復(fù)合垂直流—水平流人工濕地系統(tǒng)處理二級(jí)生化尾水的實(shí)驗(yàn)研究
發(fā)布時(shí)間：2018-07-25 20:08
【摘要】：我國(guó)污水處理廠二級(jí)尾水排放量大,且氮、磷濃度較高,對(duì)自凈能力有限或已受到污染的受納水體來(lái)說(shuō),排放的尾水中較高的氮、磷濃度仍會(huì)造成地表水污染和受納水體的富營(yíng)養(yǎng)化現(xiàn)象。尤其在我國(guó)西北干旱半干旱地區(qū),由于地域、氣候等區(qū)域性因素,大多數(shù)污水處理廠出水污染物濃度僅能達(dá)到《城鎮(zhèn)污水處理廠污染物排放標(biāo)準(zhǔn)》(GB18918-2002)中的一級(jí)B標(biāo)準(zhǔn),甚至超出該標(biāo)準(zhǔn)。另一方面,我國(guó)水資源呈現(xiàn)出總量多但人均占有量少、水環(huán)境污染嚴(yán)重和廢水排放逐年快速增長(zhǎng)的現(xiàn)狀,污水深度處理和尾水資源化利用成為降低受納水體的污染負(fù)荷和緩解水體的自凈壓力、推進(jìn)城市化建設(shè)進(jìn)程和解決城市缺水問(wèn)題的首要選擇。人工濕地系統(tǒng)以其投資及運(yùn)行成本低、運(yùn)行維護(hù)方便、去除氮磷能力強(qiáng)等特點(diǎn)而被廣泛應(yīng)用于各種水體治理,因此研究人工濕地系統(tǒng)對(duì)污水廠尾水的深度處理也具有重大意義。針對(duì)西北地區(qū)某些城鎮(zhèn)污水處理廠的實(shí)際出水水質(zhì)中有機(jī)物濃度低和氮、磷濃度相對(duì)較高的特點(diǎn),本實(shí)驗(yàn)以廢磚塊和頁(yè)巖陶粒為人工濕地的基質(zhì)填料,并將西北地區(qū)常見(jiàn)植物蘆葦和香蒲作為人工濕地的主要植物,在室外自然條件下構(gòu)建復(fù)合垂直流-水平潛流人工濕地小試裝置,研究了系統(tǒng)在啟動(dòng)階段、穩(wěn)定運(yùn)行階段和植物收割后對(duì)二級(jí)生化尾水中有機(jī)物(COD、BOD5)、氨氮(NH_4~+-N)、總氮(TN)及總磷(TP)等污染物的去除效果。同時(shí),為考察二級(jí)生化尾水中較高濃度的氮、磷對(duì)兩種濕地植物的影響程度,實(shí)驗(yàn)于植物移栽初期及收割前期分別檢測(cè)人工濕地系統(tǒng)下行流池、上行流池和水平流池中兩種濕地植物的生長(zhǎng)生理指標(biāo)和光合參數(shù),分析了濕地植物蘆葦和香蒲在處理二級(jí)生化尾水前后的生理生長(zhǎng)特性變化,最終得出了以下結(jié)論:(1)在實(shí)驗(yàn)的啟動(dòng)階段,隨著移栽的蘆葦和香蒲的逐漸成活生長(zhǎng),植物根系輸氧能力增強(qiáng),基質(zhì)內(nèi)好氧、兼氧、厭氧微生物數(shù)量逐漸增多,系統(tǒng)對(duì)COD、NH_4~+-N、TP的去除率由最初的52.94%、37.80%、53.51%分別上升至68.18%、76.61%、81.57%,此階段蘆葦和香蒲植株平均高度由移栽時(shí)的32cm、38cm增長(zhǎng)到68cm、63cm,復(fù)合垂直流濕地床(IVCW段)植物長(zhǎng)勢(shì)好于水平流濕地床(HF段)。(2)穩(wěn)定運(yùn)行階段濕地系統(tǒng)對(duì)NH_4~+-N、TN和TP的去除效果隨著水力負(fù)荷增大而減小,而對(duì)COD、BOD5的凈化效果受水力負(fù)荷影響較小。在0.15m3/(m2·d)的低水力負(fù)荷下,進(jìn)水NH_4~+-N、TN和TP濃度在8.40~14.81mg/L、11.02~18.97mg/L、0.81~1.53mg/L之間時(shí),復(fù)合垂直流-水平流人工濕地系統(tǒng)出水COD、BOD5和TP濃度分別低于《地表水環(huán)境質(zhì)量標(biāo)準(zhǔn)》(GB 3838-2002)中的Ⅰ類、Ⅳ類、Ⅲ類水質(zhì)標(biāo)準(zhǔn)限值,而出水NH_4~+-N、TN濃度雖未達(dá)到地表水環(huán)境質(zhì)量標(biāo)準(zhǔn),但已遠(yuǎn)遠(yuǎn)低于《城鎮(zhèn)污水處理廠污染物排放標(biāo)準(zhǔn)》(GB18918-2002)的一級(jí)A標(biāo)準(zhǔn)。(3)穩(wěn)定運(yùn)行階段復(fù)合垂直流-水平流人工濕地對(duì)COD、NH_4~+-N、TN和TP的去除負(fù)荷隨進(jìn)水負(fù)荷的增加而呈線性增加趨勢(shì),而且并未表現(xiàn)出減緩的趨勢(shì),表明復(fù)合垂直流-水平流人工濕地在本實(shí)驗(yàn)范圍內(nèi)還能承載更高的進(jìn)水污染負(fù)荷以充分發(fā)揮其納污去污能力。(4)在穩(wěn)定運(yùn)行階段,復(fù)合垂直流-水平流人工濕地系統(tǒng)在0.15m3/(m2·d)、0.25m3/(m2·d)、0.35m3/(m2·d)三種水力負(fù)荷條件下沿程COD、NH_4~+-N、TN和TP濃度呈現(xiàn)出先迅速降低、后緩慢下降的趨勢(shì),且濕地系統(tǒng)表層N、P的去除效率要高于中下層,尤其在復(fù)合垂直流濕地床下行流池進(jìn)水端表層0~30cm范圍內(nèi)污染物均有一個(gè)快速降解的過(guò)程。(5)不同植物對(duì)氮、磷等污染物的吸收富集能力存在一定差異,各濕地床植物吸氮量高于吸磷量,而且植物收割對(duì)氮的去除能力有明顯影響。因此,在實(shí)際應(yīng)用中應(yīng)根據(jù)耐污性強(qiáng)弱和氮磷吸收量的大小合理選擇和配置適宜于不同流程的濕地植物,同時(shí)還應(yīng)選擇適當(dāng)?shù)臅r(shí)機(jī)收割濕地植物以強(qiáng)化人工濕地的污染物凈化效果。(6)整個(gè)實(shí)驗(yàn)過(guò)程中,蘆葦和香蒲長(zhǎng)勢(shì)良好,植物葉片中丙二醛(MDA)和游離脯氨酸(Pro)含量隨濕地床污染物濃度升高而不同程度的增加,說(shuō)明兩種植物具有一定的自我防御能力,可以很好的適應(yīng)二級(jí)生化尾水中污染物的脅迫。另外,尾水處理前后兩種植物葉片凈光合速率(Pn)、氣孔導(dǎo)度(Gs)、胞間CO2濃度(Ci)隨復(fù)合垂直流-水平流人工濕地系統(tǒng)流程加長(zhǎng)而增大,表觀葉肉導(dǎo)度(AMC)、氣孔限制百分率(Ls)則相反,這表明二級(jí)生化尾水中適量的有機(jī)物、氮素、磷素等可以為香蒲和蘆葦提供一定的營(yíng)養(yǎng)物質(zhì)而使得植株光合作用能力增強(qiáng),進(jìn)一步證明實(shí)驗(yàn)選擇蘆葦和香蒲作為人工濕地植物處理尾水是合理可行的。(7)復(fù)合垂直流-水平流人工濕地系統(tǒng)在啟動(dòng)-穩(wěn)定運(yùn)行-植物收割后三個(gè)階段均可以有效削減進(jìn)水污染物負(fù)荷,適用于城市污水的深度處理,二級(jí)水平流濕地床在一級(jí)復(fù)合垂直流濕地床處理效率的基礎(chǔ)上可以提高15~25%。這表明選擇具有發(fā)達(dá)的根系及通氣組織、較強(qiáng)耐污能力的濕地植物和來(lái)源廣泛、疏松多孔、性質(zhì)穩(wěn)定的濕地基質(zhì)對(duì)構(gòu)建人工濕地強(qiáng)化去污效果具有重要的意義。
