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You are here : eLibrary : IAHR World Congress Proceedings : 35th IAHR Congress - Chengdu (2013) : THEME 2 - JOHN F. KENNEDY STUDENT PAPER COMPETITION : Experimental Study of Bio-fouling Control of Limnoperna Fortunei in Water Transfer Tunnels
Experimental Study of Bio-fouling Control of Limnoperna Fortunei in Water Transfer Tunnels
Author : Mengzhen Xu
The golden mussel (Limnoperna fortunei) is a filter-collector macroinvertebrate species originating from southern China. It easily invades water transfer tunnels and attaches onto tunnel walls and structures with extremely high density, resulting in bio-fouling, pipe clogging, structure corrosion, a decrease in water transfer efficiency, and water pollution. It has become a prevalent problem and has caused concern all over the world. However, an effective and environment-friendly method of controlling golden mussel invasions has not been found yet. This study is aimed to find measures that would prevent golden mussel invasion and bio-fouling in the water transfer tunnels of the East River Water Source Project (ERWSP), which transports water from the East River to Shenzhen, southern China for 10 million people?s production and daily life. Long-term samplings and observations of East River water were performed to study the golden mussel?s invading pattern. Flume experiments were done to study the golden mussel?s attachment onto 14 different materials and performance in turbulent flows. Measures of preventing golden mussel invasion in tunnels were proposed based on the experimental results. Furthermore, an integrated ecological prevention pool was designed and constructed for experimental study of golden mussel invasion prevention in scale model tunnels of the ERWSP. Results of long-term observations indicated that the golden mussel underwent the planktonic veliger stage in water. The planktonic veligers invaded into tunnels with water flow, and attached and developed into mussels on the tunnel walls. Attachment experiment results showed that after golden mussels attach to the tunnel wall, they successively experienced an unstable veliger-attachment stage and then a stable mussel-attachment stage with their byssuses. Golden mussels preferred geotextile cloth during the unstable attachment stage, but preferred bamboo material during the stable attachment stage. When the golden mussels attached stably on materials, the attachment force positively correlated to the mussel length. The average flow velocity that caused golden mussels to dislodge from materials showed a linear relationship with the product of the number and average diameter of the byssuses used for attaching. Flume experiment results indicated that the veligers were killed in high-frequency turbulence when the eddy scale was comparable with the veliger size. The killing rate of veligers positively correlated with the average flow velocity and action time of the turbulence. The integrated pool was designed to prevent golden mussel veligers from entering into tunnels by attracting veligers to attach onto geotextile cloth, attracting mussels to attach on bamboo, and killing veligers with high-frequency turbulence. An eight-month experiment of the pool showed that this method successfully controlled the golden mussel invasion and bio-fouling in the model tunnels. The mussel density on the attachment materials decreased sharply when the distance of the materials from the pool entrance increased; the turbulence was effective in killing veligers that escaped from the attachment materials. Absolutely no golden mussel attached on the model tunnels. Thus, the measure used in the integrated ecological prevention pool is recommended as a successful measure for controlling the golden mussel invasion and bio-fouling in water transfer tunnels.
File Size : 950,659 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 35th IAHR Congress - Chengdu (2013)
Date Published : 18/07/2016
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