水污染处理文献综述英文上课讲义

1、水污染处理文献综述英文Application of multi-soil-layer system (MSL) in rural wastewater treatmentAbstract: with the continuous improvement of living in rural farmers, the water con sumpti on of reside nts is in creas ing, rural sewage emissi ons will con ti nue to in crease, if n ot treat effectively, the water

2、 en vironment in rural areas will be serious deteriorated, and in flue nce the life quality of rural residents. In this case this paper presents a dece ntralized sewage treatme nt system, multi-soil-layer system tech no logy (MSL) applicati on in the rural sewage treatme nt, this paper summarizes th

3、e new tech no logy, you can better un dersta nd and practice, especially in the develop ing coun tries where is in n eed of this tech no logy. In the foreseeable future, it can protect public health and the susta in able developme nt of the en vir onment, and it also provides a new way for rural sew

4、age treatme nt.Key words: rural sewage; multi-soil-layering system; distributed1. IntroductionIn rece nt years, with the continu ous developme nt of economy, peoples liv ing sta ndards con ti nue to improve, rural econo mic developme nt is also very rapid, but the rural econo mic developme nt and en

5、 vir onmen tal developme nt is not synchroni zed, serious rural water pollution. While high technical sewage treatment plants, such as cen tralized sewage treatme nt pla nts are invo Ived in large inv estme nt costs, high operati ng costs,Because of econo mic con stra in ts, such systems are less su

6、itable for livestock farms and small communities in rural areas. While the multi-media-soil layer system(MSL) sewage treatme nt system, this dece ntralized sewage treatme nt system, it has less inv estme nt, low operat ing costs, high han dli ng load. Besides, the utility model overcomes the defects

7、 of the prior soil percolation which is easy to be blocked from the space structureThe sewage treatme nt system is one kind of the purificati on tech no logy of sewerage treatme nt soil developed in Japa n in twentieth Century, the soil system will be modularized, and the module is set up around the

8、 water in the soil layer to avoid clogg ing, and addi ng natural organic materials to soil modules can improve the purification ability of the system.The MSL system con sists of a Permeable layer (PL) and a soil mixing layer block (SMB), The Permeable layer is usually composed of larger particles fi

9、llers such as gravel, pumice, perlite and zeoliteHigher porosity can effectively preve nt cloggi ng of the soil water layer.At the same time, the formation of aerobic environment is conducive to organic degradati on. The mixed layer soil is mainly pack ing soil mixed with other 20%-30% other materia

10、ls such as activated carb on, wood, ir on and other material or soil with local resources.The organic material added in the soil mixed layer can improve the biological decompositi on and adsorpti on capacity of the system, and can also improve the supply of hydrogen in the process of nitrogen remova

11、l and promote the removal of n itroge n.There are many researches on MSL system treati ng urba n sewage, livestock wastewater and river water at home and abroadResearchers in Chi na, Ye Hai et af1 studied the effect of surface load on polluted river water treated by multi-soil-layer system.S ong Yin

12、 g2 had studied the treatme nt effect of multi medium soil in filtratio n system for turtle breedi ng wastewaterZou Jun3 also poin ted out that multi-soil-layer material selection will have a certain impact on the domestic sewage treatment efficiency. In foreign countries, especially in Japan, Thail

13、and and Indon esia, MSL systems have bee n used to han dle various types of wastewater, but the domestic of this tech no logy in sewage treatme nt in rural areas there is no comprehe nsive studhis article through to the MSL system tech no logy process ing rural domestic sewage research, in order to

14、provide some tech ni cal support for the MSL system in the practical applicati on of rural sewage treatme nt.2.1characteristics of rural sewageFor a long time, Chinas pollution control on rural attention and inv estme nt far less tha n the city, 96% of the villages without drain age pipe network and

15、 sewage treatment system, The random discharge of domestic sewage has become one of the main reasons for the deterioration of water quality in the basin, and is also an important factor causing the rural water environment pollution and lake eutrophication.At the same time, it seriously affects the s

16、afety of production and living in the rural areas, and seriously affects the economic developmeiThe main features of rural sewage in China are:The amount is huge and in creases year by year. Statistics show that in 2OO2.There are 3.205 million tons of national rural domestic sewage daily emissions.T

17、he total nitrogen emission is about 283.1t, total phosphorus daily emissi on is about 56.6t, basically without any treatme nt directly discharged.Water quality and water quantity fluctuation are huge. Rural sewage water is not stable, differe nt periods have differe nt water quality, gen erally do n

18、ot contain heavy metals and toxic and harmful substa nces, but contains more syn thetic deterge nt and bacteria, viruses.More sources. In additi on to huma n feces, kitche n gen erated sewage, there are household cleaning, domestic waste Iandfill leachate gen erated sewage, which will the n en ter t

19、he river part of the sewage, will cause greater pollutio n.Low treatment rate. Part of the system can not run low temperature, rural sewage daily variation coefficient and seasonal variation coefficient, the system a few time high load operation, if there is little sewage, it will stop running .Wide

20、 and scattered. Scattered geographical distribution of villages caused sewage dispersion and it is difficult to collect.2.2 the main source of rural sewageRural sewage refers to the formati on of sewage of the rural areas in the life and producti on process, in cludi ng rural producti on wastewater