[Abstract]:The wastewater treatment plant of China has a large two level tail water discharge, high nitrogen and phosphorus concentration, higher nitrogen and phosphorus concentration in the tailor water discharged from the polluted water body with limited self purification capacity or polluted water. Regional factors, the concentration of effluent from most sewage treatment plants can only reach the first grade B standard in the pollutant discharge standard of urban sewage treatment plant (GB18918-2002), even beyond the standard. On the other hand, the water resources in our country show a large amount but less per capita, the pollution of water environment and the discharge of waste water are increasing rapidly year by year. The advanced treatment of sewage and utilization of tailwater resources have become the primary choice to reduce the pollution load of the received water and relieve the self purification pressure of the water body, promote the process of urbanization and solve the problem of water shortage in the city. It is applied to the treatment of various water bodies, so the study of the artificial wetland system is also of great significance to the depth treatment of the tail water of the sewage plant. In this paper, the waste brick and shale ceramsite are used as the matrix of the constructed wetland for the low concentration of organic matter and the relatively high concentration of nitrogen and phosphorus in the actual effluent quality of some municipal wastewater treatment plants in Northwest China. The common plant reeds and cattails in Northwest China were used as the main plants in the artificial wetland. Under the outdoor natural conditions, a compound vertical flow horizontal subsurface constructed wetland was constructed. The system was studied at the starting stage, the stable operation stage and the two grade biochemical tail water (COD, BOD5), and ammonia nitrogen (NH_4~+-N) after the plant harvest. The effect of total nitrogen (TN) and total phosphorus (TP) on the removal of pollutants. At the same time, in order to investigate the effect of nitrogen and phosphorus on the two kinds of wetland plants in the two grade biochemical tail water, the growth physiological index of two wetland plants in the artificial wetland system, the upstream pool and the horizontal flow pool were tested at the early stage of plant transplanting and the early harvest. The physiological characteristics of reeds and cattails of wetland plants and cattails were analyzed before and after the treatment of two grade biochemical tail water. The following conclusions were concluded: (1) in the starting stage of the experiment, with the gradual survival of reed and cattail, the oxygen transport capacity of plant roots increased, and the number of aerobic and anaerobic microbes in the substrate was increased. Gradually increasing, the removal rate of COD, NH_4~+-N and TP increased from 52.94%, 37.80%, 53.51% to 68.18%, 76.61%, 81.57% respectively. The average height of reeds and cattail plants from the transplanted 32cm, 38cm to 68cm, 63cm, and the compound vertical flow wetland bed (IVCW section) was better than the horizontal flow wetland bed (HF section). (2) stable operation order. The removal effect of the segment wetland system on NH_4~+-N, TN and TP decreases with the increase of hydraulic load, while the purification effect for COD, BOD5 is less affected by the hydraulic load. In the low hydraulic load of 0.15m3/ (M2 d), the influent is NH_4~+-N, TN and TP concentration is between the 8.40~14.81mg/L, the vertical flow and the horizontal flow. The concentration of COD, BOD5 and TP in the effluent of the ground system is lower than that of category I, type IV, and class III water quality standard in the environmental quality standard of surface water (GB 3838-2002), while the NH_4~+-N and TN concentration of the effluent has not reached the standard of surface water environmental quality, but it is far below the first grade A standard of the pollutant discharge standard of urban sewage treatment plant (GB18918-2002). (3) stability. The removal load of COD, NH_4~+-N, TN and TP of the composite vertical flow and