生物酸化污泥回用在批式运行的污泥生物淋滤工艺中的效果

Recycling Acidified Bioleached Sludge in Bioleaching of Heavy Metals in Tannery Sludge by Sequence Batch Operation Model

以制革污泥为对象，利用上批淋滤结束后的生物酸化污泥既含大量微生物又具有较强酸度的特点，用其回流以达到使原始污泥预酸化和接种微生物的双重效果，建立用生物淋滤技术序批式处理制革污泥的工艺．用硫酸调节原始污泥pH至5．5左右，接入质量分数为20％的菌种和0．4％的能源物质进行污泥中重金属的生物淋滤处理，取淋滤过程不同阶段中pH3．5、3．0、2．5、1．95的生物酸化污泥作菌种，同时用硫酸对待处理污泥预酸化进行下批生物淋滤处理．此外，采用刚淋滤结束的pH1．95的生物酸化污泥代替硫酸进行污泥的预酸化和接种．结果表明，用淋滤过程中pH3．5～1．95的生物酸化污泥作菌种，污泥的pH值都能够下降到2．0以下，而且不同pH值的生物酸化污泥作菌种的淋滤效果差异并不显著，说明淋滤过程中pH在3．5以下的污泥都可以作为菌种，接人到下一批次待处理的污泥中进行生物淋滤．连续6批次的污泥淋滤试验表明，用刚淋滤结束的pH〈2的生物酸化污泥回流既能完全代替浓硫酸对原始污泥进行预酸化，并又兼有接种作用．每批处理4d均能稳定完成淋滤过程．因此，工程应用中只需在待处理污泥中添加上批淋滤结束的酸化污泥便可。使生物淋滤持续批式运行，大大简化了处理工艺．

The incorporation of acidified bioleached sludge containing lots of microorganisms and stronger acidity into original tannery sludge is a key step to develop sequence batch operation model for bioleaching of heavy metals in tannery sludge. In the initial phase, the bioleaching trial was conducted after original tannery sludge was pre-acidified with sulfur acid, inoculated with 20% of the inoculums containing Acidithiooxidans only, and mixed with energy substrate at a rate of 0.4 % . The acidified sludge at pH 3.5, 3.0, 2.5 and 1.95, obtained from the different stage of the bioleacbing process, was explored to act as a new inoculums used in the next batch bioleaching process. Meanwhile, the acidified bioleached sludge at pH 1.95 was taken simultaneously as inoculums and the substance to pre-acidify original sludge. The results show that bioleached sludge at pH 3.5 - 1.95 can be used successfully as inoculums for the next batch bioleaching trial with the similar bioleaching efficiency, by which pH of the treated sludge can be reduced to less than 2 within 5 days for hydraulic residence time （HRT） of bioleaching. Furthermore, the bioleached sludge at pH 1.95 could not only replace sulfuric acid to pre-acidify the original sludge but also act as inoculums for the bioleaching treatment. It was found in successive 6 batch bioleaching trials that HRT could be reduced to 4 days through recycling bioleached sludge at pH 1.95. Therefore, in engineering practice, continuous sequence batch operation for bioleaching process could be carried out through mixing original sludge with bioleached sludge at pH 〈 2.