| The ecologically and environmentally-friendly aquaponics technology has been widely concerned and applied with the environmental problems arising in the traditional aquaculture.In order to establish a perfect model of aquaponics system,this,experiment used methods of national water quality detection and comparative experiments to study treatment effect of nitrogen and phosphorus in water by aquaponic system in each experiment,and make fitting equation about change curve of nitrogen and phosphorus.The results show that in water purification:The first,cyclic flow is beneficial to the transformation of NH4+-N to NO2--N,and addition of matrix is beneficial to the transformation of NH4+-N to NO2--N.In hydrostatic water group,the removal rate of NH4+-N is 32.8%,concentration of NO2--N increased to 0.04 ± 0.01 mg/L,the removal rate of PO43--p is 19.3%.In circulating water group,the removal rate of NH4+-N is 81.7%,concentration of NO2--N increased to 0.64 ± 0.02 mg/L,the removal rate of PO43--P is 19.7%.In circulating water with stroma group,the removal rate of NH4+-N is 100%,concentration of NO2--N rise first and then decline,the removal rate of PO43--P is 41.8%.Cyclic flow is beneficial to the transformation of NH4+-N to NO2-N,but it has no significant effect on the conversion of NO2--N to NO3--N.At the same time,there is no significant effect on the treatment of PO43-P.The addition of matrix is beneficial to the transformation of NH4+-N to NO2--N.It is also beneficial to the transformation of NO2--N to NO3--N.At the same time,it is also beneficial to the treatment of PO4-P.Therefore,it is the best to select the circulating water system which is designed to add the matrix to the nitrogen and phosphorus treatment of water.Secondly,compared with the overflow type,the tidal type that the way water passes through the planting bed has better effect on the comprehensive treatment of N and P.The concentration of NH4+-N in tidal type group decreased to 0 mg/L in 11th d,the overflow type group is in 13th d.The highest concentration of NO2--N in tidal type group is 0.05±0.01 mg/L,the overflow type group is 0.22±0.01 mg/L.The removal rate of PO43--P in tidal type group is 33.1%,the overflow type group is 36.1%.The treatment effect of NH4+-N and NO2--N in the tidal type group is better than that in the overflow type group,but there is little difference of treatment effect of PO43--P between two group.Therefore,it is better to select the tidal type for water quality treatmentThirdly,compared with the fine sand,the coral stone as the stroma of the planting bed has better effect on the comprehensive treatment of nitrogen and phosphorus.The concentration of NH4+-N in coral stone group decreased to 0 mg/L in 11th d,the fine sand group is in 12th d.The highest concentration of NO2--N in coral stone group is 0.05 ±0.02 mg/L,the fine sand group is 0.23±0.01 mg/L.The removal rate of PO43--P in coral stone group is 33.1%,the fine sand group is 60.3%.The treatment effect of NH4+-N and NO2--N in the coral stone group is better than that in the fine sand group,but the effect of PO43--P in the fine sand group is better.But considering NH4+-N and NO2--N are more toxic to cultured species,so it is better to select the coral stone for water quality treatment.Forthly,the water flow rate of 450 L/h at the inlet of the planting bed is the best for the treatment of N.The concentration ofNH4+-N in 150 L/h group decreased to 0 mg/L in 14th d,300 L/h group is in 13th d,450 L/h group is in 12th d,600 L/h group is in 13th d.The highest concentration of NO2--N in 150 L/h group is 0.056 ± 0.003 mg/L,300 L/h group is 0.053 ±0.002 mg/L,450 L/h group is 0.047 ±0.001 mg/L,600 L/h group is 0.049 ±0.001 mg/L.The removal rate of PO43--p in 150 L/h group is 20.6%,300 L/h group is 28.9%,450 L/h group is 34.1%,600 L/h group is 40.0%.Although the water flow rate of 600 L/h at the inlet of the planting bed is the best for the treatment of phosphorus,there is little difference between the 450 L/h experimental group and the 600 L/h experimental group.Therefore,the influent flow rate of the inlet of the planting bed is 450 L/h,and the treatment effect ofthe system on nitrogen and phosphorus is the best.About the fitting cuive,the concentration of PO43--P and NH4+-N in each experimentgroup varies with time can use the equation:y =a/1+eb+cx+d to fit(P=0.0000,<0.01,PO43--P:R2≥0.9549,NH4+-N:R2≥0.9471).The concentration of NO2--N in each experiment group varies with time can use the equation:y=a/1+b/ecx+dx2+fx3 to fit(P=0.0000,<0.01,R2≥0.9825).Finally,as the volune of the matrix coral used in the experimental system is 0.154 m3,the specific relationship between the catfish and the capsicum is calculated:MF=3.40+MV/13.68(phosphorus)MF=6.64+MV/3.45(nitrogen)MF:total weight of fish(kg)MV:total weight of vegetables(kg)If the weight of the vegetable is calculated according to the weight of the fish,the weight of the larger vegetable is selected of two formulas.If the weight of the fish is calculated according to the weight of the vegetable,the weight of the smaller fish is selected oftwo formulas. |
