ABSTRACT

Controlling biofilm retention time in moving bed biofilm reactor (MBBR) and maintaining its performance for A-stage carbon redirection requires a reliable method to use as side stream biocarriers treatment. This paper investigates biofilm detachment and residual biofilm activity under multiple physicochemical treatment scenarios aiming to provide an applicable technique for control of biofilm retention time. Different mixing intensities (i.e. 30–120 rpm), filling fractions (i.e. 20%–100%), and pH (i.e. 2–12) were evaluated. Two continuously operating MBBRs were subjected to pH shocks of 2 and 12 to evaluate the impact of residual acidic or alkaline compounds on performance. The highest solids detachment (i.e. 70 ± 5%) was found in alkaline conditions and independent of mixing intensity and filling fraction. Biofilm detachment test revealed that alkaline shock produced higher detachment levels in a longer exposure time when compared to acidic conditions. The kinetic tests revealed 60% and 90% of the residual biofilm activity was lost at pH 12 and 2. The continuously operating MBBRs subjected to pH shocks of 2 and 12 demonstrated a 50% loss of soluble COD removal capability within one hydraulic retention time. Extracellular polymeric substances changes in its structure and surface properties influencing the degree of biofilm detachment and its solubilization properties leading to differences in biofilm resilience. The findings have shown that by applying a side stream alkali treatment it could be possible to control biofilm retention time ensuring its detachment up to 70% and a reduced impact on the residual biofilm activity returning to the reactor.

摘要

控制移动床生物膜反应器 (MBBR) 中的生物膜保留时间并保持其在 A 级碳重定向中的性能需要一种可靠的方法来用作侧流生物载体处理。本文研究了多种物理化学处理方案下的生物膜脱落和残留生物膜活性，旨在为控制生物膜保留时间提供适用的技术。评估了不同的混合强度（即 30–120 rpm）、填充分数（即 20%–100%）和 pH 值（即 2–12）。两台连续运行的 MBBR 经受 2 和 12 的 pH 冲击，以评估残留酸性或碱性化合物对性能的影响。在碱性条件下发现了最高的固体分离（即 70 ± 5%），并且与混合强度和填充率无关。生物膜脱离测试表明，与酸性条件相比，碱性冲击在更长的暴露时间内产生更高的脱离水平。动力学测试表明 60% 和 90% 的残留生物膜活性在 pH 值 12 和 2 下丧失。连续运行的 MBBR 经受 2 和 12 的 pH 冲击表明在一个水力停留时间内可溶性 COD 去除能力丧失 50%。细胞外聚合物的结构和表面性质的变化影响生物膜的脱离程度及其增溶性质，从而导致生物膜弹性的差异。研究结果表明，通过应用侧流碱处理，可以控制生物膜保留时间，确保其分离高达 70%，并减少对返回反应器的残留生物膜活性的影响。