horizontal flow constructed wetland in the fixed operation stage increases linearly with the increase of the influent load, and does not show a slow trend. It shows that the composite vertical flow horizontal flow constructed wetland can also carry the higher influent pollution load in this experiment. (4) in the stable operation stage, the compound vertical flow and horizontal flow constructed wetland system in 0.15m3/ (m2. D), 0.25m3/ (m2. D), 0.35m3/ (m2. D) under three kinds of hydraulic loads, the COD, NH_4~+-N, TN, and the concentration of TN and decreased slowly decline, and the removal efficiency of the wetland system is higher than that of the middle and lower levels. There is a rapid degradation process in the 0~30cm range of the surface layer of the influent end of the downflow pool of the compound vertical flow wetland. (5) there is a certain difference in the absorption and enrichment ability of different plants to nitrogen and phosphorus, and the uptake of nitrogen in the wetland bed plants is higher than that of the phosphorus uptake, and the plant harvesting has a significant influence on the removal of nitrogen. Therefore, in practical application, we should choose and configure wetland plants suitable for different processes according to the strength of the resistance to pollution and the amount of nitrogen and phosphorus absorption. At the same time, we should choose the appropriate time to harvest the wetland plants to strengthen the purification effect of the pollutants in the constructed wetland. (6) in the whole experiment, the reed and the cattail are in good growing trend and in the leaves of plants. The content of malondialdehyde (MDA) and free proline (Pro) increased with the increase of the pollutant concentration in the wetland bed, indicating that the two plants have a certain self defense ability and can adapt to the stress of the pollutants in the two grade biochemical tail water. In addition, the net photosynthetic rate (Pn), the stomatal conductance (Gs), and the stomatal conductance (Gs) of the two plant leaves before and after the tail water treatment The CO2 concentration (Ci) increased with the lengthening process of the composite vertical flow horizontal flow constructed wetland system. The apparent mesophyll conductivity (AMC) and the stomatal limit percentage (Ls) were the opposite. This showed that the proper amount of organic matter, nitrogen and phosphorus in the two grade biochemical tail water could provide a certain nutrient for the cattail and reed, which could enhance the photosynthesis ability of the plant. It is further proved that the experimental selection of reeds and cattails as artificial wetland plants is reasonable and feasible. (7) the composite vertical flow horizontal flow constructed wetland system can effectively reduce the influent load in the three stages after the starting - stable operation - plant harvest. It is suitable for the deep treatment of municipal sewage and the two level horizontal flow wetland bed. On the basis of the treatment efficiency of the first grade compound vertical flow wetland bed, 15~25%. can be improved, which indicates that the selection of developed roots and aeration tissues, the strong pollution resistant wetland plants and the wide and porous, porous and porous wetland matrix are of great significance to the construction of the artificial wetland to strengthen the pollution removal effect.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X703
本文編號(hào)：2144936
