With the development of society and economy, the urban sewage treatment facilities are not perfect, and the sewage pollutes the water environment more and more seriously. With the introduction of the "Action Plan...With the development of society and economy, the urban sewage treatment facilities are not perfect, and the sewage pollutes the water environment more and more seriously. With the introduction of the "Action Plan for Water Pollution Prevention" and other documents, the ecological and environmental protection system has been continuously improved. The construction of municipal sewage treatment plant has attracted peoples attention. The sewage pond is an important part of the sewage treatment plant. The design of the pond is related to the sewage treatment efficiency. It is necessary to study and optimize the structural design of the water tank in the sewage treatment plant to improve the sewage treatment efficiency. This paper introduces the engineering design process of municipal sewage treatment plant, and sums up the structural design technology of the water tank of the sewage treatment plant, so as to provide reference for the construction of municipal sewage treatment project.展开更多
With the rapid development of China's economy and society, the development speed of industry is also accelerating. Before 1949, China was still an agricultural country, with little progress in industry. In just a ...With the rapid development of China's economy and society, the development speed of industry is also accelerating. Before 1949, China was still an agricultural country, with little progress in industry. In just a few decades, China's industry has made a qualitative leap, promoting China from an economically backward agricultural country into the world's largest industrial producer, and made remarkable achievements. The most direct manifestation of the development of industry is the establishment of a large number of factories, the factory will inevitably discharge a large amount of sewage, wastewater in the production process, resulting in water quality deterioration. These industrial wastewater contains a lot of lead, mercury and other harmful chemicals, and its emissions have also caused a certain degree of pollution to people's domestic water. If measures are not taken to purify water resources, it will harm people's health, especially for children, which can not be underestimated.展开更多
Aims Forest fragmentation and reduced tree population densities can poten-tially have negative impacts on mating patterns,offspring genetic diversity and reproductive performance.the aim of the present study is to tes...Aims Forest fragmentation and reduced tree population densities can poten-tially have negative impacts on mating patterns,offspring genetic diversity and reproductive performance.the aim of the present study is to test these hypotheses comparing an extremely fragmented,low tree density(~0.02 trees/ha)holm oak(Quercus ilex l.)stand from Central spain with a nearby high tree density stand(~50 trees/ha).Methods We genotyped adult trees and seeds from the low-density stand(436 seeds from 15 families)and the high-density stand(404 seeds from 11 families)using nine microsatellite markers.With these data,we performed paternity analyses,determined pollen flow,mating patterns and pollen pool structure,and estimated progeny genetic diversity in both stands.We also studied seed set and production and performed a pollen supplementation experiment to determine whether reduced tree density has limited foreign pollen availability.Important Findings We have found extensive pollen immigration(>75%)into the low tree density stand and monte Carlo simulations revealed that pollen moves larger distances than expected from null models of random dispersal.mating patterns and differentiation of pollen pools were similar in the high-density stand and the low-density stand but we found higher inter-annual differentiation of pollen pools in the for-mer.Progeny genetic diversity and self-fertilization rates did not dif-fer between the low-density stand and the high-density stand.seed set rates were significantly lower in the low-density stand than in the high-density stand and experimental cross-pollen supplementation evidenced that foreign pollen availability is indeed a limiting factor in the former.However,seed crops did not differ between the low-density stand and the high-density stand,indicating that limitation of foreign pollen is not likely to be of great concern in terms of reduced seed production and potential recruitment.Poor forest regeneration due to other ecological and human factors is probably a more important threat for the persistence of fragmented and low tree density stands than reduced pollen flow and only extremely small and isolated tree populations would be expected to suffer severe loss of genetic diversity in the long term.展开更多
文摘With the development of society and economy, the urban sewage treatment facilities are not perfect, and the sewage pollutes the water environment more and more seriously. With the introduction of the "Action Plan for Water Pollution Prevention" and other documents, the ecological and environmental protection system has been continuously improved. The construction of municipal sewage treatment plant has attracted peoples attention. The sewage pond is an important part of the sewage treatment plant. The design of the pond is related to the sewage treatment efficiency. It is necessary to study and optimize the structural design of the water tank in the sewage treatment plant to improve the sewage treatment efficiency. This paper introduces the engineering design process of municipal sewage treatment plant, and sums up the structural design technology of the water tank of the sewage treatment plant, so as to provide reference for the construction of municipal sewage treatment project.
文摘With the rapid development of China's economy and society, the development speed of industry is also accelerating. Before 1949, China was still an agricultural country, with little progress in industry. In just a few decades, China's industry has made a qualitative leap, promoting China from an economically backward agricultural country into the world's largest industrial producer, and made remarkable achievements. The most direct manifestation of the development of industry is the establishment of a large number of factories, the factory will inevitably discharge a large amount of sewage, wastewater in the production process, resulting in water quality deterioration. These industrial wastewater contains a lot of lead, mercury and other harmful chemicals, and its emissions have also caused a certain degree of pollution to people's domestic water. If measures are not taken to purify water resources, it will harm people's health, especially for children, which can not be underestimated.
基金Postdoctoral JAE-Doc(Consejo Superior de Investigaciones Científicas)and Juan de la Cierva(Ministerio de Economía y Competitividad)contracts(to J.O.,R.B.and A.M.).Junta de Comunidades de Castilla-La Mancha and European Social Fund(PII1C09-0256-9052)CONSOLIDER-MICINN(CSD2008-00040)Ministerio de Ciencia e Innovación(CGL2008-00095/BOS).
文摘Aims Forest fragmentation and reduced tree population densities can poten-tially have negative impacts on mating patterns,offspring genetic diversity and reproductive performance.the aim of the present study is to test these hypotheses comparing an extremely fragmented,low tree density(~0.02 trees/ha)holm oak(Quercus ilex l.)stand from Central spain with a nearby high tree density stand(~50 trees/ha).Methods We genotyped adult trees and seeds from the low-density stand(436 seeds from 15 families)and the high-density stand(404 seeds from 11 families)using nine microsatellite markers.With these data,we performed paternity analyses,determined pollen flow,mating patterns and pollen pool structure,and estimated progeny genetic diversity in both stands.We also studied seed set and production and performed a pollen supplementation experiment to determine whether reduced tree density has limited foreign pollen availability.Important Findings We have found extensive pollen immigration(>75%)into the low tree density stand and monte Carlo simulations revealed that pollen moves larger distances than expected from null models of random dispersal.mating patterns and differentiation of pollen pools were similar in the high-density stand and the low-density stand but we found higher inter-annual differentiation of pollen pools in the for-mer.Progeny genetic diversity and self-fertilization rates did not dif-fer between the low-density stand and the high-density stand.seed set rates were significantly lower in the low-density stand than in the high-density stand and experimental cross-pollen supplementation evidenced that foreign pollen availability is indeed a limiting factor in the former.However,seed crops did not differ between the low-density stand and the high-density stand,indicating that limitation of foreign pollen is not likely to be of great concern in terms of reduced seed production and potential recruitment.Poor forest regeneration due to other ecological and human factors is probably a more important threat for the persistence of fragmented and low tree density stands than reduced pollen flow and only extremely small and isolated tree populations would be expected to suffer severe loss of genetic diversity in the long term.
