Biochemical parameters and toxicological characteristics of compost obtained from grits, biological sludge and bark coming from kraft mill solid wastes industry

摘要

Application of unstable compost can cause fitotoxicity inhibiting the growth of plants and could cause damages to the cultures that compete by oxygen or causing fitotoxicity to the plants due to the insufficient degradation of the organic matter (Brodie et al., 1994). Growth of plants and tests of germination seeds are the techniques commonly used to evaluate maturity of compost. In this context quality of three compost with different grits addition was evaluated by means of stability and maturity evaluation. The compost obtained from kraft mill secondary sludge with bark and different content of grits 5, 6, 8, 10,11% and humidity was assessed through biochemical assays (fluorescein diacetate, dehydrogenase, urease activities) to evaluate stability. In addition, germination index of Raphanus sativum and Lycopersicon esculentum L., toxicological test were used to evaluate maturity. Enzymatic activities for the compost evaluated presented similar values to those reported by other investigators of radish seed (Raphanus sativum) in compost of kraft pulp mill fulfills the norm of compost Chilean 2880 (80%). Two-Way ANOVA analysis determined that both seeds germination index and compost (independent variables) are directly related however, Raphanus sativum showed a significant effect (p＜0.05) in relation to Lycopersicon esculentum L.. The ToxiChromopad test showed presence of fitotoxic substances only in compost with a high doses of grits (10% and 11%).