JP2016028805A - Tide-sensitive water area river purification method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove contaminated water remaining on a lower layer of a river of a tide-sensitive water area where there is a partition for preventing sea water from going upstream, and increase dissolved oxygen in water for achieving water quality purification.SOLUTION: An air lift is disposed on a place where there is no hindrance to navigation of a ship, such as a bridge footing at a river of a tide-sensitive water area, and compressed air is supplied to the air lift for pumping up contaminated water on the river lower layer, then the pumped contaminated water is fed to a waste water disposal facility, or, the pumped contaminated water which was pumped during ebb tide is made flow with upstream flow toward downstream, thereby water quality of the tide-sensitive water area river is purified. In addition, because dissolved oxygen in water is increased by gas-liquid mixing by the air lift, water quality purification of the tide-sensitive water area river is enhanced.SELECTED DRAWING: Figure 1

Description

  In the present invention, an air lift is disposed in a place where there is no hindrance to navigation of a ship such as a bridge pier over a river in a tidal area where there is a partition to prevent the sea water from going upstream, and compressed air is supplied to the air lift. The present invention relates to a method for purifying the water quality of a river in a tidal water area by pumping up and removing sewage containing aggregated particles in the lower layer of the river in the tidal water area.

  Conventionally, as a method of purifying the water quality of rivers in the tidal area where sewage is stagnant due to the small amount of water flowing from the river, the amount of water flowed by introducing water from other rivers and pumping and discharging groundwater. A method has been proposed in which the amount of water is increased and the sewage is washed away.

  Regarding the method of introducing water from other rivers, it is not easy to allocate water to other uses by water rights such as agriculture, fishery, and industry because it takes a long time to obtain the consent of the vested right holder. In addition, the construction of the diversion channel requires a large amount of money and time for land acquisition and diversion channel construction.

  The method of pumping up and discharging groundwater may cause land subsidence due to a drop in groundwater level.

  In tidal water areas where fresh water such as river water and sewage flowing in from the upstream and seawater are mixed together, particles in seawater and freshwater particles agglomerate. Aggregated particles in which several individual particles agglomerate are larger than the particles before agglomeration, so that the settling speed is increased and the particles settle to the lower river. For this reason, water pollution progresses because the aggregated particles increase in the lower layer of the river and stagnate.

In rivers in the tidal area, water flows upstream and downstream due to tides. Seawater heavier than fresh water at the time of rising tide is called salt water wedge when it goes under the fresh water and goes upstream, and goes upstream with water containing aggregated particles in the lower part of the river. In tidal rivers with barriers such as weirs and steps to prevent the seawater from going upstream, the seawater is blocked by the partitions and stagnates, causing aggregated particles to settle and water pollution to proceed.
Since the river water flowing in from the upstream is fresh water and lighter than seawater, it flows downstream through the upper river. Therefore, the flow velocity flowing downstream during the tide is higher in the upper river than in the lower river. That is, the water containing the aggregated particles in the lower layer of the tidal water area where the seawater is partitioned so as not to go upstream is likely to stagnate.
(See Non-Patent Document 1.)

A hinge-type gate sluice has been proposed and effective as a means of purifying water quality in rivers and canals in such tidal waters. However, since the ship cannot navigate while the hinged gate is in operation, the gate must be lowered to the riverbed when the ship is sailing.
(See Patent Document 1.)

  Dredging is known as a method for removing sludge from the bottom of rivers, canals and harbors. Sludge accumulated on the bottom of rivers and the like is removed after a certain period of time by dredging, but dredging requires a large amount of money. During this time, water pollution will progress.

JP 2008-274728 A

“Kawaguchi Barrage”, Tetsuo Murakami, Yatsuka Saijo, Seto Okuda, published by Kodansha, Chapters 1 and 3.

  In order to solve the problems of the prior art, the present invention removes sewage containing agglomerated particles staying in the lower layer of the river in the tidal area without hindering navigation of the ship, and increases dissolved oxygen in the water to increase the tidal area. It provides a method for purifying the water quality of rivers.

  The present invention is intended to purify the water quality of rivers in tidal water areas where the amount of water flowing from the upstream is small, using an air lift arranged in a place where there is no hindrance to vessel navigation, such as the piers of bridges over the rivers. That is, compressed air is supplied to an air lift to pump up sewage containing aggregated particles in the lower stream of the river and send it to a sewage treatment plant, or it is pumped up to the upper stream of the river at the time of tide to flow downstream to promote water quality purification.

