Water aeration is often required in water bodies that suffer from anoxic conditions, usually caused by adjacent human activities such as sewage discharges, agricultural run-off, or over baiting a fishing lake. Aeration can be achieved through the infusion of air into the bottom of the lake, lagoon or pond or by surface agitation from a fountain or spray like device to allow for oxygen exchange at the surface and the release of noxious gasses such as carbon dioxide, methane or hydrogen sulfide. The researchers review types of water aerator in The Kingdom of Thailand and also in the world. Water Wheel Low Speed Floating Mechanical Surface Aerator Chaipattana, Model RX-2, was the most popular in Kingdom of Thailand. Next, the paper describes the idea towards the development and performance enhancement of a Stand Alone Solar Water Wheel Low Speed Surface Aerator Chaipattana RX-2-3 without battery, reduced power consumption and increased oxygen dissolved in water.

1. The Fourth National Symposium and the Second International Symposium Concerning the Research
Work Presentation at Bangkok Thonburi University
The Symposium on Interdisciplinary Research for Academic Development
July 23, 2016 08.00 am ‐18.00 pm, at Building 14 Bangkok Thonburi University
Faculty of Engineering, Bangkok Thonburi University, Thailand. airscan_t@yahoo.com (1)
Faculty of Technology and Innovation, Bangkok Thonburi University, Thailand. (2)
Overview of Low Speed Surface Aerator Chaipattana towards Performance
Enhancement and Development of a Stand Alone Solar Water Wheel
Suravut Snidvongs(1)(2)
, Jongjit Hirunlabh(1)
, Joseph Khedari(2)
Abstract
Water aeration is often required in water bodies that suffer from anoxic conditions, usually
caused by adjacent human activities such as sewage discharges, agricultural run-off, or over
baiting a fishing lake. Aeration can be achieved through the infusion of air into the bottom of the
lake,lagoonorpondorbysurfaceagitationfrom afountainorspray likedevicetoallowforoxygen
exchange at the surface and the release of noxious gasses such as carbon dioxide, methane or
hydrogen sulfide.
The researchers review types of water aerator in The Kingdom of Thailand and also in the
world. Water Wheel Low Speed Floating Mechanical Surface Aerator Chaipattana, Model RX-2,
was the most popular in Kingdom of Thailand. Next, the paper describes the idea towards the
development and performance enhancement of a Stand Alone Solar Water Wheel Low Speed
Surface Aerator Chaipattana RX-2-3 without battery, reduced power consumption and increased
oxygen dissolved in water.
Keywords: Water Wheel Aerator, Solar Water Wheel Low Speed Surface Aerator Chaipattana.
Introduction
Dissolved oxygen (DO) is a major contributor to water quality. Not only do fish and other
aquatic animals need it, but oxygen breathing aerobic bacteria decompose organic matter. When
oxygenconcentrationsbecomelow,anoxicconditionsmaydevelopwhichcandecreasetheabilityof
the water body to support life.
Aeration methods
Water aerations was any procedure by which oxygen is added to water. This being the
only criterion, there are a variety of ways to aerate water. There are two broad areas, surface
aeration and subsurface aeration.

