Experimental study on control of Limnoperna fortunei biofouling in water transfer tunnels

Abstract

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 biofouling, 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 invasion has not yet been approved. This study is aimed to propose measures for preventing golden mussel invasion and biofouling in the water transfer tunnels of the East River Water Source Project (ERWSP), which transfers water from the East River to Shenzhen, southern China for 10 million people. Long-term samplings and observations of the East River water were performed to study the golden mussel's invading pattern. Flume experiments were done to study the golden mussel's attachment on 14 different materials and performance in turbulent flows. An integrated ecological prevention pool was designed and constructed based on the flume experimental results for preventing the golden mussel invasion in the scale model tunnels of the ERWSP. The major technology of the ecological pool was preventing the golden mussel from entering the tunnels by attracting veligers to attach on geotextile cloth, attracting mussels to attach on bamboo, and killing veligers with high-frequency turbulence. An eight-month application experiment showed that the ecological pool successfully controlled the golden mussel invasion and biofouling in the scale model tunnels. The mussel density on the attachment materials decreased sharply as the distance of the materials from the pool entrance increased; the turbulence was effective in killing veligers that escaped from the attachment materials. No mussel was found on the model tunnels. Thus, the integrated ecological prevention pool is recommended as a successful measure for controlling the golden mussel invasion and biofouling in water transfer tunnels.