Water quality protection in Sweden has a more than 80-year history. The needed knowledge has by large been imported. Now, to some extent the development of phosphorus removal technology may be Swedish contribution to ...Water quality protection in Sweden has a more than 80-year history. The needed knowledge has by large been imported. Now, to some extent the development of phosphorus removal technology may be Swedish contribution to advanced knowledge. This paper presents the development in Sweden, mainly a close to 50-year period. Starting in the late 1960s, a standard of <0.5 mg P/l was the normally raised effluent criteria, regardless of the magnitude of the discharge flow. The successive sharpening of the discharge levels has today resulted in a level of 0.2 to 0.3 mg P/l typically. As a matter of fact, even levels of 0.1 to 0.15 mg P/l have been discussed. The period should a large extent demonstrated both improved technologies and a far better efficiency with respect to the use of chemicals and energy. Some important points in this development may be the understanding of the Oxygen Consumption Potential, as well as the identified needs for an improved nitrogen removal. Lately the problems of complex pollution agents and predominantly the remains of pharmaceutical agents have been identified. To illustrate the development during the 50-year period, two examples are presented from the Swedish context. The main conclusion in this paper is that the Swedish history on phosphorus removal illustrates how empirical science in practice sometimes works, including a never-ending need for an open mind and a readiness to take revised and improved knowledge on board.展开更多
This review article addresses the use of biological activated carbon in water treatment and its techniques for its development, with the premise of analyzing the potential of Activated Carbon (AC) in the treatment of ...This review article addresses the use of biological activated carbon in water treatment and its techniques for its development, with the premise of analyzing the potential of Activated Carbon (AC) in the treatment of water for human consumption. For this end, it aims to identify the techniques used for the production of AC, use and its benefits, production from vegetable waste for water treatment. Activated carbon has the ability to selectively collect gases, liquids and impurities inside its pores, which is the reason it is widely used in filtration systems and for that the treatment of water, the coal fulfills the function of adsorbent, retaining in its pores certain types of impurities: large particles that cause undesirable color, taste or odor in the water. In the treatment of effluents, coal is used for clarification, deodorization and purification of effluents.展开更多
We investigated the morphology and germination of Tamarindus indica seeds in order to discover the ef- fects of variation in seed sources and pre-sowing treatments on germination. The experiment was carried out in the...We investigated the morphology and germination of Tamarindus indica seeds in order to discover the ef- fects of variation in seed sources and pre-sowing treatments on germination. The experiment was carried out in the nursery of the Forestry and Wood Technology Discipline, Khulna University, Bangladesh. Seeds were collected from different but healthy trees from various locations in Bangladesh and subjected to four pre-sowing treatments, i.e., control, immersion in cold water （4℃ for 24 h）, immersion in hot water （80℃ for 10 min） and scarification with sand paper. Seed germination was carried out in poly-bags with a mixture of topsoil and cow dung in the ratio of 3：1. The average length of the fresh seeds was 1.35 ＋ 0.26 cm, their width 1.07 ＋ 0.20 cm and thickness 0.69 ＋ 0.11 cm. The results revealed that pre-sowing treatments affected the germination process of seeds, which significantly increased the germination percentage with the cold water （81.67%） and scarification with sand paper （82.33%） treatments, compared with those in the control （58.33%） and hot water treatment （59.00%）. In all treatments germination started on average within 5 to 7 days after the start of the treatments and were completed from 13 to 19 days later. The greatest success in germination （82.33%） was found in scarification with sand paper, followed with 81.67% in the cold water treatment. The results of analyses of variance （ANOVA） showed significant differences （p 〈 0.05） in germination closing dates, seed germination periods and germination percentages among the treatments but no significant difference among seed sources. However, the effect of the interaction between seed source variation and pre-treatment differed significantly in seed germination closing dates and germination percentages. We recommend cold water treatment （submersion of seed at a temperature of 4℃ for a 24-h period） for seed germination of T. indica in rural Bangladesh.展开更多
