基于正交实验的生物慢滤池水质净化效果的研究

THE PURIFICATION EFFECT OF WATER QUALITY BY BIOLOGICAL SLOW FILTER BASED ON ORTHOGONAL EXPERIMENT

生物慢滤池具有菌-藻共生的特性。以滤层厚度、上覆水深、滤速、氮磷比及有无藻类生长等5个因素设计混合正交实验,以TN和TP的去除效果为指标,通过优化运行参数,得到生物慢滤池(BSF)优化运行工况。结果表明,滤层厚度对TN去除效果影响显著,上覆水深和氮磷比对TN去除效果影响较为显著;有无藻类生长和氮磷比对TP去除效果影响显著。在考虑单因素和显著性影响条件下,得到BSF去除氮磷的优化工况为:在有藻状态下,水深为80 cm,滤层厚度为80 cm,进水m(N):m(P)为20:1,滤速为0.1 m/h;在此工况下,出水的TN和TP含量均低于GB18918-2002的一级A标准,且无外加碳源和除磷药剂,出水可作为景观环境用水,节约了水资源,降低了处理成本。

Biological slow filter has the characteristic of bacteria and algae symbiosis. Five factors of biological slow filter system including the filter layer thickness, upper water depth, filter velocity, the ratio of nitrogen and phosphorus and the presence of algae, mixed orthogonal experiments were designed with removal effect of TN and TP as index to optimize the operation parameters. The results showed that the removal efficiency of TN the filter layer thickness as well as water depth and the ratio of nitrogen and phosphorus. The removal rates of TP were also significantly affected by the presence of algae and the ratio of nitrogen and phosphorus. Considering individual factor and significance simultaneously, it was concluded that the best conditions of the biological slow sand filtration to remove nitrogen and phosphorus were as following： in the presence of algae, the water depth was 80 cm, the thickness of filter layer was 80 cm, the m（N）：m（P） was 20：1 and filter velocity was 0.1 m/h. In this condition, the effluent TN and TP were lower than A standard of level 1 in the OB 18918-2002. Furthermore, with no external carbon source and medicament for removing phosphorus, water resources were saved and the treatment cost was reduced while effluent could be regarded as water for landscape environment.