【作者】 李淑兰；

【导师】 吴晓芙； 胡曰利； 刘英；

【作者基本信息】 中南林业科技大学 ， 生态学， 2007， 博士

【摘要】 影响我国废水处理的关键因素是成本问题,如何在保证处理效果的前提下大幅度降低建设和运行成本是发展新技术的首要目标和相关研究领域中的主要任务。人工湿地污水处理技术具有高效率、低能耗的特点,因此,近年来,在城镇污水处理中该技术倍受关注。同时,湿地技术的运用能更好地保护水环境,符合可持续发展的理念。本论文包含两个重点部分,一是城镇污水处理人工湿地(Constructed Wetland)组合模式的构建；二是人工湿地处理猪场厌氧废液的可行性研究。主要研究结果如下：(1)城镇污水处理人工湿地组合模式的构建。利用组合增效与生态平衡原理,建立了以生物调节池(A)、好氧反应池(B)、潜流湿地(C)、表流湿地(D)为基本单元的污水处理组合模式。试验结果表明：①组合模式具有系统稳定、运行高效的特点,并具有季节时效上的可调控功能和生态自适应功能。②与各处理单元相比,组合模式功能更强。A单元的功能主要强化对污水中有机污染物的降解；B单元的设计不仅对CODCr、TN、TP的去除有良好的表现,而且本单元培养的微生物可提高整个系统的生物降解能力；C单元中,部分蛭石和红壤通过有效吸收污水中的阴、阳离子,从而去除污水中N、P和各种有毒金属离子,以维持整个系统在冬季生命活动降低时仍有较好的去除效果；和C单元一样,D单元主要是靠植物积累和水生生物消化来稳定出水水质。③“1+1>2”,组合模式在去除TN、TP和CODCr方面,均可达到较好的效果。将不同处理技术与工艺进行组合,不仅可以提高系统处理效果,而且可增强系统稳定性,应对季节变化。④组合系统中引进的植物作用主要在于吸收转化污水中N和P。分析可知：a)不同植物体内N、P含量随植物器官和季节而变化。b)对大型挺水植物(即潜流湿地植物)而言,N、P主要分布在植株地上部分,这种分布便于通过收获植物去除系统中的N和P；浮水植物体内N、P含量高于挺水植物。c)各单元中植物吸收对N、P去除的贡献率与单元进水负荷有关,植物对N、P的吸收在低负荷系统中占明显优势；表流湿地单元中植物吸收对N、P去除的贡献率高于生物调节池和潜流湿地两个单元。⑤组合模式“三大效益”突出。本系统的用地面积小于2 m2/t,比达到相同处理水平的常规湿地用地面积缩小了2倍以上,因此相应提高了成本效益；该系统还具有高效低耗,节约土地资源等特点,被广泛地应用到城镇污水处理方面,能更好地保护水环境和水生生态系统。(2)城镇污水处理复合生物蛭石床潜流湿地的构建。以减少占地面积、避免床层淤塞、增大湿地含氧量和提高湿地植物的利用价值为设计理念,建立了一个以生物蛭石为填料的三级跌流式复合床。结果表明：①在较高水力负荷下(1.0m3/m2.d),仍保持了较好的处理效果,系统对污水中的各污染物的总去除率在65%以上,出水水质基本达到二级排放标准。②本试验中的四种湿地植物的管理难度由易到难排序为：香蒲<美人蕉<水葫芦<水蕹菜；单位面积生物量的月均增长量Am值从大到小顺序是：水葫芦>美人蕉>水蕹菜>香蒲。③三级跌流设计有利于提高生物蛭石床内污水中的DO值。当跌流高度大于45 cm时,单次跌流增氧量达0.57 mg/L以上,其中一级跌流过程的复氧率更是高达75%,这充分说明在潜流湿地污水处理系统中采用跌流设计来增加污水中溶解氧量的方法是可行的。(3)人工湿地处理猪场厌氧废液的可行性研究。本研究优先选取了适宜南方生长的、可用于猪场作饲料的空心菜、水稻和水葫芦三种植物,通过盆栽试验来处理猪场厌氧废液。结果表明：①各处理体系对CODcr的最终去除效果为：水葫芦>水稻>空心菜>对照；对TP的最终去除效果为：水葫芦>空心菜>水稻>对照系统；对NH4+-N的最终去除效果为：水葫芦>对照体系>水稻>空心菜；对TN的最终去除效果为：对照系统>空心菜>水稻>水葫芦。在对NH4+-N和TN的去除中,对照系统都有比较好的表现,原因是对照系统中没有植物对藻的抑制,后期藻的出现增强了对照系统对NH4+-N和TN的去除作用。②用饲料植物处理猪场厌氧废液,恢复和构建了一条物质、能量循环链,实现猪场污水的生态处理,达到真正意义上的污水“零”排放,建立了可行的猪场循环经济模式。更多还原