2. 2
1.Surface aeration
1.1. A fountain consists of a motor that powers a rotating impeller. The impeller pumps
water from the first few feet of the water and expels it into the air.[2]
This process utilizes air-water
contact to transfer oxygen. As the water is propelled into the air, it breaks into small droplets.
Collectively, these small droplets have a large surface area through which oxygen can be
transferred. Upon return, these droplets mix with the rest of the water and thus transfer their
oxygen back to the ecosystem.
Fountains are a popular method of surface aerators because of the aesthetic appearance
thattheyoffer.However, mostfountains are unable to produce alargeareaofoxygenated water.[2]
Also, running electricity through the water to the fountain can be a safety hazard.
1.2.Floating surface aerators typical mechanical surface aerator at work. It is often
difficult for this type of machine to aerate the entire water column.
Floating surface aerators work in a similar manner to fountains, but they do not
offer the same aesthetic appearance. They extract water from the first 1–2 feet of the water body
andutilizeair-watercontact totransfer oxygen. Instead ofpropelling waterintotheair,theydisrupt
thewateratthewatersurface.Floatingsurfaceaeratorsarealsopoweredbyon-shoreelectricity.[2]
Surface aerators are limited to a small area as they are unable to add circulation or oxygen to
much more than a 3 meter radius. This circulation and oxygenating is then limited to the first
portion of the water column, often leaving the bottom portions unaffected.
1.3.Paddle wheel aerators also utilize air-to-water contact to transfer oxygen from the air in the
atmosphere to the water body. A one-horsepower paddle wheel aerator. The splashing may
increase the evaporation rate of the water and thus increase the salinity of the water body. They
are most often used in the aquaculture field. Constructed of a hub with attached paddles, these
aerators are usually powered by a tractor power take-off, a gas engine, or an electric motor. They
tend to be mounted on floats. Electricity forces the paddles to turn, churning the water and
allowing oxygen transfer through air-water contact.[2]
As each new section of water is churned, it
absorbs oxygen from the air and then upon its return to the water, restores it to the water. In this
regard paddlewheel aeration works very similarly to floating surface aerators.
2. Subsurface aeration
Subsurface aeration seeks to release bubbles at the bottom of the water body and allow
them to rise by the force of buoyancy. Diffused aeration systems utilize bubbles to aerate as well
as mix the water. Water displacement from the expulsion of bubbles can cause a mixing action
to occur, and the contact between the water and the bubble will result in an oxygen transfer.[3]

3. 3
2.1. Jetaerationsubsurfaceaerationcanbeaccomplished bytheuseofjetaerators,
which aspirate air, by means of the venturi principle, and inject the air into the liquid.
2.2.Coarse bubble aeration is a type of subsurface aeration wherein air is pumped
from an on-shore air compressor.[4]
Through a hose to a unit placed at the bottom of the water
body. The unit expels coarse bubbles (more than 2 mm in diameter),[5]
which release oxygen
when they come into contact with the water, which also contributes to a mixing of the lakes
stratified layers. With the release of large bubbles from the system, a turbulent displacement of
water occurs which results inamixingofthewater.[3]
In comparison to otheraerationtechniques,
coarse bubble aeration is very inefficient in the way of transferring oxygen. This is due to the
large diameter and relatively small collective surface area of its bubble. [3]
2.3. Fine bubble aeration is an efficient technique of aeration in terms of oxygen
transfer due to the large collective surface area of its bubbles.
Fine bubble aeration is an efficient way to transfer oxygen to a water body. A
compressor on shore pumps air through a hose, which is connected to an underwater aeration
unit. Attached to the unit are a number of diffusers. These diffusers come in the shape of discs,
plates, tubes or hoses constructed from glass-bonded silica, porous ceramic plastic, PVC or
perforated membranes made from EPDM (ethylene propylene diene Monomer) rubber.[2]
Air
pumped through the diffuser membranes is released into the water. These bubbles are known
as fine bubbles. The EPA defines a fine bubble as anything smaller than 2mm in diameter.[5]
This
type of aeration has a very high oxygen transfer efficiency (OTE), sometimes as high as 15
pounds of oxygen / (horsepower*hour) (9.1 kilograms of oxygen / (kilowatt*hour)).[2]
On average,
diffused air aeration diffuses approximately 2–4 cfm (cubic feet of air per minute) (56.6-113.3
liters of air per minute), but some operate at levels as low as 1 cfm (28.3 L/min) or as high as 10
cfm (283 L/min).
Fine bubble diffused aeration is able to maximize the surface area of the
bubbles and thus transfer more oxygen to the water per bubble. Additionally, smaller bubbles
take more time to reach the surface so not only is the surface area maximized but so are the
number of seconds each bubble spends in the water, allowing it more time to transfer oxygen to
the water. As a general rule, smaller bubbles and a deeper release point will generate a greater
oxygen transfer rate.[6]
However, almost all of the oxygen dissolved into the water from an air bubble
occurs when the bubble is being formed. Only a negligible amount occurs during the bubbles
transit to the surface of the water. This is why an aeration process that makes many small

