Influence mechanisms of macro‐infrastructure on micro‐environments in the recirculating aquaculture system and biofloc technology system

Abstract

Aquaculture intensification has emerged as a potential sustainable aquaculture strategy to contribute to the Food and Agriculture Organisation's United Nations Sustainable Development Goals associated with food security. Recirculating aquaculture systems (RASs) and biofloc technology systems (BFTs) are typical land-based intensive aquaculture facility models that have been widely researched and applied.The rapid growth of both systems has boosted human nutrition and the regional economy but has also caused concerns about animal welfare, ecological protection, water treatment effectiveness and public health. One of the key links between aquaculture and ecological issues is the treatment of harmful particulates in wastewater, particularly organic metabolic microparticles. These microparticles are derived from decomposition waste feed, faeces and biofilm and provide a surface for bacterial growth and proliferation. The increase in microparticle abundance can directly affect bacterial activity and abundance and adversely affect the environment. Furthermore, the decomposition and motion of these particles are related to the mechanical stress caused by the water flow pattern in aquaculture tanks. The internal configurations of the tank can control the hydrodynamic characteristics, such as the water velocity, uniformity, pressure and turbulence in aquaculture tanks, and thus influence the morphology of particles. This review analyses and discusses how macro-infrastructure influences the microenvironment in aquaculture tanks. These results provide a theoretical foundation and practical implications for improving the performance of aquaculture systems and environmental management in intensive aquaculture. It is concluded that optimisation of infrastructure design is key to improving the water flow patterns and self-cleaning performance of tanks and achieving high efficiency of RASs and BFTs, and is critical for the fulfilment of the Sustainable Development Goals in aquaculture.

Investigation of the inlet layout effect on the solid waste removal in an octagonal aquaculture tank

“…However, these investigations were mainly focused on the effect of single factors on the tank performance and did not consider the possible effect of turbulence generated by the interaction between the jetting position and the jetting angle. Significantly, Zhao et al (2022) pointed out that flow velocity in culture tanks can be adjusted to provide much higher swimming speeds and thus effectively exercise fish. Therefore, the design of the velocity must meet the self-cleaning ability and speed requirements of the fish growth jointly in actual aquaculture engineering.…”

“…Generally, aquaculture tanks are fabricated in five geometries, including rectangular, circular, octagonal, rectangular round chamfering, and runway. Among these geometries, octagonal tanks are easier to handle and construct than other tanks so that octagonal tanks have been more common in operational production (Zhao et al, 2022). Davidson and Summerfelt (2004) studied the effects of the inlet structure on the self-cleaning features of large circular aquaculture tanks and found that the appropriate direction of the inlet structure increases the rotation velocity in the tank.…”

“…The octagonal RAS tank is a common culture tank with good space management, shared side walkways, and homogeneous fluid mixing, which is widely used in aquaculture farms. Considering the production and welfare of animals in intensive aquaculture, the design and application of octagonal tanks should be given more attention in future research (Xue et al, 2021;Zhao et al, 2022). However, there is no in-depth investigation of the effects of inlet layout on the performance of octagonal RAS tanks.…”

Circular bio‐economy in aquaculture

“…With regard to Conceptualizing and/or designing circular production systems , we called for ‘Circular production systems, such as aquaponics, integrated multi‐trophic aquaculture systems, etc.’. For this topic, four interesting reviews emerged, one relevant for marine aquaculture, 18 two relevant for inland aquaculture 19 and one for both 20,21 . Some lesser known approaches were taken to the forefront by Garibay‐Valtez et al, 20 Lothmann and Sewilam, 18 and Zhao et al, 21 while promising solutions were revisited from a wider industry perspective by Marousek et al 19 …”

“…For this topic, four interesting reviews emerged, one relevant for marine aquaculture, 18 two relevant for inland aquaculture 19 and one for both 20,21 . Some lesser known approaches were taken to the forefront by Garibay‐Valtez et al, 20 Lothmann and Sewilam, 18 and Zhao et al, 21 while promising solutions were revisited from a wider industry perspective by Marousek et al 19 …”