School of Environmental Studies and Department of Chemical Engineering, Queen's University, Kingston, ON, K7L 3N6, Canada.
Wastewater Department, Rothsay, Rothsay, A Division of Darling International Canada Inc., Dundas, ON, L9H5G1, Canada.
Water Res. 2015 Oct 1;82:104-17. doi: 10.1016/j.watres.2015.05.014. Epub 2015 May 12.
A full-scale (FS) activated sludge system treating wastewater from a meat rendering plant with a long history of sludge management problems (pin-point flocs; >80% of floc <50 μm diameter; poor settling) was the focus of a study that entailed characterization of floc properties. This was coupled with parallel well-controlled lab-scale (LS) sequencing batch reactors (SBRs) treating the same wastewater and operated continuously over 1.5 years. Distinct differences in the proportion of proteins and polysaccharides associated with extracellular polymeric substances (EPS) were observed when comparing the properties of flocs from the FS and the LB systems. Further differences in the proportion of tightly bound (TB) and loosely bound (LB) fractions of EPS were also observed for flocs derived from conditions where differences in settling and dewatering properties of flocs occurred (i.e. FS and LS systems). FS flocs contained higher levels of EPS along with a higher proportion of LB than TB EPS, and possessing characteristics associated with non-filamentous bulking (SVI >150 mL/g). Floc formed in the LS system, following inoculation from sludge taken from the FS system, was markedly larger in size (>70% of floc >300 μm diameter), spherical in shape, compact and firm, and appeared to be granular in form. Flocs formed in the LS system, when an anoxic phase was introduced into the react stage of the SBR cycle, were found to be more hydrophobic and contained more TB and less loosely bound (LB) EPS when compared to the FS floc. TB-EPS contained a greater amount of protein, whereas the polysaccharide content of LB-EPS was larger. Protein was predominantly localized in the core region of granular flocs where cells were compactly packed. When assessing the operating conditions of the FS and LS systems parameters that appear to impact the floc properties and the transition to a granular form include dissolved oxygen (DO) concentration and food to microorganism (F/M) ratio.
一个全面规模（FS）的活性污泥系统处理一家历史悠久的污泥管理问题的肉类加工厂废水（点状絮体；>80%的絮体直径<50μm；沉降性能差）是一项研究的焦点，该研究涉及絮体特性的表征。这与平行的、控制良好的实验室规模（LS）序批式反应器（SBR）处理相同废水相结合，连续运行了 1.5 年以上。比较 FS 和 LB 系统的絮体特性时，观察到与细胞外聚合物物质（EPS）相关的蛋白质和多糖的比例存在明显差异。对于在沉降和脱水性能存在差异的条件下（即 FS 和 LS 系统）衍生的絮体，也观察到 EPS 的紧密结合（TB）和松散结合（LB）分数的比例进一步不同。FS 絮体含有更高水平的 EPS，以及更高比例的 LB 而不是 TB EPS，并具有与非丝状膨胀相关的特性（SVI>150mL/g）。从 FS 系统中取出的污泥接种 LS 系统中形成的絮体，尺寸明显更大（>70%的絮体>300μm 直径），呈球形，紧凑且坚固，并且看起来呈颗粒状。当将缺氧阶段引入 SBR 周期的反应阶段时，在 LS 系统中形成的絮体被发现具有更高的疏水性，并且与 FS 絮体相比，含有更多的 TB 和更少的松散结合（LB）EPS。TB-EPS 含有更多的蛋白质，而 LB-EPS 的多糖含量更大。蛋白质主要位于细胞紧密堆积的颗粒絮体的核心区域。在评估 FS 和 LS 系统的运行条件时，似乎影响絮体特性和向颗粒形式转变的参数包括溶解氧（DO）浓度和食物与微生物（F/M）比。
