Environmental Engineering Department, Civil Engineering Faculty, Istanbul Technical University, Istanbul, Turkey; BioCo Research Group, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, 9000 Gent, Belgium.
Environmental Engineering Department, Civil Engineering Faculty, Istanbul Technical University, Istanbul, Turkey.
Water Res. 2023 May 15;235:119920. doi: 10.1016/j.watres.2023.119920. Epub 2023 Mar 28.
Biogas production from anaerobic sludge digestion plays a central role for wastewater treatment plants to become more energy-efficient or even energy-neutral. Dedicated configurations have been developed to maximize the diversion of soluble and suspended organic matter to sludge streams for energy production through anaerobic digestion, such as A-stage treatment or chemically enhanced primary treatment (CEPT) instead of primary clarifiers. Still, it remains to be investigated to what extent these different treatment steps affect the sludge characteristics and digestibility, which may also impact the economic feasibility of the integrated systems. In this study, a detailed characterization has been performed for sludge obtained from primary clarification (primary sludge), A-stage treatment (A-sludge) and CEPT. The characteristics of all sludges differed significantly from each other. The organic compounds in primary sludge consisted mainly of 40% of carbohydrates, 23% of lipids, and 21% of proteins. A-sludge was characterized by a high amount of proteins (40%) and a moderate amount of carbohydrates (23%), and lipids (16%), while in CEPT sludge, organic compounds were mainly 26% of proteins, 18% of carbohydrates, 18% of lignin, and 12% of lipids. The highest methane yield was obtained from anaerobic digestion of primary sludge (347 ± 16 mL CH/g VS) and A-sludge (333 ± 6 mL CH/g VS), while it was lower for CEPT sludge (245 ± 5 mL CH/g VS). Furthermore, an economic evaluation has been carried out for the three systems, considering energy consumption and recovery, as well as effluent quality and chemical costs. Energy consumption of A-stage was the highest among the three configurations due to aeration energy demand, while CEPT had the highest operational costs due to chemical use. Energy surplus was the highest by the use of CEPT, resulting from the highest fraction of recovered organic matter. By considering the effluent quality of the three systems, CEPT had the highest benefits, followed by A-stage. Integration of CEPT or A-stage, instead of primary clarification in existing wastewater treatment plants, would potentially improve the effluent quality and energy recovery.
从厌氧污泥消化中生产沼气，对于污水处理厂提高能源效率甚至实现能源中和起着核心作用。已经开发出专门的配置，通过厌氧消化将可溶性和悬浮有机物最大限度地转移到污泥流中以生产能源，例如 A 级处理或化学增强的初级处理 (CEPT)，而不是初级澄清器。然而，仍需要研究这些不同的处理步骤在多大程度上影响污泥特性和可消化性，这也可能影响集成系统的经济可行性。在这项研究中，对来自初级澄清（初沉污泥）、A 级处理（A 污泥）和 CEPT 的污泥进行了详细的特性分析。所有污泥的特性差异显著。初沉污泥中的有机化合物主要由 40%的碳水化合物、23%的脂质和 21%的蛋白质组成。A 污泥的特点是蛋白质含量高（40%）、碳水化合物含量适中（23%）和脂质含量（16%），而在 CEPT 污泥中，有机化合物主要是 26%的蛋白质、18%的碳水化合物、18%的木质素和 12%的脂质。从厌氧消化初沉污泥（347±16mL CH/g VS）和 A 污泥（333±6mL CH/g VS）中获得的甲烷产量最高，而从 CEPT 污泥中获得的甲烷产量较低（245±5mL CH/g VS）。此外，还对这三个系统进行了经济评估，考虑了能量消耗和回收，以及出水质量和化学成本。由于曝气能耗，A 级的能量消耗是三个配置中最高的，而由于化学品的使用，CEPT 的运营成本最高。由于回收的有机物比例最高，CEPT 的能源盈余最高。考虑到三个系统的出水质量，CEPT 的效益最高，其次是 A 级。在现有的污水处理厂中，采用 CEPT 或 A 级代替初级澄清，有可能提高出水质量和能源回收。
