Fruit and vegetable waste used as bacterial growth media for the biocementation of two geomaterials.

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.

Constructing and reconstructing 'best interests': An interpretative examination of substitute decision-making under the Mental Capacity Act 2005.

The Mental Capacity Act 2005 (MCA) authorises substitute decision-making in England and Wales, in relation to 'acts in connection with care or treatment', for a person lacking the capacity to make an autonomous decision, if it is both necessary and in his or her 'best interests'. The approach adopted by the MCA is consistent with the common law, but widens both the scope and procedures of a 'best interests' determination to allow for a general model of substitute decision-making in everyday health and social care. However, by decontextualising substitute decision-making, the MCA's procedures relating to 'best interests' may prove to be problematic in three ways: first, by failing to resolve adequately certain ethical dilemmas that pervade this area; secondly, by reducing applied substitute decision-making to a series of compulsory generalised instructions; and, finally, by necessitating deliberation but offering little practical guidance to the process of determination. Whilst the codification of five statutory principles in the MCA is designed to foster the empowerment of vulnerable adults, the realisation of these procedural and conceptual problems may have a negative impact on the implementation of the Act.