Experimental and theoretical analysis were made on the natural humic acid removal and the membrane fouling of ultrafiltration （UF） with in-line coagulation. The results showed dissolved organic carbon （DOC） and UV...Experimental and theoretical analysis were made on the natural humic acid removal and the membrane fouling of ultrafiltration （UF） with in-line coagulation. The results showed dissolved organic carbon （DOC） and UV254 removals by the UF with in-line coagulation at pH 7 were increased from 28% to 53% and 40% to 78% in comparison with direct UF treatment respectively. At the same time, the analysis of high performance liquid chromatography showed that UF with coagulation had significant improvement of removal of humic acid with molecular weights less than 6000 Da in particular. Compared to direct UF, the in-line coagulation UF also kept more constant permeate flux and very slight increase oftransmembrane pressure during a filtration circle. Two typical membrane fouling models were used by inducing two coefficients Kc and Kp corresponding to cake filtration model and pore narrowing model respectively. It was found that membrane fouling by pore-narrowing effect was effectively alleviated and that by cake-filtration was much decreased by in-line coagulation. Under the condition of coagulation prior to ultrafiltration at pH 7, the cake layer formed on the membrane surface became thicker, but the membrane filtration resistance was lower than that at pH 5 with the extension of operation time.展开更多
This pilot study involved the application of a crossflow ultrafiltration （UF） membrane module employing hollow fiber polysulphone membranes in the reclamation of protein and oligosaccharides from soy protein wastewa...This pilot study involved the application of a crossflow ultrafiltration （UF） membrane module employing hollow fiber polysulphone membranes in the reclamation of protein and oligosaccharides from soy protein wastewater. The optimal membrane molecular weight cut-off （MWCO） was selected as 10 ku upon retaining ratios of protein and oligosaccharides as well as the variation of permeate flux. The effects of pretreatment strategy and operating conditions, such as transmembrane pressure （TMP）, feed pH and velocity on flux were studied. According to the experimental result, the optimal operating conditions were determined as temperature 45 ℃, pH 4.5, TMP 0.2 MPa and feed velocity 10 L·s^-1. In addition, the permeate flux recovery by pure water backflushing and chemical cleaning was investigated. The experimental result showed that backflushing with pure water could only recover the lost permeate flux by 30%, and the decrease of backflushing interval was helpful in improving UF permeate productivity. Chemical cleaning test revealed that the combination of sodium hydroxide and EDTA was an ideal agent for cleaning the fouled membranes.展开更多
水厂排泥水处理过程中会产生较大量的污泥脱水液。为避免南水北调引江水资源的浪费,同时积极推进水厂的“零排放”建设目标,面向以引江水为水源的超滤处理工艺,评价了将污泥脱水液回流至原水池进行稀释回用的可行性。考察了不同污泥脱水...水厂排泥水处理过程中会产生较大量的污泥脱水液。为避免南水北调引江水资源的浪费,同时积极推进水厂的“零排放”建设目标,面向以引江水为水源的超滤处理工艺,评价了将污泥脱水液回流至原水池进行稀释回用的可行性。考察了不同污泥脱水液/引江原水混合比例下超滤系统的运行特性,发现当污泥脱水液适当稀释后,其对超滤净水效果和膜污染的影响急剧降低,当稀释比例达到1∶800时,出水水质与跨膜压增长曲线已接近引江原水直接超滤的情况。试验中引江原水的跨膜压增长速率为19.7 k Pa/d,而污泥脱水液原液则达到25.8 k Pa/d。当两者以1∶800比例稀释后,跨膜压增长速率下降为21.3 k Pa/d,接近于引江原水。膜表面微观表征结果显示随着稀释比例的提高,滤饼层厚度、溶解性有机物、特征官能团红外峰强、污染元素相对质量分数均显著降低,逐渐下降到与原水直接超滤相近的水平。引江原水组的超滤膜滤饼层厚度为1.77μm,而污泥脱水液原液组的滤饼层厚度为4.00μm,污染程度较重。两者按1∶800比例稀释后的滤饼层厚度降低至1.82μm,污染程度显著降低。研究结果可为南水北调受水城市超滤水厂的“零排放”建设提供参考。但值得注意的是,污泥脱水液的合理处置与利用问题目前仍处于起步和探索阶段,未来仍需从水质生物安全性和化学安全性的角度加以系统评估。同时可考虑氧化、吸附、微滤分离等预处理手段,以提高污泥脱水液回用过程的安全性。展开更多