[Abstract]:The wastewater treatment plant of China has a large two level tail water discharge, high nitrogen and phosphorus concentration, higher nitrogen and phosphorus concentration in the tailor water discharged from the polluted water body with limited self purification capacity or polluted water. Regional factors, the concentration of effluent from most sewage treatment plants can only reach the first grade B standard in the pollutant discharge standard of urban sewage treatment plant (GB18918-2002), even beyond the standard. On the other hand, the water resources in our country show a large amount but less per capita, the pollution of water environment and the discharge of waste water are increasing rapidly year by year. The advanced treatment of sewage and utilization of tailwater resources have become the primary choice to reduce the pollution load of the received water and relieve the self purification pressure of the water body, promote the process of urbanization and solve the problem of water shortage in the city. It is applied to the treatment of various water bodies, so the study of the artificial wetland system is also of great significance to the depth treatment of the tail water of the sewage plant. In this paper, the waste brick and shale ceramsite are used as the matrix of the constructed wetland for the low concentration of organic matter and the relatively high concentration of nitrogen and phosphorus in the actual effluent quality of some municipal wastewater treatment plants in Northwest China. The common plant reeds and cattails in Northwest China were used as the main plants in the artificial wetland. Under the outdoor natural conditions, a compound vertical flow horizontal subsurface constructed wetland was constructed. The system was studied at the starting stage, the stable operation stage and the two grade biochemical tail water (COD, BOD5), and ammonia nitrogen (NH_4~+-N) after the plant harvest. The effect of total nitrogen (TN) and total phosphorus (TP) on the removal of pollutants. At the same time, in order to investigate the effect of nitrogen and phosphorus on the two kinds of wetland plants in the two grade biochemical tail water, the growth physiological index of two wetland plants in the artificial wetland system, the upstream pool and the horizontal flow pool were tested at the early stage of plant transplanting and the early harvest. The physiological characteristics of reeds and cattails of wetland plants and cattails were analyzed before and after the treatment of two grade biochemical tail water. The following conclusions were concluded: (1) in the starting stage of the experiment, with the gradual survival of reed and cattail, the oxygen transport capacity of plant roots increased, and the number of aerobic and anaerobic microbes in the substrate was increased. Gradually increasing, the removal rate of COD, NH_4~+-N and TP increased from 52.94%, 37.80%, 53.51% to 68.18%, 76.61%, 81.57% respectively. The average height of reeds and cattail plants from the transplanted 32cm, 38cm to 68cm, 63cm, and the compound vertical flow wetland bed (IVCW section) was better than the horizontal flow wetland bed (HF section). (2) stable operation order. The removal effect of the segment wetland system on NH_4~+-N, TN and TP decreases with the increase of hydraulic load, while the purification effect for COD, BOD5 is less affected by the hydraulic load. In the low hydraulic load of 0.15m3/ (M2 d), the influent is NH_4~+-N, TN and TP concentration is between the 8.40~14.81mg/L, the vertical flow and the horizontal flow. The concentration of COD, BOD5 and TP in the effluent of the ground system is lower than that of category I, type IV, and class III water quality standard in the environmental quality standard of surface water (GB 3838-2002), while the NH_4~+-N and TN concentration of the effluent has not reached the standard of surface water environmental quality, but it is far below the