Chan Wu-Chung, Lin Zong-Yi
Civil Engineering Department, Chung-Hua University, Hsinchu, 30067 Taiwan, ROC.
Bioprocess Biosyst Eng. 2004 Jul;26(4):223-30. doi: 10.1007/s00449-004-0355-3. Epub 2004 Mar 26.
In this study, an optimal process to prepare a synthetic material having nutrient (PVA/peat/KNO(3) composite bead) is developed. The equilibrium water-soluble nitrogen content in the composite bead prepared by this process is 8.25-10.06 mg N/g dry solid. The mass-transport process for the water-soluble nitrogen dissolved out of the composite bead was also investigated. The dissolved out process occurs in two stages: external mass transport occurs in the early stage and the intraparticle diffusion process occurs in the long-term stage. The rate of water-soluble nitrogen dissolved out in both stages is concentration dependent. The path of nitrogen dissolved out is that the nitrogen dispersed in the peat and PVA phases simultaneously diffused into the outer PVA phase and out of the bead surface. The moisture holding capacity of the composite bead bed is better than the compost bed. The percentage of removed volatile organic compounds (VOCs) can remain at levels higher than 99% for a longer time (about 230 d) as the composite bead immersed in a KNO(3) aqueous solution before packing with an optimal concentration of KNO(3) aqueous solution of 0.384 M. The rate of nitrogen dissolved out in the intraparticle diffusion process could be used as an index to predict the microbial growth rate in the biofilter.
在本研究中，开发了一种制备具有养分的合成材料（聚乙烯醇/泥炭/硝酸钾复合珠）的优化工艺。通过该工艺制备的复合珠中平衡水溶性氮含量为8.25 - 10.06毫克氮/克干固体。还研究了复合珠中溶解出的水溶性氮的传质过程。溶解出过程分两个阶段发生：早期发生外部传质，长期阶段发生颗粒内扩散过程。两个阶段中水溶性氮的溶解速率均与浓度有关。氮溶解出的路径是分散在泥炭和聚乙烯醇相中的氮同时扩散到外部聚乙烯醇相并从珠表面出来。复合珠床的持水能力优于堆肥床。当复合珠在填充前浸入0.384 M的最佳浓度硝酸钾水溶液中时，去除挥发性有机化合物（VOCs）的百分比可以在较长时间（约230天）内保持高于99%的水平。颗粒内扩散过程中氮的溶解速率可作为预测生物滤池中微生物生长速率的指标。
