Sunita J. Varjani

Microbial degradation of petroleum hydrocarbons

Petroleum hydrocarbon pollutants are recalcitrant compounds and are classified as priority pollutants. Cleaning up of these pollutants from environment is a real world problem. Bioremediation has become a major method employed in restoration of petroleum hydrocarbon polluted environments that makes use of natural microbial biodegradation activity. Petroleum hydrocarbons utilizing microorganisms are ubiquitously distributed in environment. They naturally biodegrade pollutants and thereby remove them from the environment. Removal of petroleum hydrocarbon pollutants from environment by applying oleophilic microorganisms (individual isolate/consortium of microorganisms) is ecofriendly and economic. Microbial biodegradation of petroleum hydrocarbon pollutants employs the enzyme catalytic activities of microorganisms to enhance the rate of pollutants degradation. This article provides an overview about bioremediation for petroleum hydrocarbon pollutants. It also includes explanation about hydrocarbon metabolism in microorganisms with a special focus on new insights obtained during past couple of years.

Core Flood study for enhanced oil recovery through ex-situ bioaugmentation with thermo- and halo-tolerant rhamnolipid produced by Pseudomonas aeruginosa NCIM 5514.

The aim of this work was to study the Microbial Enhanced Oil Recovery (MEOR) employing core field model ex-situ bioaugmenting a thermo- and halo-tolerant rhamnolipid produced by Pseudomonas aeruginosa. Thin Layer Chromatography (TLC) revealed that the biosurfactant produced was rhamnolipid type. Nuclear Magnetic Resonance analysis showed that the purified rhamnolipids comprised two principal rhamnolipid homologues, i.e., Rha-Rha-C10-C14:1 and Rha-C8-C10. The rhamnolipid was stable under wide range of temperature (4°C, 30-100°C), pH (2.0-10.0) and NaCl concentration (0-18%, w/v). Core Flood model was designed for oil recovery operations using rhamnolipid. The oil recovery enhancement over Residual Oil Saturation was 8.82% through ex-situ bioaugmentation with rhamnolipid. The thermal stability of rhamnolipid shows promising scope for its application at conditions where high temperatures prevail in oil recovery processes, whereas its halo-tolerant nature increases its application in marine environment.

Critical review on biosurfactant analysis, purification and characterization using rhamnolipid as a model biosurfactant

Surfactants are one of the most versatile group of chemicals used in various industrial processes. Their market is competitive, and manufacturers will have to expand surfactant production in ecofriendly and cost effective manner. Increasing interest in biosurfactants led to an intense research for environment friendly and cost-efficient production of biosurfactant. Structural diversity and functional properties of biosurfactants make them an attractive group of compounds for potential use in wide variety of industrial, environmental and biotechnological applications. Screening methods make task easier to obtain potential biosurfactant producing microorganisms. Variety of purification and analytical methods are available for biosurfactant structural characterization. This review aims to compile information on types and properties of biosurfactant, microbial screening methods as well as biosynthesis, extraction, purification and structural characterization of biosurfactant using rhamnolipid as a model biosurfactant. It also describes factors affecting rhamnolipid production. It gives an overview of oil recovery using biosurfactant from Pseudomonas aeruginosa.

Treatment of dye wastewater using an ultrasonic aided nanoparticle stacked activated carbon: Kinetic and isotherm modelling

The present work explains the biosorption of malachite green dye from aquatic systems by nano zero valent iron stacked activated carbon (NZVI-AC), which was prepared by dual surface modification strategy. NZVI-AC was characterized by using FTIR, SEM-EDX, XRD and TGA. NZVI-AC exhibited efficient performance in dye biosorption properties. Experimental variables such as time, pH, dye concentration, temperature and biosorbent dosage influenced Langmuir adsorption capacity of 187.3 mg/g. The present biosorption system was best described by pseudo-first order kinetics. The dye was completely knocked out of the solution within 60 min at equilibrium. The thermodynamic behaviour of NZVI-AC was exothermic, feasible and spontaneous. Experimental data was engaged to validate new solid-liquid phase equilibrium model, showing the average absolute relative deviation 7.72%. Hence the procedure was non-toxic, potential to retain biosorbent from the solution, applicable for multiple cycles. In context, NZVI-AC can be recommended for the treatment of dyes from industrial effluent.

Computational Modelling and Prediction of Microalgae Growth Focused Towards Improved Lipid Production

In response to compelling demands worldwide for sources of renewable and eco-friendly energy feedstock, research and development in microalgae as a sustainable alternative has garnered interest. In order to make microalgae-derived fuel more competitive than fossil fuels in terms of cost, bottlenecks like scalability, better biomass production and enhanced lipid production without nutritional stress need to be resolved. In this chapter, the various computational modelling methods applied to microalgae growth in various environmental conditions have been reviewed. The possibility and potential of employing these models for better lipid production have also been highlighted, as better predictability of models can lead to better transgenic algal platform. Moreover, the upcoming models integrating omics data with flux analysis have also been discussed that has resulted in updated simulation due to the incorporation of data about novel genes. Lastly, the need for close collaboration between biochemical engineers, molecular biologists and modellers have been emphasised to validate the models on natural environment apart from laboratory conditions.

Improving methane yield and quality via co-digestion of cow dung mixed with food waste

Methane (CH4) production and quality were enhanced by the co-digestion of cow dung and food waste (FW) mixed with organic fraction of municipal solid waste (OFMSW) under optimized conditions in bench and semi continuous-scale mode for a period of 30 days. A bacterium capable of high yield of CH4 was enriched and isolated by employing activated sewage sludge as the inoculums. The thirteen bacterial isolates were identified through morphological and biochemical tests. Gas chromatography was used to analyze the chemical compositions of the generated biogas. CH4 yields were significantly higher during co-digestion of Run II (7.59 L) than Run I (3.7 L). Therefore, the co-digestion of FW with OFMSW and Run II was observed to be a competent method for biogas conversion from organic waste resources.

