treatment using different macrophytes

Nitrogen removal processing in different constructed wetlands treating different kinds of wastewater often varies, and the contribution to nitrogen removal by various pathways remains unclear. In this study, the seasonal nitrogen removal and transformations as well as nitrogen balance in wetland microcosms treating slightly polluted river water was investigated. The results showed that the average total nitrogen removal rates varied in different seasons. According to the mass balance approach, plant uptake removed 8.4–34.3 % of the total nitrogen input, while sediment storage and N₂O emission contributed 20.5–34.4 % and 0.6–1.9 % of nitrogen removal, respectively. However, the percentage of other nitrogen loss such as N₂ emission due to nitrification and denitrification was estimated to be 2.0–23.5 %. The results indicated that plant uptake and sediment storage were the key factors limiting nitrogen removal besides microbial processes in surface constructed wetland for treating slightly polluted river water.     

人工湿地处理城市污水启动期运行特性

选取4种植物(鸢尾、香蒲、麦冬和美人蕉)和3种基质(炉渣、沸石和砾石),通过植物和基质的不同组合构建了7组潜流型人工湿地,研究不同植物、相同基质及不同基质、相同植物条件下,湿地处理城市污水的启动期运行特性。结果表明,对COD去除率,砾石>炉渣>沸石,美人蕉>鸢尾>香蒲>麦冬;对TN去除率,沸石>砾石>炉渣,美人蕉>香蒲>麦冬>鸢尾;对NH4+-N去除率,沸石>砾石>炉渣,香蒲>美人蕉>麦冬>鸢尾;对TP去除率,炉渣>砾石>沸石,香蒲>美人蕉>鸢尾>麦冬。植物种植前,炉渣、沸石和砾石不同基质湿地的COD去除率没有明显差异;在TN和NH4+-N的去除上,沸石远优于炉渣和砾石。植物种植后,3种基质的TP去除率在10.75%左右。鸢尾、麦冬和美人蕉3种植物湿地的COD去除率随运行历程呈上升趋势,而香蒲由于生长状况不佳,去除率呈下降趋势。美人蕉湿地TN去除率较其它3种植物湿地高,各植物湿地NH4+-N去除率差异不显著。4种植物湿地TP去除率在9.24%左右。     

菖蒲和空心菜在处理微污染河水潜流人工湿地中的应用

为了探讨修复微污染河水的潜流湿地中植物对污染物去除效果的影响及其生长变化,在野外条件下构建2座分别栽种菖蒲和空心菜的水平潜流人工湿地,并以未栽种植物的湿地作空白。分析了湿地中污染物的去除效果,考察了湿地中植物的生物量、根系活力和氮磷含量的变化。植物湿地中污染物净化效果优于空白湿地,菖蒲和空心菜湿地对氨氮(NH+4-N)、总氮(TN)、总磷(TP)和高锰酸盐指数(CODMn)的平均去除率分别为61.1%和57.5%,31.5%和39.7%,24.7%和25.5%,20.4%和20.7%。实验结果表明,湿地中菖蒲的根系鲜重是空心菜的4.2倍,但其根系活力低于空心菜。2种植物均可在湿地中正常生长,但受湿地中营养盐浓度的限制性影响,移栽后的植物组织氮磷含量与移栽前相比下降了11.8%~20.3%。植物在净化微污染河水的潜流人工湿地中对N、P的去除起重要作用。     

管式反应器处理生活污水的效能

研发了一种基于射流曝气的管式反应设备,考察了负荷和DO对反应器处理效能的影响。实验结果表明,在温度为15℃、DO 6.0 mg/L、有机负荷为1.0 kg COD/(m3.d)、氮负荷为0.30 kg TN/(m3.d)、HRT为8 h的条件下,管式反应器可使生活污水的COD、NH4+-N及TN分别从335 mg/L、105 mg/L及110 mg/L降至43 mg/L、14 mg/L及18 mg/L,去除率分别为87%、86%和83%。DO对反应器脱氮效能影响显著,DO为6 mg/L时,能构建出同步硝化反硝化系统,NH4+-N和TN的去除率分别为96.6%和86.7%。     

曝气对潜流人工湿地污染物沿程降解规律的影响

通过构建曝气及未曝气潜流人工湿地小试实验系统,研究曝气对人工湿地床体中污染物沿程变化规律的影响。实验结果表明,曝气对污染物沿程降解规律的影响与污染物种类有关,在净化COD和氨氮时,曝气人工湿地污染物主要以水平推流式降解为主,未曝气系统床体中则出现分层现象,深度为40 cm以上的床体区域中污染物以水平推流式降解为主,40 cm以下区域则以垂直梯度降解方式为主。对于磷来说,两对比系统均以水平推流降解方式为主,但不同深度上的降解速率有所差异,曝气系统30~50 cm的床体中间层降解速率较快,而未曝气系统50 cm以下的床体底层降解速率较快。将对比系统总体净化效果进一步比较发现,对于COD的去除来说,温度的影响大些,而对于氨氮和TP的去除来说,曝气的影响则更为显著。     