21、and rural domestic sewage two aspectRural domestic sewage refers to the reside nts liv ing in the process of toilet discharge of sewage, bath, laundry and kitche n sewage, etcRural producti on sewage refers to livestock and poultry breeding, aquaculture, agricultural products process ing and other h

22、igh concen trati on of orga nic wastewateBecause Chinas rural living is scattered, rural domestic sewage showed a small amount and wide dispers ion Lack of appropriate sewage collecti on, treatme nt facilities, domestic sewage without treatme nt will be free to discharge, the health of rural reside

23、nts to bri ng greater harnAt the same time, rural sewage production also poses a greater threat to the rural ecological en vir onment.2.3mai n tech no logies of dece ntralized domestic sewage treatme ntBeginning in 1970s, Japan, the United States, Europe and other developed coun tries on the use of

24、dece ntralized sewage treatme nt of rural sewage treatme nt, has accumulated a lot of experie nee, achieved good results.The Un ited States si nee the mid-20th cen tury bega n the con structi on of rural sewage treatme nt facilities, in 1972 promulgated the first complete clea n water, the n accord

25、ing to the distributed process ing tech no logy in 2002 promulgated the dece ntralized sewage treatme nt system application manual5. 1987, In Denmark promulgated a decentralized sewage treatment guideline. Germany from 2003 to impleme nt the dece ntralized n eedle in frastructure system project rese

26、arch, use membra ne bioreactor purificati on to treat remote rural sewage. Australia proposed a sewage treatme nt land use systdm.While research and applicati on of rural sewage dece ntralized treatme nt in China bega n in late 1980s,Compared with developed countries and regions, there are still man

27、y gaps in laws and regulations system, technical standard system and man ageme nt and service systemn rece nt years, domestic scholars have done a lot of research on rural domestic sewage,a nd puts forward some mature process ing tech no logy, in clud ing aerobic biological treatme nt, an aerobic bi

28、ological treatme nt tech no logy, soil in filtrati on tech nique and physical and chemical process ing tech no logy etcThere are many scholars in the multi-soil-layer system improveme nt and applicati on developme nt of the Japa nese, it has also done a lot of research, some scholars found through e

29、xperime nts: to earthworm soil in filtrati on layer can also solve the problem of blockage of MSL system, but also can guara ntee the win ter operati on effect in wi nteN9-10】.2.4 Multi-soil-layer system (MSL) tech nology2.4.1Structural characteristics of multi-media-soil layer systemMulti-soil-laye

30、r treatme nt (MSL) system is a ki nd of land sewage treatme nt systemMai nly composed of Permeable layer (PL) and a soil mixing layer block (SMB), From top to bottom are waterproof layer, gravel layer, soil layer and mixed layer (two alternately arranged), in additi on, the MSL tech no logy has a ce

31、rta in terrain fall from the in let to the outlet, mainly by the drop let water can automatically flow in the system, at the same time to purity11】.2.4.2 Purification mechanism of multi-soil-layer systemWastewater contains high concen trati ons of BOD, COD, ammo nia n itroge n, phosphate ions and or

32、ga nic matte W/he n the wastewater into the MSL system, the orga nic matter in wastewater can be adsorbed on the surface of zeolite and soil through physical and chemical effects, followed by decompositi on of soil layer in microorga ni sm, and phosphorus removal is mainly through the soil layer of

33、iron is oxidized to ferric hydroxide after the formati on of in soluble iron, the n adsorpti on in wastewater the formatio n of phosphate coprecipitatio nNitroge n removal is mainly through nitrification and denitrification by ammonia ion, and fin ally reduced to n itroge n discharge system.243 Adva

34、 ntages of multi-soil-layer systemMulti-media-soil layer system is used to treat wastewater from traditional soil infiltration system. It has the disadvantages of low treatme nt load, large gro und, easy to block n itroge n and phosphorus removal and other shortcoming612. The MSL system with soil mo

35、dular as the core concept, its unique brick type internal structure can form a plurality of aerobic and an aerobic en vir onment in order to promote the removal of polluta nts, Am ong them, the permeable layer greatly improves the water permeability of the system to preve nt clogg ing, addi ng n atu

36、ral materials in the soil in creases the purificati on capacity of the system.ConclusionsWith the econo mic reform and developme nt, Chi nas en vir onmen tal awarenessis also improving, water pollution in rural areas have also obtained more and more attention, The MSL system applicable to the small

37、population, scattered in rural areas, the decentralized sewage treatme nt system can be widely in stalled and used in the rural society, especially in rural areas of developing countries such as Chinese, Chineseis in n eed of such tech no logy, susta in able developme nt can protect the public healt

38、h and the en vir onment.ReferenceYe Hai Ye et al. Effect of surface load on polluted river water treated by multi-soillayer systemJ. China water supply and drainage, 2012,28 (19): 74-77Ying Song et al.Treatment of turtle aquaculture effluent by an multi-soil-layersystemJ .J ournal of Zhejia ng Un iv

39、ersity Scie nee B.2015,16(2):145-154Zou Jun, Chen Xin et al. Effect of material selection of multi-soil-layer system on domestic wastewater treatment efficiencyJ. Journal of ecology and rural en viro nment, 2010,26 (1): 14-18Zhang Keqia ng et al. Rural sewage treatme nt tech no logyM Beiji ng: China Agricultural Scie nee and Techn ology Press, 2006.10Chen Jinming et al. Policy and experienee of managing decentralized wastewatertreatme nt systems in the Un ited States J. China water