Valentino Francesco, Morgan-Sagastume Fernando, Fraraccio Serena, Corsi Giovanna, Zanaroli Giulio, Werker Alan, Majone Mauro
Department of Chemistry, "Sapienza" University of Rome, P.le Aldo Moro 5, 00185, Rome, RM, Italy,
Environ Sci Pollut Res Int. 2015 May;22(10):7281-94. doi: 10.1007/s11356-014-3268-y. Epub 2014 Jul 5.
An innovative approach has been recently proposed in order to link polyhydroxyalkanoates (PHA) production with sludge minimization in municipal wastewater treatment, where (1) a sequencing batch reactor (SBR) is used for the simultaneous municipal wastewater treatment and the selection/enrichment of biomass with storage ability and (2) the acidogenic fermentation of the primary sludge is used to produce a stream rich in volatile fatty acids (VFAs) as the carbon source for the following PHA accumulation stage. The reliability of the proposed process has been evaluated at lab scale by using substrate synthetic mixtures for both stages, simulating a low-strength municipal wastewater and the effluent from primary sludge fermentation, respectively. Six SBR runs were performed under the same operating conditions, each time starting from a new activated sludge inoculum. In every SBR run, despite the low VFA content (10% chemical oxygen demand, COD basis) of the substrate synthetic mixture, a stable feast-famine regime was established, ensuring the necessary selection/enrichment of the sludge and soluble COD removal to 89%. A good process reproducibility was observed, as also confirmed by denaturing gradient gel electrophoresis (DGGE) analysis of the microbial community, which showed that a high similarity after SBR steady-state had been reached. The main variation factors of the storage properties among different runs were uncontrolled changes of settling properties which in turn caused variations of both sludge retention time and specific organic loading rate. In the following accumulation batch tests, the selected/enriched consortium was able to accumulate PHA with good rate (63 mg CODPHA g CODXa(-1) h(-1)) and yield (0.23 CODPHA CODΔS(-1)) in spite that the feeding solution was different from the acclimation one. Even though the PHA production performance still requires optimization, the proposed process has a good potential especially if coupled to minimization of both primary sludge (by its use as the VFA source for the PHA accumulation, via previous fermentation) and excess secondary sludge (by its use as the biomass source for the PHA accumulation).
最近提出了一种创新方法，旨在将城市污水处理中聚羟基脂肪酸酯（PHA）的生产与污泥减量联系起来，其中：（1）序批式反应器（SBR）用于同时处理城市污水以及选择/富集具有储存能力的生物质；（2）初沉污泥的产酸发酵用于生产富含挥发性脂肪酸（VFA）的物流，作为后续PHA积累阶段的碳源。通过在两个阶段使用底物合成混合物，分别模拟低强度城市污水和初沉污泥发酵的出水，在实验室规模上评估了所提出工艺的可靠性。在相同的操作条件下进行了六次SBR运行，每次都从新的活性污泥接种物开始。在每次SBR运行中，尽管底物合成混合物的VFA含量较低（基于化学需氧量（COD）为10%），但仍建立了稳定的 feast-famine 模式，确保了污泥的必要选择/富集以及可溶性COD去除率达到89%。观察到了良好的工艺可重复性，微生物群落的变性梯度凝胶电泳（DGGE）分析也证实了这一点，该分析表明在达到SBR稳态后具有高度相似性。不同运行之间储存特性的主要变化因素是沉降特性的未控制变化，这反过来又导致了污泥停留时间和特定有机负荷率的变化。在随后的积累批次试验中，尽管进料溶液与驯化时不同，但所选/富集的菌群能够以良好的速率（63 mg CODPHA g CODXa(-1) h(-1)）和产量（0.23 CODPHA CODΔS(-1)）积累PHA。尽管PHA的生产性能仍需优化，但所提出的工艺具有很大潜力，特别是如果与减少初沉污泥（通过将其用作PHA积累的VFA来源，经过先前的发酵）和剩余二沉污泥（通过将其用作PHA积累的生物质来源）相结合。