4. 4
bubbles is better than one that makes fewer larger ones. The breaking up of larger bubbles into
smaller ones also repeats this formation and transfer process.[7]
One of the drawbacks to fine bubble aeration is that the membranes of ceramic
diffusers can sometimes clog and must be cleaned in order to keep them working at their
optimum efficiency. Also, they do not possess the ability to mix as well as other aeration
techniques, such as coarse bubble aeration.[2]
Water Wheel Low Speed Surface Aerator Chaipattana
His Majesty the King is continuously concerned about the problem of environmental
deterioration,especiallypollutedwaterwhichemitanunpleasant smellanddamagesthepeople's
health and the global atmosphere. The level of water pollution in Thailand has become such a
severe health threat that finding solutions is not easy. This has so concerned His Majesty that
he has inspected numerous areas in Bangkok as well as in the provinces that suffer from water
pollution. In response, he has initiated several ideas for remedying water pollution.[1]
These
include improvements to the existing water ways such as swamps and ponds, dredging as
deemed appropriate and, improving the condition of polluted water. During the initial stages of
these inspection tours, 1984 – 1987. His Majesty recommended that clean water be used to dilute
and thus alleviate water pollution, as well as touse water hyacinth and other aquatic vegetation.
To filter the water. These approaches were effective, but only to a certain extent. From
1988 on, water pollution had grown so severe that normal methods were unable to cope
effectively with the problem. His Majesty emphasized an integrated treatment system using the
aerator, because water hyacinth treatment needs a vast area and has a limited capacity to
reduce contamination. His Majesty therefore instructed that a mechanical aeration device be
built that is low-cost and can be manufactured within the country, a Thai product for Thai
people, in the hope of easing the government's burden in coping with water pollution.
The· Water Wheel Low Speed Floating Mechanical Surface Aerator, or Chaipattana
Aerator, is an invention devised at the behest of His Majesty the King for use in the treatment of
polluted watergeneratedbyresidentialandindustrialcommunities.Thisdevicehasmultipleuses,
including aeration propulsion and mixture by agitation. It can be installed as a stationary or mobile
unit. Altogether, nine models have been made but the second one, RX-2, which was patented by
His Majesty the King, is the most appropriate for use in treating polluted water.
Towards the end, His Majesty instructed the Chaipattana Foundation to provide
budgetary assistance for studies and research for this.new invention, by constructing a water

5. 5
pollution treatment device in conjunction with the Royal Irrigation Department. This resulted in
the manufacture of the mechanical aerator that came to be known all over the country as the
Chaipattana Aerator.
The Nine Models
Based on His Majesty's principles, the Royal Irrigation Department built, studied and
conducted research on nine models of the aerators, which have been tested for water pollution
treatment appropriate for different areas, known as Model RX-1 to 9. These different mechanical
aerators have been installed in wastewater treatment systems at several sites since May 1989.
They are constantly being improved in order to meet the goal that water pollution treatment be
efficient, easy to use, costs effective, need little maintenance, and be durable.
1. Fine Bubble Chaipattana Aerator, Model RX-1
2. Low Speed Surface Aerator Chaipattana Aerator, Model RX-2
3. Super Air Bubble Chaipattana Aerator, Model RX-3
4. Venturi Chaipattana Aerator, Model RX-4
5. Chaipattana Air Jet Chaipattana Aerator, Model RX-5
6. Paddle Wheel Chaipattana Aerator, Model RX-6
7. Hydro Air Chaipattana Aerator, Model RX-7
8. Bio-Filter Chaipattana Aerator, Model RX-8
9. Water Fountain Chaipattana Aerator, Model RX-9
The Prototype
His Majesty gave the principles related to the aerator and its function to the Royal
Irrigation Department, Ministry of Agriculture and Cooperatives, on 24 December 1988.[1] The
Office of Water Machine Research and Development of the Royal Irrigation Department's
Workshop Division was given the task of inventing the aerator to treat polluted water. A model
RX-2 and the idea were given for the development of a prototype floating mechanical surface
aerator with propellers to drive and churn the water into a fine spray for a thorough aeration,
quickly oxygenating the water. As the water is lifted to mix with the air and drops back, air
bubbles are created which sink momentarily, transferring oxygen to the water. This type of
aerator is therefore useful in water aeration, agitation and flow direction.
Principles and Operation of the Chaipattana Aerator RX-2

