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:

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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.