An experiment in seed morphology and seed germination techniques of Albizia procera was carried out in the nursery of the Forestry and Wood Technology Discipline, Khulna University, Bangladesh in order to discover the...An experiment in seed morphology and seed germination techniques of Albizia procera was carried out in the nursery of the Forestry and Wood Technology Discipline, Khulna University, Bangladesh in order to discover the source variation in seeds and pre-sowing treatment effects on seed germination. Mature seeds ofA. procera were collected from healthy trees in home garden plan- tations from five different districts in Bangladesh and treated with four pre-sowing treatments, i.e., control, immersion in cold water （4~C for 24 h） and immersion in hot water （80~C for 10 min and 100~C for 1 min）. The average length, width and thickness of seeds were calculated as 0.502 ＋ 0.485, 0.420 ~ 0.060 and 0.191 ~ 0.118 cm, respectively. Germination was conducted in poly-bags with a mixture of topsoil and cow dung in a ratio of 3：1. The results revealed that pre-sowing treatments affected the rate of germination of seeds, which significantly increased the germination percentages of seeds in hot water treatments compared with those in control （60.60%） and the cold water treatment （4℃ for 24 h, 63.53%）. The highest germination success was 82.07% in the treatment of im- mersion in hot water （80℃） for 10 min, followed by 79.00% in immersion in hot water （100℃） for l rain. Germination started 4 to 6 days after seed sowing and completed in a period of 22 to 25 days in all treatments. ANOVAs showed statistically significant dif- ferences （p 〈 0.05） in seed germination starting dates, closing dates, germination percentages and rates of germination among treat- ments, but no significant differences in seed germination starting dates, closing dates, germination period, germination percentages and rates of germination among the seed sources. The study also revealed that the interaction between seed source variation and treat- ment effect significantly differed in seed germination starting dates, closing dates, germination percentages and rates of germination. The hot water （100℃ for 1min） treatment is recommended for seed germination ofA. procera in rural Bangladesh.展开更多
To date,significant efforts have been devoted to eliminating hazardous components to purify wastewater through the development of various nanomaterials.Covalent organic frameworks(COFs),an important branch of the poro...To date,significant efforts have been devoted to eliminating hazardous components to purify wastewater through the development of various nanomaterials.Covalent organic frameworks(COFs),an important branch of the porous crystalline family,possess the peculiarity of ultrahigh surface area,adjustable pore size,and facile functionality.Exciting studies from design fabrication to potential applications in water treatment by COF-based membranes(COMs)have emerged.This review summarizes various preparation strategies and synthesis mechanisms for COMs,including layer-by-layer stacking,in situ growth,interfacial polymerization,and electrochemical synthesis,and briefly describes the advanced characterization techniques for COMs.Moreover,the application of COMs in heavy metal removal,dye separation,purification of radionuclides,pollutant detection,sea water desalination,and so on,is described and discussed.Finally,the perspectives on future opportunities for designing COMs in water purification have been proposed.展开更多
文摘Water quality protection in Sweden has a more than 80-year history. The needed knowledge has by large been imported. Now, to some extent the development of phosphorus removal technology may be Swedish contribution to advanced knowledge. This paper presents the development in Sweden, mainly a close to 50-year period. Starting in the late 1960s, a standard of <0.5 mg P/l was the normally raised effluent criteria, regardless of the magnitude of the discharge flow. The successive sharpening of the discharge levels has today resulted in a level of 0.2 to 0.3 mg P/l typically. As a matter of fact, even levels of 0.1 to 0.15 mg P/l have been discussed. The period should a large extent demonstrated both improved technologies and a far better efficiency with respect to the use of chemicals and energy. Some important points in this development may be the understanding of the Oxygen Consumption Potential, as well as the identified needs for an improved nitrogen removal. Lately the problems of complex pollution agents and predominantly the remains of pharmaceutical agents have been identified. To illustrate the development during the 50-year period, two examples are presented from the Swedish context. The main conclusion in this paper is that the Swedish history on phosphorus removal illustrates how empirical science in practice sometimes works, including a never-ending need for an open mind and a readiness to take revised and improved knowledge on board.
文摘This review article addresses the use of biological activated carbon in water treatment and its techniques for its development, with the premise of analyzing the potential of Activated Carbon (AC) in the treatment of water for human consumption. For this end, it aims to identify the techniques used for the production of AC, use and its benefits, production from vegetable waste for water treatment. Activated carbon has the ability to selectively collect gases, liquids and impurities inside its pores, which is the reason it is widely used in filtration systems and for that the treatment of water, the coal fulfills the function of adsorbent, retaining in its pores certain types of impurities: large particles that cause undesirable color, taste or odor in the water. In the treatment of effluents, coal is used for clarification, deodorization and purification of effluents.
