Rehabilitation of Total Petroleum Hydrocarbons and Heavy Metals Co-contaminated Soil by Bioaugmentation, Co-planting and Organic Amendments

Abstract

Soil is the receptor of all the organic and inorganic pollutants in the environment. Different anthropogenic activities lead to soil contamination with variety of different contaminants which then can be taken up by plants and enter the food chain posing many health hazards. The phenomenon of co-contamination is very common as there are very less chances of presence of single pollutant in contaminated area. Sometimes a bioremediation strategy applied for one pollutant causes the mobility or availability of the pollutants residing next to it, which again contaminate the matrix. Current bioremediation and phytoremediation technologies are more focused into the method which can deal the multiple pollutants at the same time. In this study, co-contamination of heavy metals and total petroleum hydrocarbons (TPHs) is targeted by co-planting of Zea mays L. and Ricinus Communis in phase-I and Lolium perenne and Ricinus Communis in Phase-II, which will degrade TPHs in soil and phytoextract metal in plants. Pot experiment was conducted on co-contaminated soil with TPH, and HMs along selected bacterial strains. Compost was also used as organic amendment in some treatments. Treatments with Bacillus safensis strain inoculum and co-plantation and compost showed highest TPHs removal. Cd, uptake was 46.47 mg/kg, Pb 54 mg/kg and Zn 95.77 mg/kg. Highest plant biomass (3.97g) was observed in treatment. Chlorophyll a, b and carotenoids content improved plant health in C.B + M + Bacillus safensis + Compost treatments. MDA, H2O2, Apx etc. were high in treatment and significant reduction was observed in inoculated treatments. CFU was highest in the treatments with Bacillus safensis strain inoculum and co-plantation and compost. Results of current study indicated that phyto assisted remediation by co-plantation, bacterial inoculation and organic amendment not only helps to degrade the TPHs but also aids plant in removal of HMs. Key words: Co-contamination, heavy metals, co-cropping, phytoremediation, bacteria, compost