Efficiency of microbial inoculation for a cleaner composting technology

There are contrasting opinions on the utilisation of microbial inoculant (MI) as a bioremediation technology for composting. The effectiveness can be affected by a diversity of factors, and the reproducibility of results can be a great challenge. This study aims to review the effectiveness of MI, specified as isolated or cultured single and consortium micro-organisms, for composting, with the main component of lignocellulosic waste (LW) and the organic portion of municipal solid waste (OPMSW). The potential for the enhancing effect of each parameter, i.e. compost quality parameters: pH, germination index, nitrogen content, phosphorus content, potassium content, C/N ratio; composting parameters: temperature, odour, enzymatic activities, organic matter content, microbial population, volume reduction, humification, is discussed and evaluated. Based on 13 analysed parameters, the use of MI tends to exert a significant positive effect on the composting of LW compared to that of OPMSW. There has not been a full consensus on the efficiency of MI for composting as it varies on a case-by-case basis. A decision framework is required for the application of MI for different composting scenarios. This overview proposes MI technology, which has been generally less practical than optimising the physicochemical parameters of the composting due to the higher variation in the composting efficiency. Comprehensive comparison studies between the two approaches are needed for further verification which can contribute to the support of composting as a clean technology. The unnecessary uses of resources (e.g. MI, electric, fuel) can consequently be avoided for environmental footprint minimisation.