ABSTRACT

Counter-diffusional biofilms are efficient in the removal of nitrogen from low strength wastewaters. Although counter-diffusion is usually established using expensive gas-permeable membranes, a polyurethane sheet is used to separate the aerobic and anoxic environments in the novel foam aerated biofilm reactor (FABR). Foam sheets with thicknesses of 10, 5 and 2 mm and synthetic wastewater with COD/N ratios of 5 and 2.5 were evaluated. The 2 mm thick foam reactor did not show good biomass adherence and, therefore, did not show N removal efficiency. The 5 and 10 mm reactors, in both COD/N ratios, showed similar total nitrogen and COD removal performance, up to 60% and 80%, respectively. The denitrification efficiency was close to 100% throughout the experimental period. Nitrification efficiency decreased with microbial growth, which was recovered after removal of excessive biomass. Lower values of polyurethane foam thickness and COD/N ratio did not provide a higher nitrification rate, as expected. The increase in resistance to mass transfer was associated with the growth of biomass attached to the foam rather than to its thickness and resulted in specialization of the microbial communities as revealed by 16S amplicon sequencing. FABR reveals as a promising alternative for simultaneous removal of nitrogen and COD from low COD/N ratio wastewaters.

摘要

反扩散生物膜可有效去除低浓度废水中的氮。尽管通常使用昂贵的透气膜来建立反扩散，但在新型泡沫充气生物膜反应器 (FABR) 中使用聚氨酯片材来分隔好氧和缺氧环境。评估了厚度为 10、5 和 2 毫米的泡沫板以及 COD/N 比为 5 和 2.5 的合成废水。2 mm 厚的泡沫反应器没有显示出良好的生物质粘附性，因此没有显示出 N 去除效率。5 毫米和 10 毫米反应器，在两种 COD/N 比率下，显示出相似的总氮和 COD 去除性能，分别高达 60% 和 80%。整个实验期间反硝化效率接近100%。硝化效率随着微生物的生长而降低，在去除过量的生物质后回收。正如预期的那样，较低的聚氨酯泡沫厚度和 COD/N 比值不会提供较高的硝化率。传质阻力的增加与附着在泡沫上的生物质的生长有关，而不是与泡沫的厚度有关，并导致微生物群落的专业化，如 16S 扩增子测序所揭示的那样。FABR 揭示了从低 COD/N 比率废水中同时去除氮和 COD 的有前景的替代方案。传质阻力的增加与附着在泡沫上的生物质的生长有关，而不是与泡沫的厚度有关，并导致微生物群落的专业化，如 16S 扩增子测序所揭示的那样。FABR 揭示了从低 COD/N 比率废水中同时去除氮和 COD 的有前景的替代方案。传质阻力的增加与附着在泡沫上的生物质的生长有关，而不是与泡沫的厚度有关，并导致微生物群落的专业化，如 16S 扩增子测序所揭示的那样。FABR 揭示了从低 COD/N 比率废水中同时去除氮和 COD 的有前景的替代方案。