  The air lift is a pump that pumps up compressed air by blowing compressed air from the bottom into a pipe soaked in water and has a specific gravity smaller than that of external water. Therefore, there is little failure and there is no worry of wear due to mud. If the pressure of the compressed air supplied to the airlift is higher than the water pressure at the bottom of the river at the time of the high tide, the lower layer water can be pumped up. Compressed air can be supplied by a roots blower or an air compressor.

  In tidal rivers, the water flows up and down due to tidal flow, and the upper layer is faster than the lower layer due to the addition of water from the upstream during the tide. At the time of rising tide, there is also the influence of salt water wedge, so the lower layer stream containing aggregated particles goes upstream, and where there is a partition to prevent the seawater from going upstream, the aggregated particles tend to accumulate. For this reason, clean water in the upper layer flows downstream, and dirty water containing aggregated particles in the lower layer stagnate. Therefore, if the water intake port of the airlift is arranged in the lower layer of the river, compressed air is supplied to the airlift, the dirty water containing the aggregated particles in the lower layer of the river is pumped up and sent to the sewage treatment plant, and the contamination of the river is reduced.

  Also, if dirty water containing aggregated particles in the lower layer of the river pumped up by the airlift is flowed downstream along with the upper layer flow at the time of tide, the river contamination will be reduced. In this case, the agglomerated particles contained in the lower layer water pumped up by the air lift are dispersed and finely divided by gas-liquid mixing, so that the sedimentation speed is lowered, and at the time of ebb tide, the agglomerated particles are flowed far downstream. In addition, an increase in dissolved oxygen in water due to the mixing of air and water is also effective for water purification. Incorporating a static mixer into the air lift is also effective in dispersing aggregated particles and increasing dissolved oxygen.

  By placing the airlift in a place where there is no hindrance to the navigation of the ship, such as the pier of a bridge over the river, the ship can navigate as before the installation of the airlift.

  The present invention provides an air lift in a place where there is no hindrance to navigation of the ship, such as a bridge pier over a river, and supplies compressed air to the air lift, so that there is no hindrance to the navigation of the ship, and sewage containing aggregated particles in the lower layer The water is pumped up and sent to a sewage treatment plant, or it is flowed downstream with the upper layer flow at the time of ebb tide, and the dissolved oxygen in the water increases due to the mixing of air and water. . It is also possible to purify the water quality of canals in the tidal area where sewage flows.

Air lift attached to the pier Flow chart from air lift to sewage treatment plant

Embodiments of a tidal water area river water purification method according to the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a view in which an airlift 1 is mounted on a pier 5 with an airlift fixture 6 and a compressed air pipe fixture 7. By blowing compressed air from the compressed air pipe 2 into the water suction port 3 at the lower part of the air lift 1, a mixed state of light liquid with a light specific gravity is created from the outside of the air lift 1, and the water near the river bottom 9 is pumped upward by the difference in specific gravity. The water is discharged from the water discharge port 4 to the river surface 8. If compressed air is blown at the time of tide, the water near the river bottom 9 flows downstream along with the water on the river water surface 8. Moreover, the dissolved water in the water increases due to the gas-liquid mixture, and the river water quality is purified.

  FIG. 2 is a flowchart from the air lift to the sewage treatment plant. When compressed air is supplied from the compressor 10 through the compressed air pipe 2 to the air lift 1, the sewage near the river bottom 9 is pumped up and is sent to the sewage treatment plant 14 through the sewage tank 12 through the sewage pipe 12 via the sewage tank 11. To be processed.

1 Airlift 2 Compressed air pipe
3 Water inlet
4 Water outlet 5 Pier
6 Airlift fixture
7 Compressed air pipe fixture 8 River water surface 9 River bottom 10 Compressor 11 Sewage tank 12 Sewage pump 13 Sewage pipe 14 Sewage treatment plant

Claims (2)

  This is a method to purify the river water quality in the tidal water area where there is a partition to prevent the sea water from going upstream, and air lifts are placed in places where there is no hindrance to vessel navigation such as bridge piers over the river in the tidal water area A method for purifying river water quality in tidal waters, wherein compressed air is supplied to an air lift, sewage in the lower river is pumped and sent to a sewage treatment facility. A method for purifying river water quality in a tidal water area, wherein compressed air is supplied to the airlift according to claim 1 at the time of tide, and sewage in a lower river is pumped up to the upper river to flow downstream.

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