6. 6
This aerator has a water bucket to drive water in a circle and stir it so it mixes with air from
which the oxygen can be rapidly fused. When the dispersed water falls down again, air bubbles
emerge, causing an oxygen evacuation.[1]
Thefloatingmechanicalaeratorcanbeadjustedverticallytosuitthelevelofwatersurface.
Its basic components are:
a. A twelve-sided aerator frame.
b. Six water scoops installed around the frame, each with scoop perforated to
release water in a spray.
c. The scoops are rotated by a motorized gear, which gives them speed and allows
them to force the water down to a depth of about 0.50 m and then splash it up in a spray 1.00 m
above the surface. This results in maximum contact between water and air, which allows oxygen
to dissolve quickly into the water.
d. When the wastewater is lifted to be aerated and then falls, air bubbles also sink
below the surface.
e. When the scoop plunges below the water's surface, a pocket of air is created in
the scoop until it is fully submersed. This enhances the effectiveness of oxygen transfer.
f. The aerated water is then evacuated by the motion of the scoop and the rocking
of the buoy, which combine to add oxygen to water below the surface. Aeration, agitation and
Control of the flow direction thus occur simultaneously.
The machine is capable of treating water pollution with BOD of 250 mg/L at a rate of 600
m3
/day and is effective in reducing BOD by more than 90%. It is extremely cost effective, at only
Baht0.96/m3
orintermsofpollutantsremoved, Baht3.84/kgofBOD.Atpresent,theprivatesector
and many governmental agencies are using this patented invention. The device has thus gone
through several steps and, as the ninth such machine in the world, is of a higher order than
existing inventions, demonstrating His Majesty's capacity and genius.
This aerator used induction motor 1,500 W (2 HP) at 3,000 RPM with gear ratio 1:600 to
make it turns 5 revolution per minute.
Therefore, this Chaipattana Aerator can be utilized as a filter and stirring device, and the
flow of water can be directed. The Royal Irrigation Department has researched and developed
this aerator as four sub-models,

7. 7
Fig.1. Water Wheel Low Speed Floating Mechanical Surface Aerator, Model RX-2-2.
Source: Chaipattana Foundation, January 20, 2012.
Model A (RX-2-1) Water spraying buckets are rotated by the transmitting power system,
using both roller chain and chain sprocket, together with 1:50 reduction gear attached to a two-
horsepower electric motor at 0.9 kgO2hphr-1
(1.21 kgO2kWhr-1
).
Model B (RX-2-2) Water spraying buckets are rotated by the transmitting power system
using 1:300, two-horsepower electric reduction gear motor, driving on one side at 1.2 kgO2hphr-1
(1.61 kgO2kWhr-1
), they have similar operations but different driving power and propellers.
Model C Similar in feature to Model A, but different in application in that it is not stationary
but mobile, this model is used in case of no accessible electric power in the water source. It is
driven by gasoline engine and the direction is controlled by an attendant.
Model D: Water spraying buckets are rotated by 1:50 reduction gear motor, together with
1:6 reduction spur gear, two-horsepower electric motor.
The Results of RX-2-2
The Royal Initiative has produced highly satisfactory results of RX-2-2. It has reduced
water opacity, reduced unpleasant odors and raised the oxygen content of the water. Aquatic
creatures such as turtles, tortoises, and fish can once more inhabit the water safely. Pollutants
and contaminants have been reduced to specified standards. This model has been adopted for
wider distribution as it has proven to be the most efficient and economical model. At present,
various governmental agencies have requested the Chaipattana Foundation, through the Royal
Irrigation Department, to assist expeditiously in the treatment of waste water.
Performance enhancement and development of Model RX-2-3 Aerator
In this research the researchers outlinethe main ideas toward performance enhancement

