Fish farm effluents are suitable growth media for Nannochloropsis gaditana, a polyunsaturated fatty acid producing microalga

Abstract

Fish farm effluents may be used as culture media for marine microalgae, the cell mass of which constitute an excellent fish feed rich in bioactive compounds. In the current investigation different fish farm effluents were tested as culture media for Nannochloropsis strains. Among them, Nannochloropsis gaditana grew well on the effluent released from the sedimentation tank (EST), which is the final step of the wastewater treatment. Mono‐algal but non‐aseptic cultures were conducted in two types of photo‐bioreactors, namely stirred tank reactor (STR) and open pond simulating reactor (OPSR) working under various photoperiods. N. gaditana grew well under full illumination mode on phosphate rich EST in the STR, producing 847.0 mg/L of dry cell mass containing 7.8%, w/w lipids, while when cultivated on phosphate limited EST, cell mass production was slightly lower but lipid biosynthesis was favored, with the lipid content reaching 24.7%, w/w in dry cell mass. In all trials, Nannochloropsis cell mass contained significant quantities of proteins and polysaccharides. Neutral lipids were predominant over polar lipids. Both glycolipid and phospholipid fractions were rich in polyunsaturated fatty acids, especially in eicosapentaenoic acid. We conclude that fish farm wastewaters can be re‐used as microalgae growth media, which is of financial and environmental importance.

Mixotrophic cultivation of Spirulina platensis in dairy wastewater: Effects on the production of biomass, biochemical composition and antioxidant capacity

“…The biomass yields and growth rates of S . platensis observed in this study were higher than those observed in the studies reported by Tsolcha et al [16], Economou et al [36] and Dourou et al [37]. All of these microalgae cultivations were performed under non-aseptic conditions that, despite minimizing the cost of the process, led to lower biomass yields.…”

The Circular Economy Approach to Improving CNP Ratio in Inland Fishery Wastewater for Increasing Algal Biomass Production

“…Nutrients such as nitrogen and phosphorus are the main ones responsible for eutrophication in water bodies nearby fishery production sites [10]; therefore, the removal of those nutrients is a critical step to prevent negative impacts on the local water environments [11,57]. Wastewater was analyzed for the content of nitrates, phosphates, and other parameters required to identify the quality of the water (Table 1).…”

“…The application of microalgal cultures as a sustainable process for the removal of nutrients has been studied on wastewater from Oreochromis niloticus [3,20,22,[24][25][26]38], Lates calcarifer [8], shrimp culture [29][30][31], Mugil cephalus [10,32], Sparus aurata [10,16], Scophthalmus maximus [39], and even synthetic wastewater [32,36]. According to the results, the percentage of NO 3 removed (>95%) is similar to that reported by most authors; however, the rate of PO 4 was lower than other authors since the wastewater was supplemented with external P.…”

“…The latter contributes to the sustained increase in organic residues and toxic compounds in aquatic systems [9]. Nutrients such as nitrogen Water 2022, 14, 749 2 of 16 and phosphorus are the main ones responsible for eutrophication in water bodies nearby fishery production sites [10]; therefore, the removal of those nutrients is a critical step to prevent negative impacts on the local water environments [11].…”

Space Aquaculture: Prospects for Raising Aquatic Vertebrates in a Bioregenerative Life-Support System on a Lunar Base

“…To return treated water back to the fish tank, it can be cleaned so it is safe for fish growth and welfare (Mladineo et al, 2010). Moreover, fish farm effluent is a suitable media for cultivating Nannochloropsis gaditana, a marine algae with a high PUFA content (Dourou et al, 2018). Several studies have reported the possibility of feeding aquaculture fish with microalgae (mostly marine) included in the fish feed formulation.…”