Zhang Chao, Chen Yinguang
State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
Environ Sci Technol. 2009 Aug 15;43(16):6164-70. doi: 10.1021/es9005948.
Recently, waste activated sludge (WAS) fermentation for short-chain fatty acids (SCFAs) production has drawn much attention because the waste biosolids produced in wastewater treatment plants (WWTP) can be reused, and the produced SCFAs can be applied to promote biological nutrient removal (BNR). Usually, after WAS fermentation, the fermentation liquid is separated and then the recovery of ammonium and phosphorus, which are released during WAS fermentation, is conducted to prevent the increase of nitrogen and phosphorus loadings to WWTP. As an alternative to the traditional process, this paper investigated the recovery of ammonium and phosphorus in the formation of struvite before sludge-liquid separation, and its positive effecton the following sludge-liquid filtration separation. First, the conditions for ammonium and phosphorus recovery from the WAS fermentation mixture were optimized by response surface methodology (RSM). Then, the effect of ammonium and phosphorus recovery on sludge filtration dewatering was investigated. With ammonium and phosphorus recovery, it was observed that the specific resistance to filtration (SRF), the capillary suction time (CST), and the sludge volume after filtration reduced by 96.9, 99.6, and 88.7%, respectively, compared with no ammonium and phosphorus recovered sludge. Third, the mechanisms for ammonium and phosphorus recovery significantly enhancing sludge dewatering capacity were investigated. The formation of struvite, the neutralization of 5 potential, the increase of magnesium ion, which was added during ammonium and phosphorus recovery, and the decrease of sludge polymeric substance caused the improvement of sludge dewatering. Finally, the fermentation liquid was used as the additional carbon source of BNR, and the nutrient removal efficiency was obviously enhanced.
最近，利用剩余活性污泥（WAS）发酵生产短链脂肪酸（SCFAs）备受关注，因为污水处理厂（WWTP）产生的废弃生物固体可得到再利用，且所产生的SCFAs可用于促进生物脱氮除磷（BNR）。通常，WAS发酵后，会对发酵液进行分离，然后回收WAS发酵过程中释放的铵和磷，以防止进入WWTP的氮和磷负荷增加。作为传统工艺的替代方法，本文研究了在污泥-液体分离之前鸟粪石形成过程中铵和磷的回收情况，以及其对后续污泥-液体过滤分离的积极影响。首先，采用响应面法（RSM）优化了从WAS发酵混合物中回收铵和磷的条件。然后，研究了铵和磷回收对污泥过滤脱水的影响。通过回收铵和磷发现，与未回收铵和磷的污泥相比，比过滤阻力（SRF）、毛细吸水时间（CST）和过滤后的污泥体积分别降低了96.9%、99.6%和88.7%。第三，研究了铵和磷回收显著提高污泥脱水能力的机制。鸟粪石的形成、电位的中和、铵和磷回收过程中添加的镁离子的增加以及污泥聚合物的减少导致了污泥脱水性能的改善。最后，将发酵液用作BNR的额外碳源，营养物去除效率明显提高。
