Session- Analytical Methods II
Profile Analysis and Functional Modelling of Enzymatic Activities During Composting of Vegetable Wastes
Cunha Queda, A.C.(1), Coelho, C.A. (2), Vallini, G. (3), Bruno de Sousa, R.(1)
(1) Instituto Superior de Agronomia, Dept. of Environ. and Agric. Chemistry, Tapada da Ajuda, 1349-017 Lisbon, Portugal, (2) Instituto Superior de Agronomia, Dept. of Mathematics, Tapada da Ajuda, 1349-017 Lisbon, Portugal, (3) Univ. Verona, Dept. Sci. and Technology, Ca' Vignal 1, Strada le Grazie 15, I-37134 Verona, Italy
An important tool to understand the biochemical transformations of organic matter during the composting process is the profile analysis and functional modelling of enzymatic activities. Hydrolases related to the C, N and P cycles are responsible for the degradation of organic compounds of initial matrices. Two composting trials were performed. The main component of the composting initial matrices was vegetable waste from the Lisbon municipal market. This material was mixed with straw and corrugated cardboard for the first trial and with straw, wood chips and forest residues for the second trial. The enzymatic activities analysed were lipases (C10), acid and alkaline phosphatases, total cellulases, b-glucosidase, N-acetyl-b-D-glucosaminidase, and proteases. Enzymatic activities were evaluated by quantitative methods, using different substrates. A statistical profile analysis was carried out mainly in order to evaluate the plausibility of the hypothesis of profile parallelism for pre-determined classes of enzymes was investigated. In order to better assess these enzymatic profiles a functional modelling of several hydrolase activities was also performed. For each trial functional enzymatic profiles were fitted and the possibility of fitting a common model for the above mentioned pre-determined classes of hydrolases was researched. The results show that although a common family of models may be fitted to all the enzymatic profiles, as a function of time, no single model is usually adequate to fit the enzymatic profiles for a given group of hydrolases. Nevertheless, for a given trial, models with some common parameters may be fitted for the hydrolases in a given class.
Evaluation of Aerobic Composting Processes of Agricultural Wastes By Reversed Phase High Performance Liquid Chromatography (HPLC)
Stefano GREGO (1), Danilo Corradini (2), Maria C. Moscatelli (1), Katia Liburdi (1), Sara Marinari (1) and Enrico Mincione (1)
(1) Dept. Agrobiologia-Agrochimica, Univ. Della Tuscia, Via S. C. De Lellis, 01100 Viterbo, (2) Istituto di Cromatografia, Area della Ricerca del CNR, Roma, Italy
We have employed reversed-phase high performance liquid chromatography (RP-HPLC) in conjunction to either mass spectrometry (MS) or UV detector for monitoring the variation of functionalized nonpolar organic compounds during the development of an aerobic composting process of agricultural wastes. Weighed amounts of agricultural wastes sampled at different time intervals during the aerobic composting process were extracted by hexane, dichloromethane, ethyl acetate, methanol and water. The fraction extracted by dichloromethane has been analyzed by RP-HPLC. The analysis has revealed the presence of molecules that are not degraded by the biotransformation, such as ursolic acid and b-sitosterol, which for this reason could be used as indexes of quality of the compost. It has also been observed that compounds of molecular mass in the range 200-800 mass units, eluting the RP column with the more polar mobile phase composition decrease in number with increasing the composting time. Minor changes are observed for the more nonpolar compounds of comparable molecular mass that seem to be affected to a minor extent by the aerobic biotransformation. However, in a more mature compost also the nonpolar compounds eluting the column with the less polar mobile phase decrease in number at the end of the composting process with the exception of b-sitosterol, which is determined also in a ten months processed compost. In this more mature compost the RP-HPLC-MS analysis reveals that the fraction extracted by dichloromethane is mainly composed of organic compounds of higher molecular mass (500-800 mass units) and medium polarity.
TMECC, Test Methods for the Examination of Composting and Compost
W.H. Thompson, P.D. Millner, M.E. Watson, and P.B. Leege
Editor-in-Chief, and Co-Editors of TMECC, USA
Test Methods for the Examination of Composting and Compost provides detailed protocols to verify compost product safety and market claims, and to enable comparison of analytical results. TMECC includes benchmark methods to sample, monitor, and analyze materials at all stages of the composting process. Standardized Test Methods: Compost producers, users, and others need accurate assessments of compost quality, but uniform methods are not currently employed to compost samples submitted to different labs. We illustrate this problem by demonstrating the effect of three common analytical methods to measure electrical conductivity (EC), a key measure of compost quality. Replicated analytical results revealing large differences due to method are presented for EC along with results for a plant bioassay which assesses phytotoxicity. These findings reinforce the need for use of standardized test methods, such as those in TMECC. Developing Measures: There is widespread acceptance of the need for developing measures of compost maturity and stability. There is a notable lack of consensus about how much emphasis should be placed on measures of maturity vs. stability. The maturity index represents an advance in integrating the measures of maturity and stability. It is a three-step decision tool for classifying composts by their relative level of maturity, but it incorporates measures of stability in the decision process. The maturity index considers three characteristics of a product: C:N ratio; stability (microbial activity by respirometry), and potential phytotoxicity (bioassay tests and chemical analyses). The protocol is presented with supporting data. The 2001 reference release of TMECC was jointly published by The US Composting Council and USDA and is available through the USGPO.
Quantification of the Turnover of Biomacromolecules During Composting By 13C-CPMAS-NMR
VEEKEN, ADRIE and Hamelers, Bert
Dept. Environmental Technology, Wageningen University, The Netherlands
Polysaccharides, aliphatics, lignins and proteins are the four classes of biomacromolecules that are the main substrates during composting. These biomacromolecules are also directly related to compost functions as improver of soil fertility and soil structure and as biocontrol agent. Few studies have focussed on the biomacromolecular composition of compost and the turnover of specific biomacromolecules during composting. Proximate analysis (wet chemical methods) for characterising organic matter are time-consuming and do not allow for a true separation between different classes of biomacromolecules. Carbon-13 Cross Polarisation Magic Angle Spinning NMR (13C-CPMAS-NMR) provides a way to characterise the biomacromolecular composition of insoluble biomacromolecules directly from bulk material without chemical extraction. The potential and problems with respect to obtaining quantitative information on the four types of carbon (aliphatic, O-alkyl, aromatic and carbonyl) by (13C-CPMAS-NMR spectroscopy are discussed. A new method was proposed by Veeken et al (2001) to calculate the turnover of the four classes of biomacromolecules from quantitative (13C-CPMAS-NMR spectra. However, the method did not take into account the biomass production, which contributes to the (13C-CPMAS-NMR signal. By taking into account the high yield of biomass during arobic degradation, a significant increase in turnover of polysaccharides and proteins in comparison with Veeken et al. (2001) was obtained. The new approach will be illustrated for composting of straw-rich pig manure in a high-rate reactor and in a passively aerated static pile. The two processes showed distinct differences in degradation of the four biomacromolecules, which were related to the conditions of the composting process. (13C-CPMAS-NMR) gives us a tool to quantify the turnover of specific biomacromolecules during composting. Moreover, the quantitative biomacromolecular composition of composts may be related to specific functions of composts. Thus, (13C-CPMAS-NMR) can assist us to innovate the composting process and produce high-quality composts.