岸邊濕地硝酸鹽遷移轉(zhuǎn)化特性模擬研究
發(fā)布時(shí)間：2018-08-26 09:45
【摘要】：我國(guó)《地表水環(huán)境質(zhì)量標(biāo)準(zhǔn)》(GB3838-2002)對(duì)湖、庫水體的總氮濃度和集中式生活飲用水地表水源地的硝酸鹽氮(N03--N)濃度有嚴(yán)格的標(biāo)準(zhǔn)限值要求,對(duì)一般河流水體的總氮和NO3--N濃度無限值要求,而入湖河流是面源N03--N污染進(jìn)入湖、庫水體的重要輸移通道。在削減NO3--N的方法中,天然或人工濕地是最具發(fā)展前景的方法之一,因此岸邊濕地的建立對(duì)陸源性面源NO3--N污染進(jìn)入水體起重要攔截作用。利用模擬岸邊濕地試驗(yàn)裝置,以硝酸鹽為主要研究對(duì)象,開展?jié)竦匚锢斫Y(jié)構(gòu)和運(yùn)行參數(shù)影響研究,以期獲得最適濕地結(jié)構(gòu)參數(shù)和運(yùn)行參數(shù),同時(shí)基于污染物削減的一級(jí)動(dòng)力學(xué)原理,建立濕地N03--N去除動(dòng)力學(xué)模型及其拓展式,為岸邊濕地的優(yōu)化設(shè)計(jì)和運(yùn)行管理提供依據(jù)。物理結(jié)構(gòu)因素：長(zhǎng)寬比、植物密度和水深；運(yùn)行參數(shù)：水溫、碳氮比(R)、進(jìn)水NO3--N濃度(Cin)、進(jìn)水水力負(fù)荷(q)和進(jìn)水pH。結(jié)果表明：(1)濕地結(jié)構(gòu)因素中,長(zhǎng)寬比和水深是NO3--N削減的重要影響因素,植物(菖蒲)密度并非重要影響因素。本試驗(yàn)條件下,長(zhǎng)寬比為4：1的濕地的NO3--N+NO2--N去除率最高。較0.15 m水深和0.30m水深濕地,0.40 m水深的濕地具有更優(yōu)的N03--N削減效率,水深較大利于NO3--N削減�？瞻�(菖蒲0株.m-2)、密度1(14株·m-2)和密度2(28株·m-2)濕地的NO3--N+NO2--N平均去除率間差別較小。(2)①環(huán)境溫度的上升利于NO3--N的削減,NO3--N+NO2--N去除率隨溫度的上升而提高,分三個(gè)階段：第一階段為水溫低于13℃的低速增長(zhǎng)期(增速1.3%/℃)；第二階段為13℃～24℃間的快速增長(zhǎng)期(2.0%/℃)；第三階段為24℃～28℃間的增速減緩期(1.5%/℃)。水溫大于13℃時(shí),出水NO2--N濃度(CNO2--N)隨水溫升高而減小,水溫小于13℃時(shí),CNO2--N隨水溫升高而增大。②NO3--N去除率隨R的增加而快速提高,R為4時(shí),去除率達(dá)96%。CNO2--N隨R的增加表現(xiàn)為先上升后下降。③伴隨Cin的增加,出水NO3-N濃度先增大后降低,CNO2--N持續(xù)增大,且增速加快。NO3--N+NO2--N面積去除率隨進(jìn)水濃度的升高而增大。④NO3--N+NO2--N去除率隨著q的增加而降低。面積去除率隨q的提高而增大,其過程為先快速增加,后增速減緩,最后趨于穩(wěn)定。⑤進(jìn)水pH降至5.0時(shí),NO3--N去除率下降明顯,濕地反硝化作用受限。(3)建立的一級(jí)動(dòng)力學(xué)模型拓展式對(duì)試驗(yàn)濕地硝酸鹽削減效果的預(yù)測(cè)具備準(zhǔn)確性�；谝患�(jí)動(dòng)力學(xué)模型,將水溫、R、Cin、q因素耦合入一級(jí)反應(yīng)速率常數(shù)(K),構(gòu)建模型拓展式。拓展式能有效降低模型參數(shù)的不確定性,提高模型的設(shè)計(jì)精度。結(jié)果顯示,濕地去除NO3--N符合一級(jí)動(dòng)力學(xué)模型；K與水溫間符合Arrhenius公式(擬合系數(shù)R2：0.96),溫度系數(shù)e值為1.06;K20與R間符合指數(shù)關(guān)系(R2：0.95)；K20與Cin間為線性關(guān)系(R2：0.94);K20與q間呈現(xiàn)二次函數(shù)關(guān)系(R2：0.93)。將水溫、R、Cin、q因素?cái)M合入K以構(gòu)建一級(jí)動(dòng)力學(xué)模型拓展式,拓展式準(zhǔn)確性評(píng)價(jià)結(jié)果表明其預(yù)測(cè)具備準(zhǔn)確性(ε：0.97;R2：0.99)。岸邊濕地對(duì)控制陸源NO3--N污染進(jìn)入水體有重要價(jià)值。濕地結(jié)構(gòu)因素和運(yùn)行參數(shù)的影響研究可為岸邊濕地的設(shè)計(jì)、運(yùn)行和管理提供重要的理論依據(jù)。同時(shí),一級(jí)動(dòng)力學(xué)模型拓展式的構(gòu)建完善了濕地N03--N削減模型參數(shù),提高動(dòng)力學(xué)模型在濕地設(shè)計(jì)和效果預(yù)測(cè)中的可靠性和適用性。
[Abstract]:China's "Surface Water Environmental Quality Standard" (GB3838-2002) has strict standard limits on the total nitrogen concentration of lakes, reservoirs and the nitrate nitrogen (N03-N) concentration of surface water sources for centralized drinking water. It has unlimited requirements on the total nitrogen and NO3-N concentration of general river water bodies, while the river entering the lake is non-point source N03-N pollution entering the lake and the reservoir water bodies are polluted by N03-N. Natural or constructed wetlands are one of the most promising methods to reduce NO3-N. Therefore, the establishment of coastal wetlands plays an important role in intercepting the entry of terrestrial non-point source NO3-N pollution into water. Based on the first-order kinetic principle of pollutant reduction, the N03-N Removal Kinetic Model and its extended formula were established to provide the basis for the optimal design and operation management of coastal wetlands. Running parameters: water temperature, C/N ratio (R), influent NO3-N concentration (Cin), influent hydraulic load (q) and influent pH. The results show that: (1) Among the structural factors of wetland, the aspect ratio and water depth are the important factors affecting the reduction of NO3-N, and the density of plant (Acorus calamus) is not the important factor. Compared with 0.15 m depth and 0.30 m depth wetlands, the wetlands with 0.40 m depth had better N 03-N reduction efficiency, and the water depth was significantly higher than that with NO3-N reduction. The removal rate of O3-N+NO2-N increases with the increase of temperature, which can be divided into three stages: the first stage is the low-speed growth period when the water temperature is lower than 13 (6550 NO2--N) decreases with the increase of water temperature. When the water temperature is less than 13 ~C, the removal rate of CNO 2--N increases rapidly with the increase of water temperature. When R is 4, the removal rate of NO3--N reaches 96%. CNO 2--N increases first and then decreases with the increase of Cin. The removal rate of NO3 - N + NO2 - N increased with the increase of influent concentration. The removal rate of NO3 - N + NO2 - N decreased with the increase of influent concentration. The removal rate of NO3 - N increased with the increase of influent concentration. The process increased rapidly first, then slowed down, and finally stabilized. Based on the first-order