【作者】 冯丽娟；

【导师】 徐向阳；

【作者基本信息】 浙江大学 ， 环境工程， 2013， 博士

【摘要】 太湖流域平原河网素有“鱼米之乡、丝绸之府”美誉,近年来随着城镇化快速发展和现代农业规模化集约化水平提升,环境水体污染问题日益突出,水源水质达标率低,饮用水安全形势严峻。20世纪90年代以来,太湖流域平原河网地区自来水厂逐渐在传统混凝-沉淀-消毒工艺前增设生物膜预处理单元,可明显改善水质降低后续处理负荷,但目前仍存在功能微生物增殖慢持留难、脱氮性能差、微量有机物去除能力有限及低温处理效果差等突出问题。为此,论文在解析杭嘉湖平原河网典型水源污染特征基础上,开展了原水生物膜预处理工艺启动、原水脱氮除碳以及农药类环境激素去除以及强化同步脱氮与农药类环境激素去除的新工艺研究,主要内容如下：1、为明晰杭嘉湖平原河网水源污染特征,系统调查了杭嘉湖平原河网典型水源有机物、氮磷等常规指标污染特征,应用SPE-GC/MS技术开发了多种农药类环境激素同步分析方法,开展了农业发达地区农药类环境激素污染现状、时空分布特征及风险评价研究。结果表明杭嘉湖平原河网水源以有机物、氮素污染为主,其质量浓度范围分别为7.4～17.5mgL-1(CODMn)和1.6～8.4mg L-1(TN),均不能达到《地表水环境质量标准》(GB3838-2002)Ⅲ类水质标准。其中,运河水系主要超标因子为CODMn、 NH4+-N和TN；苕溪水系河道型水源TN超标严重(以NO3--N为主),水库型水源TN(以NO3--N为主)和TP超标。各水源地有机物和氮素污染随季节变化明显,整体表现为冬春季节TN水平较高,而有机物污染夏秋季节较重。应用SPE-GC/MS技术重点开发了7大类21种典型农药类环境激素同步检测方法(4种有机氯类、4种有机磷类、6种拟虫菊酯类、2种酰胺类、2种苯胺类、2种氨基酸甲脂类、1种含氮杂环类),分析发现各水源地均存在农药类环境激素污染,目标污染物总和浓度为37.9～2948.9ng L-1,主要污染物为三氯杀螨醇、氯氰菊酯、毒死蜱、氰戊菊酯和2,4-滴。聚类分析表明不同时期不同地区水源农药类环境激素污染差异大小为：不同水系>季节变化>相同水系不同支流,其中苕溪水系污染水平总体低于运河水系；夏秋季节农药类环境激素水平高于冬春季节(与有机物污染季节变化规律一致)。风险评价结果表明,各水源地农药类环境激素健康风险水平在可接受范围,但其弓引起的高生态风险不容忽视。因此,杭嘉湖平原河网水源有机物、氮素与农药类环境激素等多种污染物强化去除工艺亟待研发。2、针对微污染环境功能微生物增长慢、挂膜周期长、处理效果不佳等问题,开展了生物膜预处理快速启动方式研究。从生物膜载体、接种方式、进水负荷等角度优化,构建了冬春季节不同载体和不同运行条件的生物膜预处理反应器,两月后各反应器均获得良好的NH4+-N和CODMn去除性能,平均去除率范围分别为84.4%-94.2%和69.7%-76.6%。其中弹性填料反应器NH4+-N和CODMn去除性能明显高于AquaMats(?)生态基反应器；分析挂膜前后生物膜内总细菌群落结构发现,弹性填料均于挂膜两周左右即富集到较稳定的细菌群落结构,快于AquaMats(?)载体。其中弹性填料富集生物膜优势菌以Pseudomonas、Sphaerotilus和Janthinobacterium为主,尤以有机物好氧降解菌Janthinobacterium较多,从而可获得较高的有机物去除性能；AquaMats(?)富集生物膜优势菌除以上三种菌外,还含有Corynebacterium aurimucosum等优势菌,好氧菌Janthinobacterium相对较少,推测与AquaMats(?)内含大量微孔结构有关。应用弹性填料结合闷曝排泥、流量递增启动方式可有效缩短系统氨氧化缓滞期,NH4+-N去除率提前一周达到50%以上,稳定时期NH4+-N(94.2%)和CODMn(76.6%)获得高效去除。生物膜微生物群落结构分析表明闷曝排泥挂膜结合流量递增的挂膜方式可减少异养细菌多样性,弹性填料反应器用此启动方式可于挂膜两周左右即获得稳定的氨氧化菌群结构,表明异养细菌多样性减少有利于快速富集到稳定的氨氧化菌群落结构,从而提前获得较高NH4+-N去除性能。测序结果显示生物膜成熟时氨氧化菌优势菌为Nitrosomonas和Nitrosospira.因此,以弹性填料为生物膜载体,结合闷曝排泥接种方式和流量递增进水模式,可快速富集到稳定的微生物群落结构,有效缩短氨氧化缓滞期,加快生物膜预处理单元快速稳定启动,并能获得高效氨氮和有机物去除性能。3、针对杭嘉湖平原河网水源有机物、氮素污染重且地区差异大等问题,开展了适于不同水质特征的原水强化脱氮除碳生物膜预处理工艺技术研发。针对较高C/N比原水水质,以提高生物系统内碳源有效利用率为目的,研究分段配水对生物膜预处理系统脱氮除碳性能与微生物群落结构的影响。结果发现以1：1流量分段配水后系统TN平均去除率可从29.5%±2.2%增至35.0%±2.7%,平均碳源有效利用率从0.199(mg mg-1)增至0.21(mg mg-1);微生物群落结构分析表明分段配水后反应器中后段填料生物膜菌群多样性明显提高,Hyphomicrobium、Pseudomonas、Pantoea等与氮素、有机物去除有关的功能菌得到富集,揭示了采用多点配水策略可一定程度上强化生物膜预处理过程碳源有效利用率和脱氮微生物富集。针对以氮素污染为主、低C/N比原水水质,开展了进水C/N比、HRT联合优化的原水强化脱氮除碳工艺研究。结果表明,系统脱氮氮性能与进水C/N比呈正相关,当C/N比大于3.7时出水NO3--N浓度低于1.0mg·L-1,微生物群落分析表明细菌多样性随着C/N比增加而有所提升。基于TOC和UV254的消毒副产物模型预测发现三卤甲烷产生量随进水C/N比增加亦呈现增长趋势。为同步控制出水有机物和氮素浓度,优选2.2为进水C/N比。以此为基础,调控HRT至18h,可获得最高碳源有效利用率和脱氮效率,出水NO3--N (0.88±0.03mg L-11)和TOC浓度(2.86±0.67mg L-1)均在较低水平,满足《生活饮用水卫生标准》(GB5749-2006).4、针对杭嘉湖平原河网水源地农药类环境激素污染生态风险高、生物去除研究缺乏等问题,开展了生物膜预处理工艺基质种类(氨氮、硝氮及有机物)、溶解氧水平等对微量农药类环境激素去除影响,探讨生物预处理脱氮与微量农药类环境激素去除相关性。以氯氰菊酯、毒死蜱为代表性农药类环境激素,进水浓度为微量水平(≈1μg L-1)。研究不同基质种类对农药类环境激素去除性能影响发现,好氧硝化阶段提高氨氮浓度,其增加的氨氮氧化量对微量氯氰菊酯、毒死蜱去除影响不显著,但外加碳源后氯氰菊酯和毒死蜱去除率分别从80.0±2.7%和68.4±0.8%上升到85.0±0.3%和75.1±3.9%,推测好氧条件微量农药类环境激素去除主要靠异养菌去除而非氨氧化自养菌；缺氧反硝化阶段提高硝氮浓度亦不能显著提升氯氰菊酯和毒死蜱去除率,但投加外碳源后反硝化完全,且氯氰菊酯和毒死蜱去除率分别从65.0±1.3%和32.9±5.7%增至77.9±1.6%和46.9±8.0%,可实现同步强化脱氮与农药类环境激素去除,原因在于外碳源投加可同步增强脱氮与农药类环境激素去除功能菌富集,如Methylovorus、 Hyphomicrobium、Thauera、Paracoccus等。