Kooijman G, De Kreuk M K, van Lier J B
Section Sanitary Engineering, Civil Engineering, University of Technology Delft, Stevinweg 1, Delft 2628CN, The Netherlands E-mail:
Water Sci Technol. 2017 Oct;76(7-8):1629-1639. doi: 10.2166/wst.2017.314.
To lower energy consumption at a sewage treatment plant (STP), primary settling could be enhanced to direct more chemical oxygen demand (COD) to anaerobic digestion (AD) for increased biogas production and decreased aeration. Primary settling can be chemically enhanced by applying flocculation aids (FAs). FAs are refractory compounds that may affect all sludge treatment facilities. In this study the consequences are investigated of the application of FAs for chemically enhanced primary treatment (CEPT) on AD and subsequent dewatering of digested sludge in a conventional STP. It was found that FAs maintain their effect throughout all sludge processing facilities. With CEPT, more readily degradable solids were removed, resulting in a higher bio methane potential of the primary sludge. In AD, FAs lowered the viscosity; meanwhile an increased hydrolysis rate was observed. But FAs also partially irreversibly bound substrate in such way that it is not available for biological degradation anymore. In subsequent dewatering of digested sludge, a higher dry solids concentration was observed with CEPT. A computer simulation showed that in a conventional STP, CEPT would not be economically feasible. However, several benefits were discussed that can make CEPT an interesting option for future low COD/N-tolerant STPs with, for example, Anammox processes for N removal.
为降低污水处理厂（STP）的能源消耗，可强化初沉，将更多化学需氧量（COD）导入厌氧消化（AD），以增加沼气产量并减少曝气。可通过施加絮凝助剂（FAs）对初沉进行化学强化。FAs是难降解化合物，可能会影响所有污泥处理设施。在本研究中，调查了在传统STP中，将FAs应用于化学强化一级处理（CEPT）对AD及后续消化污泥脱水的影响。研究发现，FAs在所有污泥处理设施中均保持其作用。采用CEPT时，更多易降解固体被去除，使得初沉污泥的生物甲烷潜力更高。在AD过程中，FAs降低了粘度；同时观察到水解速率提高。但FAs也会以某种方式部分不可逆地结合底物，使其不再可用于生物降解。在后续消化污泥脱水过程中，采用CEPT时观察到更高的干固体浓度。计算机模拟表明，在传统STP中，CEPT在经济上不可行。然而，讨论了若干好处，这些好处可使CEPT成为未来低COD/耐氮STP（例如采用厌氧氨氧化工艺进行氮去除）的一个有吸引力的选择。