【Abstract】 Cost is the key factor affecting wastewater treatments in China, and therefore the development of new techniques with objectives to reduce construction and operation cost when at the same time enhance treatment efficiency has become the major task in related fields. Accounted for by their characteristics of high treatment efficiency and low energy consumption, constructed wetlands used for municipal sewage treatments have received great attention during recent years. Another important aspect of applying wetland techniques to protect water environment is that it meets the concept of sustainable development.The present thesis consists of two major parts:Part I is focused on the establishment of an integrated constructed wetland system used for municipal sewage treatment, and Part II is a feasibility study to investigate the potential use of constructed wetlands for treatment of wastewater from pig farms after pre-anaerobic treatment. The main results are summarized as follows:(1) Establishment of an integrated constructed wetland system for municipal sewage treatment. Based on the principle of effect amplification of combined treatment processes and the theory of ecological balance, the system was established with multiple functions. The integrated model consists of A) a biological regulation pool, B) an aerobic reactor, C) a sub-surface flow wetland and D) a surface flow wetland. Experimental results show that:①The system, with adjustable and controllable characters and ecological self-adaption mechanisms endurable to seasonal changes, is a relatively stable system with high treatment efficiency.②The system with multiple functions performs much better than any individual unit applied. Unit A is used for primary degradation of organic pollutants; unit B is designed not only for reduction of CODcr, TN and TP to lower levels but also for increase of the micro-organism concentration aiming at enhancement of the bio-digestion ability of the whole system; unit C is filled with proper portions of vermiculite and red soil, which, with high cation and anion adsorption capacities, can not only be used to remove N, P and different poisonous metal ions but also to maintain the treatment efficiency at high levels in winter seasons when the bio-activity of the integrated system is low.; and unit D, associated with Unit C, where plant and aquatic lives play important roles in uptake and bio-digestion, functions in stabilizing water quality before discharge.③With high removal rate of TN, TP and CODCr the integrated system gives a combined effect of "1+1>2". Combination of different treatment processes resulted in not only enhanced treatment efficiency but also strengthened sustainability of the system against seasonal changes.④Plant species introduced in the system play important roles in absorption and transformation of N and P. Results from analyses indicated that a) The content of N and P in plants also varies in plant tissues and as well with seasons. b) For large-sized terraneous plants (plants growing in subsurface wetland), the proportion of N and P is high in above-ground tissues, which can thus be readily removed by harvest. Phytoplanktonic plants (free-floating aquatic plants) have higher N and P content than that of terraneous plants. c) The contribution ratio of plant uptake to N and P removal is related to the influent load of the wastewater. Plant uptake of N and P is higher in lower influent-load system. The contribution ratio of plant uptake in surface flow wetland to N and P removal is thus greater than that in biological regulating pool and subsurface flow wetland.⑤Integrated system yields "three beneficial effects". The land use of the system is less than 2 m2/t, which is reduced by 2 times more than that of conventionally constructed wetland systems for achieving the same treatment efficiency, leading thus to a significant improvement in terms of cost-effectiveness. Accounted for by its satisfactory treatment efficiency, low energy consumption and reduced land use area, the established model can be well applied as a municipal sewage treatment system in protection of water environment and conservation of aquatic ecosystems.(2) Establishment of a bio-vermiculite bed subsurface flow wetland. A three-stage terrace dropping-flow process using bio-vermiculite as bed fillers is established with purposes in design to reduce land use area, avoid bed silting, increase oxygen level and raise the use value of wetland plants. The results show that:①The optimal treatment efficiency can be obtained at relatively high hydraulic load (1.0 m3/m2.d). The total removal rate of the system for various pollutants in the sewage is greater than 65% and in general the effluent quality satisfies the GB discharge standard classⅡ.②For the four tested plant species, the degree of facilitation in management follows the order:Typha latifolia L.<Canna indica Linn<Eichhornia crassipes (Mart.) Solms< Pomoea aquatica Forsk; the growth rate (bio-mass/month/unit area) is in turn:Eichhornia crassipes (Mart.) Solms> Canna indica Linn> Pomoea aquatica Forsk> Typha latifolia L.③The three-stage terrace dropping-flow process increases the DO level in the bio-vermiculite-bed layers. With a falling height higher than 45 cm, the oxygen concentration in a single water drop is higher than 0.57 mg/L and the oxygen recovery rate of the one-stage drop reaches 75%, indicating that the designed process is effective in improving the oxygen condition in the subsurface flow wetland system.(3) Feasibility study on potential use of constructed wetlands for treatment of liquid waste from pig farms after pre-anaerobic treatment. Three selected plant species, Pomoea aquatica Forsk, Oryza sativa and Eichhornia crassipes (Mart.) Solms are the popular ones growing in the south areas widely used as folders in hoggeries. Pot experiments were conducted to test the effect of these plant species for treatment of liquid waste from rural pig farms:①The order of treatment efficiency in terms of removal rate for CODCr is:Eichhornia crassipes (Mart.) Solms>Oryza sativa>Pomoea aquatica Forsk>control; that for TP is:Eichhornia crassipes (Mart.) Solms>Pomoea aquatica Forsk>Oryza sativa>control; for NH4+-N:Eichhornia crassipes (Mart.) Solms>control>Oryza sativa> Pomoea aquatica Forsk; and for TN:control> Pomoea aquatica Forsk> Oryza sativa> Eichhornia crassipes (Mart.) Solms. The removal rate of NH4+-N and TN is relatively high in the control pot and the reason is that in the pot where there is no inhibiting effect of plants on algae growth, high amounts of algae emerge in the later phase period and raise thus the removal rate of NH4+-N and TN to higher levels.②As a circulation economy mode by applying this ecological treatment method using folder plants to treat liquid wastes from pig farms, a bio-mass/energy circulation chain is established and the final goal of this trial is to obtain substantial "zero" discharge under the condition that high economic benefit is further ensured.更多还原