不同密度螺-草结构对养殖尾水净化效果的比较研究

COMPARATIVE PURIFICATION EFFECTS OF DIFFERENT DENSITIES OF SNAILS AND MACROPHYTES ON AQUACULTURE WASTEWATER

为减少水产养殖污染物排放,以苦草为对照组,构建环棱螺螺-草生态系统净化池塘养殖尾水,比较不同密度螺-草结构对养殖尾水的净化效果,同时探讨螺草互作对水质的影响。结果表明不同密度螺-草组合对养殖尾水均有较好的净化效果,以中密度组(螺密度50ind/m3)的去除效果最优,25d对Chl-a、CODMn、TN、TP、NH4+-N、NO3--N和浊度的去除率分别达到98%、39.7%、44.2%、86.9%、58.2%、82.3%和91%,其中以17～25d的营养物质去除率最高,水质由原来的Ⅳ类、Ⅴ类水提升为Ⅲ类水;环棱螺-苦草互作对水体的净化效果与苦草对照组差异不显著,表明其互利关系不明显;环棱螺-苦草组合对CODMn和TN的去除效果不是很理想,可能是由于实验中以黄土为底泥,其中的异养微生物较少引起的。

In order to reduce the aquaculture wastewater,this paper discussed the effect on water quality by the snail（Bellamya purifica）and macrophyte（Vallisneria spiralis）through constructing the snail and macrophyte ecological system and comparing the purification effects by the snail and macrophtye with different density.The result showed that all the snail and macrophyte treatments of various density had good purification effects,but by contrast,the middle density one（50ind/m3）worked best.The removal rates of Chl-a,CODMn,TN,TP,NH4＋-N,NO3——N and the turbidity were 98%,39.7%,44.2%,86.9%,58.2%,82.3% and 91%,respectively in the 25 days＇experiment,among which the 17~25 days＇nutrient had the highest removal rate.And the water quality had evolved from the level of Ⅳ and Ⅴ to Ⅲ.Since there was only a slight difference in purification between the Bellamya purifica and Vallisneria spiralis,the mutually beneficial relationship between them was not obvious.However,perhaps due to the loess sediment caused by the shortage of heterotrophic microorganism,the removal effect of CODMn and TN by Bellamya purifica and Vallisneria spiralis was not perfect.