Solid-state 13C NMR to assess organic matter transformation in a subsurface wetland under cheese-dairy farm effluents

Solid-state w(13)C NMR were used to follow organic matter transformation ill a Subsurface wetland under the effluent of a small cheese-dairy farm Under a Mediterranean climate. The results showed that the ratios Commonly used to quantify humification, (aromaticity and Alkyl-C/O-Alkyl-C ratios) call be considered as relevant chemical indicators of organic matter transformation. Polysaccharides were transformed throughout the Subsurface wetland whereas aromatic, phenolic and alkyl compounds accumulated. Furthermore, Phenolic-C signal and O-Alkyl-C signal were negatively correlated to proteases and beta-galactosidase activities showing that recalcitrant molecules actually accumulated. These results were correlated with high purification yields: the average decrease in chemical demand in oxygen was 90.75% and that in Total Kjeldahl Nitrogen was 75.65%. Thus Subsurface wetlands call be considered as all efficient technology to purify effluents with high organic matter contents, such as cheese-dairy effluent. under drastic climate conditions. Furthermore this study highlights the fact that solid-state C-13 NMR is a Suitable toot to follow organic matter transformation. (C) 2009 Elsevier Ltd, All rights reserved.