因此,好氧条件农药类环境激素去除性能显著高于缺氧条件(P<0.05),为同时获得脱氮与农药类环境激素高效去除,建议生物膜预处理在提高有机物基质水平基础上采用好氧、缺氧组合工艺。5、基于前期研究结果,利用植物生物质作为固体碳源,开展了植物生物质投加强化脱氮与农药类环境激素同步去除工艺技术研究。以芦苇为代表性植物生物质,研究发现其分解过程营养物质前期一周释放迅速后期逐渐下降,有机物释放速度快于氮素,其中氮元素主要为氨态氮形式。应用芦苇营养物质释放特征,研究生物膜预处理系统快速启动技术。结合闷曝排泥法,分别投加芦苇0.4kg/m3和1.2kg/m3,发现两组反应器均于10d左右即可获得90%以上NH4+-N去除率；投加芦苇1.2kg/m3的反应器TN去除率亦于10d获得稳定高效去除(67.04±3.7%),而投加芦苇0.4kg/m3芦苇反应器延迟一周左右获得TN稳定去除(65.4±5.5%)；运行稳定时两组反应器出水TOC浓度均维持在较低水平(≈2.0mg L-1)。结果表明芦苇投加1.2kg/m3仅需10d即可启动A/O/A生物膜工艺,同时获得较好脱氮除碳效果。连续运行反应器4个月,系统TOC、NH4+-N去除性能无显著变化,系统高效稳定运行,TN去除在系统运行后期出现一定幅度下降。将反应器芦苇和弹性填料分开运行发现单种载体系统NH4+-N和TN去除率分别为36.3±6.1%、56.5±2.0%(仅含芦苇)和82.94±1.5%、40.34±7.3%(仅含弹性填料),表明芦苇载体富集的生物膜反硝化性能优于硝化性能,弹性填料富集的生物膜硝化性能优于反硝化性能,两种载体组合可获得高效硝化和反硝化效果。研究芦苇二次投加强化生物膜预处理工艺性能表明,通过二次投加芦苇2.4kg/m3(每天20g逐次投加),以均匀分布方式(UD)和非均匀分布方(NUD)式布设。芦苇二次投加后总氮可稳定维持75%以上高效去除2个月左右,且采用非均匀分布方式可获得较高的氨氮、总氮去除性能；芦苇二次投加后氯氰菊酯和毒死蜱去除率明显分别明显上升至80%、46.3%(UD)和79.7%、44.7%(NUD).表明芦苇二次投加可强化系统脱氮与农药类环境激素去除性能,且以非均匀分布方式为佳。为避免芦苇投加初期营养释放迅速使得系统短时间内出水有机物、氨氮浓度偏高问题,建议二次投加过程适当降低逐次投加量(<20g/d)。更多还原

【Abstract】 Hang-Jia-Hu plain is well known for the reputation of ’the land of fish and rice, the mansion of silk and satin’. In recent years, with the accelerating urbanization as well as the development of modern large-scale and intensive agriculture, the pollution of natural water, includng drinking source water, has become an important problem attracting more attention. Since1990s, the aerobic biofilm pre-treatment unit has been used as added to the traditional process of coagulation-sedimentation-disinfection in the waterworks in Hang-Jia-Hu plain. This modified process can obviously improve the water quality and reduce the subsequent processing load. However, there are still some problems need to be resolved, such as the slow growth rate of functional microbial community, the poor removal efficiencies of total nitrogen and trace toxic organics as well as the adverse effect of seasonal variation. Based on the investigation of typical pollution characteristics of drinking source water in Hang-Jia-Hu plain, the fast start up methods of biofilm reactor under low temperature, the enhancing removal of organics, nitrogen and endocrine-disrupting pesticides (EDPs) via biofilm pretreatment were studied. A new biofilm pretreatment process with plant biomass addition for multi-pollutants simultaneously removal was developed. The main contents are presented as follows:1) To ascertain the pollution characteristics of source water, the organic matter, nitrogen and phosphorus pollution characteristics of typical source water in Hang-Jia-Hu plain river network were systematical investigated. The levels, spatial and temporal distribution as well as the risk assessment of EDPs were studied based on SPE-GC/MS. Results showed that the major pollutants of source water in river network of Hang-Jia-Hu plain were organics and nitrogen compounds and the eutrophication is serious. The concentration ranges