水培植物对循环水养鱼系统的水质净化研究

Effect of hydroponic plants on water quality purification in a recirculating aquaculture system

为研究循环水养殖系统水培植物对水质的改善效果,利用水蕹菜在温室大棚中进行为期15 d的养殖水体水质净化试验。试验系统以罗非鱼为养殖对象,循环率20次/d,养殖密度5 kg/m3,植物栽培区水力负荷10 m3/(m2·d)。试验结果表明:栽培区水蕹菜对氨氮(NH4+-N)、亚硝酸盐氮(NO2--N)、硝酸盐氮(NO3--N)、总氮(TN)、化学耗氧量(COD)、总磷(TP)等的去除率分别7.3%、19.6%、14.5%、12.5%、13.5%、1.7%。试验结束后,罗非鱼总增重630 g,水蕹菜的生长速率58.3 mg/(m2·d)。总体来看,养殖水体中的营养盐可以满足水蕹菜正常生长,水蕹菜对养殖水体表现出较好的净化能力,水体中NH4+-N、NO2--N、COD、TP的浓度基本维持平衡不累积上升,NO3--N和TN虽略有累积,但可通过增大栽培区面积、降低系统水力负荷,达到净化水质的目的。研究表明水培植物是循环水养殖系统净水技术的选择方向之一。

In order to study the effect of hydroponic plants on water quality purification, a recirculating aquaculture system in greenhouse was built for the experiment, which used tilapia as the raising species and Ipomoea aquatica as the cultivation hydroponic plants. The system＇s recirculating rate was 20 times per day, tilapia culture density was 5 kg/m3 , and the hydraulic loading rate of the plants cultivation area was 10 m3/ （ m2 · d）. The whole testing period was 15 days and the results showed that the ammonia nitrogen removal rate between the inlet and outlet of the cultivation area was 7.3% on average, nitrite nitrogen 19.6% , nitrate nitrogen 14.5%, TN 12.5%, COD 13.5% and TP 1.7%. After 15 experimental days, tilapia gained 630 g, Ipomoea aquatica growth rate was 58.3 mg/（ m2 · d）. General speaking, nutrients in the system can mostly satisfy the normal growth of Ipomoea aquatic. NH4＋-N, NO2--N, COD and TP in the system were all keeping balance, but NO3 --N and TN were a little increased. Enlarging the plants cultivation area can effectively solve this problem. So it is easy to see that making good use of hydroponic plants can actually be one option for the water purification in recirculating aquaculture systems.