A Study of Nitrogen Dynamics in an Integrated Stellate Sturgeon and Spinach Aquaponic System with Different Crop Densities

Abstract

Obtaining and maintaining a healthy, productive aquaponic system requires intensive scienti ic research, monitoring and also adjustments, when necessary. To quantify the nitrogen budget for a stellate sturgeon-spinach integrated LECA grow bed aquaponic system, where three plants densities were used. The experiment was made in triplicate, using a 12 aquaponic units LECA grow bed aquaponic system. Three crops densities were used (V1-59crops/m 2 , V2-48crops/m 2 and V3-39crops/m 2 and V4-no crops, only with LECA grow bed). Fish were were fed with 41% brute protein feed, at an average feeding ratio of 1.75% of total biomass. Water samples were taken and analysed by using photometric methods (Merck kits). The stellate sturgeon meat, spinach and also faeces nitrogen content was determined by Kjeldahl method. Differences between the removal rates for each of the three variants of tested crops densities were signi icant higher (p<0.05) at V1 compared to V3 and also higher at all three variants comparing them to the control variant. The amount of ammonium removal rates from bio ilter and LECA grow bed was signi icant (p<0.05). Also, differences between spinach nitrogen composition from V3 compared to V1 were found signi icant higher (p<0.05). The nitrogen content from ish meat and ish faeces was found to be within normal limits, appear also in the literature. Considering the nitrite and nitrate concentrations, only spinach grown in aquaponic conditions, as presented above, at densities of 59crops/m 2 , is marketable. In addition, it can be concluded that spinach growth in LECA grow bed aquaponic systems have a higher nitrogen content, comparing with the one growth using loating rafts technique.

Life cycle assessment (LCA) and Techno-economic analysis (TEA) of tilapia-basil aquaponics

“…The study conducted by Petrea et al in 2013 concluded that the nitrite and nitrate content of spinach could be affected by plant density, and they also stated that spinach-trout aquaponics met food safety requirement (Petrea et al, 2013). Some studies focused on the hydraulic loading rate and plant ratio (Endut et al, 2010); while others focused on calcium and phosphorous dynamic (Petrea et al, 2014).…”

“…The study conducted by Petrea et al in 2013 concluded that the nitrite and nitrate content of spinach could be affected by plant density, and they also stated that spinach-trout aquaponics met food safety requirement (Petrea et al, 2013). Some studies focused on the hydraulic loading rate and plant ratio (Endut et al, 2010); while others focused on calcium and phosphorous dynamic (Petrea et al, 2014). A study conducted by Liang and Chien in 2013 suggested that increasing feeding frequency and extending photo period would increase fish and plant yield, and decrease water nitrogen and phosphorus accumulation ( Liang and Chien, 2013).…”

Life cycle assessment (LCA) and techno-economic analysis (TEA) of various biosystems

“…No LCA or TEA has been conducted to DDGS fractionation. There are some researches (Bailey et al, 1997;Rokacy, 2004;Villarroel et al, 2011;Petrea et al, 2013;Bunyaviroch et al, 2013;Sace and Fitzsimmons, 2013; Love et al, 2014; 2015) on aquaponics, including nutrient cycle and economic cost and profit of various aquaponics systems, but no complete LCA and TEA has been conducted to aquaponics located on mainland of U.S., which indicates there are some data gaps to explore more in the future.…”

“…Recently, researches mainly focused on how to optimize aquaponics operation. The study conducted by Petrea et al in 2013 concluded that the nitrite and nitrate content of spinach could be affected by plant density, and they also stated that spinach-trout aquaponics met food safety requirement (Petrea et al, 2013). Some studies focused on the hydraulic loading rate and plant ratio (Endut et al, 2010); while others focused on calcium and phosphorous dynamic (Petrea et al, 2014).…”

“…The study conducted by Petrea et al in 2013 concluded that the nitrite and nitrate content of spinach could be affected by plant density, and they also stated that spinach-trout aquaponics met food safety requirement (Petrea et al, 2013). Some studies focused on the hydraulic loading rate and plant ratio (Endut et al, 2010); while others focused on calcium and phosphorous dynamic (Petrea et al, 2014). A study conducted by Liang and Chien in 2013 suggested that increasing feeding frequency and extending photo period would increase fish and plant yield, and decrease water nitrogen and phosphorus accumulation ( Liang and Chien, 2013).…”