of CODMn and TN were7.44-17.52mg·L-1and1.62～8.35mg-L·1, respectively, exceeding the limit of class III in surface water quality standards (GB3838-2002). The major pollutants of source water from Canal Rivers were CODMm, NH4+-N and TN, while TN (mainly NO3--N) in Tiaoxi stream catchment was the main pollutant, but TN and TP pollution was significant in reservoirs. Temporal distribution characteristics demonstrated that the levels of organics and nitrogen obviously changed with seasonal variation, and nitrogen levels were much higher in winter-spring than that in other seasons, but an opposite situation was observed in the variation of organics.Simultaneous detection methods using SPE-GC/MS technology were developed for the detecting of7categories and21kinds of typical EDPs (four organochlorines, four organophosphoruss, six pyrethroidss, two amides, two anilines, two carbamates and one triazine). These results showed that EDPs were often detected in source water with a total concentration of37.9～2948.9ng L-1. The main EDPs were dicofol, cypermethrin. chlorpyrifos, fenvalerate and2,4-D. Cluster analysis obtained the differences order of EDPs pollution of different drainage> seasonal variation> different tributaries in the same drainage. The levels of EDPs pollution in Tiaoxi stream were much lower than those of Canal Rivers; EDPs levels in summer and fall were higher than those in winter and spring, which was consistent with the seasonal variation of organics. Risk assessment results showed that EDPs levels were in an acceptable range, which could not directly impair human’s health but could cause high ecological risk. The enhanced biofilm pretreatment process should be developed for the removal of multi-pollutants in source water.2) As to the problems of start-up of biofilm reactor under low temperature and low nutrients levels, a method for fast start up of biofilm pretreatment process was developed. Optimizing carriers, inoculation methods and influent loads, modified biofilm pretreatment reactors with different carriers and under different operating conditions were studied for the operation in winter-spring season. After two months-operation, the average removal efficiencies of NH4+-N and CODMn were84.4%-94.2%and69.7%-76.6%, respectively. The removal efficiencies of NH4+-N and CODMn with elastic filler were much higher than those with AquaMats(?). The analysis of bacterial community structure showed that the bacterial community structure of biofilms adhered to the elastic filler was stable within two weeks, which was fast than that on the AquaMats(?). The dominant bacteria of biofilm adhered to elastic filler were Pseudomonas, Sphaerotilus and Janthinobacterium. Janthinobacterium was aerobic bacteria in charge of degrading organics, which was more than other species adhered to elastic filler and assuring the high removal efficiency of organics. The dominant bacteria of biofilm adhered to AquaMats(?) carrier contained the dominant bacteria of Pseudomonas, Sphaerotilus, Janthinobacterium, and