Evaluation of Next-Generation Sequencing Technologies for Environmental Monitoring in Wastewater Abatement

The waste generation and disposal into natural water bodies become a serious topic to be concerned by researchers today. Consequently, there is a demand for new strategies and technologies to address wastewater treatment and subsequent recycle and reuse especially in arid/semiarid areas. The harmful microbial load in raw sewage, toxic chemicals, and nutrients may cause pollution and can render water utilities unfit for human consumption or recreational activities. Biological treatment process is advantageous and constitutes tools to biodegrade organic matter, transfer toxic compounds into harmless products, and remove nutrient in wastewater microbiology. Bio-monitoring employs sentinel or indicator species in water bodies to infer water quality, ecosystem health status, and to protect public health from waterborne risks. Next-Generation Sequencing is one of the most leveraging studies focus on the ecology of microbial-mediated processes that influence freshwater quality such as algal blooms, contaminant biodegradation, and pathogen dissemination. Sequencing methods targeting small subunit (SSU) rRNA hypervariable regions have allowed for identification of microbial species which serve as bioindicators for sewage contamination in raw, treated, semi-treated water utilities. In addition, hidden diversity of unknown or uncultured microorganisms reveals the genetic capabilities for biodegradation of toxins and other contaminants. This chapter aims to provide brief knowledge about the development of bioindicators for sewage pollution and microbial source tracking, characterizing the distribution of toxin and antibiotic resistance genes in water samples. The assessment of biological risk, suitability, and unfairness inherent in the application of Next-Generation Sequencing may be a prior concern.

Polycyclic Aromatic Hydrocarbons from Petroleum Oil Industry Activities: Effect on Human Health and Their Biodegradation

Nowadays pollution control and abatement are critical issues faced by environmental scientists due to rapid industrialization. Petroleum industry is one of the major industries which release hydrocarbon pollutants in environment. Polycyclic aromatic hydrocarbons (PAHs) are the priority pollutants which are released into the environment by exploration activities of petroleum industries. The indiscriminate accumulation of petroleum hydrocarbon pollutants can be hazardous to the human life and aquatic biota. Due to toxicity of these pollutants, establishing efficient and environment-friendly method to degrade and detoxify these pollutants is an important research challenge. Various physiochemical methods are applied all over the world to remediate of petroleum hydrocarbon pollutants. Bioremediation technique has been developed for treatment of crude oil pollutants using biological agents like bacteria, fungi, algae, and plants. Applications of certain microorganisms have gained importance in the field of applied environmental microbiology. The application of microbes to degrade pollutants is getting attention due to its environmental and economic benefits. They can be used to change bioavailability and toxicity of petroleum hydrocarbons present in polluted soil and aqueous environment. This paper explores hydrocarbons present in petroleum crude. The effect of petroleum hydrocarbon pollutants on human health and environment is also discussed. This chapter also explains microbial degradation of these pollutants.

Introduction to Waste Bioremediation

Incomplete discharge of waste materials into the environment is of concern due to its slow degradability, highly soluble and biomagnification features in animals and plants. Conventional treatment techniques include chemical precipitation, ion-exchange, reverse osmosis and combustion are effective but energy intensive and consumes huge amounts of chemicals which may give rise to secondary problems such as spillage, corrosion and toxicity. The application of biological approach notably from use of microorganisms is an interesting alternative. Microorganisms such as bacteria, yeast and algae are known to survive in waste-containing environments owing to its ability to reduce, accumulate, sequester, absorb and oxidize different types of waste materials into forms, mostly making it less soluble and easily precipitated, that is, less toxic to the environment. This monograph covers biological approaches to remediate waste generated from various industries such as petroleum, electronic, textile, electroplating and landfill site(s). The role of microbes in composting and anaerobic digestion processes is also discussed. Apart from this effectiveness of microbes living in legumes of plant to remediate toxic heavy metals are also reported.

Biosynthetic Technology and Environmental Challenges

Bio-based processes and products are getting more and more acceptance nowadays mainly because of the environmental friendly process. Many current petroleum-derived products would be replaced by less expensive and better performing products based on renewable materials in near future. This will help for achieving economic and environmental sustainability. Bioeconomy is now emerging as a major industrial breakthrough and new biomass-based products are emerging due to the advancement in technologies. These potential benefits of bio-based products could justify future public policies that encourage a transition to renewable raw materials for production of organic chemicals, fuels and materials. Biosynthetic approaches for production of various industrially important chemicals and products through microbial and plants routes have been discussed in this book. The environmental challenges for its production under biorefinery approach and the various methods for addressing the environmental issues have been discussed in detail. S. J. Varjani (&) Gujarat Pollution Control Board—Paryavaran Bhavan, Gandhinagar 382010, Gujarat, India e-mail: drsvs18@gmail.com P. Binod Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram 695019, Kerala, India e-mail: binodkannur@gmail.com S. Kumar Solid and Hazardous Waste Management Division, CSIR-NEERI, Nehru Marg, Nagpur 440020, Maharashtra, India e-mail: s_kumar@neeri.res.in S. K. Khare Biochemistry Section, Department of Chemistry, Indian Institute of Technology Delhi, New Delhi 110016, India e-mail: skkhare@chemistry.iitd.ac.in