【作者】 胡海燕；

【导师】 王修林； 单宝田；

【作者基本信息】 中国海洋大学 ， 海洋化学， 2007， 博士

【摘要】 水产养殖业在近年来得到了迅猛的发展。大量养殖废水的排放给周边环境造成的巨大的影响,水域环境的恶化,赤潮频发,生态平衡和生物多样性也遭到破坏。养殖水域的水质下降也给我国渔业经济带来了巨大损失。氨氮是水产养殖废水中的主要污染物,也是最难以去除的物质。目前专门针对水产养殖废水的技术还比较少,大都是借鉴传统污水处领的方法。对于海水体系来说,海水中的盐度效应,以及养殖废水中污染结构与常见陆源污水的差异,增加了养殖废水的处理难度。目前研究较多的是泡沫分离、过滤等物理处理技术。这些物理处理设施具有造价和运行费用低等优点,但不能去除溶解性污染物,特别是对氨氮不能有效地去除。本文针对淡水养殖和海水养殖两种废水分别系统考察了不同方法对氨氮的去除效果和作用特点。根据考察的结果和处理目的的对处理方法进行了筛选。并较为深入地探讨了每种方法最佳的使用条件。在此基础上进行养殖废水氨氮处理工艺设计,并粗略地估算处理成本,简单地分析了可能产生的经济效益。为水产养殖废水中氨氮的处理提供了一定的参考。本论文研究所得到的实验结果可概括为以下几个方面:1.针对淡水养殖废水考察了不同方法对氨氮的去除效果和特点,并根据废水的污染程度及处理目标设计相应的工艺组合。(1)固定化活性污泥法对淡水养殖废水中的氨氮有很好的去除作用。通过平均设计因子实验,结果表明其中固定化活性污泥的最佳制备工艺为PVA80g/L、海藻酸钠4g/L、活性碳10 g/L、二氧化硅8g/L、碳酸钙0.5g/L、甲壳素5g/L。污泥/包埋剂为1:4,固定化颗粒粒径为3mm。最佳使用条件为固定化颗粒用量为150 g/L,停留时间4-8h是,温度25-30℃,pH值为7-9,在COD500mg/L范围内,氨氮去除率随着COD负荷升高而升高。(2)螺旋藻经过驯化可以以氨氮为氮源生长。随着氨氮浓度的增高,对螺旋藻的抑制作用和毒性也越来越强。螺旋藻用于处理水体中的氨氮,应以浓度在50mg/L以下的水体为宜。用于处理水产养殖废水中的氨氮时使用的最佳条件为pH6-11,温度25-40℃。加入有机物能够促进螺旋藻的生长繁殖,螺旋藻的藻密度与COD负荷呈正相关。藻最佳的使用浓度为91×104个/mL。(3)淡水养殖废水经过过滤等预处理后,要使出水的氨氮的浓度达到综合污水排放标准,经过内置固定化活性污泥的曝气池处理一定的时间即可达到要求。当停留时间为5小时的条件下,氨氮出水浓度达到我国污水综合排放二级标准(低于25mg/L),0.547元/ m3;当停留时间为6小时的条件下,氨氮出水浓度达到我国污水综合排放二级标准(低于15mg/L),水处理成本为0.656元/ m3。要使出水氨氮的浓度达到养殖回用的要求,需利用螺旋藻的吸收作用进一步处理。使用螺旋藻处理8h后,氨氮浓度低于0.5mg/L,可以满足循环养殖的要求。若螺旋藻投加密度为废水经过螺旋藻处理后藻密度可达106/ml以上,处理每m3养殖废水可获得经济效益0.34元。2.针对海水中体系中除氮微生物较缺乏这一点,通过逐级提高海水比例的方式驯化活性污泥和螺旋藻。结合考察了不同方法对氨氮的去除效果和特点,并根据废水的污染程度及处理目标设计相应的工艺组合。(1)通过逐级提高海水比例的方式驯化活性污泥可以使之最终能够基本适应海水环境。应用于海水养殖废水的处理可以有效地去除其中的氨氮。处理的最佳条件为温度25-35℃,pH7-9,停留时间为12-16h。(2)臭氧可用于海水养殖废水中低浓度氨氮的去除,可作为深度处理的一种手段。其反应速度快,在1h内就可以完成。缺点是处理成本较高。(3)小球藻Chlorella pynenoidos、聚球藻Synechocoocus sp、盐藻Dunallelia salina、三角褐指藻Phaeodactylum tricornutum可以以氨氮作为唯一氮源而生长繁殖,可以有效去除海水养殖废水中氨氮。(4)若不计污泥池、藻塘建设、人力投入等费用。如果要达到污水综合排放一级标准,使用活性污泥法处理海水养殖废水的成本为0.713元/m3废水。采用螺旋藻进行深度处理36h后,氨氮浓度达到回用的要求,同时收获的藻折合经济效益约0.30元。采用臭氧进行深度处理,按作用1h计算,成本为8.415元/m3废水。更多还原

