Remediation Of Agricultural Soils Contaminated With Total Petroleum Hydrocarbons Through The Use Of Compost And Earthworms

Abstract

Contamination by poor management of total petroleum hydrocarbons (TPH) causes negative impacts on the soil affecting agricultural areas. Therefore, it is a priority to investigate technological alternatives for its solution. The objectives were to determine the efficiency of treatments that include compost and earthworms (Eisenia foetida) in the remediation of soils contaminated with TPH in three types of substrates, as well as to establish the variation of substrate properties and their relationship with TPH removal. The study was conducted "ex situ", where three treatments were evaluated combining soil contaminated with TPH (SCTPH) and compost with earthworms (CCLT) in the following proportions: T1) 25% SCHTP and 75% CCLT; T2) 50% SCHTP and 50% CCLT and T3) 75% SCTPH and 25% CCLT. The results showed that all treatments were able to reduce the initial TPH content of the contaminated soil in the different fractions (F1, F2 and F3); however, T1 was more efficient in the removal of TPH, achieving remediation below the national EQS for agricultural soils. Regarding substrate properties, all treatments were able to increase organic matter, pH and cation exchange capacity; they attenuated the C/N ratio and stabilized electrical conductivity at non-saline levels. The linear correlation coefficients reveal that the C/N ratio; salinity and CEC at the end of the remediation process presented significant association with respect to the TPH removed; the highest correlation coefficient was between TPH and CEC with an inverse relationship between both.