Corvnebacterium aurimucosum. However, the aerobic bacteria Janthinobacterium is less than that adhered to elastic filler, which may be related to the microporous structure of AquaMats(?) carrier.The lag period of ammonia oxidation could be effectively shortened using the elastic filler combined the method of discharging sediment and gradually increasing influent velocity, and the removal efficiency of NH4+-N reached above50%a week early. The analysis of bacterial community structure found that this method could reduce the heterotrophic bacterial diversity but facilitate the rapid enrichment of ammonia oxidizing bacteria, which is help to obtain a higher NH4+-N removal performance in advance. The ammonia oxidation autotrophic bacteria were stable in biofilm within two weeks. Sequencing analysis results showed that the dominant ammonia oxidizing bacteria in mature biofilm were Nitrosomonas and Nitrosospira. Therefore, using elastic filler as the carrier with the biofilm culturing methods of discharging sediment and gradually increasing influent velocity could effectively shorten the lag phase of ammonia oxidation, accelerate the startup of biofilm pre-treatment unit, and obtain high removal performances of ammonia nitrogen and organics.3) As to the serious pollution of organics and nitrogen and distinct regional differences of river network source water in Hang-Jia-Hu plain, the biofilm pretreatment processes for nitrogen and carbon removal in various water qualities were studied based on heterotrophic denitrification technology. For the treatment of raw water with a high C/N and improve the utilization of carbon source in biological systems, the effects of step-feeding process on the performance of biofilm pretreatment system for carbon and nitrogen removal and on the microbial community structure were examined. This result showed that the average TN removal effiency increased obviously from29.5±2.2%to35±2.7%by step-feeding process. The average effective utilization rate of carbon source increased from0.211to0.199(mg mg-1). Microbial community structure analysis indicated that the bacteria diversity of biofilm in the middle or back reactor increased. The functional bacteria of Hyphomicrobium and Pseudomonas, which were responsible for nitrogen and organics removal, enriched in rector. It was revealed that step-feeding process could strengthen biofilm pretreatment process, enhancing the utilization efficiency of carbon source and enrichment of denitrifying bacteria.For the treatment of raw water with serious nitrogen pollution and low C/N ratio, the biofilm pretreatment process by optimizing C/N ratio and HRT and adding external carbon source was studied. Results showed that the denitrification efficiencies were positively correlated to the C/N ratio. The effluent NO3--N concentrations were below1.0mg L-1when C/N ratios were more than3.7. The disinfection by-products forecast model based on TOC and UV254forecasted that the production of THMs increased with the increase