first grade A standard of the pollutant discharge standard of urban sewage treatment plant (GB18918-2002). (3) stability. The removal load of COD, NH_4~+-N, TN and TP of the composite vertical flow and horizontal flow constructed wetland in the fixed operation stage increases linearly with the increase of the influent load, and does not show a slow trend. It shows that the composite vertical flow horizontal flow constructed wetland can also carry the higher influent pollution load in this experiment. (4) in the stable operation stage, the compound vertical flow and horizontal flow constructed wetland system in 0.15m3/ (m2. D), 0.25m3/ (m2. D), 0.35m3/ (m2. D) under three kinds of hydraulic loads, the COD, NH_4~+-N, TN, and the concentration of TN and decreased slowly decline, and the removal efficiency of the wetland system is higher than that of the middle and lower levels. There is a rapid degradation process in the 0~30cm range of the surface layer of the influent end of the downflow pool of the compound vertical flow wetland. (5) there is a certain difference in the absorption and enrichment ability of different plants to nitrogen and phosphorus, and the uptake of nitrogen in the wetland bed plants is higher than that of the phosphorus uptake, and the plant harvesting has a significant influence on the removal of nitrogen. Therefore, in practical application, we should choose and configure wetland plants suitable for different processes according to the strength of the resistance to pollution and the amount of nitrogen and phosphorus absorption. At the same time, we should choose the appropriate time to harvest the wetland plants to strengthen the purification effect of the pollutants in the constructed wetland. (6) in the whole experiment, the reed and the cattail are in good growing trend and in the leaves of plants. The content of malondialdehyde (MDA) and free proline (Pro) increased with the increase of the pollutant concentration in the wetland bed, indicating that the two plants have a certain self defense ability and can adapt to the stress of the pollutants in the two grade biochemical tail water. In addition, the net photosynthetic rate (Pn), the stomatal conductance (Gs), and the stomatal conductance (Gs) of the two plant leaves before and after the tail water treatment The CO2 concentration (Ci) increased with the lengthening process of the composite vertical flow horizontal flow constructed wetland system. The apparent mesophyll conductivity (AMC) and the stomatal limit percentage (Ls) were the opposite. This showed that the proper amount of organic matter, nitrogen and phosphorus in the two grade biochemical tail water could provide a certain nutrient for the cattail and reed, which could enhance the photosynthesis ability of the plant. It is further proved that the experimental selection of reeds and cattails as artificial wetland plants is reasonable and feasible. (7) the composite vertical flow horizontal flow constructed wetland system can effectively reduce the influent load in the three stages after the starting - stable operation - plant harvest. It is suitable for the deep treatment of municipal sewage and the two level horizontal flow wetland bed. On the basis of the treatment efficiency of the first grade compound vertical flow wetland bed, 15~25%. can be improved, which indicates that the selection of developed roots and aeration tissues, the strong pollution resistant wetland plants and the wide and porous, porous and porous wetland matrix are of great significance to the construction of the artificial wetland to strengthen the pollution removal effect.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X703
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