市政再生水补水的电厂循环冷却水系统微生物特征及控制技术研究

发布时间：2018-04-22 05:34

本文选题：市政再生水 + 电厂循环冷却水　；参考：《北京交通大学》2013年博士论文

【摘要】：采用市政再生水作为电厂循环冷却水的补水水源是我国解决城市水危机的关键措施之一。与自然水体相比,市政再生水中微生物数量多,有机物和营养物质含量高,采用市政再生水作为补水水源,电厂循环冷却水系统将面临更为复杂的微生物问题。本文在常规水质和微生物指标分析的基础上,综合应用现代分子生物学DNA技术、电化学分析和扫描电镜技术,实验室研究与现场试验相结合,首次系统全面地研究了市政再生水补水的电厂循环冷却水系统的水质特征、微生物特征、微生物对金属腐蚀行为的影响以及微生物化学控制技术,主要结论如下： (1)根据23项水质指标的全分析结果,市政再生水中电导率、TDS、氯离子、表面活性剂含量是地表水的2～4倍,CODMn、总磷、溶解性总磷、溶解性正磷、总氮含量是地表水的1.5-2倍,细菌总数高1个数量级,表明采用市政再生水替代地表水作为补水水源,电厂循环冷却水系统的结垢趋势减缓,但腐蚀程度和微生物风险增大。 (2)市政再生水补水的电厂循环冷却水系统中,增大浓缩倍数,氯离子、电导率、硬度、硫酸根浓度成倍增加,浊度略有增加,铁离子浓度不变,表明水质的腐蚀性增强,析晶垢、颗粒垢、沉积物增多；CODMn浓度增加,氨氮浓度降低,表明硝化和亚硝化自养菌的代谢速率高于异养菌。升高温度,水中的硬度、浊度、正磷酸根浓度降低,表明析晶垢、微粒垢增多；CODMn浓度持续下降,氨氮浓度趋于稳定,异养菌数量大幅增长,因碱度降低,硝化菌和亚硝化菌的生长受到限制。 (3)市政再生水中污垢产量比地表水低44%,但单位质量污垢中的细菌总数和铁细菌含量分别是地表水的8.6倍和2.7倍,表明市政再生水替代地表水作为补水水源,电厂循环冷却水系统的污垢产量降低,但微生物腐蚀的影响增大。电镜扫描图片显示,碳钢在地表水中以均匀腐蚀为主,市政再生水中则为点蚀。 (4)市政再生水补水的电厂循环冷却水系统中,浓缩倍数和温度增加,污垢量增大,因此系统传热阻力和能耗损失增加。流速提高,污垢量变化不大,但污垢热阻升高,粘附率提高,剪切作用使污垢的密实度和粘附性能增强,机械清除难度增大。微生物对系统最不利的运行条件是：浓缩倍数4.0倍、温度35℃、流速0.8m/s～1.0m/s。添加缓蚀阻垢剂后,循环冷却水中有机物增加了92%,磷含量增大了43.5倍,因此导致污垢产量增加40%,污垢中粘液形成菌、异养菌总数增加80%,表明缓蚀阻垢剂导致微生物风险加剧。 (5)市政再生水含有悬浮微生物28种,优势菌种隶属于变形菌门β-变形菌纲的嗜甲基菌科。进入循环冷却水系统后,悬浮和固定微生物的物种分别为18种和44种,优势菌种仍然隶属于变形菌门的β-变形菌纲。添加水处理药剂后,循环冷却水中悬浮微生物种数为38种,菌种的数量分布较为均匀,优势菌种转变为隶属于厚壁菌门的葡萄球菌科,微生物种群结构改变的主要原因是循环水中有机物和磷含量的大幅增加。 (6)市政再生水补水的电厂循环冷却水系统中,虽然碳钢腐蚀最严重、不锈钢腐蚀最轻,但微生物对不锈钢腐蚀的影响却最大。以15d的平均腐蚀率计算,不锈钢MIC所占的比例为36.36%,是碳钢的1.6倍,黄铜的2.4倍。电镜扫描结果表明,不锈钢点蚀造成的微生物分布不均,可能是其MIC腐蚀严重的主要原因。 (7)市政再生水补水的电厂循环冷却水系统中,微生物化学控制技术研究结果表明,与异噻唑啉酮、生物分散剂DREWSPERSE738相比,氯锭和次氯酸钠对悬浮和固定微生物的作用效果最优。结合实际,建议采用氯锭为微生物控制药剂,同时根据其对细菌总数、铁细菌和硫酸盐还原菌的有效作用时间试验结果,确定其投加周期为3天。正交试验的结果显示,增加阻垢缓蚀剂,碳钢缓蚀剂和黄铜缓蚀的投加剂量,氯锭的杀菌率会相应增加。通过现场动态中试试验,提出微生物化学控制投药参数为：氯锭150mg/L,阻垢缓蚀剂8mg/L,黄铜缓蚀剂6mg/L,碳钢缓蚀剂6mg/L。
[Abstract]:Municipal Reclaimed water is one of the key measures to solve the urban water crisis in China, which is one of the key measures to solve the urban water crisis in our country. Compared with the natural water body, the number of microbes in the Municipal Reclaimed Water, the high content of organic matter and nutrients, the use of Municipal Reclaimed Water as water supply source, the circulating cooling water system of the power plant will be more complicated. Microbial problems.
Based on the analysis of conventional water quality and microbiological indexes, the modern molecular biology DNA technology, electrochemical analysis and scanning electron microscopy (SEM), laboratory research and field test are combined. The water quality characteristics, microbiological characteristics and microbiological characteristics of the circulating cooling water system in a power plant with reclaimed water for Municipal Reclaimed Water are systematically studied for the first time. The main conclusions are as follows:
(1) according to the total analysis results of 23 water quality indexes, the content of electrical conductivity, TDS, chloride ion and surface active agent in municipal regenerated water is 2~4 times that of surface water, CODMn, total phosphorus, dissolved total phosphorus and dissolved positive phosphorus, the total nitrogen content is 1.5-2 times of surface water, and the total number of bacteria is 1 orders of magnitude, indicating the use of Municipal Reclaimed Water instead of surface water as water supplement water. The scaling trend of the circulating cooling water system of power plants has slowed down, but the degree of corrosion and the risk of microorganism have increased.
(2) in the circulating cooling water system of power plant of Municipal Reclaimed Water, increasing concentration multiplier, chloride ion, electrical conductivity, hardness, sulphuric acid root concentration multiplied, turbidity a little increase, iron ion concentration constant, indicating that the water quality is corrosiveness enhancement, crystallization scale, particle scale and deposit increase; CODMn concentration increases, ammonia nitrogen concentration decreases, nitrification and subunit concentration The metabolic rate of nitrifying autotrophic bacteria was higher than that of heterotrophic bacteria. The increase of temperature, the hardness of the water, the turbidity, the concentration of the diphosphate, the increase of the particle scale, the decrease of the concentration of CODMn, the stability of the ammonia nitrogen, the increase of the number of heterotrophic bacteria, the decrease of the alkalinity, the restriction of the growth of nitrosation bacteria and nitrifying bacteria.
