Evaluating Sewage Sludge Contribution During Co-Composting Using Cause-Evidence-Impact Analysis Based on Morphological Characterization

Abstract

The methods of compost preparation from sewage sludge and their modes of application to the agricultural fields have profound impacts on the soil ecology and environment. Besides their chemical conditioning effect on soil organic matter, they also impart physical attributes to the soil texture and structure. Though it is expected that compost addition improves water holding capacity and nutrient sequestration, there is lack of clarity in correlating the outcomes with conditions of excess nutrient storage/leaching despite the benefits on crop yield. In this study, we present a systematic cause-evidence-impact relationship on the feedstock, processing and applications of co-composted organic matter. Various analytical tools were compared to elucidate the unique characteristics of co-composted sewage sludge to get a realistic understanding of the complex soil-compost interactions. Results from the spectroscopic characterization reveal the implications of selection of bulking agents and sludge pre-treatment in determination of the final quality of the compost. The results attribute significant parent material influence to the formation of well-defined porous structures. The impacts of compost quality on the soil and crop can be proactively determined in terms of elemental composition, functional groups and stability indices. Thus the present approach provides good scope for customizing compost preparations and applications to get the preferred field outputs.