BIOFILM START-UP ON DIFFERENT BIOFILM START-UP ON DIFFERENT

FILTER MEDIAFILTER MEDIA

Min Jiang, Weiwei Miao, Chunfang LuoMin Jiang, Weiwei Miao, Chunfang Luo

Shanghai Ocean UniversityShanghai Ocean University

Apr 21, 2023Apr 21, 2023

AquaFish CRSPUSAID

Travel funding for this presentation was provided by

AquaFish Collaborative Research Support

Program

The Aquaculture CRSP is funded in part by United States Agency for International

Development (USAID) Grant No. EPP-A-00-06-00012-00.The opinions expressed herein are those of the authors and do not necessarily reflect

the views of the US Agency for International Development.

• Introduction

• Materials and methods

• Results and discussion

• Conclusions

Filter media

• Introduction

Aquaculture industry

Environmentally friendly technologies

Recirculating system

Water quality

diseases

Environmental impacts

Bio-filter system

• Materials and methods

Aquaculture waste water

pH 8.12

TAN-N (mg/L) 32.95

NO2-N (mg/L) 6.69

NO3-N (mg/L) 2.81

PO4-P (mg/L) 5.60

CODMn (mg/L) 82.37

Alk (mmol/L) 2.62

HT (mmol/L) 4.92

General conditions of the recirculating system

Volume of Waste water: 10L

Volume of Filter: 220mL

Velocity of flow: 63.3L/h

DO: 7.5±0.23mg/L

Water quality of the initial aquaculture waste water

for biofilm start-up

Bio-fiber fill Netlike plastic fill plastic ball

coral sand porcelain ring

Five kinds of

filter media

During the first 108h, water samples for quality analyses were collected from the tank every 12h. (8:30 & 20:30)

After that, samples were collected every 24h. (8:30)

The whole experiment lasted for 22days.

pH

Environmental quality standards

for surface water

GB 3838—2002

People’s Republic of China

TAN-N

NO2-N

NO3-N

PO4-P

CODMn

Alk

HT

• Results and discussion

Concentrations of TAN,NO2-N and NO3-N in thebiofilter with coral sand media

0

10

20

30

40

50

60

0 5 10 15 20 25Time(d)

Con

c.(m

g/L

)

TAN

Nitrite-N

Nitrate-N

Nitrite increased corresponding to the rapidly decreasing of TAN during the first phase of start-up and kept growing up for 6 days after TAN had reached a steadily low level. While nitrate increased during all the experimental period.

Concentrations of TAN, NO2-N and NO3-N in the biofilter with coral sand media changed regularly.

Same situation happened in biofilters with the other four media while the days needed to reach the stable low concentration of NO2-N were different.

Fig.2 Nitrite-N concentrations in the biofilterswith different media

0

10

20

30

40

50

60

0 5 10 15 20 25Time(d)

NO

2-N

(mg/

L)

bio-fibre fill

netlike plastic fill

plastic ball

coral sand

porcelain ring

During the start-up period, coral sand media showed the best efficiency of turning TAN to NO2-N and then NO3-N. NO2-N was less than 1.0 mg/L after 12 days.

Netlike plastic fill and porcelain ring were the worst.

The intervenient were plastic ball and bio-fibre fill.

Bio-fiber Netlike plastic

plastic ball

coral sand

porcelain ring

pH and Total alkalinity decreased rapidly during first several days and then increased slowly to stable values. The biofilter with coral sand media had higher pH and alkalinity than others.

Changes of pH duri ng bi ofi l mstart- up peri od

4

5

6

7

8

9

0 2 4 6 8 10 12 14 16 18 20 22 24

t i me(d)

pH

bi o- fi bre fi l lnet l i ke pl ast i c fi l lpl ast i c bal lcoral sandporcel ai n r i ng

Changes of Al kal i ni ty

0. 00

1. 00

2. 00

3. 00

4. 00

0 2 4 6 8 10 12 14 16 18 20 22 24

t i me d（ ）

Amm

ol·

L-1

（）

bi o- fi bre fi l lnet l i ke pl ast i c fi l lpl ast i c bal lcoral sandporcel ai n r i ng

pH and Total alkalinity decreased rapidly during first several days and then increased slowly to stable values. The biofilter with coral sand media had higher pH and alkalinity than others.

Hardness in five filters nearly doubled after 22 days. Hardness in filters with coral sand, bio-fibre fill and porcelain ring were higher than the other two.

Changes of Hardness

0

2

4

6

8

10

12

0 2 4 6 8 10 12 14 16 18 20 22t i me d（ ）

Htmm

ol·

L-1

（）

bi o- fi bre fi l lnet l i ke pl ast i c fi l lpl ast i c bal lcoral sandporcel ai n r i ng

Phosphate-P was consumed. Biofilters with coral sand and porcelain ring had less phosphate-P than others.

Changes of PO43- - P

0. 00

2. 00

4. 00

6. 00

8. 00

10. 00

0 2 4 6 8 10 12 14 16 18 20 22

t i me d（ ）

PO43-

-Pmg

·L

（-1

）

bi o- fi bre fi l lnet l i ke pl ast i c fi l lpl ast i c bal lcoral sandporcel ai n r i ng

Different ability of COD removal was approved in 5 biofilters.

Removal rate of COD

0

20

40

60

80

100

0 5 10 15 20 25

time(d)

rem

oval

rate

(%)

bio-fibre fill

netlike plastic fill

plastic ball

coral sand

porcelain ring

• conclusionsChange of water quality: regularity

Biofilm start-up: coral sand media> plastic ball≈ bio-fibre fill > Netlike ≈ porcelain ring

Advantage(1)Biofilm forming rapidly(2)Alkalinity and pH buffer(3)Higher consumption of

phosphate(4)Relatively higher COD

removal

Disadvantage (1)Increasing hardness(2)Heavy

coral sand

Thanks for your attention