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Due to fast changes in the development of economy and rise of
urbanization, the river pollution occurred continuously,which causes changes in
the river ecosystem and critically disturbed the ecosystem.A very large amount
of domestic and industrial wastewater spilled into the river and polluted the
water system badly. Due to whichriver function as a water resource was lost and
urban ecology and aquatic environment were declined. The causes of urban river
pollution and ecological effects of river pollution are becoming more hypercritical.

The objective of study was to determine pollution in river
water, sediment and fish to evaluate polluted and non-polluted locations. Water
quality can be improved by artificial aeration. 2.

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Surface water act as a receptor of pollutants which come
from urbanized attachments or water heads Fast urbanization leads to
degradation 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 to
develop a cost effective techniques to reduce water pollution and its side
effects and to increase water quality.

REMEDIATION TECHNIQUES:-

1.     
Physical
Remediation

 

(1)     Aeration:

 

Aeration can re-establish and increasethe growth and capacity
for survival of micro-organisms to improve the river water quality. The
aeration method is a simple and effective method which came in existence to be
utilized since to return the early river into its original condition. A
technology having numerous applications and  factors should be taken into account,
includingriver conditions, source properties, water quality rising improvements
and etc. having the fixedaeration, mobile aeration and water aeration methods
which are selected  to deal with thepollution
control to  improve water quality over a
short period of time. Since the 1960s, the mobileoxygenation method was used as
well as the fixed aeration method for the urban river aeration, which was
simple method and used by many countries to reduce urban river pollution.

Presently, the use of river aeration method in foreign
countriesshowed that the artificial aeration can improve water quality efficiently.
The river aeration method has been used successfully in the treatment of the
Oeiras Riverin Portugal, the Emsche River in Germany, Thames River in UK and
Homewood Canal in U.S. Theaeration equipment was used in the treatment of the
Homewood Canal of U.S. in 1989, whichenhanced the dissolved oxygen in bottom
water and by which the biomass of river was increased. Theriver aeration method
was 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 Busan
South Korea.

To improve the environment, eight aeration equipments were
placed in Qing River with eachpower of 11.025 KW during Beijing Asian Games as
early as 1990, by which the level of dissolvedoxygen rose from 0 to 6mg/L, and
the removal rate of BOD5 also reached 60% by which all odors in the riverare
removed. Shanghai Academy of Environmental Sciences had set some aeration
pointsin 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 anaerobic
condition originally increased), the production of the aerobic microorganisms
was enhanced greatly and theremoval rate of organic pollutants in water was up
to 10.7% ?23%.
The concentration of BOD5 andNH4+-N lessened by 2.492mg/L, 1.217 mg/L and 0.322
mg/L after aeration in the Guanchengsection of the Dongguan Canal. By using BIO
method, Wang Chengxin and conducted a pilot study onaeration in Shanghai Suzhou
River. The results expressed that the pure oxygenaeration could lessen the
CODcr of the black-odor water and the removal rate could reach from 19.5% to56%.

2.2.Water
Diversion to Flush Out Pollutants

Through water diversion,it is feasible to control river pollution.
The clean water can dilute pollutedrivers resulting in the black and stink of
water body remove quickly and the self-purification capacityof water body
improved. The water diversion to flush out pollutants was applied in Fuzhou,
Zhongshan andother cities in China in which the calculation of diversion scale
was the key technology based on the effluentwater quality. For instance, Hong
Lijian examined the effect of flushing out pollutants of diversion scaleabout
Fuzhou River thay was applied to engineering design but the project was large
and the cost was relatively high.

2.3.Sediment
Dredging

The different dredging methods can produce different environmental
effects. Usually,resuspension of sediment will be caused by the extensive
operation way of grab or drag-suction dredger. 6. Thewater injection dredging
was a type of sediment dredging method in situ by which efficiencyincrease and
reduce cost and this approach was adopted in the sediment dredging of UK port
channel and XuanWu Lake in China 7. Cutter suction dredger is the most latest
type of environmental dredging and such dredging boat bounded with the
automatic control and monitoring systems to improvedredging accuracy greatly. It
was used in the Wu Li Lake, Chao Lake in Anhui and Dianchi Lake inKunming in
China to dredge sediment 8.

3. Chemical Remediation

3.1.
Flocculation and Sedimentation

The sedimentation and flocculation method can be used to the
water treatment by a large numberof suspended solids and algae that was simple
to operate and easy to maintain. It was effective to treat. The infrastructure
costs and pharmacy costs were high. At the same time, it was connected withsecondary
pollution hence it cooperated with other processes as a pretreatment phenomena.
Poly aluminum chloride (PAC) flocculation was non-polluting, that wasfor recovery
and removal of algae. The concentration ofPAC was 5mg/L, the time of rapid
mixing was 3min, the concentration of casein was 15mg/L, and pH=7-8 for the
best agent suction.

3.2.
Removal of Algae by Chemical Agent

Copper sulphate was used for algal removal (also bleaching
powder, alum,poly aluminum and ferrous sulfate, etc). Effectively, it could
remove the algae and reduce the smell of water to put the copper sulfate which
change the value of water PH. The calciumhypochlorite can kill the green algae,
cyanobacteria and diatoms which causing the water bloom. On the treatment of
cyanobacterial bloom based on chemical algicide with mainingredient of acetic
acid, 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 Technologies

Indigenous or cultivated microbes and other organisms are
used in bioremediation to

transform the harmful and poisonous pollutants to non-toxic
substances under the controllable

environment. In order  to eliminate the gasoline pipeline leak in
Pennsylvaniain 1972 bioremediation process was used. It played a significant
role as the main means. It was likely the firstlarge-scale application at this
time. It was a important step in the development of bioremediation andattracted
more and more concerning.

The bioremediation could be divided into artificial and
natural bioremediation according to the degree of human intervention,  and the prioer could be divided into in-situ
bioremediation and ex-situbioremediation. The in-situ bioremediation, on one
hand, means to use bioremediation technologydirectly in polluted rivers without
any pollutant transported. Indigenousmicrobes which sometimes combine with
domesticated microbes are used by this method. In the Ex-situ bio-remediation
the polluted water was taken out from the contaminated areas for transportation.

Therefore, the bioremediation was advancedrapidly from 1990as
engineering technology for river pollution controlling,. There are many
benefits for the bioremediation technology, such as reduced cost with low
environmental influence, reducing pollutantconcentration by the maximum extent,no
secondary pollution or pollutant movement, available for the sites where
general pollution treatmenttechnology is hard to be applied. This
bioremediation technology is the only most promisingremediation.

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