超滤—反渗透双膜法处理渤海湾海水试验研究
发布时间：2018-11-11 12:46
【摘要】：我国北方沿海省市地区人均水资源量仅为263m3，水资源短缺已经成为限制沿海地区经济发展的主要问题。在一些新开发的海岛上，淡水资源极为缺乏，淡水的供应通常依靠从内陆输入，成本较高且供水可靠性较差。膜法海水淡化是一种解决沿海地区和海岛水资源短缺的有效技术。本试验对超滤-反渗透双膜法处理渤海湾海水的效能与运行稳定性进行了研究，对双膜法工艺的运行参数进行了优化，以期为中小型双膜法海水淡化设备的设计提供参考。 通过改变超滤运行条件，研究了通量、清洗周期与清洗方式对超滤膜污染、产水率以及出产水质的影响，发现超滤膜处理海水时，较短的清洗周期可以及时去除膜表面积累的污染物，有利于膜渗透性的恢复。当正冲与反冲同步进行时，冲洗压力增大，对膜表面污染物去除作用有所加强，有助于降低跨膜压差；补充加强化学反洗，可以有效的控制跨膜压差的增长，将维持跨膜压差在一个较低的水平。本试验条件下，超滤处理海水通量选择为83L/m2h，清洗周期35min，清洗方式为正冲同步进行，冲洗45s，同时每12h补充加强化学反洗，加强化学反洗采用酸碱交替清洗。超滤出水水质良好，完全满足反渗透进水要求，超滤出水SDI值比较稳定且变化不大，稳定在3.2左右，超滤通量、清洗周期以及清洗方式的改变对超滤膜出水SDI影响较小，超滤出水浊度低于0.09NTU。 改变反渗透压力和浓水回流量，考察了对产水量、回收率、脱盐率、产出淡水水质等的影响。结果表明水压力增大，反渗透产水量上升，回收率上升，同时透盐量基本不变，所以出产淡水含盐量减小，反渗透系统脱盐率变大；浓水回流能够有效增加系统回收率，减小了反渗透产水量与膜堆回收率，出产淡水的含盐量增加，反渗透系统脱盐率减小；回流量越大，，导致产出淡水含盐量迅速上升，能耗增加。在本试验条件下，反渗透给水压力选择为5.5MPa，浓水回流量选择为浓水总量的50%。在该条件下较长时间（30d）运行过程中，反渗透产水量未发生明显下降，基本保持在60L/h左右，系统产水回收率为21.7%；出水含盐量为117mg/L左右，脱盐率为99.45%；UV254和三维荧光光谱分析表明系统对海水中溶解性有机物具有很好的去除效果；系统产水水质检测结果符合国家饮用水水质指标，达到饮用标准。
[Abstract]:The amount of per capita water resources in the coastal areas of northern China is only 263 m3. The shortage of water resources has become the main problem restricting the economic development of coastal areas. In some newly developed islands, fresh water resources are extremely scarce, freshwater supply usually depends on inland input, high cost and poor reliability of water supply. Membrane desalination is an effective technique to solve the shortage of water resources in coastal areas and islands. In this paper, the efficiency and operational stability of ultrafiltration and reverse osmosis double membrane process for seawater treatment in Bohai Bay were studied, and the operation parameters of double membrane process were optimized in order to provide a reference for the design of medium and small scale double membrane seawater desalination equipment. By changing the operating conditions of ultrafiltration, the effects of flux, cleaning period and cleaning method on the fouling, water yield and water quality of ultrafiltration membrane were studied. The short cleaning cycle can remove the pollutants accumulated on the membrane surface in time, which is beneficial to the recovery of membrane permeability. When the positive impact and recoil are carried out simultaneously, the washing pressure increases and the removal of pollutants on the membrane surface is strengthened, which is helpful to reduce the transmembrane pressure difference. Adding chemical backwash can effectively control the increase of transmembrane pressure difference and maintain the transmembrane pressure difference at a lower level. Under the experimental conditions, the water flux of ultrafiltration treatment was 83L / m ~ 2 h, the cleaning period was 35min, the cleaning mode was positive flush synchronously, the washing was carried out for 45s, at the same time, the chemical backwash was strengthened every 12 hours, and the acid-base alternate cleaning was used to strengthen the chemical backwash. The quality of ultrafiltration effluent is good, which fully meets the requirement of reverse osmosis influent. The SDI value of ultrafiltration water is stable and little change, which is about 3.2. The change of ultrafiltration flux, cleaning period and cleaning method has little effect on SDI of UF membrane effluent. The turbidity of ultrafiltration water is less than 0.09 NTU. The effects of reverse osmosis pressure and reflux of concentrated water on water yield, recovery rate, desalinization rate and fresh water quality were investigated. The results show that with the increase of water pressure, the water yield of reverse osmosis (RO) increases, the recovery rate increases, and the amount of permeable salt remains unchanged, so the salt content of fresh water produced decreases and the desalinization rate of RO system increases. Concentrated water reflux can effectively increase the system recovery, reduce reverse osmosis water production and membrane reactor recovery, increase the salt content of fresh water, and decrease the desalinization rate of reverse osmosis system. The larger the reflux, the higher the salt content and energy consumption of the produced fresh water. Under the experimental conditions, the pressure of reverse osmosis feed water is 5.5 MPA, and the reflux of concentrated water is 50% of the total amount of concentrated water. During the operation for a long time (30 days), the reverse osmosis (RO) water production did not decrease significantly, and remained around 60L/h, and the recovery rate of the system was 21.70.The salt content of effluent was about 117mg/L and the desalination rate was 99.45%. UV254 and three dimensional fluorescence spectrum analysis show that the system has a good removal effect on dissolved organic matter in seawater, and the results of system water quality detection accord with the national drinking water quality index and reach the drinking standard.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P747.5
