不同水力负荷下人工湿地对海水养殖尾水污染物的净化特征

Purification characteristics of constructed wetland under different hydraulic loads after treatment of marine aquaculture tailwater

中文关键词: 海水养殖尾水  人工湿地  水力负荷

英文关键词: Mariculture tailwater  Constructed wetland  Hydraulic load

中文摘要:

      海水养殖尾水的达标排放是海水养殖产业面临的主要问题之一，人工湿地作为一种生态、综合水处理技术，可有效去除养殖尾水中的氮、磷等污染物，获得适宜的水力负荷条件是该技术推广和应用的前提。构建一套复合垂直流人工湿地处理系统，研究3种水力负荷条件(V1=0.50、V2=0.19、V3=0.10 m/d)对牙鲆(Paralichthys olivaceus)养殖尾水的处理效果的影响。结果显示，3种水力负荷状态下，该系统对于海水养殖尾水中主要污染物的处理效果差异显著。进水中的化学需氧量(COD)浓度相对较低时，去除率均较低(最高去除率为36.25%)，水力负荷状态对COD的去除率影响不明显。水力负荷为0.50 m/d时，总氮(TN)的去除率为49.50%；在0.10 m/d时，TN去除率达到85.90%。活性磷酸盐(PO43–-P)的去除率受到水力负荷的影响较小，最低去除率为77.44%。水力负荷状态会影响系统内氮、磷的浓度变化：在不同水力负荷下，下行池中氮污染物去除率在80%以上；上行池则会在高水力负荷状态下产生硝酸盐氮(NO3–-N)或亚硝酸盐氮(NO2–-N)的累积，影响出水水质。PO43–-P的吸附转化主要发生在下行池的中上层，水力负荷越大，PO43–-P的吸附转化就越靠近系统后程。

英文摘要:

      One of the main problems faced by the aquaculture industry is the discharge of marine aquaculture tailwater. Constructed wetlands may work as a comprehensive water treatment technology, effectively removing pollutants such as nitrogen and phosphorus in aquaculture tail water. For the proper implementation of constructed wetland technology, hydraulic load conditions must be optimized. The treatment effect of vertical flow constructed wetland system on the tail water of Paralichthys olivaceus was studied under three hydraulic loads (V1=0.50 m/d, V2=0.19 m/d, V3=0.10 m/d). The treatment effect of the system for the main pollutants in the aquaculture tailwater was significantly different under three hydraulic loading conditions. When the concentration of chemical oxygen demand (COD) in the influent water was relatively low, the removal rate was also low, with a peak removal rate of only 36.25%. The effect of hydraulic loading on the removal rate of COD was not obvious. When the hydraulic load was 0.50 m/d, the removal rate of total nitrogen (TN) was only 49.50%; however, when the hydraulic load was 0.10 m/d, the TN removal rate was 85.90%. The removal rate of active phosphate (PO43–-P) was less affected by hydraulic load, showing a removal rate of more than 77%. Hydraulic load affects the removal effect of nitrogen and phosphorus in the system; for example, in the downstream unit the removal rate of nitrogen pollutants was more than 80%, whereas in the upstream unit, nitrate nitrogen (NO3–-N) or nitrite nitrogen (NO2–-N) accumulated under high hydraulic loads. The adsorption and conversion of PO43–-P mainly occurred in the upper and middle layers of the downstream unit; the larger the hydraulic load, the closer the adsorption and conversion of PO43–-P was to the rear of the system.