【作者】 李亚强；

【导师】 崔福义； 赵庆良；

【作者基本信息】 哈尔滨工业大学 ， 市政工程， 2008， 博士

【摘要】 我国污水处理多采用二级生化处理工艺,一次性投资大、运行费用高、建设周期长、占地面积大,为了探寻一条简洁灵活、基建省、运行费用低、且能适于中小城镇污水处理的工艺流程,本课题提出“混凝-人工湿地”处理工艺。为减少混凝药剂费用,实验以当地电厂固体废弃物——粉煤灰为原料,采用酸溶法制备粉煤灰混凝剂并应用于混凝单元,混凝出水再经过模拟潜流人工湿地进一步处理。同时,将酸溶粉煤灰得到的Al、Fe盐溶液通过慢速滴碱法研制出了聚合硫酸铝铁（PAFS）,应用于工业废水的处理。酸溶反应温度的提高能协同酸浸液浓度的增加显著提高粉煤灰中的铝铁溶出性能。常压下沸腾条件直接酸溶,可使粉煤灰中Al、Fe溶出率达到10%、33%以上,混凝剂中含Al₂（SO₄）₃ 19.3g/L、Fe₂（SO₄）₃ 7.5g/L ;在4.0ml/L投加量下处理污水的效果和市售混凝剂相当,但产泥量较大,每处理1m3污水,约有6kg残留粉煤灰微粒成为污泥。添加助溶剂并没有改善粉煤灰的酸溶活性,而和纯碱高温焙烧后,Al的溶出性提高。100g粉煤灰与6g的Na₂CO₃混匀后在805℃下焙烧1h,产物冷却粉碎后在沸腾回流条件下与4mol/L的H₂SO₄反应0.5h、余温冷却0.5h,即得到粉煤灰混凝剂,其中含Al₂（SO₄）₃ 32.7g/L、Fe₂（SO₄）₃ 7.1g/L;处理生活污水的投量为1ml/L时,处理效果明显优于相同投量下的市售混凝剂,COD、SS和TP的去除率分别达到64%、93%和91%,剩余SS、TP已经达到《城镇污水处理厂污染物排放标准（GB 18918-2002）》的一级B标准。对于PAFS的制备,考查了Al/Fe摩尔比、Na₂CO₃浓度、滴定终点的pH值、Al+Fe的总浓度、碱化剂种类等因素对产品混凝性能的影响,确定了最佳合成条件为100g/L的Na₂CO₃溶液慢速滴定溶出液至pH=1.1¹.2左右。样品制备时pH值越大,[Al,Fe]_a越少,[Al+Fe]_b和[Al+Fe]_c增加。最佳条件下获得的PAFS,其中[Al,Fe]_a占57.06%,[Al+Fe]_b占5.58%,[Al+Fe]_c占37.36%。随着时间的延长,样品的pH值有下降的趋势,结合Ferron比色法测定的形态变化结果,这是熟化过程中低聚物分子与游离OH-络合生成较高聚合度分子所致。PAFS中既有以羟基桥联的铁的聚合物,也有以羟基桥联的铝的聚合物。PAFS的烧杯实验结果显示,处理乳品废水的效果优于PAC,并且用量较少。适宜pH值范围为6⁹,静沉15min即可达到COD去除率63.9%,SS去除率94.4%。潜流人工湿地处理混凝预处理后的生活污水,在0.03⁰.10m³/（m²·d）的水力负荷下,进水COD负荷为5.62¹8.11g/（m2·d） ,水力停留时间6.73¹.95d,菖蒲和美人蕉湿地对COD的去除率为64%⁷7%,出水COD小于60mg/L,满足《城镇污水处理厂污染物排放标准（GB 18918-2002）》一级B标准。两级湿地串联运行可提高氨氮去除效率;在0.05m³/（m²·d）水力负荷下,进水氨氮负荷为2.156g/（m²·d）,水力停留时间3.97d,出水氨氮和TN分别为40.46mg/L和46.80mg/L,去除率分别达到11.97%和15.44%。进水TP浓度低时,砾石床潜流人工湿地存在基质释放P现象;进水TP约0.3⁰.5mg/L,而出水TP浓度约为1mg/L,但仍远低于《城镇污水处理厂污染物排放标准（GB 18918-2002）》二级标准。更多还原