8. 8
Water Wheel Low Speed Floating Mechanical Surface Aerator, Model RX-2-2 for a standalone
system without battery, reduce power consumption and increase oxygen dissolved in water, RX-
2-3.
This aerator has the same feature as RX-2-2, the different is the wheel turn in opposite
direction as Contra Rotation. It reduces the torque transfer to the fuselage. This causes all power
transfer to the water bucket makes it reduce power.
Fig.2. Contra Rotation Gear with Induction Motor Gear
The researchers also optimize the holes size and pattern. These allows water bucket to
drive water in a circle and stir it in smaller droplet so it mixes with air from which the oxygen can
be better fused. When the dispersed water falls down again, air bubbles emerge, causes an
oxygen evacuation.
Fig.3. Water Wheel Low Speed Floating Mechanical Surface Aerator, Model RX-2-3.
This aerator used induction motor 400 W (1/2 HP) at 1,420 RPM with gear ratio 1:450 to
make it turns 3 revolution per minute. RX-2-3 could direct install with 300 W x 2 PV panels without

9. 9
battery and could operates daily.
Therefore, this Chaipattana Aerator can be utilized as a filter and stirring device, and the
flow of water can be directed. The Royal Irrigation Department has researched and developed
this aerator as two sub-models, Model E (RX-2-3) at higher oxygen dissolved rate, they have
similar operations but different driving power and propellers.
Summary
Holes size and pattern, speed of Water Wheel, and flow rate has effect on power
consumption of Water Wheel Aerator. If optimized it could reduce power consumption and
improve dissolved oxygen in water. Contra Rotation could reduce fatigue in fuselage and transfer
most of power to drive water wheel. RX-2-3 could use induction motor 400 W (1/2 hp) 1,420 RPM
with gear ration 1:450 at water bucker speed 3 revolution per minute. PV panels 300 W x 2 without
battery. It isexpected tooperate daily athigh oxygen transferrate. This model is expected to face
wider distribution due to its’ high efficiency and low cost.
References
1. Chaipattana Low Speed Surface Aerator, Model RX-2, Chaipattana Foundation, Bangkok,
Thailand, 48/08-008 RX-2 ONE BLUE, 21 August 2006.
2. Tucker, Craig. Pond Aeration SRAC Factsheet 3700. Southern Regional Aquaculture
Center, September 2005.
3. Bolles, Steven A. "Modeling Wastewater Aeration Systems to Discover Energy Savings
Opportunities." Process Energy Services, LLC. November 2006.
4. "Lake Aeration and Circulation". Illinois Environmental Protection Agency. Retrieved 13
September 2009.
5. United States Environmental Protection Agency (September 1999). "Wastewater
Technology Fact Sheet: Fine Bubble Aeration." Office of Water. Washington DC.
6. Taparhudee, Wara (2002). "Applications of Paddle Wheel Aerators and Diffused-Air
System in Closed Cycle Shrimp Farm System". www.aseanbiotechnology.info
7. Meck, Norm (1996) Pond Water Chemistry, Dissolved Oxygen, Koi Club of San Diego,
Revised August 26, 1996.
8. The Chaipattana Aerator's History, Research and Development, Chaipattana Foundation,
24 December, 1988.