School of Environment, Harbin Institute of Technology, Harbin, 150090, PR China; State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, PR China.
School of Civil Engineering, Guangzhou University, Guangzhou, 510006, PR China.
J Environ Manage. 2022 Aug 1;315:115148. doi: 10.1016/j.jenvman.2022.115148. Epub 2022 May 2.
Lysozyme can efficiently accelerate solubilization and hydrolysis of waste activated sludge (WAS) for anerobic digestion. However, the effect of lysozyme was easily to be inhibited by metal ions in WAS. The impact of magnesium ions (Mg) on lysozyme catalyze WAS disintegration was investigated in this study. The effect of lysozyme on WAS hydrolysis could be hindered by Mg. Relatively high concentrations (>50 mg/L) of Mg in sludge significantly reduced the release of soluble polysaccharides and proteins from WAS, while sulfate ions or chloride ions caused no such effect. Proteins were difficult to be extracted from extracellular polymeric substances (EPS) of WAS in the presence of Mg (>10 mg/L) due to the divalent cation bridging (DCB) behavior, while the extraction of polysaccharides was not significantly affected. The polysaccharides and proteins in the inner EPS layer were transferred to the outer layer during the lysozyme treatment, and total quantities of both components maintained constantly. At least 23.1% lysozymes were trapped in the liquid phase of 100 mg Mg/L in the first hour. Mg could significantly affect the transfer of lysozyme from liquid phase to the inner layer of sludge. Mg neutralized the negative surface charge of the sludge particles, which hindered the absorption of positively charged lysozyme molecules by sludge flocs from the liquid phase. The proteins of TB-EPS had higher ratios of α-helixes and tighter structures than those in LB-EPS, which could impede the lysozyme transfer to the cell wall.
溶菌酶可以有效地促进厌氧消化中废活性污泥（WAS）的溶解和水解。然而，溶菌酶的作用很容易被 WAS 中的金属离子抑制。本研究考察了镁离子（Mg）对溶菌酶催化 WAS 解体的影响。溶菌酶对 WAS 水解的作用会受到 Mg 的阻碍。污泥中较高浓度（>50mg/L）的 Mg 会显著降低 WAS 中可溶性多糖和蛋白质的释放，而硫酸根离子或氯离子则没有这种影响。由于二价阳离子桥联（DCB）作用，当 Mg 浓度高于 10mg/L 时，蛋白质很难从 WAS 的细胞外聚合物物质（EPS）中提取出来，而多糖的提取则没有受到显著影响。在溶菌酶处理过程中，EPS 内层中的多糖和蛋白质转移到外层，并且两种成分的总量保持不变。在第一个小时内，至少有 23.1%的溶菌酶被 100mg/L Mg 捕获在液相中。Mg 可以显著影响溶菌酶从液相向污泥内层的转移。Mg 中和了污泥颗粒的负表面电荷，从而阻碍了带正电荷的溶菌酶分子从液相被污泥絮体吸收。TB-EPS 的蛋白质具有比 LB-EPS 更高的α-螺旋比例和更紧密的结构，这可能会阻碍溶菌酶向细胞壁的转移。
