【作者】 李昂；

【导师】 张雁秋；

【作者基本信息】 中国矿业大学 ， 环境工程， 2010， 博士

【摘要】 低碳源城市废水中的有机物较少,碳、氮与碳、磷的浓度比例小,使得反硝化菌和聚磷菌(phosphate accumulating organisms,即PAOs)之间对碳源的需求矛盾凸显,大部分城市污水处理厂的现有生物工艺很难满足高效除磷脱氮对碳源的要求,导致外排水中氮磷浓度超标,有效处理低有机物浓度、高氮磷含量的污水对传统生物除磷脱氮工艺而言成为极大的挑战。因此,进行此类污水的达标治理成为当前环保界所面临的行业性难题,也是目前的研究热点之一。本论文的研究工艺为污泥吸附除磷脱氮工艺,是基于污泥吸附特性提出的一种碳源需求量低的活性污泥法工艺,采用污泥吸附+厌氧+多级好氧/缺氧的运行方式。回流污泥和进水同时进入污泥吸附池,利用活性污泥的吸附性能,将进水中的部分CODC“r贮存”在污泥中,吸附后污泥进入厌氧段释磷,污泥浓度较高,厌氧释磷时间缩短;上清液分多点配入多级好氧/缺氧段,提高厌氧池以及整个处理系统的平均污泥浓度,促进PAOs、硝化菌、反硝化菌等目的菌群的增殖优势;进水点设置在缺氧段,为反硝化菌提供有机碳源;同时多级好氧缺氧的运行方式,使得硝化产物随即在缺氧段被消耗,避免对硝化和吸磷过程产生抑制作用。本论文分别从活性污泥吸附有机物的特性和PAOs的厌氧释磷机理出发,提出了污泥吸附模型和一种新的厌氧释磷模型,并通过实验研究与数据拟合分别对模型进行分析。利用模型和实验,研究了污泥吸附除磷脱氮工艺的运行参数,考察了污泥吸附除磷脱氮工艺的除磷脱氮能力,并分析了工艺系统中活性污泥的生物相和微生物菌群。主要研究成果如下:(1)提出了污泥吸附模型S t= S 0’ e-kT。其中,S0 ’为0时刻污水中的CODCr浓度,单位mg/L;k为污泥对污水中CODCr的吸附速率常数,与污水中的有机物种类、污泥浓度、污泥特性等因素有关,单位min-1。模型分析表明,污泥浓度越高、污泥的吸附效果越好;吸附时间越长,污泥的吸附性也得到加强,其中污泥浓度对吸附效果的影响比吸附时间对吸附效果的影响更明显。在一定范围内,有机物浓度对污泥吸附效果的影响不明显。通过污泥吸附实验,进行了污泥吸附模型的拟合,结果表明该模型能较好地描述不同污泥浓度条件下的污泥对有机物的吸附过程。(2)提出了一种新的厌氧释磷模型/[1 ( 0 ) / 0]其中, P0为0时刻系统内的TP浓度,单位mg/L; Pm为最大可释磷质量浓度,单位mg/L,与PAOs在污泥中的比例及其特性有关;K为PAOs厌氧释磷常数,单位L/(mg·min),与污泥浓度、有机物种类有关。通过厌氧释磷实验,进行了厌氧释磷模型的拟合,结果表明该模型能较好地描述不同污泥浓度条件下PAOs的厌氧释磷过程。厌氧释磷常数K受PAOs性状、污泥浓度、有机物种类以及可释磷量等因素的综合影响。实验条件下,厌氧释磷常数K值在0.01~0.02 L/(mg·min)范围内。(3)提出了“污泥吸附+厌氧+多级好氧/缺氧”新工艺。利用污泥吸附模型、厌氧释磷模型和实验手段,研究了污泥吸附除磷脱氮工艺的运行参数,运行参数定为:污泥吸附时间22 min,回流比0.8,好氧缺氧级数五级,上清液分配比例100%,溶解氧浓度2.5 mg/L~3.0 mg/L,污泥龄20 d(4)实验研究表明,污泥吸附除磷脱氮工艺系统具有较好的除磷脱氮能力,NH3-N、TN和TP去除率分别在91.7%、89.1%和87.2%左右。出水TP指标达到《国家城镇污水处理厂污染物排放标准》(GB18918-2002)一级B出水标准,其他水质指标均达到一级A出水标准。(5)污泥吸附除磷脱氮工艺实验系统中的沿程水质变化表明,系统中碳源分配较为合理、污泥浓度高、厌氧释磷效率高、缺氧区前后端存在NH3-N浓度差。在相同的实验运行参数条件下,污泥吸附除磷脱氮工艺的除磷脱氮效果优于传统A~2/O工艺的除磷脱氮效果。在出水水质(除TP外)达到《国家城镇污水处理厂污染物排放标准》(GB18918-2002)一级A出水标准的前提下,污泥吸附除磷脱氮工艺所能处理城市废水的最低碳氮比3。(6)通过污泥生物相观察和菌群选择培养,发现污泥吸附除磷脱氮工艺实验系统中具有较多的硝酸菌、亚硝酸菌和反硝化菌。与其他工艺相比,污泥吸附除磷脱氮工艺实验系统中的硝酸菌和反硝化菌数量较少,但亚硝酸菌较多。更多还原

