Performance of energy-saving water exchange device used in tidal wetland to improve water quality

1. Associate Professor, Department of Bioenvironmental Systems Engineering. National Taiwan University, Taiwan2. Corresponding Author, Ph.D Candidate. Department of Bioenvironmental Systems Engineering. National Taiwan

University, Taiwan (f92622045@ntu.edu.tw)3. Research Fellow, Biodiversity Research Center, Academia ,Taiwan4. Post Doc., Biodiversity Research Center, Academia ,Taiwan

Hou Wen-Shang 1, Teng Te-Hui* 2, Hsieh Hwey-Lian 3, Chen Chang-Po 3 and Huang Shou-Chung 4Geophysical Research AbstractsVol. 13, EGU2011-10155-4, 2011EGU General Assembly 2011© Author(s) 2011

Abstracts In natural waters, the stratification will happen to environmental conditions changes such as surface velocity, water temperature, depth, and dissolved oxygen. When the water depth closed to the sediment, water quality was usually present in inferior situation. Aerators, use to enhance water quality in lakes and reservoirs recent year is a physical purification without add chemical agents (for example: Alum) and the makeup water will not produce harmful substances. Aeration tally with the environment friendly concept of dealing with corrupt water and has good economic returns and improving efficiency. Continuous type aerator has a characteristic that consumes higher energy and cause the massive water bodies becoming turbulence under high-power motor operate. Turbulence will break the stratification fast and elevate dissolved oxygen. Under mixing action in the water will disturb original fish and the algae perches in different depth. Hwa-Chiang waterfowl habitat is located in the heart of Taipei. Its core area, Taipei City Waterfowl Reservation, is one of internationally important tidal wetlands and has been designated as important bird area. However, the wetland has faced urban water pollution. This study focus on ecological conditions of the Hwa-Chiang waterfowl habitat used artificial tidal pond and Solar Energy Air-Lift Column (SEALC) to enhance water quality and habitat ecological biodiversity. SEALC is a water exchange device which consumes 3.5 watts motor continuous inject air into the air chamber, when the air chamber accumulate different amount of air with depths, and intermittent large bubble produced by buoyancy driven water exchange. Established long-term measurement data of environment conditions to monitor system efficient, parameters included dissolved oxygen (DO) distribution, sediment oxygen demand (SOD), ORP, velocity and water temperature. Operate conditions such as water exchange capacity, economic benefits and working efficiency will be discussed.

Waterfowl habitatTidal wetland

Sediment accumulation

HabitatDeterioration

Metro

po

lis sew

age F

oo

d

Def

icie

ncy

No Sediment Erosion

Not interrupt aquatic organism

Ecosystem protection

Green energy

Enhance water quality

Low turbulence

Principles of SEALC

for Waterfowl habitat

Tidal pond elevation diagram N 25˚02’16.8” E 21˚29’21.1”

Taipei city, Taiwan

Longterm monitored SOD value of Hwa-Chiang waterfowl habitat

0

5

10

15

20

25

30

3/11

/200

9

5/11

/200

9

7/11

/200

9

9/11

/200

9

11/1

1/20

09

1/11

/201

0

3/11

/201

0

5/11

/201

0

7/11

/201

0

9/11

/201

0

11/1

1/20

10

1/11

/201

1

SOD

( g

/ m

2 / d

)

Original After SEALC treated area

SPECIFICATIONS OF POWER SYSTEM

28.5*11.5*160.5ADC12V300 pondAir compressor

29*15*201.1ADC12VChallengeAir pump

-2VADC12VAnlyTimer

35*17*18-DC12VYUASABattery

Power system

29*15*201.1ADC12VChallengeAir pump

-2VADC12VAnlyTimer

20*17*17-DC12VYUASABattery

66*31*2MAX20WDC16.8VSUNTECHSolar board

Solar board system

L*W*H (cm)PowerVoltageBrand

Economic Analysis

609.7660

914.63100

350.6120

198.1712

137.26

76.223.5

Operating Cost ( ＄.)Electricity power (Watt)

1. The price not includes solar board.

2. Exchange rate is 1 US. Dollar = 32.8 NT. Dollar

3. In Taiwan 1 kw*Hr electricity costs 2.6 NT. Dollar.

SUITABLE POWER USE SUGGESTIONWater depth (m) Ⅰ Ⅱ Ⅵ

≦1 3.5w 3.5w 3.5w＞1～3 3.5w 3.5w 6w＞3～10 6w 6w 6w＞10～20 12w 12w 12w＞20～30 60w 60w 60w＞30 ＞60w ＞60w ＞60w

Result

Flow fieldMethod

1.0Water depth (m)

78.5area (m2)

10.0Diameter (m)

Water diffusion

1.56±0.04SAE (kgO2/hr/kw)

(3.37±0.12)×10-3SOTR (kgO2/hr)Standard Aeration Efficiency

3.6~22.2Intermittent time (Sec)

178.8Water capacity per NT. (max)

0.016Electricity consumption per NT.

0.006Electricity consumption ( kw / hr)

13000Cost (NT.)

Time

¤ô

¦ì

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

DO

(pp

m)

0

1

2

3

4

5

´éª@¬W¥X¤ô¤f DO (ppm)¼é¦Á ¶Z´éª@¬W1M¤ô ±¤U10¢QDO¶Z´éª@¬W5M¤ô ±¤U10¢QDO

2010/1/15 2010/1/16 2010/1/17 2010/1/18

Dissovled Oxygen of Hwa-Chiang waterfowl habitatLongterm monitored ORP value of Hwa-Chiang waterfowl habitat