Apport des biosolides dans la décontamination et la fertilité d’un sol sableux contaminé aux hydrocarbures aromatiques polycycliques

Abstract

In order to improve the fertility of a sandy soil contaminated with polycyclic aromatic hydrocarbons, increasing quantities of biosolids obtained from the treatment and drying of septic tank sludge (control or (T0), soil not contaminated with hydrocarbons; (T1), soil contaminated with hydrocarbons; (T2), hydrocarbon-contaminated soil to which we added 15% biosolids; (T3), contaminated soil to which we added 30% biosolids and (T4), contaminated soil to which we added 45% biosolids) was mixed with contaminated soil to test the germination and growth of roots and stems of Abelmoschus esculentus and Amarantus cruentus after 90 days. Results showed that on day 5 following soil application of biosolids, the germination rate of Abelmoschus esculentus was ≥ 80% in all substrates, while Amarantus cruentus seeds germinated at over 80% only in treatments T3 and T4. Root growth on day 14 showed that the length of okra (Abelmoschus esculentus) roots was significant for T4 substrates first and then T3. Stem length was marked for T4 and T3. Abelmoschus esculentus roots and stems developed well in T4 and T3 substrates. The physicochemical properties of the substrates indicated that total nitrogen, total phosphorus, assimilable phosphorus, total organic carbon and electrical conductivity increased in substrates containing biosolids. Doses of 30 and 45% biosolids applied to hydrocarbon-contaminated soil had a positive effect on the germination and growth of roots and stems of two, reflecting the reduced toxicity of hydrocarbon-contaminated soil due to biosolids.