【Abstract】 The secondary biochemical treatment processes were mostly adopted in China to treat municipal wastewater. However, because of their high primary investment and operating cost, long construction period and large floor area, a new flexible wastewater treatment process, named combined chemically enhanced primary treatment （CEPT）-constructed wetlands treatment system, was presented in this study, aiming at the development of an effective process with less capital investment and operating cost available in medium and small cities. To reduce the chemical dosage cost for the CEPT process, fly ash （FA） produced from a local power plant was firstly utilized to develop an efficient compound coagulant. The effluent from wastewater coagulation unit was then applied to feed the designed subsurface-flow constructed wetland （SSFCW） to further remove the remained pollutants. Meanwhile, a Na₂CO₃ solution was slowly added to the acid leaching fly ash solution to prepare the polyaluminum ferric sulfate（PAFS）, which was applied to coagulation of industrial wastewater.Cooperating with acid leachant concentration increasing, the enhancement of leaching temperature could greatly promote aluminum and ferrum leaching from FA. Reacting at boiling temperature under atmospheric pressure, the converting efficiencies of Al and Fe could achieve 10% and 33%,respectively. Effective composition of prepared fly ash coagulant were 19.3g/L Al₂（SO₄）₃ and 7.5g/L Fe₂（SO₄）₃. When fly ash coagulant was dosed at a rate of 4.0ml/L, sewage treatment effect was equivalent with that of commercial coagulant. However, the volume of sludge was still large, since 6kg fly ash particles would turn into chemical sludge when disposing per cubic metre sewage. The addition of Cl- or F- to fly ash didn’t improve acid leachability. Acid leachability of Al was improved after FA roasting with Na₂CO₃ at high temperature. According to mass ratio of Na₂CO₃ to FA 0.06, roast the mixture at 805℃for 1 h, then leach the clinker by 4 mol/L （[H⁺]） sulfuric acid at boiling temperature for 0.5h with the water vapor condensed. Being cooled, complex coagulant was obtained, which contained Al₂（SO₄）₃ of 32.7g/L and Fe₂（SO₄）₃ of 7.1 g/L. When this complex coagulant was dosed at a rate of 1ml/L, sewage treatment effect was remarkably superior to that of commercial coagulant with equal dosage, and the removal rates of COD, TP and SS could achieve more than 64%, 91% and 93%, respectively. The coagulation effluent TP and SS had already met the level IB of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant （GB18918-2002）.Through researches done on affection to coagulation performance of PAFS by checking various Al/Fe mol ratios, Na₂CO₃ concentration, pH of PAFS, Al+Fe concentration and types of base solution, it was proved a successful condition when Na₂CO₃ of 100g/L was slowly added to the acid solution until the pH of the acid solution raised to 1.1¹.2. The result showed that [Al,Fe]_a decreased as pH of PAFS raised while [Al+Fe]_b and [Al+Fe]_c increased. For PAFS with pH of 1.1¹.2, the [Al,Fe]_a species was the main component, 57.06%, with 5.58% of [Al+Fe]_b and 37.36% of [Al+Fe]_c. The change of pH of PAFS with aging time to a lower value was in agreement with the transformation of Al and Fe species of oligomers to high polymers. PAFS was composed of OH-Al complexes and OH-Fe complexes.PAFS had shown a high coagulation effect, superior to that of PAC for dairy wastewater treatment at the same dosage. The optimum coagulation pH range of PAFS is 6⁹. After sedimentation period of 15min, removal efficiencies of COD and SS by this type of coagulant reached 63.9% and 94.4%, respectively.When the coagulation effluent was further treated in the following SSFCW system with hydraulic loading 0.03⁰.10m³/（m²·d）, COD loading 5.62¹8.11g/（m²·d）, hydraulic retention time（HRT） 6.73¹.95d,COD could be removed up to 64%⁷7% with the final effluent COD less than 60 mg/L, which met the level IB of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant （GB18918-2002）. Wetlands working in series could enhance ammonia nitrogen removal. With hydraulic loading 0.05m³/（m²·d）, ammonia nitrogen loading 2.156 g/（m²·d）, HRT 3.97d, effluent ammonia nitrogen was 40.46mg/L, with removal rate 11.97%, while total nitrogen（TN） removal rate was 15.44%, with effluent TN 46.80mg/L. In this lab-scale experiment, SSFCW system with gravel bed presented phosphorus release phenomena, with influent TP 0.3⁰.5mg/L while effluent TP about 1.0mg/L. However the effluent TP was still far below the levelⅡof the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant （GB18918-2002）.更多还原