低曝气下PAC强化SBR工艺同步脱氮除磷

采用序批式反应器(SBR)处理模拟生活污水,研究不同曝气量(30、24、18和12 L/h)下活性污泥同步脱氮除磷规律,并在最佳曝气量下,比较了粉末活性炭-序批式反应器(PAC-SBR)和SBR的脱氮除磷效率,分析了低曝气下PAC-SBR的运行特性和优越性。实验结果表明,当曝气量为24 L/h时,SBR内出水效果较好,其COD、TN和TP的平均去除率分别可以达到90.02%、81.13%和88.12%。在这个最佳曝气量下,PAC-SBR具有明显的优势,其COD、TN和TP的平均去除率均高于SBR,并且PAC-SBR具有较好的污泥沉降性能和较高的活性污泥浓度。在PAC-SBR中,活性污泥以PAC作为微生物载体强化了生物降解效果,并改善了低曝气下污泥絮体的结构,促使反应器内先后形成缺氧-厌氧-微氧/缺氧-缺氧的环境,利于同步硝化反硝化和反硝化聚磷,提高了PAC-SBR的同步脱氮除磷效率。     

潜流人工湿地对微污染河水的净化效果

为了探讨潜流人工湿地对微污染河水的净化效果,在野外条件下构建潜流人工湿地,分析了湿地中pH、氧化还原电位(ORP)和DO的进出水变化,考察了湿地中污染物的净化效果,探讨了温度对湿地净化效果的影响。各湿地进、出水DO浓度相差不大;除美人蕉湿地外,其余湿地出水pH较进水变化较小;植物湿地出水ORP较进水均有所增大。植物湿地对污染物的去除效果均优于空白湿地,且随着气温的升高,NH4+-N、TN和CODMn的去除率逐渐增加,去除率分别可达90%、50%和20%。TP去除率却未随温度发生明显变化,始终波动在30%～60%之间。相关性分析结果表明湿地中NH4+-N和TN的去除率与温度相关,较低的有机物浓度造成CODMn的去除率与温度相关性差,由于湿地对磷的去除主要以颗粒态磷(PP)为主,TP的去除与温度不相关。     

Alternative solid carbon source from dried attached-growth biomass for nitrogen removal enhancement in intermittently aerated moving bed sequencing batch reactor

The feasibility of using dried attached-growth biomass from the polyurethane (PU) foam cubes as a solid carbon source to enhance the denitrification process in the intermittently aerated moving bed sequencing batch reactor (IA-MBSBR) during the treatment of low COD/N containing wastewater was investigated. By packing the IA-MBSBR with 8 % (v/v) of 8-mL PU foam cubes saturated with dried attached-growth biomass, total nitrogen removal efficiency of 80 % could be achieved for 10 consecutive cycles of operation when the intermittent aeration strategy of consecutive 1 h of aeration followed by 2 h of non-aeration period during the REACT period of the IA-MBSBR was adopted. Negligible release of ammonium nitrogen (NH₄ ⁺–N) and slow-release of COD from the dried biomass would ensure that the use of this solid carbon source would not further burden the treatment system. The slow-releasing COD was found to have no effect in promoting the assimilation process and would also allow the carbon source to be used for many cycles of operation. The ‘carbon-spent’ PU foam cubes could be reused by merely drying at 60 °C at the end of the operational mode. Thus, the dried attached-growth biomass formed on the PU foam cubes could be exploited as an alternative solid carbon source for the enhancement of denitrification process in the IA-MBSBR.     

垂直流人工花卉湿地模拟系统净化污水的效果

通过在垂直流模拟人工土柱上种植不同的花卉植物，研究了垂直流花卉人工湿地对污水COD、BOD5、TN和TP的净化效果的影响。结果表明，所选用的5种陆生花卉，甚至鲜切花卉对化粪池污水有比较好的净化效果，它们对BOD5的去除率可达到92．04％以上，对TP的去除率甚至可达到97．77％以上。而且种植花卉植物的人工湿地出水水质要好于不种植物的对照湿地系统。     

高速泳动床对村镇微污染水体的预处理效果

利用高速泳动床反应器作为预处理装置处理村镇微污染水体,出水进入组合人工湿地。结果表明,实验阶段高速泳动床在HRT为1.2 h时,尽管泳动床进水各污染物浓度较低,但反应器对COD、TN和TP仍具有较明显(P<0.05)的去除效果,平均去除率分别为11.3%、14.6%和25.8%。高速泳动床反应器对氨氮去除效果尤为明显,去除率达到46.9%。此外,高速泳动床反应器内硝化作用较强,出水中硝态氮含量平均增加率为45.5%,弥补了后续人工湿地硝化作用不强、除氨氮效果不佳的缺点。     

垂直流人工花卉湿地模拟系统净化污水的效果

通过在垂直流模拟人工土柱上种植不同的花卉植物,研究了垂直流花卉人工湿地对污水COD、BOD5、TN和TP的净化效果的影响.结果表明,所选用的5种陆生花卉,甚至鲜切花卉对化粪池污水有比较好的净化效果,它们对BOD5的去除率可达到92.04%以上,对TP的去除率甚至可达到97.77%以上.而且种植花卉植物的人工湿地出水水质要好于不种植物的对照湿地系统.     