基金The National Natural Science Foundation of China (No. 50138020)
文摘Experimental and theoretical analysis were made on the natural humic acid removal and the membrane fouling of ultrafiltration （UF） with in-line coagulation. The results showed dissolved organic carbon （DOC） and UV254 removals by the UF with in-line coagulation at pH 7 were increased from 28% to 53% and 40% to 78% in comparison with direct UF treatment respectively. At the same time, the analysis of high performance liquid chromatography showed that UF with coagulation had significant improvement of removal of humic acid with molecular weights less than 6000 Da in particular. Compared to direct UF, the in-line coagulation UF also kept more constant permeate flux and very slight increase oftransmembrane pressure during a filtration circle. Two typical membrane fouling models were used by inducing two coefficients Kc and Kp corresponding to cake filtration model and pore narrowing model respectively. It was found that membrane fouling by pore-narrowing effect was effectively alleviated and that by cake-filtration was much decreased by in-line coagulation. Under the condition of coagulation prior to ultrafiltration at pH 7, the cake layer formed on the membrane surface became thicker, but the membrane filtration resistance was lower than that at pH 5 with the extension of operation time.
基金Mega-Projects of S&T Research for the 10th Five- Year Plan from Ministry of S&T of the People’s Republic of China(2001BA501A02B) Shenzhen S&T Tri- item Foundation (S040145)
文摘This pilot study involved the application of a crossflow ultrafiltration （UF） membrane module employing hollow fiber polysulphone membranes in the reclamation of protein and oligosaccharides from soy protein wastewater. The optimal membrane molecular weight cut-off （MWCO） was selected as 10 ku upon retaining ratios of protein and oligosaccharides as well as the variation of permeate flux. The effects of pretreatment strategy and operating conditions, such as transmembrane pressure （TMP）, feed pH and velocity on flux were studied. According to the experimental result, the optimal operating conditions were determined as temperature 45 ℃, pH 4.5, TMP 0.2 MPa and feed velocity 10 L·s^-1. In addition, the permeate flux recovery by pure water backflushing and chemical cleaning was investigated. The experimental result showed that backflushing with pure water could only recover the lost permeate flux by 30%, and the decrease of backflushing interval was helpful in improving UF permeate productivity. Chemical cleaning test revealed that the combination of sodium hydroxide and EDTA was an ideal agent for cleaning the fouled membranes.
文摘水厂排泥水处理过程中会产生较大量的污泥脱水液。为避免南水北调引江水资源的浪费,同时积极推进水厂的“零排放”建设目标,面向以引江水为水源的超滤处理工艺,评价了将污泥脱水液回流至原水池进行稀释回用的可行性。考察了不同污泥脱水液/引江原水混合比例下超滤系统的运行特性,发现当污泥脱水液适当稀释后,其对超滤净水效果和膜污染的影响急剧降低,当稀释比例达到1∶800时,出水水质与跨膜压增长曲线已接近引江原水直接超滤的情况。试验中引江原水的跨膜压增长速率为19.7 k Pa/d,而污泥脱水液原液则达到25.8 k Pa/d。当两者以1∶800比例稀释后,跨膜压增长速率下降为21.3 k Pa/d,接近于引江原水。膜表面微观表征结果显示随着稀释比例的提高,滤饼层厚度、溶解性有机物、特征官能团红外峰强、污染元素相对质量分数均显著降低,逐渐下降到与原水直接超滤相近的水平。引江原水组的超滤膜滤饼层厚度为1.77μm,而污泥脱水液原液组的滤饼层厚度为4.00μm,污染程度较重。两者按1∶800比例稀释后的滤饼层厚度降低至1.82μm,污染程度显著降低。研究结果可为南水北调受水城市超滤水厂的“零排放”建设提供参考。但值得注意的是,污泥脱水液的合理处置与利用问题目前仍处于起步和探索阶段,未来仍需从水质生物安全性和化学安全性的角度加以系统评估。同时可考虑氧化、吸附、微滤分离等预处理手段,以提高污泥脱水液回用过程的安全性。