(3) the fouling production in municipal regenerated water is 44% lower than that of surface water, but the total number of bacteria and iron bacteria in the unit mass fouling are 8.6 times and 2.7 times of the surface water respectively. It indicates that the Municipal Reclaimed water is the substitute for the surface water as a supplement water source, and the fouling output of the circulating cooling water system in the power plant is reduced, but the influence of microbial corrosion is increased. The film shows that carbon steel is mainly uniform corrosion in surface water and pitting in Municipal Reclaimed water.
(4) in the circulating cooling water system of the power plant of the Municipal Reclaimed Water, the concentration multiplier and the temperature increase, the amount of dirt increases, so the heat transfer resistance and the loss of energy consumption increase. The flow velocity increases, the amount of fouling changes little, but the fouling resistance increases and the adhesion rate increases. The shear effect makes the density and adhesion property of the fouling increase, and the mechanical clearance is more difficult. The most unfavorable operating conditions for the microorganism are: 4 times the concentration multiplier, the temperature 35 degrees C, and the addition of corrosion and scale inhibitor from 0.8m/s to 1.0m/s., the organic matter in the circulating cooling water is increased by 92%, the phosphorus content is increased by 43.5 times, thus the fouling yield is increased by 40%, the mucous forming bacteria in the fouling and the heterotrophic bacteria increase 80%, indicating the inhibition and scale inhibition. The risk of microbes is aggravated by the agent.
(5) Municipal Reclaimed Water contains 28 suspended microorganisms, and the dominant strains belong to the methylation bacteria of beta deformable bacteria. After entering the circulating cooling water system, there are 18 species and 44 species of suspended and fixed microbes, and the dominant strains still belong to the beta deformable bacteria of deformable bacteria. After adding water treatment agents, the circulating cooling water is added. The number of suspending microbes is 38 species, and the distribution of the bacteria is more uniform. The dominant strain is transformed into the family Staphylococcus family. The main reason for the change of the microbial population structure is the significant increase in the content of organic matter and phosphorus in the circulating water.
(6) in the circulating cooling water system of the power plant of the Municipal Reclaimed Water, although the corrosion of carbon steel is the most serious and the stainless steel has the lightest corrosion, the microorganism has the greatest impact on the stainless steel corrosion. With the average corrosion rate of 15d, the proportion of stainless steel MIC is 1.6 times that of carbon steel and 2.4 times of the brass. The uneven distribution of microorganisms caused by corrosion may be the main reason for the serious corrosion of MIC.
(7) in the circulating cooling water system of the power plant of Municipal Reclaimed Water, the results of microbial chemical control technology show that, compared with isothiazolinone and biological dispersant DREWSPERSE738, chlorine ingots and sodium hypochlorite have the best effect on the suspension and fixed microorganism. The results of the effective time test on the total number of bacteria, iron bacteria and sulfate reducing bacteria have been determined to determine the addition period of 3 days. The results of orthogonal test show that the increase of the inhibition rate of the corrosion inhibitor, the corrosion inhibitor of carbon steel and the inhibition of brass corrosion will increase correspondingly. The microbial chemical control is put forward through the field dynamic pilot test. The dosage parameters are: chlorine ingot 150mg/L, scale inhibitor 8mg/L, Brass Corrosion Inhibitor 6mg/L, carbon steel corrosion inhibitor 6mg/L..

【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU991.4

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