镍对栅藻深度处理生活污水的影响研究

将栅藻包埋固定在海藻酸钙凝胶珠中,对人工污水进行深度净化,研究其在不同质量浓度Ni2+条件下对污水中氨氮和正磷酸盐的净化效率,以及净化过程中藻类叶绿素a质量浓度、过氧化物酶(POD)活性变化和去污过程中藻细胞富集Ni2+的情况。结果表明,低质量浓度Ni2+可引起藻细胞应激性反应,光合活性提高,解毒机制增强,未影响氨氮和正磷酸盐的净化效率;高质量浓度Ni2+会造成藻细胞伤害,光合活性减弱,POD活性下降,氨氮和正磷酸盐的净化效率减小。Ni2+对栅藻深度处理生活污水影响程度依据其在水体中的质量浓度。

Effects of nickel on nutrient removal for municipal wastewater tertiary treatment by Scenedesmus sp.

This paper aims to study the effect of nickel on the nutritious ingredient removal from the urban sewage tertiary treatment by using Scenedesmus sp.For our research purpose,we have done a careful observation of the content of chlorophyll A and peroxidase activity in the sewage and investigated nickel enrichment by using algae.The result of our study shows that: Nickel at lower concentrations(0.1 mg/L and 0.5 mg/L) do not likely lead to any obvious impacts on the algal growth,rather it is likely to lead to the reductase reaction of the algae cells,the increase of photosynthetic metabolic activity and the strengthening of the detoxity mechanism,though it is not likely to improve the removing efficiency of nitrogen and phosphate.However,the increase of the concentration of Ni2+(5 mg/L,10 mg/L,20 mg/L) proves to decrease their removal efficiency.After eight days’ treatment,ammonia-nitrogen removal efficiency tends to reach 67% at Ni2+ lower concentrations(0 mg/L,0.1 mg/L,0.5 mg/L,1 mg/L) and ortho-phosphate removal efficiency tends to reach 85.7%,84.3%,82.3% and 79.3%,respectively.Nevertheless,with the increase of the concentration of Ni2+(5 mg/L,10 mg/L,20 mg/L),their removal efficiency prove to be only 47.6%,44.9%,45.5% after 4-days treatment and orthophosphate removal efficiency tend to reach 62.9%,65.0%,60.7%,respectively. Furthermore,five days later,their removal efficiency began to decrease remarkably.It is probably because the nickel enrichment by algae tends to inhibit the chlorophyllide reductase activity and biosynthesis of chlorophyll.In addition, the membrane system of chloroplast may likely be damaged with the content of chlorophyll decreased,which may lead to the subsequent decrease of photosynthesis rate.In such a situation,the POD relative activity of algae tends to increase first and decrease later.The decreased content of chlorophyll A and POD activities indicate that the cells have been hurt.Thus,it can be concluded that the effect of nickel on the nutrient removal for municipal sewage tertiary treatment by Scenedesmus sp.depends on its concentration in the sewage.Enrichment of Ni2+ by algae may likely be affected by the initial concentration of Ni2+,biomass of algae and balance concentration,for it involves a quick passive absorption and a slow energy-consumption process.Our research has thus proved that there exists a great enrichment ability of heavy metals by using Scenedesmus sp.,which can be applied in nickel contaminated urban sewage tertiary treatment.