Development of bioremediation technologies using. biosurfactants for decontamination of sludge, soil and. sediment from hazardous organics

Transcription

1 i Development of bioremediation technologies using biosurfactants for decontamination of sludge, soil and sediment from hazardous organics SYNOPSIS In the modern developing world, contamination of environment on the earth is a major issue. In areas of high population density and industrial activity, release of xenobiotic compounds into the soil and the wider environment have led to higher concentrations of these contaminants than would be expected from natural processes alone. This contamination leads to potential toxic effects on biological resources and often, indirectly on human health. As a result, there is a need to identify and cleanup sites that have become heavily contaminated so that they do not pose unnecessary risks to health. Andhra Pradesh is an industrially well developed state where most of the industries are situated around state capital Hyderabad. This industrial hub include industries like bulk drug, pesticide, pharmaceutical plastics, ceramics, industrial chemicals, petroleum hydrocarbons etc..,covering nearly 4000 small scale industries and 200 medium to large scale industries. Due to inefficient treatment and accidental spillages and improper handling of chemicals and industrial effluents are the main causes of contamination of soil and water in lakes where the untreated effluents finally settle and grossly producing

2 ii polluted sediments and soil. Many remedial technologies like physical, chemical or biological techniques were developed for decontamination of polluted sites. Moreover, biological techniques gained importance over physical or chemical technologies due its techno-economic perspective. For the large contaminated sites these bioremediation technologies were preferred for decontamination. In this Ph.D programme, the author has evaluated some bioremediation methodologies for the decontamination of polluted soil, sediment and sludge collected from various industrially contaminated sites. Degradation of xenobiotics, mostly hydrophobic compounds is an important task in biodegradation. The bioavailability of these hydrophobic compounds is less and hence retards the biodegradation rate. From the literature it is known that when hydrophobic compounds are treated with addition of surfactants, the biodegradation rate was enhanced due to the increase in bioavailability to the microorganisms. In recent studies, biosurfactants gained importance over chemical surfactants in bioremediation. Keeping this point in view, initially, the author had taken up production of rhamnolipid, a biosurfactant produced by a predominant bacteria Pseudomonas aeruginosa using various economic substrates. Further bioremediation of the contaminated soil which was contaminated with petroleum hydrocarbons near IOC, the sediment from a highly contaminated lake Khazipally with industrial effluents and the sludge from common effluent treatment plant

3 iii at JETL was taken up and the role of rhamnolipid in biodegradation was evaluated. The bioremediation of Anthracene spiked soil was also carried out using crude rhamnolipids obtained from Pseudomonas aeruginosa. Brief Description of Thesis The present work deals with the development of economical methods for higher yield of rhamnolipid by suggesting the use of low-cost raw materials. The effect of two different carbon sources used fried groundnut oil and glycerol along with four nitrogen sources (NaNO3, NH4NO3, NH4 Cl, and Yeast extract) were examined for rhamnolipid production. In this study, two strains of Pseudomonas aeruginosa, acquired culture, J1 (MTCC, Chandigarh) and isolated culture J2 (JETL sludge), were used to optimize a substrate for maximum rhamnolipid production by varying carbon and nitrogen sources. The rhamnolipid, thus produced was further utilized in the bioremediation of contaminated soil, sediment and sludge. The role of rhamnolipids in the evaluating the potential of different bioremediation approaches such as natural attenuation, biostimulation and bioaugmentation to decontaminate the polluted samples. The study also investigates the usefulness of selected biological parameters and spectroscopic methods for monitoring and assessing the results of the bioremediation process by taking up lab scale studies. Organization of the Thesis The thesis is organized into five chapters.

4 iv In chapter 1 a general introduction on land contamination, soil, sediment contamination, bioremediation definitions, Sources of contamination, methodologies of bioremediation treatment along with the scope and significance of the study were presented. In Chapter 2 discusses literature review on the production of biosurfactants, production of rhamnolipids, application of rhamnolipids in bioremediation, and the application of bioaugmentation, biostimulation and natural attenuation in the remediation of contaminated soil/sediment/sludges. It also presents a brief review on various works related to biodegradation on hazardous organics and role of various biosurfactants in the biodegradation of hydrophobic hazardous wastes. Chapter 3 presents theoretical analysis with the explanation of the biosurfactants, their application in bioremediation, their advantages and disadvantages in bioremediation and also theory involved in the production of rhamnolipids from Pseudomonas aeruginosa. This chapter also involves the bioremediation methodologies which includes metabolic modes and factors affecting bioremediation, environmental requirements, and microbial populations for bioremediation. It also illustrates various physical, chemical and biological processes involved in natural attenuation, bioaugmentation and biostimulation technologies. It also illustrates the application of bioassays as indicator of biodegradation.

5 v Chapter 4 was presented in three sections viz. Section 4A, Section 4B and Section 4C. Section 4A discusses various materials and methods used in the production of rhamnolipids from Pseudomonas aeruginosa. Section 4B discusses materials and methods used in the bioremediation studies of contaminated soil/sediments/sludges in lab scale process. A detailed experimental protocol for the evaluation of bioremediation methods such as natural attenuation, biostimulation and bioaugmentation was presented in this section. A detailed methodology was presented for various physical, chemical and microbiological parameters whose performance signifies the success of bioremediation treatments. Section 4C presents the materials and methods used in the bioremediation of Anthracene spiked soil. The detailed methodology of spiking and various bioremediation methods like natural attenuation, biostimulation and bioaugmentation was presented in this section. Chapter 5 also contains three sections, viz Section 5A, Section 5B and Section 5C. Section 5A discusses the results of the study carried out in the production of rhamnolipids, by Pseudomonas aeruginosa. It discusses the isolation and production of rhamnolipids from Pseudomonas aeruginosa, separation, purification and quantification of rhamnolipids.

6 vi It also presents the results for comparison of rhamnolipid production between the cultures J1 and J2. Section 5B presents the results obtained in the Physico-chemical characterization of soil, sediment and sludge in order to assess the pollution status of the study area. In the context of bioremediation studies the performance of each treatment (Natural attenuation, biostimulation and bioaugmentation) was evaluated by studying various chemical and biological parameters such as total organic carbon degradation, basal respiration, microbial biomass carbon (Cmic), metabolic quotient (qco2), dehydrogenase activity and phyto toxicity. The study demonstrated that bioaugmentation assisted with rhamnolipids and nutrients was more effective in removing organic contaminants in all the three samples as compared to the treatments devoid of rhamnolipid addition. The same trend was observed in biostimulation treatment with aeration and nutrient addition. Section 5C illustrated results obtained in the bioremediation of Anthracene spiked soil. The physico chemical analysis of soil before and after treatment using various bioremediation approaches like natural attenuation, biostimulation and bioaugmentation was evaluated in this section. The performance of each treatment was evaluated by analyzing various chemical and biological parameters like total organic carbon degradation, basal respiration, microbial biomass carbon (Cmic), metabolic quotient (qco2), dehydrogenase activity and phyto toxicity. The

7 vii degradation of anthracene with response to the treatments was presented. From the present work it was concluded that by using various economical substrates like groundnut oil in production of rhamnolipids was a cost effective process when compared to commercially available biosurfactant products. Application of the rhamnolipids produced was proved to be efficient in the bioremediation of contaminated soil, sediment, sludge and anthracene when compared with the treatments not received in addition of rhamnolipids. Among the three bioremediation process, bioaugmentation was proven to be the cost effective technology when compared to natural attenuation and biostimulation process. Chapter 6 Major conclusions and the recommendations were made on the results obtained to carry out further research. Bibliography for the entire thesis was given after results and discussion chapter.