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●To conserve 21st century environment and water front●
Save our Earth!!
地球の水をまもろう!

   − Content −

1.Basic of Water

2.Water Crisis

3.Water Environment Measure

§1.Water measure
Basic measure
Organic matter
Nutrient salts (N・P)
Daily wastewater
Industrial wasteawter
Farmland・livestock wastewater

§2.Rivers
River purification function
Method in river
Type of direct purification

§3.Lakes・marshes
Method in lakes・marshes
Lakes・marshes area
Lakes・marshes from rivers
Direct purification

§4.Ocean
Method in ocean
Prevention of contamination
Pollution prevention tech
Prenvention of red tide
Tideland recovering tech
Seaweed bed recovering tech




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   本文

Chapter 3 Water Environment Measure

§2.Purification measures for rivers

Contamination in rivers emerges due to inflow of inorganic and organic matters (including harmful substances). Considering except the harmful materials, when the organic matters which are measured by the BOD are over than the purification capacity in the rivers, dissolved oxygen in the rivers is consumed and then it becomes anaerobic condition whic hleads ill effects to an odorous emission and living things.  
 In the direct purification measures for rivers, artificially reinforcement and supplement toward natural purification power is carried out. Also, it is effective to conduct appropriate management and use minimum energy for contamination reduction in rivers.


Water purification function of rivers

 In rivers, solid matters and soluble substances are reduced or changed by dilution, sedimentation, filtration, bed load, adsorption, decomposition and oxidation due to river channel shape, flow condition, and various living things. Rivers have self-cleaning effect of these mechanisms.
 It calls the natural purification function of rivers, basically there is a phenomenon described below.

Natural purification function in river

Sedimentation

 Rivers are formed by repetitions of shallow and deep water, and the size of each of shallow and deep water are different in upstream, midstream and downstream, though basics are repeated these.
 In this case, deep water's flow rate is reduced significantly as compared to shallow water, so that the effect of sedimentation will increase. In the shallow, there is a place to decrease the flow rate to between the stones in the shallow, which is also smaller than deep water, but still play the role of sedimentation.


Filtration

 Rivers are composed of surface and subsoil water. Subsoil water is the surface water which is purified through sediment soil and sand in riverbed. Subsoil water is mixed into the surface water in the places such as drop and weirs, then surface water will clean subjected to dilution effect.

 
Filtration function in rivers

The adsorption, oxidation and decomposition by living things

a.The adsorption, oxidation and decomposition by microorganisms
 In the river, the biofilm attached on the surface of the rock or gravel in riverbed absorbs organic matter and inorganic. Organic matter is oxidized and decomposed by the group of organisms biofilm.

Oxidation, adsorption, absorption by living things

 When CarbonFiber is installed in water, it forms a biofilm by the large surface area. Then, it promotes organic matter of the adsorption and decomposition.

b.The adsorption and absorption by aquatic plants
 Various aquatic plants live in river channel. Due to adsorption・degradation by attached group of microorganisms on surface of plant and absorption of soluble substances from the roots, nitrogen and phosphorus in river water or underground water are absorbs as nutrients. As a ersult, contamination is reduced. Further, the dense zone of the plants causes to reduce the flow and emerges sedimentation. As a result, it may contribute to cleaning.
 Function of plants in water is to absorb and remove nitrogen and phosphorus, but the absorption amount is the amount which is necessary for the growth of plants. Thus, it is difficult to removal of all of the nutrients with advanced pollution.


Dissolution of oxygen by drop and flow

 Oxygen in the atmosphere is dissolved by the drop of the river channel and ripples in the shallows, and dissolved oxygen in the water is retained. As a result, it has been contributing to the conservation of biological function to adhere to algae and stone surface.

Shallow design

 In urban pollution of the river plains, because gradient is small and flat, it is not fulfill the function of the shallows. Moreover, the amount of oxygen penetration is low, so it will put a drop of engineering and for oxygen supply.


Dilution

 Because clean water confluent to the dirty river, polluted water is diluted and the amount of water increases, then water pollution concentration is reduced. As a result, water quality will be improved.


Bed load transport

 By the river self purification, oxidized, adsorpted, and absorpted substances are compressed and deposited on the riverbed as peeled off or sludge by the flow rate. Deposited sludge is bed load flow rate by very fast when it flood, then purification function of the river will be restored.


掃流による浄化機能の回復の模式図

 The natural cleansing action are classified physical action, chemical action and biological action as follows.