【Abstract】 Municipal sewage with low carbon source increases the contradictions between denitrification and phosphorus release. In most municipal sewage treatment plants, effluent qualities could not reach the present criterions, because the carbon source is too little to meet the demanding of conventional biological treatment processes. How to achieve an effective treatment efficiency becomes a great problem in the treatment of municipal wastewater with low carbon source.In this paper, a nutrient removal process by sludge adsorption was employed for the treatment of municipal wastewater with low C/N ratio. The whole flow included sludge adsorption stage, anaerobic phosphorus release stage, as well as multiple aerobic nitrification and anoxic denitrification stage. Influent and returned sludge were pumped into sludge adsorption tank, in which influent CODCr was adsorped by activated sludge. After sedimentation, the adsorption sludge flowed into anaerobic zone for phosphorus release, and the adsorption supernatant was distributed to multiple aerobic and anoxic zones,. By doing so, the sludge concentration in the whole system could be increased, which was preferable for the proliferation of phosphate accumulating organisms (PAOs) and nitrifiers. Supernatant was distributed into anoxic zones to supply carbon source for denitrifiers. By the operation mode of multiple aerobic and anoxic reactions, NO3-N and NO2-N produced by nitrification were consumed in anoxic zones in time, avoiding its inhibitation on nitrification and aerobic phoshorus accumulation.Based on the mechanisms of sludge adsorption and phosphorus release, both the model on sludge adsorption and the model on phosphorus release were put forward and analyzed by experimental studies and data fitting. With the two models, sludge adsorption time and phosphorus release time were determined. The technical research on the experimental nutrient removal process by sludge adsorption was carried out in the conditions determined by experiments. With microbiological analysis, the sludge characteristics and floras were analyzed. The chief achievements are as follows.(1) Put forward the sludge adsorption model as S t= S 0’ e-kT, in which, S0 ’ was initial CODCr concentration, and k was the adsorption rate constant, which was related to sludge concentration, organics variety, and so on.From the model, the sludge adsorption effect was influenced by sludge concentration and adsorption time, with the sludge concentration as the chief factor. By fitting analysis, the sludge adsorption model could well describe the sludge adsorption process.(2) Put forward a new phosphorus release model as in which, Pm was maximum TP concentration in PAOs that could be released, P0 was initial TP concentration, and K was the phosphorus release rate constant. From the model, phosphorus release effect was influenced by sludge concentration, as well as release time and organics variety. High sludge concentration and long release time were beneficial for phosphorus release. By fitting analysis, the phoshorus release model could well describe the phosphorus release process. The phosphorus release rate constant was related to PAOs characteristics, sludge concentration, organics variety and TP concentration in PAOs that could be released. In the experimental conditions, the value of K was between 0.01~0.02 L/(mg·min).(3) Put forward a new activate sludge process for nutrient removal, which was the nutrient removal process by sludge adsorption. According to the sludge adsorption model and the phosphorus release model, the design parameters for the nutrient removal processs by sludge adsorption were determined, with the adsorption time 22 min, and anaerobic phosphorus release time 50 min. The sludge concentration was high to 10 g/L, so the phosphorus release time was greatly decreased.From the experimental results, the operation parameters were set as multiple aerobic/anoxic orders 5, adsorption time 22 min, returned sludge ratio 0.8, sludge age 20 d, and DO concentraion 2.5~3.0 mg/L in aerobic zones.(4) The results during the stable operation showed that with the nutrient removal process by sludge adsorption conditions, the removal rates of NH3-N, TN, and TP were 91.7%, 89.1%, and 87.2%, respectively. Effluent qualities (except TP meeting ClassⅠ-B criteria) could meet the“ClassⅠ-A criteria specified in Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant”(GB18918-2002).(5) In the whole experimental process system, carbon source was rationally utilized. There exsited significant NH3-N and CODCr concentration changes in the anoxic tanks, indicateing the occurrences of denitrification and ammonia oxidation. The phosphorus release amount of PAOs was high even in relatively short time.In the same operation conditions, the nutrient removal effect of the nutrient removal process by sludge adsorption was superior to that of traditional A~2/O process. On the premise of the effluent qualities (except TP meeting ClassⅠ-B criteria) meeting the“ClassⅠ-A criteria specified in Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant”after treatment by the nutrient removal process by sludge adsorption, the influent C/N ratio was 3 at least.(6) From the analysis and comparison on floras with other two treatment systems, there were less nitromonas and denitrifiers, but more nitrosomonas in the nutrient removal system by sludge adsorption.更多还原