污水中氮素在无植物生长土壤中的迁移与去除试验研究

Experiment for Wastewater Nitrogen Transportation in Soil under Non-plants Conditions

通过土柱模型试验,模拟研究了在无植物生长条件下,污水中不同形式氮素在土壤处理过程中的渗透、淋溶、转化、去除等特征。试验结果表明,在土柱上层土壤中(从土柱上端计10cm深度以内)铵氮浓度随着土壤深度的增加而呈现明显降低的趋势。在土柱上层土壤以下,铵氮浓度基本较小。对于硝酸盐氮和总氮来说,试验初期未出现排水前,在土柱中、上层土壤中(从土柱上端计70cm深度以上),硝酸盐氮和总氮的浓度呈现先增加、后下降的变化趋势;当土柱底部出现排水后一段时间,土柱中、上层土壤中硝酸盐氮和总氮浓度仍呈现出持续弱增长的趋势;随着排水次数的增加,土柱下层土壤中硝酸盐氮和总氮浓度则呈现出明显持续下降的变化趋势。同时,实验结果还表明,在无植物生长条件下,土壤对污水中氮素的去除作用明显,就本文使用污水来说,总氮去除率在30%以上;另外,值得注意的是,由于长期污水排放将会增加地下水等水体污染概率。

In this paper, the model soil column experiment was conauctea to simulatethe infiltration, leaching, transformation, remoral and other features of sewage nitrogen in the soil under the condition without plant growth. The results showed that in the up- per layer of the soil column in which the depth was less than 10 cm from the soil column upper end, the ammonium nitrogen concen tration decreased significantly with the increase of soil depth; in the following layer, the ammonium nitrogen concentration basically is small. When the draining did not appear at the beginning of the trial, in the upper layer in which the depth was less than 70 cm from the soil column upper end, the nitrate nitrogen and total nitrogen concentration increased at first, then decreased. When the draining appeared, the nitrate nitrogen and total nitrogen concentration of the upper soil layer still showed continuous weak growth trend. With the increase of the drainage times, the nitrate salt nitrogen and total nitrogen concentrations in the subsoil of soil column decreased significantly. At the same time, the results showed that the wastewater nitrogen removal effect of soil is significant under the condition without plant growth. For the wastewater which selected in the test, the total nitrogen removal efficiency is above 30 %. Additionally, the probability of groundwater contamination would increase due to the long-term waste water leaching.