Development and experiment of movable pond aquaculture water quality regulation machine based on solar energy

Abstract: Pond aquaculture plays a very important role in China's aquaculture industry and is the main source of aquatic product supply. For the regulation and control of pond aquaculture water quality, a movable pond aquaculture water quality regulation machine based on solar energy (SMWM) was designed and the prototype had been manufactured. This machine is solar-powered and can move upon the water, mainly consisted of solar power device, sediment lifting device, water walking device and working control system. The solar power device provides power for the entire machine, while the water walking device drives the whole equipment moving on the water. The sediment lifting device orbits around the main part of the equipment (the solar power device, water walking device and working control system), affecting large area of pond. Tests on the mechanical properties revealed that the minimum illumination of SMWM becoming working was 13 000 lx; The no-load running noise was 68 dB; The moving speed upon the water was 0.02-0.03 m/s. In the illumination intensity of 13 000-52 500 lx, the running speed of the sediment lifting device orbiting around the main part was 0.13-0.35 m/s, the capacity of water delivery was 110-208 m3/h. Illumination intensity was an important factor influencing the moving speed and capacity of water delivery of the sediment lifting device. The stronger of illumination intensity was, the values of moving speed and water delivery capacity higher. The sediment lifting device was foldaway and the angle of suction chamber can be adjusted. By adjusting the angle, the machine can work well in ponds with different water depthes from 0.5 m to 2 m. The sucking sediment performance of sediment lifting device was related to the distance of suction mouth of lifting device to pond bottom. The smaller of the distance was, the more sediment being sucked to the surface water. In aquaculture pond, the most suitable distance was 10-15 cm. Moreover, by adjusting the length of connecting rod and the direction of traction rope, the working area of the machine can be more than 80%. For the water quality, the using of SMWM in pond aquaculture caused decreased TN, NH3+-N and NO2--N concentrations and increased TP concentration in water. The content of TN and available phosphorus in sediment was reduced. These findings implied that the SMWM could promote the transformation of nitrogen and phosphorus nutrients in water. In addition, results from fish production showed that the SMWM caused the yields of feed-eating fish and filter-feeding fish enhanced by more than 30% and 25%, respectively. The feed coefficient of the feed-eating fish was decreased by more than 24%. In an entire aquaculture period, the machine saved the electrical power by more than 2 400 kW. These results indicated that the SMWM might be suitable for pond aquaculture in China. Its structure and working performance had met the design requirement. The SMWM possesses the advantages of stable operation, large working area, good water quality regulation effect and notable yield-increasing effect. Applying this machine in pond aquaculture for the regulation and control of water quality is feasible.