DESCRIZIONE
The invention relates to a bioreactor 20 for treating at least one fluid and/or cultivating phototrophic organisms, comprising at least one fluid path and at least one first substrate 29. The first substrate 29 is permeable to fluid but impermeable to phototrophic organisms and comprises at least one first surface 30 for carrying the phototrophic organisms, wherein the first substrate 29 is disposed such that at least the first surface 30 is exposed to ambient air. The first substrate 29 further comprises at least one second surface which is at least partially in contact with the fluid path. According to the invention a circuit for circulating the fluid is provided, wherein the circuit comprises the fluid path and at least one fluid processing unit 28 which is in fluid communication with the fluid path. The invention further concerns an arrangement comprising the bioreactor, wherein the bioreactor is in fluid communication with at least one aquaculture system and waste water derived from the aquaculture system is processed in the bioreactor and then recirculated to the aquaculture system. The invention also relates to a method for treating at least one fluid and/or cultivating phototrophic organisms, wherein the fluid is processed by means of the fluid processing unit. [Image Omitted]