The Effect of Bioremediated Diesel Polluted Soil. (original) (raw)

LABORATORY STUDIES ON THE BIOREMEDIATION OF SOIL CONTAMINATED BY DIESEL

The most widely used energy and fuel resources are hydrocarbons such as crude oil and petroleum distillates. The accidental discharge of these petroleum products contribute in making hydrocarbons the most common environmental pollutants. Bioremediation helps to destroy or render harmless various contaminants using natural biological activity. The present study utilizes the potential of bioremediation to remediate soil contaminated with diesel. Eight bioreactors were used for the study, out of which four bioreactors were maintained at optimum environmental conditions and the remaining four were kept without any maintenance to serve as control bioreactors. Contaminated soil was prepared by mixing fresh soil and diesel so as to attain 10% TPH concentrations by weight of soil. Each bioreactor was filled with 3 kg of contaminated soil.

Organic Wastes to Enhance Phytotreatment of Diesel- Contaminated Soil.

Toxic inorganic and organic chemicals are major contributors to environmental contamination and pose major health risks to human population. In this work, Dracaena reflexa and Podocarpus polystachyus were investigated for their potential to remove hydrocarbons from 2.5% and 1% diesel fuel-contaminated soil amended individually with 5% organic wastes (tea leaf, soy cake and potato skin) for a period of 270 days. Loss of 90% and 99% oil was recorded in soil contaminated with 2.5% and 1% oil with soy cake amendment, respectively, compared with 52% and 62% in unamended soil with D. reflexa at the end of 270 days. Similarly, 84% and 91% oil loss was recorded for P. polystachyus amended with organic wastes in 2.5% and 1% oil, respectively. Diesel fuel disappeared more rapidly in the soil amendment with SC than in other organic waste supplementation. It was evident that plants did not accumulate hydrocarbon from the soil, while the number of hydrocarbon-utilizing bacteria was high in the rhizosphere, thus suggesting that the mechanism of the oil degradation was rhizodegradation. The kinetic model result indicated a high rate of degradation in soil amendment with SC at 1% with D. reflexa compared with other treatments. Thus, a positive relationship was observed between diesel hydrocarbon degradation with plant biomass production. Dracaena reflexa with organic wastes amendment has a greater potential of restoring hydrocarbon-contaminated soil compared to P. polystachyus plant.

Potential of grasses and rhizosphere bacteria for bioremediation of diesel-contaminated soils

Revista Brasileira de …, 2011

Os processos de remediação de acidentes ambientais causados por hidrocarbonetos de petróleo geralmente envolvem soluções de alto custo. Uma solução alternativa, de baixo custo e com relevância prática e ecológica é a associação de plantas e microrganismos, os quais contribuem para a degradação e remoção de hidrocarbonetos no solo. O crescimento de três espécies de gramíneas (Brachiaria brizantha, Brachiaria decumbens e Paspalum notatum) e a sobrevivência de comunidades bacterianas associadas à zona de raízes foram avaliados sob diferentes concentrações de óleo diesel. Sementes das três espécies de gramíneas foram germinadas em casa de vegetação e em diferentes doses de diesel: 0; 2,5; 5; e 10 g kg-1 solo. As plantas foram cultivadas por 10 semanas, com avaliação periódica de germinação, crescimento (peso do material fresco e seco), altura e número de bactérias no solo (vasos com plantas ou sem plantas). Houve diminuição significativa do crescimento e da biomassa de B. decumbens e P. notatum quando cultivadas em solos contaminados por óleo diesel. A presença do óleo não comprometeu o crescimento de B. brizantha, a qual apresentou elevada tolerância ao poluente. O crescimento de bactérias foi significativo (p < 0,05), sendo o aumento diretamente proporcional às doses de diesel. A presença das gramíneas em solos com diesel propiciou o crescimento de bactérias no solo em até cinco vezes, evidenciando as interações positivas entre a rizosfera e as bactérias degradadoras de hidrocarbonetos na remediação de solos contaminados com diesel.