Introduction:- pollution. According to the statistics, by the early

Introduction:-

 

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.

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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.

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.

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:

Physical Remediation:

 

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. havingthe fixedaeration, mobile aeration and water aeration methods
which are selected  to deal with the  pollution 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,
Thamas 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 equipmentswere 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 COD of the black-odor water and the
removal rate could reach from 19.5% to56%.

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.Sediment
removal:

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. 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 . Cutter suction dredger is the 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.

Chemical
Remediation:

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 phenomenon. 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.

Removal
of Algae by Chemical Agent:

Copper sulphate was used for algal
removal (also bleaching powder, alum,poly aluminum and ferrous sulfate. Effectively,
it could remove the algae and reduce the smell of water to put the copper
sulfate which alter  PH of water. The
calciumhypochlorite can kill the green algae, cyanobacteria and diatoms which causing
the water bloom. On the treatment of cyano-bacterial 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%.

 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.

Remediation by aquatic
plants:

 Aquatic plants have a certain degree of
purification for water. The plants having good absorption capacity for aquatic
pollutants could be implanted in the dirty and polluted water. Similarly water
pollutants were fixed by adsorption, absorption, accumulation anddegradation by
the plants for water purification.

Based on the laboratory experiments,
GuoChangcheng and his group verified that thepotamogeton had good cleansing
result for the polluted river water. Tong Changhua used aquatic plants to
remove eutrophication from the urban river water. The results revealed that aquatic
plants had a good capacity to remove TN, TPand nitrate nitrogen. Foxtail alga and
grain leaf pondweed could efficiently remove TN (83.84% and 77.54%), TP (91.3%)
and nitrate nitrogen (95.85% and 90.65%), but had no substantialeffect on
eliminating ammonia nitrogen (only 14% to 70%).

Remediation method by
aquatic animals:

The aquatic animals were used to reduce
the water of algal bloom and to modify the

aquatic nutrition by changing the
configuration and density of fish. The algal bloom formed by phytoplankton can
be removed by the use of silver carp, common carp and other filter-feeding
fish.

Microbial
Remediation Method:

Bio-film
formation:

The bio-film method uses bio-membrane
which is fixed to the natural river bed and micro-carrier tomove the
contaminantsof  the river by adsorption,
degradation and filtration through theartificial aeration or dissolved
oxygen.The bio-film study showed that its structure can be affected by water
condition and by the structure of substrate.

The bio-film formation  method for 
purification of  river  in Japan,  South Korea and other countries were gravel
contact oxidation method, artificial packing contact oxidation method, thin
layer flow method and underground stream purification method. Japan used the
gravel contact oxidation method for water purification of river and the removal
rates for BOD and SS were significant. In china by using non-woven fabric as
packing substrate then removal efficiency of 
SS  reached to 97 %, for BOD 88%.
Park, Y. K.used biological activated carbon to sieve and clean the polluted
Kumbo River water, and theremoval rate for 
ammonia was 90% and  the removal rate
of TOC was also significant. Lei Jin Yong used the composite pcking of pebbles
and zeolite for bio-film formation for the degradation of organic matter,
ammonia and nitrogen.

 

Microorganism
Dosing method:

This technology utilizes the specific
and effective microorganisms for the absorption, purification and transformation
of the contaminants in the river water. The production of highlyactive compound
bacteria was the significant step to determine the influence of microorganismdosing.
At that time, it was studied and utilized for the purification of sewage,
industrial wastewater and for the water of algal bloom. FLO-1200
achieved remarkable results in the river pollutioncontrol under the conditions
of river aeration.

Conclusion:

The
research in foreign countries started in Japan, U.S and some other European
countries for river control in the 50s of 20th century and after
that river pollution control became an international problem. China started
research work for river control in 1990s and has done much remediation work.

· To obtain
ecological development of the river ecosystem, the river should be treated
withbio-eco remediation and with physico-chemical remediation.

· Bioremediation
materials should be checked and the mechanism of bio-remediation should be
studied carefully before it is directly applied to the river.

· The general
conditions of many technologies such as aeration, bio-film and microbial

formationand dosing  for river 
pollution control are investigated.

· The water
pollution control for Nansha River developed by using coupled model based on
the models EFDC and WASP. For scenario analysis coupled models which lead to
recommendations to improve water quality in Nansha river. Estimation of amount
and distribution of waste-water from domestic and industrial waste water based
on the waste water treatment plant (WWTP)

scheme developed by public authority.