Effect of a Parabolic Screen Filter on Water Quality and Production of Nile Tilapia (Oreochromis niloticus) and Water Spinach (Ipomoea aquatica) in a Recirculating Raft Aquaponic System

Abstract

Aquaponics is an integrated fish and plant recirculating production system. Solid fish waste must be removed from the production system to maintain optimal water quality parameters for fish and plant health. The University of the Virgin Islands (UVI) raft aquaponic system's primary treatment device for solids removal is a cylindro-conical clarifier; however, alternative mechanical filtration devices such as a parabolic screen filter (PSF) may offer advantages. The objectives of the elevenweek experiment were to compare water quality parameters, Nile tilapia (Oreochromis niloticus) production and water spinach (Ipomoea aquatica) production in a raft aquaponic system using either a cylindroconical clarifier or parabolic screen filter for primary treatment of solids in the waste stream. Effect of Screen Filter on Production of Tilapia and SpinachInternational Journal of Recirculating Aquaculture 12 (2011) The water quality results showed no significant differences (P > 0.05) between treatments for temperature, oxygen, pH, alkalinity, EC, TAN, NO 2 -N and NO 3 -N, macronutrients and micronutrients concentrations, with the exception of copper and zinc. There was no significant difference (P > 0.05) between treatments for the total suspended solids (TSS) concentration entering either primary filtration device; however, there was a significant difference (P ≤ 0.05) between treatments for TSS concentrations exiting the primary filtration device. The PSF treatment had a significantly higher (P ≤ 0.05) TSS concentration exiting the unit and a significantly higher (P ≤ 0.05) TSS concentration in the secondary treatment device (net tank) compared to the clarifier.There were no significant differences (P > 0.05) between treatments for Nile tilapia production, average weight, survival, or feed conversion ratio. There were no significant differences (P > 0.05) in water spinach production or plant tissue analysis between treatments. In conclusion, the PSF used in this experiment performed less effectively in removing TSS compared to the clarifier, would require more labor to clean and would not be recommended for use in a larger raft aquaponic system. In addition, water spinach assimilated dissolved fish wastes well and grew vigorously in the raft aquaponic system.

Alternative Solids Removal for Warm Water Recirculating Raft Aquaponic Systems

“…There were no significant differences ( P ≥ 0.05) between treatments for temperature, oxygen, pH, alkalinity, EC, TAN, NO 2 ‐N, and NO 3 ‐N (Table ). All aforementioned parameters were within optimal ranges for a raft aquaponic system producing tilapia (Rakocy ; Al‐Hafedh et al ; Danaher et al ). There was no significant difference ( P ≥ 0.05) between treatments for TSS concentration entering or exiting either primary filtration device (Table ).…”

“…Aquaponics is the combined culture of fish and plants in a recirculating aquaculture system and has received considerable attention as a result of the system's capability to raise fish at high density, sustain water quality, minimize water exchange, and produce a marketable vegetable crop (Rakocy ; Adler et al ; Al‐Hafedh et al ; Graber and Junge ; Danaher et al ). The vegetable crop is responsible for the direct assimilation of dissolved fish wastes and products of microbial breakdown in the recirculating aquaponic system.…”

“…Screen filters are also used as a primary treatment technology to remove solids from aquaculture effluent (Cripps and Bergheim ; Makinen et al 1988) through sieving particulate matter from the incoming waste stream. Danaher et al () compared a parabolic screen filter (PSF) to the cylindro‐conical clarifier used in the UVI aquaponic system and reported that the PSF was only able to remove 5.8% of the solids entering it when compared with a 30.8% removal efficiency for the clarifier. Nonetheless, the PSF did not negatively affect Nile tilapia production, water spinach production, or water quality parameters compared with the clarifier.…”

A review on the research status and development trend of equipment in water treatment processes of recirculating aquaculture systems

“…Danaher et al . () compared a PSF with a cylindro‐conical clarifier used in a UV aquaponic system and found that the PSF was able to remove 5.8% of the solids entering it when compared with a 30.8% removal efficiency for clarifier. Through PSF filtration, removing residual feed, excrement and other large solid particles at the beginning of system operation can greatly reduce the load of the entire water treatment system and, in particular, could greatly improve the foam separation and biological filtration processes treatment effect.…”

Hydroponic systems and water management in aquaponics: a review

“…In these integrated systems, nutrients that are excreted by the fish or generated by microbial activity (Munguia-Fragozo et al, 2015;Zou et al, 2016a) are absorbed by hydroponically cultured plants, thus treating the water before it is recycled to the fish tank (Endut et al, 2009;Tyson et al, 2011;Nichols and Savidov, 2012;Medina et al, 2016;Nuwansi et al, 2016). AP has received considerable attention due to its capability to sustain water quality, minimise fresh water consumption, and provide a marketable vegetable crop (McMurtry et al, 1997a(McMurtry et al, , 1997bAdler et al, 2000a;Lennard and Leonard, 2005;Graber and Junge, 2009;Danaher et al, 2011Danaher et al, , 2013Pantanella et al, 2011Pantanella et al, , 2015Espinosa Moya et al, 2016;Shete et al, 2016). Nevertheless few microbial studies have been conducted to determine food safety status (Elumalai et al, 2017) suggesting that further research is needed to evaluate this aspect.…”