Growth performance, nutrients and microbial dynamic in aquaponics systems as affected by water temperature

摘要

Aquaponics is an integrated production of fish and hydroponic crops with recirculation of the nutrient solution in which fish wastes are used as plant fertilizers. Development towards bioeconomical based cultivation system using industrial symbioses makes application of aquaponics systems in areas with surpluses or excess heat of great interest. Within the frame of these surpluses a significant amount of energy leaves the processes as low-grade heat through flue gas stacks and cooling water. However, little knowledge is available about the effect of low water temperature on the growth and microbial parameters in an aquaponics system. Investigations in the current study were thus carried out to study the effect of water temperature of 11 degrees C compared with 21 degrees C on plant growth, nutrient and microbial dynamic in aquaponic systems. Two cultivation systems (treatments) were used, an aqua ponic system consisted of a fish tank, a biofilter and a plant unit, and a hydroponic system (control) consisted of a water tank and a plant unit. Basil and trout were used as model organisms. The experiment was run for a period of eight weeks and repeated over time. The results indicated good fish growth and better plant growth in aquaponics systems compared with hydroponic systems at both water temperatures. The growth, as indicated by plant biomass, leaf length and width as well as nitrate content in the leaves, was better at water temperature of 21 degrees C compared with 11 degrees C. Low water temperature of 11 degrees C indicated a negative effect on biofiltration, microbial dynamics and disease incidence in the system. Negative correlation between the total nitrogen removal rate and low water temperature was also indicated.