124 Evaluation of the Chemical Characteristics of Three Organic Residues and the Effect of Their Use on the Environmental Medium

Abstract

The richness of the organic residues in certain fertilizing elements justifies their valorization in horticulture. However, their contents in pathogenic and toxic elements can restrict their use. In this context, this study was conducted in order to evaluate the effect of three organic residues on the environmental medium and the risks of water contamination by the release of heavy metals. Physocarpus opulifolius `Nanus' was transplanted into four substrates. The control substrate contained 4 peatmoss: 5 composted conifer bark: 1 fine crushed gravel (by volume). The three other substrates (25% of peatmoss was substituted by organic residue) contained 10% of fresh bio-filters (FBF), 10% of composted sewage sludges (CSS), or 10% of de-inking sludges (CDS). The pots (5l) were placed in plastic vats and the drainage water was recovered in vessels (17l). The experimental design was in complete blocks with six replications. Samples of the drainage water were collected every 2 weeks for analysis. The pots were fertilized every week (400 mg/Ll of N) and growth parameters were statistically analyzed by ANOVA. The chemical analysis of the residues proves that they contain weak concentrations in organic contaminants. There is an accumulation of \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document} in drainage water following the fertilization; the same applies to sulfates and potassium. On the other hand, heavy metals are not released in important concentrations and so the lead, zinc, manganese, and copper contents do not exceed the desirable limits. Moreover, the Physocarpus plants produced in CSS substrates had a growth significantly larger than those plants produced in FBF or CDS substrates. The three organic residues do not constitute a risk of pollution for the environment.