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畜禽养殖废水含有高浓度有机物、氨氮、悬浮固体和相当数量的病原体及特定结构的有毒物质[1-2],经过好氧处理后,色度亦急剧升高,是地表水及地下水的主要污染源[3]。目前,有研究者[4]认为,畜禽养殖废水处理是一个难题,并给予了极大的关注。处理畜禽养殖废水的传统技术主要有还田技术、生态修复技术和生化处理技术[5],但是对其中多环有机物去除效果不太理想,因其分子结构复杂、化学性质稳定,使用传统方法无能为力,处理后的出水COD和色度仍然居高不下。因此,因水制宜,建立不同区域养殖废水处理模式已经成为当前的研究重点。
臭氧氧化法因其具有高效、经济、操作简便和脱色效果明显等优点,在提高难生化降解有机废水的可生化性以及显色废水的脱色方面得到了广泛应用。而单独臭氧氧化法一直面临臭氧利用效率低下、污染物去除效果不佳以及成本高昂等缺点。在非均相催化条件下,已有研究[6]表明,能够促进臭氧向羟基自由基(HO·)的转变,可提高臭氧利用率及有机物矿化效率。非均相催化臭氧化技术不仅能更加高效地分解O3产生HO·,而且催化剂以固态形式存在,在弱酸至弱碱环境中,金属元素基本不溶出[7-8],具有工艺流程简单、催化效率高、易分离、可重复利用等优点。许珊珊等[9]研究了MgO/GAC在臭氧化敌草隆和乙酸中的活性,结果表明MgO/GAC能使臭氧化的效率提高约15%~35%;将Fe-Ce/GAC催化剂用于催化降解模拟高浓度腐殖酸废水,可使COD、腐殖酸去除率分别比单纯臭氧氧化提高了40.3%、31.8%[10];使用负载铈的黄铁矿烧渣催化臭氧氧化水中活性黑5,在pH为3~10时,Ce-PyC均能保持稳定高效的催化活性,TOC去除率可达到80%[11]。但有关负载型Mn-Fe-Ce/γ-Al2O3催化剂的制备以及三元催化剂的应用目前仍鲜有研究,尤其是奶牛养殖废水应用微气泡臭氧非均相催化氧化的方法进行处理,其在单独臭氧氧化、普通催化剂/臭氧体系与三元催化剂/臭氧体系的降解效果与机理都值得深入研究。
本研究采用浸渍焙烧法制备了负载型Mn-Fe-Ce/γ-Al2O3催化剂,分别对制备条件和工艺条件进行了优化,通过SEM、XRF、BET和XRD等分析手段表征了催化剂的结构和物理化学特性,并与微气泡臭氧构成了非均相催化臭氧氧化体系,以某奶牛养殖基地一级生化处理出水为处理对象,考察了该非均相臭氧催化剂的催化活性。
Mn-Fe-Ce/γ-Al2O3催化剂的制备及其在奶牛养殖废水处理中的臭氧催化氧化性能
Preparation of Mn-Fe-Ce/γ-Al2O3 catalyst and its ozone catalytic oxidation performance in dairy farming wastewater treatment
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摘要: 不同地区的奶牛养殖废水水质具有地域性。在南方地区,常规处理工艺出水COD和色度普遍偏高,臭氧催化氧化是一种非常有潜力的技术。采用优化的浸渍焙烧的制备方法,以γ-Al2O3为载体,制备了Mn-Fe-Ce/γ-Al2O3催化剂,并对其性状进行了表征。将该催化剂用于实际奶牛养殖废水一级好氧池出水的臭氧氧化中,结果表明:经含锰、铁和铈化合物的前驱体浸渍液浸渍并进行焙烧方法得到的Mn-Fe-Ce/γ-Al2O3催化剂对奶牛养殖废水有较好的催化性能;在臭氧投加量为12.5 mg·(L·min)−1,催化剂投加量为60 g,反应20 min的条件下,COD去除率由使用γ-Al2O3时的20.4%提高到48.9%,单独使用臭氧时仅为13.8%;色度去除率可达95%;BOD5/COD达到0.54。臭氧催化氧化不仅可以去除COD和色度,而且有效改善了可生化性,为氧化出水继续使用生化法创造了条件。添加TBA作为HO·的淬灭剂实验结果表明,HO·在体系中起主要作用。研究结果可为奶牛养殖废水处理提供新的技术方法。
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关键词:
- Mn-Fe-Ce/γ-Al2O3 /
- 非均相 /
- 臭氧催化氧化 /
- 奶牛养殖废水 /
- HO·介导
Abstract: The quality of dairy farming wastewater has regional characteristic. In the southern region, COD and chroma in the effluents of conventional treatment processes are generally high. Catalytic ozonation is a kind of promising technology. The Mn-Fe-Ce/γ-Al2O3 catalyst was prepared with a γ-Al2O3 carrier and the optimized impregnation-calcination method, and its properties were characterized, then it was used to ozone oxidize the effluent from the first aerobic tank treating the actual dairy farming wastewater. The results showed that the catalyst prepared by impregnation with precursor impregnating solution containing manganese compound, iron compound and cerium compound, and calcination treatment, had good catalytic performance on the dairy farming wastewater degradation. At the ozone dosage of 12.5 mg·(L·min)−1 and the catalyst dosage of 60 g, the COD removal efficiency increased to 48.9% after 20 min oxidation, while the COD removal efficiency was only 20.4% when using γ-Al2O3, and was 13.8% when using ozone alone. The removal efficiency of chroma reached 95% and the BOD5/COD reached 0.54. Catalytic ozonation could not only remove COD and chroma, but also ameliorate biodegradability effectively, which created the conditions for the subsequent biochemical treatment of above oxidized effluent. Further experiment results of adding HO· quenchers of TBA showed that HO· plays a major role in the system. The above results provide a new technical method for the treatment of dairy farming wastewater.-
Key words:
- Mn-Fe-Ce/γ-Al2O3 /
- heterogeneous /
- ozone catalytic oxidation /
- dairy farming wastewater /
- HO· mediation
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表 1 催化剂的比表面积和总孔体积分析
Table 1. Analysis of specific surface area and total pore volume of catalyst
催化剂 比表面积/(m2·g−1) 总孔体积/(cm3·g−1) Mn-Fe-Ce/γ-Al2O3 159.969 8 0.046 016 γ-Al2O3 200.208 2 0.059 603 表 2 微气泡臭氧非均相催化氧化对奶牛养殖废水可生化性的影响
Table 2. Effect of heterogeneous catalytic oxidation of microbubble ozone on biodegradability of dairy farming wastewater
阶段 COD/(mg·L−1) BOD5/(mg·L−1) BOD5/COD NH3-N/(mg·L−1) TP/(mg·L−1) 色度/倍 处理前 460 98.4 0.21 59.09 7.52 160 处理后 235 126.9 0.54 56.30 7.25 8 -
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