Due to fast changes in the development of economy and rise ofurbanization, the river pollution occurred continuously,which causes changes inthe river ecosystem and critically disturbed the ecosystem.A very large amountof domestic and industrial wastewater spilled into the river and polluted thewater system badly. Due to whichriver function as a water resource was lost andurban ecology and aquatic environment were declined. The causes of urban riverpollution and ecological effects of river pollution are becoming more hypercritical.The objective of study was to determine pollution in riverwater, sediment and fish to evaluate polluted and non-polluted locations. Waterquality can be improved by artificial aeration. 2.
Surface water act as a receptor of pollutants which comefrom urbanized attachments or water heads Fast urbanization leads todegradation of water quality with eutrophication and pollution. 2.According to the statistics, by the early 20th century,there is no complete natural river in the world.
Therefore, it is necessary todevelop a cost effective techniques to reduce water pollution and its sideeffects and to increase water quality.REMEDIATION TECHNIQUES:-1. PhysicalRemediation (1) Aeration: Aeration can re-establish and increasethe growth and capacityfor survival of micro-organisms to improve the river water quality. Theaeration method is a simple and effective method which came in existence to beutilized since to return the early river into its original condition. Atechnology having numerous applications and factors should be taken into account,includingriver conditions, source properties, water quality rising improvementsand etc. having the fixedaeration, mobile aeration and water aeration methodswhich are selected to deal with thepollutioncontrol to improve water quality over ashort period of time. Since the 1960s, the mobileoxygenation method was used aswell as the fixed aeration method for the urban river aeration, which wassimple method and used by many countries to reduce urban river pollution.Presently, the use of river aeration method in foreigncountriesshowed that the artificial aeration can improve water quality efficiently.
The river aeration method has been used successfully in the treatment of theOeiras Riverin Portugal, the Emsche River in Germany, Thames River in UK andHomewood Canal in U.S. Theaeration equipment was used in the treatment of theHomewood Canal of U.
S. in 1989, whichenhanced the dissolved oxygen in bottomwater and by which the biomass of river was increased. Theriver aeration methodwas utilized to enhance the river water quality efficiently in Germany in 1994.
The riveraeration method was applied to reduce the black-odor of water in BusanSouth Korea.To improve the environment, eight aeration equipments wereplaced in Qing River with eachpower of 11.025 KW during Beijing Asian Games asearly as 1990, by which the level of dissolvedoxygen rose from 0 to 6mg/L, andthe removal rate of BOD5 also reached 60% by which all odors in the riverareremoved. Shanghai Academy of Environmental Sciences had set some aerationpointsin the river channel to perform the practical of water aeration and bioremediation.By this practical,the dissolved oxygen level of the water body (was in anaerobiccondition originally increased), the production of the aerobic microorganismswas enhanced greatly and theremoval rate of organic pollutants in water was upto 10.7% ?23%.The concentration of BOD5 andNH4+-N lessened by 2.492mg/L, 1.
217 mg/L and 0.322mg/L after aeration in the Guanchengsection of the Dongguan Canal. By using BIOmethod, Wang Chengxin and conducted a pilot study onaeration in Shanghai SuzhouRiver. The results expressed that the pure oxygenaeration could lessen theCODcr of the black-odor water and the removal rate could reach from 19.5% to56%.2.2.
WaterDiversion to Flush Out PollutantsThrough water diversion,it is feasible to control river pollution.The clean water can dilute pollutedrivers resulting in the black and stink ofwater body remove quickly and the self-purification capacityof water bodyimproved. The water diversion to flush out pollutants was applied in Fuzhou,Zhongshan andother cities in China in which the calculation of diversion scalewas the key technology based on the effluentwater quality. For instance, HongLijian examined the effect of flushing out pollutants of diversion scaleaboutFuzhou River thay was applied to engineering design but the project was largeand the cost was relatively high.2.
3.SedimentDredgingThe different dredging methods can produce different environmentaleffects. Usually,resuspension of sediment will be caused by the extensiveoperation way of grab or drag-suction dredger. 6. Thewater injection dredgingwas a type of sediment dredging method in situ by which efficiencyincrease andreduce cost and this approach was adopted in the sediment dredging of UK portchannel and XuanWu Lake in China 7. Cutter suction dredger is the most latesttype of environmental dredging and such dredging boat bounded with theautomatic control and monitoring systems to improvedredging accuracy greatly. Itwas used in the Wu Li Lake, Chao Lake in Anhui and Dianchi Lake inKunming inChina to dredge sediment 8.
3. Chemical Remediation3.1.Flocculation and SedimentationThe sedimentation and flocculation method can be used to thewater treatment by a large numberof suspended solids and algae that was simpleto operate and easy to maintain. It was effective to treat.
The infrastructurecosts and pharmacy costs were high. At the same time, it was connected withsecondarypollution hence it cooperated with other processes as a pretreatment phenomena.Poly aluminum chloride (PAC) flocculation was non-polluting, that wasfor recoveryand removal of algae.
The concentration ofPAC was 5mg/L, the time of rapidmixing was 3min, the concentration of casein was 15mg/L, and pH=7-8 for thebest agent suction.3.2.Removal of Algae by Chemical AgentCopper sulphate was used for algal removal (also bleachingpowder, alum,poly aluminum and ferrous sulfate, etc). Effectively, it couldremove the algae and reduce the smell of water to put the copper sulfate whichchange the value of water PH. The calciumhypochlorite can kill the green algae,cyanobacteria and diatoms which causing the water bloom. On the treatment ofcyanobacterial bloom based on chemical algicide with mainingredient of aceticacid, the research was carried out in Xuanwu Lake in Nanjing in 2005 by which,after the treatment, the total algae of theexperimental area reduced by 82.
8%. 4. Bioremediation TechnologiesIndigenous or cultivated microbes and other organisms areused in bioremediation totransform the harmful and poisonous pollutants to non-toxicsubstances under the controllableenvironment. In order to eliminate the gasoline pipeline leak inPennsylvaniain 1972 bioremediation process was used.
It played a significantrole as the main means. It was likely the firstlarge-scale application at thistime. It was a important step in the development of bioremediation andattractedmore and more concerning.The bioremediation could be divided into artificial andnatural bioremediation according to the degree of human intervention, and the prioer could be divided into in-situbioremediation and ex-situbioremediation. The in-situ bioremediation, on onehand, means to use bioremediation technologydirectly in polluted rivers withoutany pollutant transported.
Indigenousmicrobes which sometimes combine withdomesticated microbes are used by this method. In the Ex-situ bio-remediationthe polluted water was taken out from the contaminated areas for transportation.Therefore, the bioremediation was advancedrapidly from 1990asengineering technology for river pollution controlling,. There are manybenefits for the bioremediation technology, such as reduced cost with lowenvironmental influence, reducing pollutantconcentration by the maximum extent,nosecondary pollution or pollutant movement, available for the sites wheregeneral pollution treatmenttechnology is hard to be applied. Thisbioremediation technology is the only most promisingremediation.