Abstract：
This paper investigates the feasibility of using randomly collected fruit and vegetable (FV) waste as a cheap growing medium of bacteria for biocementation applications. Biocementation has been proposed in the literature as an environmentally-friendly ground improvement method to increase the stability of geomaterials, prevent erosion and encapsulate waste, but currently suffers from the high costs involved, such as bacteria cultivation costs. After analysis of FV waste of varied composition in terms of sugar and protein content, diluted FV waste was used to grow ureolytic (S. pasteurii, and B.licheniformis) and also an autochthonous heterotrophic carbonic anhydase (CA)-producing B.licheniformis strain, whose growth in FV media had not been attempted before. Bacterial growth and enzymatic activity in FV were of appropriate levels, although reduced compared to commercial media. Namely, the CA-producing B.licheniformis had a maximum OD600 of 1.799 and a CA activity of 0.817 U/mL in FV media. For the ureolytic pathway, B. licheniformis reached a maximum OD600 of 0.986 and a maximum urease activity of 0.675 mM urea/min, and S. pasteurii a maximum OD600 = 0.999 and a maximum urease activity of 0.756 mM urea/min. Biocementation of a clay and locomotive ash, a geomaterial specific to UK railway embankments, using precultured bacteria in FV was then proven, based on recorded unconfined compressive strengths of 1-3 MPa and calcite content increases of up to 4.02 and 8.62 % for the clay and ash respectively. Scanning Electron Microscope (SEM) and energy dispersive X-ray spectroscopy (EDS), attested the formation of bioprecipitates with characteristic morphologies and elementary composition of calcite crystals. These findings suggest the potential of employing FV to biocement these problematic geomaterials and are of wider relevance for environmental and geoenvironmental applications involving bioaugmentation. Such applications that require substrates in very large quantities can help tackle the management of the very voluminous fruit and vegetable waste produced worldwide.
摘要：
本文研究了使用随机收集的水果和蔬菜（FV）废物作为廉价的细菌生长培养基用于生物固着应用的可行性。在文献中提出了生物地质作为一种环境友好的地面改善方法，以增加地质材料的稳定性。防止侵蚀和封装废物，但目前面临着高昂的成本，如细菌培养费用。在分析了不同成分的FV废物的糖和蛋白质含量之后，稀释的FV废物用于生长尿素分解(S.巴斯德,和地衣芽孢杆菌），也是一种自生的异养碳酸酐酶（CA）生产地衣芽孢杆菌菌株，以前从未尝试过在FV培养基中的生长。FV中的细菌生长和酶活性处于适当水平，虽然与商业媒体相比有所减少。即,产CA的地衣芽孢杆菌在FV培养基中的最大OD600为1.799,CA活性为0.817U/mL。对于尿素溶解途径，地衣芽孢杆菌达到0.986的最大OD600和0.675mM尿素/min的最大脲酶活性，和巴氏链球菌的最大OD600=0.999和最大尿素酶活性为0.756mM尿素/min。粘土和机车灰的生物沉积，英国铁路路堤特有的地质材料，然后证明了在FV中使用预培养细菌，根据记录的无侧限抗压强度1-3MPa和方解石含量分别增加了4.02和8.62％的粘土和灰。扫描电子显微镜（SEM）和能量色散X射线光谱（EDS），证明了具有方解石晶体特征形态和基本组成的生物沉淀物的形成。这些发现表明，使用FV对这些有问题的地质材料进行生物定位的潜力，并且与涉及生物增强的环境和地质环境应用具有更广泛的相关性。这种需要大量底物的应用可以帮助解决全球生产的大量水果和蔬菜废物的管理。
