Ammonia conversion in an aquaponics system using activated carbon-coated and non-coated bioball in the biological treatment tank

Abstract

The key to efficiently converting toxic nitrogen waste (ammonia) to nitrate nitrogen in an aquaponics system is a biological treatment system that uses media. High surface area media is suitable for bacterial colonization; however, clogging due to small pores can be detrimental to the whole system. Thus, this study assessed the aquaponics system performance utilizing plastic media Cosmoball® and compared it with Cosmoball® coated with activated carbon (AC-coated) in the biological treatment tank. A laboratory-scale recirculating aquaponics system comprised a fish tank, a clarifier system to remove the solids, a biological tank filled with the plastic media, a sump tank, and a raft planting system for planting mustard green. The experiment was run in two phases: start-up to develop the biological treatment using non-coated, and AC-coated Cosmoball® and the experimental phase. Water qualities related to aquaponics such as ammonia, nitrate, pH and selected plant qualities were analyzed. It took longer for the start-up phase using uncoated Cosmoball® to stabilize than the coated ones. Once stabilized, denoted by optimal pH ranges (average 6.8), the seedlings were transferred. Nitrate during the experimental phase of the non-coated Cosmoball® reading was slightly higher, averaging around 20 ppm as compared to only averaging about 10 for the coated ones. Higher nitrate and a more optimal pH range for nutrient uptake for plant growth at around 6.5 during the planting phase when using AC-coated Cosmoball® resulted in better plant growth. Almost 4.4 times the increment of average height at 0.8 to 6.5 cm was noted for AC-coated Cosmoball®, and the number of leaves had doubled. The activated carbon coated plastic media Cosmoball® is a promising media for an aquaponics system with better plant growth.