【摘要】：我國部分地區(qū)水源受列重金屬鎘污染,經過給水廠水處理工藝凈化,原水中大部分鎘聚集到排泥水中,對受鎘污染嚴重的排泥水進行回用,會升高給水廠出水中鎘濃度超標的風險,為降低排泥水上清液中鎘的濃度,保證排泥水安全回用,本文使用六聯(lián)攪拌器,對人工配制的鎘污染排泥水進行“破碎-再絮凝”實驗。通過研究排泥水“破碎-再絮凝”過程中各條件變化對鎘遷移的影響,深入研究了“破碎-再絮凝”過程中鎘在排泥水固液兩相間的遷移轉化規(guī)律,在此基礎上提出排泥水中鎘的強化去除方法,保障自來水廠排泥水的安全回用,結果表明:(1)排泥水的“破碎-再絮凝”過程有利于上清液中鎘的去除,絮體的破碎和再絮凝過程都能吸附部分鎘。鎘的去除效果與破碎強度有關,破碎強度越大鎘的去除效果越好,試驗中的最佳破碎強度為600rpm,此時對上清液中鎘的去除率為37.9%,再絮凝過程中鎘的去除量在1.3-1.9μg/L之間,去除率約為7.9%-11.5%。(2)pH變化對鎘去除的影響較大,主要是由于pH對鎘的溶解度影響較大,pH升高有益于降低上清液鎘的深度,pH降低不利于鎘的去除,甚至污呢中的鎘有解吸的風險。(3)排泥水“破碎-再絮凝”過程中,投加適量的陽離子絮凝劑,能進一步降低上清液中鎘的濃度。絮凝劑存在最佳的投加量范圍,破酸鐵和氯化鋁的最佳投加量范圍分別在4mg/L和5mg/L左右,對鎘的強化去除量分別為2μg/L和1.5μg/L,去除率分別增加12.1%和9.1%;聚合破酸鐵和聚合氯化鋁的最佳投加量分別為22mg/L和5mg/L,對鎘的強化去除量分別為1.6μg/L和0.9μg/L,去除率分別增加9.7%和5.5%,過量的絮凝劑會導致已吸附的鎘釋放,陰離子和陽離子的PAM對鎘的影響不同,“破碎-再絮凝”過程中投加陰離子PAM對鎘的去除沒有影響,投加陽離子PAM不利于鎘的強化去除。(4)排泥水污泥中鎘主要以鐵錳氧化物結合態(tài)存在,“破碎-再絮凝”過程中上清液中鎘的深度降低,主要是由于污泥中鐵錳氧化物結合態(tài)鎘的量增加,投加絮凝劑后排泥水中的鎘也主要是在溶解態(tài)和鐵錳氧化物結合態(tài)之間適移;使用PAM調節(jié)污泥后,污泥中不穩(wěn)定的離子交換態(tài)鎘和部分鐵錳氧化物結合態(tài)鎘轉變?yōu)橛袡C結合態(tài)鎘。(5)排泥水污泥對鎘的吸附過程主要是以分子擴散模型為主的多種動力學機理共同作用的結果;吸附飽和后,繼續(xù)攪拌產生的鎘釋放過程是以準一級速率方程為主的多種動力學機理共同作用的結果。溫度升高不利于污泥對鎘的吸附。最后結合實驗的結果與分析,針對部分地區(qū)水源地受到鎘污染的情況,對水廠排泥水現(xiàn)有回用工藝提出改進建議。
[Abstract]:Some water sources in China are polluted by cadmium, which is a heavy metal. After the water treatment process of the water supply plant, most of the cadmium in the raw water accumulates into the mud discharge water, and the waste mud water which is seriously polluted by cadmium is reused. In order to reduce the concentration of cadmium in the supernatant of waste mud water and ensure the safe reuse of the sludge water, the six mixers are used in this paper. The experiment of "crushing-reflocculation" was carried out on the artificially made mud water contaminated with cadmium. By studying the effect of various conditions on cadmium migration in the process of "crushing and reflocculation" of mud discharge water, the migration and transformation of cadmium between solid and liquid phases in the process of "crushing and reflocculation" were studied in depth. On this basis, the enhanced removal method of cadmium in mud water is put forward to ensure the safe reuse of mud water from water plant. The results show that: (1) the process of "crushing and flocculation" of mud water is beneficial to the removal of cadmium in supernatant. Some cadmium can be adsorbed in the process of floc crushing and reflocculation. The removal efficiency of cadmium is related to the crushing strength. The higher the crushing intensity is, the better the removal effect is. The optimum crushing strength is 600 rpm, and the removal rate of cadmium in supernatant is 37.9 渭 g / L, and the removal rate of cadmium in flocculation process is between 1.3-1.9 渭 g / L. The removal rate was about 7.9- 11.5. (2) the change of pH had a great effect on the removal of cadmium, mainly because pH had a great effect on the solubility of cadmium. The increase of pH was beneficial to the reduction of the depth of cadmium in supernatant and the decrease of pH was not conducive to the removal of cadmium. Even cadmium in the waste water has the risk of desorption. (3) in the process of "crushing and reflocculation", adding a proper amount of cationic flocculant can further reduce the concentration of cadmium in the supernatant. The optimum dosage range of flocculant is about 4mg/L and 5mg/L respectively. The enhanced removal of cadmium was 2 渭 g / L and 1.5 渭 g / L, respectively, and the removal rates were increased by 12.1% and 9.1%, respectively. The optimum dosages of polyacid-breaking iron and polyaluminium chloride were 22mg/L and 5 mg / L, respectively. The enhanced removal of cadmium was 1.6 渭 g / L and 0.9 渭 g / L, respectively, and the removal rate was increased by 9.7% and 0.9 渭 g / L, respectively. 5.5. excessive flocculant will lead to the release of adsorbed cadmium, The effects of anionic and cationic PAM on cadmium were different, and the addition of anionic PAM in the process of "crushing and reflocculation" had no effect on the removal of cadmium. The addition of cationic PAM was not conducive to the enhanced removal of cadmium. (4) the cadmium in sludge was mainly iron-manganese oxide bound, and the depth of cadmium in supernatant decreased during the process of "crushing and reflocculation". It is mainly due to the increase in the amount of iron-manganese oxide bound cadmium in sludge, and the suitable shift of cadmium in mud water after adding flocculant between dissolved state and iron-manganese oxide bound state. After PAM is used to regulate sludge, The unstable ion-exchange cadmium and some iron-manganese oxide bound cadmium in sludge are transformed into organic bound cadmium. (5) the adsorption process of cadmium in sludge is mainly the result of various kinetic mechanisms based on molecular diffusion model. After adsorption and saturation, the release process of cadmium produced by continuous stirring is the result of a combination of several kinetic mechanisms based on the quasi first order rate equation. The increase of temperature is not conducive to the adsorption of cadmium by sludge. Finally, based on the results and analysis of the experiment, some suggestions are put forward to improve the existing reuse process of the waste mud water from the cement plant in view of the cadmium pollution in the water sources in some areas.
【學位授予單位】：西安理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：X703

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