[Abstract]:The amount of per capita water resources in the coastal areas of northern China is only 263 m3. The shortage of water resources has become the main problem restricting the economic development of coastal areas. In some newly developed islands, fresh water resources are extremely scarce, freshwater supply usually depends on inland input, high cost and poor reliability of water supply. Membrane desalination is an effective technique to solve the shortage of water resources in coastal areas and islands. In this paper, the efficiency and operational stability of ultrafiltration and reverse osmosis double membrane process for seawater treatment in Bohai Bay were studied, and the operation parameters of double membrane process were optimized in order to provide a reference for the design of medium and small scale double membrane seawater desalination equipment. By changing the operating conditions of ultrafiltration, the effects of flux, cleaning period and cleaning method on the fouling, water yield and water quality of ultrafiltration membrane were studied. The short cleaning cycle can remove the pollutants accumulated on the membrane surface in time, which is beneficial to the recovery of membrane permeability. When the positive impact and recoil are carried out simultaneously, the washing pressure increases and the removal of pollutants on the membrane surface is strengthened, which is helpful to reduce the transmembrane pressure difference. Adding chemical backwash can effectively control the increase of transmembrane pressure difference and maintain the transmembrane pressure difference at a lower level. Under the experimental conditions, the water flux of ultrafiltration treatment was 83L / m ~ 2 h, the cleaning period was 35min, the cleaning mode was positive flush synchronously, the washing was carried out for 45s, at the same time, the chemical backwash was strengthened every 12 hours, and the acid-base alternate cleaning was used to strengthen the chemical backwash. The quality of ultrafiltration effluent is good, which fully meets the requirement of reverse osmosis influent. The SDI value of ultrafiltration water is stable and little change, which is about 3.2. The change of ultrafiltration flux, cleaning period and cleaning method has little effect on SDI of UF membrane effluent. The turbidity of ultrafiltration water is less than 0.09 NTU. The effects of reverse osmosis pressure and reflux of concentrated water on water yield, recovery rate, desalinization rate and fresh water quality were investigated. The results show that with the increase of water pressure, the water yield of reverse osmosis (RO) increases, the recovery rate increases, and the amount of permeable salt remains unchanged, so the salt content of fresh water produced decreases and the desalinization rate of RO system increases. Concentrated water reflux can effectively increase the system recovery, reduce reverse osmosis water production and membrane reactor recovery, increase the salt content of fresh water, and decrease the desalinization rate of reverse osmosis system. The larger the reflux, the higher the salt content and energy consumption of the produced fresh water. Under the experimental conditions, the pressure of reverse osmosis feed water is 5.5 MPA, and the reflux of concentrated water is 50% of the total amount of concentrated water. During the operation for a long time (30 days), the reverse osmosis (RO) water production did not decrease significantly, and remained around 60L/h, and the recovery rate of the system was 21.70.The salt content of effluent was about 117mg/L and the desalination rate was 99.45%. UV254 and three dimensional fluorescence spectrum analysis show that the system has a good removal effect on dissolved organic matter in seawater, and the results of system water quality detection accord with the national drinking water quality index and reach the drinking standard.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P747.5
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