kinetic model, water temperature, R, Cin and Q were coupled into the first-order reaction rate constant (K), and the extended model was constructed. The extended model can effectively reduce the uncertainty of the model parameters and improve the design accuracy of the model. The results show that the removal of NO3-N by wetland conforms to the first-order kinetic model; K and water temperature conform to Arrhenius formula (fitting coefficient R2:0.96), temperature coefficient e value is 1.06; K20 and R conform to exponential relationship (R2:0.95); K20 and CI are linear relationship (R2:0.94); K20 and Q present quadratic function relationship (R2:0.93). The water temperature, R, Cin, Q factors are fitted into K with K. The results show that the prediction is accurate (e:0.97; R2:0.99). At the same time, the extension of the first-order dynamic model improves the N03-N reduction model parameters and improves the reliability and applicability of the dynamic model in wetland design and effect prediction.
【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：X52
本文編號(hào)：2204477
[Abstract]:China's "Surface Water Environmental Quality Standard" (GB3838-2002) has strict standard limits on the total nitrogen concentration of lakes, reservoirs and the nitrate nitrogen (N03-N) concentration of surface water sources for centralized drinking water. It has unlimited requirements on the total nitrogen and NO3-N concentration of general river water bodies, while the river entering the lake is non-point source N03-N pollution entering the lake and the reservoir water bodies are polluted by N03-N. Natural or constructed wetlands are one of the most promising methods to reduce NO3-N. Therefore, the establishment of coastal wetlands plays an important role in intercepting the entry of terrestrial non-point source NO3-N pollution into water. Based on the first-order kinetic principle of pollutant reduction, the N03-N Removal Kinetic Model and its extended formula were established to provide the basis for the optimal design and operation management of coastal wetlands. Running parameters: water temperature, C/N ratio (R), influent NO3-N concentration (Cin), influent hydraulic load (q) and influent pH. The results show that: (1) Among the structural factors of wetland, the aspect ratio and water depth are the important factors affecting the reduction of NO3-N, and the density of plant (Acorus calamus) is not the important factor. Compared with 0.15 m depth and 0.30 m depth wetlands, the wetlands with 0.40 m depth had better N 03-N reduction efficiency, and the water depth was significantly higher than that with NO3-N reduction. The removal rate of O3-N+NO2-N increases with the increase of temperature, which can be divided into three stages: the first stage is the low-speed growth period when the water temperature is lower than 13 (6550 NO2--N) decreases with the increase of water temperature. When the water temperature is less than 13 ~C, the removal rate of CNO 2--N increases rapidly with the increase of water temperature. When R is 4, the removal rate of NO3--N reaches 96%. CNO 2--N increases first and then decreases with the increase of Cin. The removal rate of NO3 - N + NO2 - N increased with the increase of influent concentration. The removal rate of NO3 - N + NO2 - N decreased with the increase of influent concentration. The removal rate of NO3 - N increased with the increase of influent concentration. The process increased rapidly first, then slowed down, and finally stabilized. Based on the first-order kinetic model, water temperature, R, Cin and Q were coupled into the first-order reaction rate constant (K), and the extended model was constructed. The extended model can effectively reduce the uncertainty of the model parameters and improve the design accuracy of the model. The results show that the removal of NO3-N by wetland conforms to the first-order kinetic model; K and water temperature conform to Arrhenius formula (fitting coefficient R2:0.96), temperature coefficient e value is 1.06; K20 and R conform to exponential relationship (R2:0.95); K20 and CI are linear relationship (R2:0.94); K20 and Q present quadratic function relationship (R2:0.93). The water temperature, R, Cin, Q factors are fitted into K with K. The results show that the prediction is accurate (e:0.97; R2:0.99). At the same time, the extension of the first-order dynamic model improves the N03-N reduction model parameters and improves the reliability and applicability of the dynamic model in wetland design and effect prediction.
【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：X52
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