APPLICATION OF WATER PURIFICATION TECHNOLOGY IN INTENSIVE SHRIMP CULTURE Lai Qiuming 1 *, Yang Yi 2,3, and Qiu Yunhao 1 1.College of Ocean, Hainan University, Haikou , Hainan province, China 2.College of Aqua-Life Science and Technology, Shanghai Fisheries University, Shanghai , China 3.Sichuan Aquacultural Engineering and Technology Research Center, Chengdu , Sichuan province, China

AquaFish CRSP USAID 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 The opinions expressed herein are those of the authors and do not necessarily reflect the views of the US Agency for International Development.

1.Background Shrimp farming has been a fast-growing industry especially in southern China. However, along with its development, waste water from shrimp farms has continuous contribution of nutrients that adds to eutrophication at different levels. Due to high stocking density, water quality is more and more difficult to be controlled in intensive shrimp ponds. In latter period, white-leg shrimp Penaeus vannamei often die because of poor water quality, which has seriously affected the farming efficiency of Penaeus vannamei.

2. Purpose of Study 1 ） Use filtration and foam separation techniques to enhance the water purification capacity of shrimp pond; To improve water quality and reduce the discharge of waste water; And to protect the environment of coastal area. 2 ） By recycling flow in the closed pond system, water mixes better than before, which leads to the improvement of water quality and less death of shrimp. Thus, the economic returns of shrimp culture is enhanced.

3. Parameters of water quality monitoring （ 1 ） DO （ 2 ） COD （ 3 ） NO N （ 4 ） NO N （ 5 ） Total ammonia （ 6 ） PO P

Figures 1. The work flow chart of water purification Filtering tank Foam separating tank Sampling point 1 Sampling point 3 Sampling point 4 Pump Paddle wheel aerator Sampling point 2

5. Research Design 1)Experimental site: Wanning Biotechnology Co., Ltd. Hainan province, China. 2)Experimental period ： Oct 2, 2006 ~ Oct 6, )Experimental pond ： size-2000 m 2, water depth m; with plastic membrane in the bottom and four sides; central drainage located at pond’s bottom; four paddle wheel aerators located evenly in the pond; white-leg shrimp Penaeus vannamei (average body weight: 5.2 g/piece); stocking density about 200 piece/ m 2. 4)During the experiment period, no water exchange. Water purification treatment systems work 24 hours per day. Water samples are collected once at 7:00 am every day.

（ 1 ） Before filtration （ 2 ） After filtration （ 3 ） Waste water （ 4 ） After Foam separation （ 5 ） Waste water

6. Results and analysis Table 1 DO Concentration of different water sample Unit ： mg/L Date Before After After foam Pond side filtration filtration separation （ Before the system operation ） ~+60.6%

Table 2 COD concentration of different water sample Unit ： mg/L Date Before After After foam Pond side filtration filtration separation （ Before the system operation ） ~ -4.57% ~ -3.60%

Table 3 NO 2 - -N concentration of different water sample Unit ： mg/L Date Before After After foam Pond side filtration filtration separation （ Before the system operation ）

Table 4 NO 3 - -N concentration of different water sample Unit ： mg/L Date Before After After foam Pond side filtration filtration separation （ Before the system operation ）

Table 5 a mmonia concentration of different water sample Unit ： mg/L Date Before After After foam Pond side filtration filtration separation （ Before the system operation ） ~22.7%

Table 6 PO 4 + -P concentration of different water sample Unit ： mg/L Date Before After After foam Pond side filtration filtration separation （ Before the system operation ）

Conclusions Results indicated that the shrimp feces and suspending organic particles were removed effectively by filtration and foam separation. The drum filtration reduced COD by 1.88% % and total ammonia nitrogen by 15.02% %, while the foam separation reduced COD by 1.78% % and increased dissolved oxygen by 39.3% %.

The application of wastewater treatment system not only improves the water quality, but also reduces wastewater discharge to the environment. Results also suggested that NO N, NO N and PO P can not be removed from the filtration and foam separation tanks. The purification system is simple, and easy to operate. It is useful for water mixing and is effective to reduce the death of shrimp in the pond’s bottom.

Thanks for your attention!