竹制填料生物接触氧化工艺处理污染河水简

针对受污染的湖溪河水质特征,以传统弹性塑料填料做对比,研究以竹球和竹丝为填料的生物接触氧化工艺,考察填料的挂膜时间、生物量和污水处理效果;确定连续曝气和间歇曝气时反应器的最优运行工况：连续曝气时为HRT=7.5 h,DO=3 mg/L;间歇曝气时为厌氧1.2 h、好氧6.3 h交替运行。实验结果表明,与弹性塑料填料相比,竹制填料挂膜速度快,竹球填料的水处理效果最好;连续曝气最优工况下竹球填料反应器中COD、TN、NH₃-N和TP的平均去除率分别为66.7%、47.9%、57.1%和30.6%;间歇曝气最优工况下竹球填料反应器中COD、TN、NH₃-N和TP的平均去除率分别64.08%、39.95%、60.7%和54.68%;竹制填料可替代传统的塑料填料作为生物接触氧化工艺的载体填料。     

Start-up of sequencing batch reactor with <Emphasis Type="Italic">Thiosphaera pantotropha</Emphasis> for treatment of high-strength nitrogenous wastewater and sludge characterization

Biological treatment of high-strength nitrogenous wastewater is challenging due to low growth rate of autotrophic nitrifiers. This study reports bioaugmentation of Thiosphaera pantotropha capable of simultaneously performing heterotrophic nitrification and aerobic denitrification (SND) in sequencing batch reactors (SBRs). SBRs fed with 1:1 organic-nitrogen (N) and NH₄ ⁺-N were started up with activated sludge and T. pantotropha by gradual increase in N concentration. Sludge bulking problems initially observed could be overcome through improved aeration and mixing and change in carbon source. N removal decreased with increase in initial nitrogen concentration, and only 50–60 % removal could be achieved at the highest N concentration of 1000 mg L^?1 at 12-h cycle time. SND accounted for 28 % nitrogen loss. Reducing the settling time to 5–10 min and addition of divalent metal ions gradually improved the settling characteristics of sludge. Sludge aggregates of 0.05–0.2 mm diameter, much smaller than typical aerobic granules, were formed and progressive increase in settling velocity, specific gravity, Ca²⁺, Mg²⁺, protein, and polysaccharides was observed over time. Granulation facilitated total nitrogen (TN) removal at a constant rate over the entire 12-h cycle and thus increased TN removal up to 70 %. Concentrations of NO₂ ^?-N and NO₃ ^?-N were consistently low indicating effective denitrification. Nitrogen removal was possibly limited by urea hydrolysis/nitrification. Presence of T. pantotropha in the SBRs was confirmed through biochemical tests and 16S rDNA analysis.     

问歇曝气周期对低C/N比污水生物脱氮的影响

研究了间歇曝气生物脱氮工艺中,曝气周期和污水的c/N比对脱氮效率的影响,以及氧化还原电位(ORP)变化规律.中试试验结果表明,TN污泥负荷为0.05 kg/(kg MLVSS.d)时,间歇曝气系统的硝化反应所需曝气时间与总反应时间比至少要在0.5以上,一周期内搅拌时间不宜超过1 h;反硝化过程中难以找到ORP曲线突变点,因此,在低c/N比污水生物脱氮中ORP难以作为工程控制参数;由于原水的碳氮比太低,TN去除率只有35%～40%左右,为提高脱氮效率有必要投入外加碳源.     

复合型人工湿地脱氮效能及其水力负荷影响规律

复合型人工湿地越来越多地被应用在面源污染管理中。不同类型的人工湿地对氮素的去除机理和去除性能是不同的。氮素在湿地生态系统中的去除受多种因素的影响和制约,不同的研究中氮素的去除效率变化较大。通过对韩国西部一复合型人工湿地中氮素的去除能力研究,分析了氮素的去除效率以及水力负荷对去除性能的影响,进而分析了人工湿地去除氮素的主要机理。结果表明,氨氮（NH＋4-N）、硝酸盐氮（NO-3-N）、凯式氮（TKN）和总氮（TN）的平均去除效率分别为13%、29%、35.3和26%。其中有机氮的去除是该复合型人工湿地中氮素去除的主要原因。水力负荷和先行干期天数对氮素的去除能力有一定影响。较长的先行干期天数和较低水力负荷可以提高氮素的去除效率。