●Physical action  :Purifying effect caused by the hydraulic characteristics of the river water
              ・Sedimentation, filtration, aeration, bed load, dilution

●Physical and chemical action:Purifying effect caused by the flow and the flow is in contact with the river bed material configuration
              ・Adsorption, aggregation, (oxidation and reduction)

●Biological action  :Purification action arising as microorganisms to survive in water
              ・Adsorption, oxidation, decomposition and synthesis of organic matter by microorganisms of the suraface of contact media
              ・Taking organic matters and nutrient salts by plants and sedimentation by contact

Method of river purification measures

●Direct Purification for Rivers
 In order to purify polluted river, polluted water goes into purification facilities and after purified reflux to the river. In another case, purification facility is directly installed into rivers. In this case it can be reduced directly in the purification facilities pollution load, so it is lots carrying out in recent years as purification method effective.
 The purification facilities, traditional, gravel contact oxidation method and string contact material has been done, but it is more effective adopted to use CarbonFiber with the separation method direct purification facility as the contact material.
 At small river, it attempts of purification facilities in stream direct to install CarbonFiber water purification devices directly into rivers.

 →Direct Purification Method for Rivers with CarbonFiber

●Influent direct water purification
 In order to purify polluted water flowing into the main stream, it performs water purification efficiently by giving a constant residence time established the contact materials such as CarbonFiber and providing the clarification basin to tributary or drainage, then influent to the the main stream. It is suitable for carrying out the purification of the main stream flow water from stream, creek and wetlands,etc.

 →The influent water purification system directly by CarbonFiber


●Water purification introduction
 It is a way of introducing clean water to polluted rivers, then improves the water quality of river pollution by dilution mainly (in some cases it is expected to improve the self-cleaning action). There is also affected by the ebb and flow of the tide, water quality improvement by changes in flow regime (weaken the reverse flow), DO of running water in rivers has supply effect.


●Bottom sediment treatment
 The sediment deposited on the bottom, since the outbreak of the bad smell, deterioration of the landscape by hoisting, consumption of DO, causing the deterioration of water quality due to nutrient elution, etc. so treating the bottom sediment is important.
 ・Dredging
   Dredging is to remove the sludge from the riverbed. Dredging of the river bed is conducted to ensure the water flow cross-section of the river channel, but it has been implemented as the removal of only the bottom sediment from the purpose of the environmental aspects of water quality conservation.
 ・Bottom sediment decomposition
 The dredging requirs large construction cost and leads to ecosystem destruction, so there are ways to decompose and remove the bottom sediment. By laying in the bottom of textile CarbonFiber, it is a way to decompose and remove the organic matter in the bottom by making a den and activate of microorganisms.


●Bypass (Running water conservation waterway)
 For the purpose of conservation of habitat and biodiversity, it improves river channel by natural construction methods and conservation of shallow and pool. Using vegetation and CarbonFiber in the channel, and amplify effective of natural purification, it secondarily improve river purification.
 Because those are planned and designed to preserve the biological environment, it handle as distinguished from the river directly purified. In addition, it is not only purification purpose, but also water improvement and the biological habitat environment maintain method, also it take as measure of DO improvement by direct aeration of the river.

●Biological environment conservation
 For the purpose of conservation of habitat and biodiversity, it improves river channel by natural construction methods and conservation of shallow and pool. Using vegetation and CarbonFiber in the channel, and amplify effective of natural purification, it secondarily improve river purification.
 Because those are planned and designed to preserve the biological environment, it handle as distinguished from the river directly purified. In addition, it is not only purification purpose, but also water improvement and the biological habitat environment maintain method, also it take as measure of DO improvement by direct aeration of the river.


Direct purification method clasification

Sedimentation
Filtration
Pysical purification Disolved oxydation by flow and drop
bed load
dilution
Bottom sediment remove
Sedimentation+Biological oxydation
Physical+Biological treatment
Filtration+Biological oxydation
Biological oxydation CarbonFiber water purification material
Biological treatment Bottom sediment treatment
Use of plants
Physical+Chemical
+Biological treatment
Filtration+Absorption+Biological oxydation
              

             Types of direct river purification and principle clasification



●CarbonFiber water purification materials
 CarbonFiber with large surface area captures and absorbs pollutants, due to swing in the water, activating microorganisms inside which decompose and remove those pollution materials. So it is suitable for contact media, CarbonFiber is water purification material purification technology used for contact media. It is extremely effective as direct river purification method.

 Conventionally, gravel, plastics and synthetic fibers have been used as contact media, but in recent years, eutrophication phenomenon is remarkable river pollution, nutrient removal effect of conventional products is small.
 Vegetation purification method is regard effective method for removal nutrient salts (nitrogen and phosphorus), however the area where advanced pollution, it is only absorption for growth of nitrogen and phosphorus, so removal rate of the per unit is lower and it require lots of area, therefore that's not a practical.

Citation:「CarbonFiber Water Purification Guideline −Environmental Water Edition−
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