of influent C/N ratios. For better controlling of effluent organics and nitrogen, the optimized C/N ratio of2.2was chosen. At the HRT of18h, the highest effective utilization rates of carbon source and removal efficiency of nitrogen source were obtained. And the low effluent concentration of NO3--N (0.88±0.03mg L-1) and TOC (2.86±0.67mg L-1) were obtained. The analysis of microbial community showed that the bacterial diversity increased with the increase of C/N ratio.4) The pollution of EDPs was notable in river network of Hang-Jia-Hu plain, but the study of biofilm pretreatment process for removing EDPs was lack. To resolve these problems, the influence of substrates (ammonia nitrogen, nitrate nitrogen and organics) and dissolved oxygen on the removal of trace EDPs in the biofilm pretreatment system was conducted. The correlation between the removal of nitrogen and the removal of trace EDPs was explored. The levels of cypermethrin and chlorpyrifos, the representative of EDPs, were trace (approximately1μg L-1).The study of the influence of various substrates on the removal of EDPs was conducted. These results showed that aerobic conditions improve the removal of ammonia nitrogen (complete nitrification but nearly no denitrification). The increased ammonia nitrogen oxidation could not significantly enhance the removal of trace cypermethrin and chlorpyrifos. However, the removal efficiency of cypermethrin and chlorpyrifos increased from80.0±2.7%and68.4±0.8%to85.0±0.3%and75.1±3.9%, respectively. We speculated that the removal of trace EDPs was mainly conducted by heterotrophic bacteria rather than ammonia oxidation autotrophic bacteria under aerobic conditions. Under anoxic conditions the nitrate nitrogen concentration increased but the removal efficiencies of cypermethrin and chlorpyrifos were not significantly improved. The complete denitrification was observed when adding external carbon source. The removal efficiencies of cypermethrin and chlorpyrifos increased from65.0±1.3%and32.9±5.7%to77.9±1.6%and46.9±8.0%, respectively.Simultaneous enhancing removal of nitrogen and EDPs was realized, this may be related to the fact that adding external carbon source can obviously enhance the enrichment of functional bacteria for removal of nitrogen and EDPs, such as Methylovorus, Hyphomicrobium, Thauera, Paracoccus, etc. Comparing with the removal performance of various EDPs at different dissolved oxygen levels, the removal performance under aerobic conditions is significantly better than that under anoxic conditions (P<0.05). In order to simultaneously remove nitrogen and EDPs, the combined aerobic and anoxic processes with the method of increasing organics level were recommended in biofilm pretreatment systems.5) Based on the previous studies achievement, biofilm process for simultaneous nitrogen and EDPs removal by adding solid carbon resource was carried out. Reed was selected as a representative solid carbon resource, and the decomposition process showed that the nutrients release rates