【Abstract】 The industry of aquaculture has been developing rapidly in recently. Great deal of aquaculture waste water was produced and entered the environment with bad effects such as entrophication and red tide. The balance of zoology and diversity of creatures were also destroyed, which lead to economical loss. Ammonia is the most important contamination of aquaculture waste water and it is very difficult to remove from the water. There are rare special technologies of method for aquaculture waste water treatment. For the sea water system, it is more difficult because of the high salinity and complexion of the composition. Physical method such as foam separation and filtration are popular methods for aquaculture waste water treatment. These methods can remove suspended particles effectively but can not reduce the concentration of solvable matters, including ammonia.In this study, several method were set to treat aquaculture waste water. Experiments were designed for fresh water and seawater separately. Ammonia removal rate of all the methods and the characters of the course were noted. Appropriate methods were selected according to the treatment result and the aim concentration. After this period, the routine of water treatment craftwork were designed. Cost and benefit were calculated cursorily. All the result refers significative data for further study of aquaculture wastewater treatment. The main results were summarized as follows:1. The results of ammonia removal of different methods in freshwater system were examined and craftwork with effective methods were set up.(1)Immobilized sludge in fluidized bed has a good ability to remove ammonia from aquaculture wastewater and its result was better than normal sludge. Experiment was designed to improve the properties of immobilized beads. The result showed that the best composition of immobilization reagent was: PVA80g/L、Sodium alga acid 4g/L、activated coal10 g/L、SiO28g/L、CaCO30.5g/L。The value of Sludge/Reagent is 1:4 (w/w),and the best diameter for beads was 3mm。When used to treat aquaculture wastewater, the best condition for work was: with beads delivery 150 g/L, resident time4-8h是,temperature 25-30℃,pH 7-9.(2)Spiralina depended on ammonia as necessary nutrient for growth after the process of domestication culture. High concentration ammonia has a toxic effect on Spiralina. The higher the concentration, the stronger the effect is. The appropriate ammonia range is below 50mg/L. The best working condition of Spiralina for ammonia removal is pH6-11,temperature 25-40℃, algae delivery amount 91×104个/mL。(3)The ammonia concentration of real aquaculture wastewater treated only by immobilized sludge can reach China discharge water quality Standard. When resident time is 5h, ammonia concentration can reach Class 2 standard(below 25mg/L),and treatment cost was 0.547yuan/ m3. When resident time is 6h, ammonia concentration can reach Class 1 standard(below 15mg/L), and treatment cost was 0.656yuan/ m3. To satisfy the quality requirement for aquaculture reuse, further treatment was needed. After treated by Spiralina for 8h, ammonia concentration is below 0.5mg/L and non-ioned ammonia is no more than 0.02mg. The water could be reused for aquaculture.2. By raising the seawater ratio in the water gradually, sludge and Spiralina at last got used to the seawater system. he results of ammonia removal of different methods in freshwater system were examined and craftwork with effective methods were set up.(1)Sludge got used to mariculture system by raising seawater ratio gradually. And the result showed that it can also reduce the ammonia concentration in mariculture wastewater. The best condition for use is: temperature25-35℃,pH7-9,resident time12-16h。 (2)Ozone was used to remove the ammonia remained after former treatment process. The reaction of Ozone with ammonia was so fast that it ended in 1h. there is a problem that producing ozone cost too much.( 3 ) Chlorella pynenoidos、Synechocoocus sp、Dunallelia salin and Phaeodactylum tricornutum origined from seawater and were selected to treat ammonia in mariculture wastewater after comparison experiment.(4)The ammonia concentration of real aquaculture wastewater treated only by sludge can reach China discharge water quality Standard after a treatment process of 12h. And the treatment cost was 0.713yuan/m3 wastewater. To satisfy the quality requirement for aquaculture reuse, further treatment was needed. After treated by Spiralina for 36h, ammonia concentration could satisfy the requirement for reuse. The algae collected produced a profit of about 0.30yuan/m3 wastewater. Using ozone as a succedent treatment may cost 8.42 yuan/ m3 wastewater.更多还原