Valorization of tannery solid wastes for sustainable enzyme induced carbonate precipitation process
Valorization of tannery solid wastes for sustainable enzyme induced carbonate precipitation process
复制标题
DOI：
10.1016/j.chemosphere.2022.136533
复制
发表时间：
2022-09-25
期刊：
影响因子：
8.8
通讯作者：
Kamini, Numbi Ramudu
中科院分区：
文献类型：
--
作者：
Sujiritha, Parthasarathy Baskaran;Vikash, Vijan Lal;Kamini, Numbi Ramudu
酶促碳酸盐沉淀法是一种新兴的利用尿素酶沉淀碳酸钙的地基改良技术。在环境影响方案中使用昂贵的实验室级化学品阻碍了其在实地应用中的实施。本研究探讨了利用制革工业产生的固体废物进行电感耦合等离子体处理的可行性。首先，以蛋白质肉质废料为氮源，从溶肌节杆菌MTCC 5604中生产胞外尿素酶，然后将其与制革石灰液悬浮固体一起用于EICP法，作为替代钙源。用1NHCl处理石灰液悬浮物，制备钙离子溶液。EICP1000 U尿素、1.0 M尿素、1.0 M CaCl2.2H2O是试管试验的最佳配方。在最佳条件下，当胶结液的加入量为5倍时，当加入实验室级CaCl2.2H2O时，砂子的最大无侧限抗压强度(UCS)为810kPA；用X射线衍射仪、傅立叶变换红外光谱仪和扫描电子能谱分析了碳酸钙析出物的晶相和形貌。结果表明，从石灰液中得到的钙在EICP中形成了更稳定的方解石，而用CaCl2.2H2O得到了方解石和球状沸石。利用制革废渣和石灰液可以减少制革生产中制革前的污染负荷和污泥的形成。结果表明，在大规模应用中实现低成本和可持续的生物固化是可行的。
Biocementation via enzyme induced carbonate precipitation (EICP) is an emerging ground improvement technique that utilizes urease for calcium carbonate precipitation. Usage of expensive laboratory grade chemicals in EICP hinders its implementation at field level applications. In this study, the feasibility of utilizing solid wastes generated from leather industry was investigated for EICP process. Initially, the proteinaceous fleshing waste was used as ni-trogen source for production of an extracellular urease from Arthrobacter creatinolyticus MTCC 5604 followed by its subsequent use in EICP with suspended solids of tannery lime liquor, as alternative calcium source. The calcium ion solution was prepared by treating suspended solids of lime liquor with 1 N HCl. The EICP was optimum with 1000 U of urease, 1.0 M urea and 1.0 M CaCl2.2H2O for test tube experiments. Sand solidification experiments under optimal conditions with five times addition of cementation solution yielded a maximum unconfined compressive strength (UCS) of 810 kPa with laboratory grade CaCl2.2H2O and 780 kPa with calcium from lime liquor. The crystalline phases and morphology of the CaCO3 precipitate were analyzed by XRD, FTIR and SEM-EDX. The results showed the for-mation of more stable calcite in EICP with calcium obtained from lime liquor, while calcite and vaterite polymorphs were obtained with CaCl2.2H2O. Utilization of fleshing waste and lime liquor in EICP could reduce the pollution load and sludge formation that are generated during the pre-tanning operations of leather manufacturing. The results indicated the viability of process to achieve cost effective and sustainable biocementation for large scale applications.