文摘We investigated the morphology and germination of Tamarindus indica seeds in order to discover the ef- fects of variation in seed sources and pre-sowing treatments on germination. The experiment was carried out in the nursery of the Forestry and Wood Technology Discipline, Khulna University, Bangladesh. Seeds were collected from different but healthy trees from various locations in Bangladesh and subjected to four pre-sowing treatments, i.e., control, immersion in cold water （4℃ for 24 h）, immersion in hot water （80℃ for 10 min） and scarification with sand paper. Seed germination was carried out in poly-bags with a mixture of topsoil and cow dung in the ratio of 3：1. The average length of the fresh seeds was 1.35 ＋ 0.26 cm, their width 1.07 ＋ 0.20 cm and thickness 0.69 ＋ 0.11 cm. The results revealed that pre-sowing treatments affected the germination process of seeds, which significantly increased the germination percentage with the cold water （81.67%） and scarification with sand paper （82.33%） treatments, compared with those in the control （58.33%） and hot water treatment （59.00%）. In all treatments germination started on average within 5 to 7 days after the start of the treatments and were completed from 13 to 19 days later. The greatest success in germination （82.33%） was found in scarification with sand paper, followed with 81.67% in the cold water treatment. The results of analyses of variance （ANOVA） showed significant differences （p 〈 0.05） in germination closing dates, seed germination periods and germination percentages among the treatments but no significant difference among seed sources. However, the effect of the interaction between seed source variation and pre-treatment differed significantly in seed germination closing dates and germination percentages. We recommend cold water treatment （submersion of seed at a temperature of 4℃ for a 24-h period） for seed germination of T. indica in rural Bangladesh.
文摘An experiment in seed morphology and seed germination techniques of Albizia procera was carried out in the nursery of the Forestry and Wood Technology Discipline, Khulna University, Bangladesh in order to discover the source variation in seeds and pre-sowing treatment effects on seed germination. Mature seeds ofA. procera were collected from healthy trees in home garden plan- tations from five different districts in Bangladesh and treated with four pre-sowing treatments, i.e., control, immersion in cold water （4~C for 24 h） and immersion in hot water （80~C for 10 min and 100~C for 1 min）. The average length, width and thickness of seeds were calculated as 0.502 ＋ 0.485, 0.420 ~ 0.060 and 0.191 ~ 0.118 cm, respectively. Germination was conducted in poly-bags with a mixture of topsoil and cow dung in a ratio of 3：1. The results revealed that pre-sowing treatments affected the rate of germination of seeds, which significantly increased the germination percentages of seeds in hot water treatments compared with those in control （60.60%） and the cold water treatment （4℃ for 24 h, 63.53%）. The highest germination success was 82.07% in the treatment of im- mersion in hot water （80℃） for 10 min, followed by 79.00% in immersion in hot water （100℃） for l rain. Germination started 4 to 6 days after seed sowing and completed in a period of 22 to 25 days in all treatments. ANOVAs showed statistically significant dif- ferences （p 〈 0.05） in seed germination starting dates, closing dates, germination percentages and rates of germination among treat- ments, but no significant differences in seed germination starting dates, closing dates, germination period, germination percentages and rates of germination among the seed sources. The study also revealed that the interaction between seed source variation and treat- ment effect significantly differed in seed germination starting dates, closing dates, germination percentages and rates of germination. The hot water （100℃ for 1min） treatment is recommended for seed germination ofA. procera in rural Bangladesh.
基金supported by National Key Research and Development Program of China(2018YFC1900105)National Natural Science Foundation of China(22276054)Beijing Outstanding Young Scientist Program.
文摘To date,significant efforts have been devoted to eliminating hazardous components to purify wastewater through the development of various nanomaterials.Covalent organic frameworks(COFs),an important branch of the porous crystalline family,possess the peculiarity of ultrahigh surface area,adjustable pore size,and facile functionality.Exciting studies from design fabrication to potential applications in water treatment by COF-based membranes(COMs)have emerged.This review summarizes various preparation strategies and synthesis mechanisms for COMs,including layer-by-layer stacking,in situ growth,interfacial polymerization,and electrochemical synthesis,and briefly describes the advanced characterization techniques for COMs.Moreover,the application of COMs in heavy metal removal,dye separation,purification of radionuclides,pollutant detection,sea water desalination,and so on,is described and discussed.Finally,the perspectives on future opportunities for designing COMs in water purification have been proposed.