of reed were fast in the initial period then slow down. The main nutrients of reed were organics and nitrogen compounds (mainly ammonia), and the release rate of nitrogen was much lower than that of organics. The nutrients release rates of reed were easily affected by environmental factors, including dissolve oxygen and biomass.The nutrients of reed would release in biofilm pretreatment system. Using this characteristic, a fast start up method of biofilm reactors was obtained. Biofilm reactors were started up with sediment discharge method, adding20g and60g reed respectively to two aeration A/O/A (anoxic/aerobic/anoxic) processes. It was found that the removal efficiencies of NH4+-N were stable up to90%after operating for10days; the removal efficiency of TN was stable at67.0±3.7%when60g reed was added, but the reactor adding20g reed delayed one week to obtain a TN removal efficiency of65.4±5.5%. The effluent TOC concentrations in both reactors were stable at a lower level of approximately2.0mg L-1. After further operation for four months, TOC and NH4+-N removal efficiencies were not improved significantly, and the removal efficiencies of TN were decreased from65.0±3.4%to54.6±2.9%After3months operation. However, the performance of both reactors was still much better than that in biofilm reactor without adding reed. Separately operating the systems with elastic filler or reeds only, the removal efficiency of NH4+-N (82.9±1.5%) in the system with elastic filler only was higher than that in the system with reeds only (36.3±6.1%), While the removal efficiency of TN (40.3±7.3%) was lower than that (56.5±2.0%) in system adding reeds only. The combination of reed and elastic filler could be help to achieve a good performance of nitrogen and organics removal.For further improving the performance of reed added biofilm process, another120g reed was added to the reactors using different distribution modes (uniform distribution and nonuniform distribution). Results showed that TN removal efficiencies were stable up to75%within two months using nonuniform distribution mode to add reed; cypermethrin and chlorpyrifos removal efficiencies were significantly increased to80%and46.3%, respectively using uniform distribution mode and increased to79.7%and44,7%, respectively using nonuniform distribution mode (P<0.05). It was proved that simultaneous nitrogen and EDPs removal was enhanced via secondary addition of reed, and nonuniform distribution mode was an attractive choice. Long-term performance and operation stability analysis showed that the removal efficiencies of TOC (74%), NK4+-N (90.7%), TN (55.0%), cypermethrin (87.1%) and chlorpyrifos (51.1%) were all still stable at high levels after operation for four months when the reeds were secondary added, which satisfied the standards of drinking water quality (GB5749-2006). To avoid the adverse effect of the quickly release of nutrition in the initial phase when reed was added, appropriate reed addition amount of less than20g/d was recommended.更多还原