Division of Industrial Electrical Engineering and Automation, Department of Biomedical Engineering, Lund University, Box 118, SE-221 00, Lund, Sweden.
CAPEC-PROCESS Research Center, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Building 229, DK-2800, Kgs. Lyngby, Denmark.
Water Res. 2017 Apr 15;113:97-110. doi: 10.1016/j.watres.2017.02.007. Epub 2017 Feb 6.
The objective of this paper is to report the effects that control/operational strategies may have on plant-wide phosphorus (P) transformations in wastewater treatment plants (WWTP). The development of a new set of biological (activated sludge, anaerobic digestion), physico-chemical (aqueous phase, precipitation, mass transfer) process models and model interfaces (between water and sludge line) were required to describe the required tri-phasic (gas, liquid, solid) compound transformations and the close interlinks between the P and the sulfur (S) and iron (Fe) cycles. A modified version of the Benchmark Simulation Model No. 2 (BSM2) (open loop) is used as test platform upon which three different operational alternatives (A, A, A) are evaluated. Rigorous sensor and actuator models are also included in order to reproduce realistic control actions. Model-based analysis shows that the combination of an ammonium ( [Formula: see text] ) and total suspended solids (X) control strategy (A) better adapts the system to influent dynamics, improves phosphate [Formula: see text] accumulation by phosphorus accumulating organisms (X) (41%), increases nitrification/denitrification efficiency (18%) and reduces aeration energy (E) (21%). The addition of iron ( [Formula: see text] ) for chemical P removal (A) promotes the formation of ferric oxides (X, X), phosphate adsorption (X, X), co-precipitation (X, X) and consequently reduces the P levels in the effluent (from 2.8 to 0.9 g P.m). This also has an impact on the sludge line, with hydrogen sulfide production ( [Formula: see text] ) reduced (36%) due to iron sulfide (X) precipitation. As a consequence, there is also a slightly higher energy production (E) from biogas. Lastly, the inclusion of a stripping and crystallization unit (A) for P recovery reduces the quantity of P in the anaerobic digester supernatant returning to the water line and allows potential struvite ( [Formula: see text] ) recovery ranging from 69 to 227 kg.day depending on: (1) airflow (Q); and, (2) magnesium ( [Formula: see text] ) addition. All the proposed alternatives are evaluated from an environmental and economical point of view using appropriate performance indices. Finally, some deficiencies and opportunities of the proposed approach when performing (plant-wide) wastewater treatment modelling/engineering projects are discussed.
本文旨在报告控制/操作策略可能对污水处理厂（WWTP）中全厂范围内磷（P）转化产生的影响。需要开发一组新的生物（活性污泥、厌氧消化）、物理化学（水相、沉淀、传质）过程模型和模型接口（水和污泥线之间），以描述所需的三相（气、液、固）化合物转化以及 P 与硫（S）和铁（Fe）循环之间的紧密联系。对基准模拟模型 2（BSM2）（开环）的修改版本进行了使用，作为评估三个不同操作方案（A、A、A）的测试平台。还包括严格的传感器和执行器模型，以再现实际的控制操作。基于模型的分析表明，氨（[Formula: see text]）和总悬浮固体（X）控制策略（A）的组合更好地适应了进水动态，通过磷积累微生物（X）（41%）更好地积累磷酸盐[Formula: see text]，提高硝化/反硝化效率（18%），并降低曝气能耗（E）（21%）。添加铁（[Formula: see text]）进行化学 P 去除（A）会促进三价铁氧化物（X、X）、磷酸盐吸附（X、X）、共沉淀（X、X）的形成，从而降低出水的 P 水平（从 2.8 降至 0.9 g P.m）。这也会对污泥线产生影响，由于铁硫化物（X）沉淀，硫化氢（[Formula: see text]）的产生减少（36%）。因此，沼气的能量产生（E）也略有增加。最后，为了回收 P，增加了脱气和结晶单元（A），这减少了返回水线的厌氧消化上清液中的 P 量，并允许潜在的鸟粪石（[Formula: see text]）回收量为 69 至 227 kg.day，具体取决于：（1）空气流量（Q）；（2）镁（[Formula: see text]）的添加量。从环境和经济角度使用适当的性能指标评估了所有提出的替代方案。最后，讨论了在进行（全厂范围）污水处理厂建模/工程项目时，所提出方法的一些缺陷和机会。
