Sunita J. Varjani

• PhD
• Sr. Associate Professor at University of Petroleum and Energy Studies

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 p...

The present research work was undertaken with a mandate to study carbon spectrum utilization and structural characterization of biosurfactant produced by indigenous Pseudomonas aeruginosa NCIM 5514, which showed unique properties to utilize a large number of carbon sources effectively for production of biosurfactant, although glucose was the best c...

The aim of this work was to study the potential of an indigenous strain of Pseudomonas aeruginosa NCIM 5514, isolated from petroleum-polluted soil, for the biodegradation of crude petroleum oil. The isolate completely decolorized 2,6-dichlorophenol indophenol in 120 h when grown at (37 ± 1 °C), indicating its hydrocarbon utilizing nature. Ex situ b...

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....

Plastics are indispensable in modern society but also pose a persistent threat to the environment. In particular, microplastics (MPs) have a substantial environmental impact on ecosystems. Municipal solid waste landfill leachates are a source of MPs, but leakage of MPs from leachates has only been reported in a few studies. As a modern city, Hong K...

Owing to the increasing worldwide population explosion, managing waste generated from the food sector has become a cross-cutting issue globally, leading to environmental, economic, and social issues. Circular economy-inspired waste valorization approaches have been increasing steadily, generating new business opportunities developing valuable biopr...

Wastewater disposal in the ecosystem affects aquatic and human life, which necessitates the removal of the contaminants. Eliminating wastewater contaminants using biochar produced through the thermal decomposition of lignocellulosic biomass (LCB) is sustainable. Due to its high specific surface area, porous structure, oxygen functional groups, and...

The current study employs nanoengineering diatom and TiO2 NPs to form diatom-Si-TiO2 nanoengineered structures to fabricate a dye sensitized solar cell (DSSC) (DsTnas-DSSC). This was characterized and spin coated on a Fluorine-doped Tin Oxide (FTO) anode plate. The counter cathode was prepared by spin coating graphene oxide on a FTO glass plate and...

The main aim of the Blue-Green City concept is the reduction of the adverse impacts of stormwater by recreating the natural water cycle with the aid of green infrastructure in...

The rise in energy consumption would quadruple in the coming century and the, existing energy resources might be insufficient to meet the demand of the growing population. An alternative and sustainable energy resource is therefore needed to address the fossil fuel deficiency. The utility of microalgae strains in the aspect of biorefinery has been...

In this study, the microalgae Haematococcus pluvialis were cultivated in wastewater inoculated into low-density polypropylene plastic air pillows (LDPE-PAPs) under a light stress. The cells were irradiated to different light stresses using white LED lights (WLs) as the control, and broad-spectrum lights (BLs) as a test for the period of 32 days. It...

Microalgae are considered as the major resource to produce biofuel. However, among many microalgae it is essential to screen those which are robust in their growth and accumulate abundant lipid in their cells leading to the formation of biofuel upon transesterification. Among the microalgal species, diatoms are one of the richest sources of crude o...

It is a great pleasure to publish this Special Issue of the Environmental Science and Pollution Research Journal (ESPR) dedicated to the -6th International Congress on Water, Waste and Energy Management (WWEM-22), -5th International Conference on Green Chemistry and Sustainable Engineering (GreenChem-22) and, -22 International Conference on Green...

Purpose of Review Annually, huge amounts of microplastics (MPs) are added to farmlands through sewage sludge (SS)/biosolid applications as a fertilizer. Most research emphasizes the enormity of the problem and demonstrates the fate, impacts, and toxicity of MPs during SS treatment processes and land applications. None has addressed the management s...

High-solid anaerobic digestion (HSAD) is an attractive organic waste disposal method for bioenergy recovery and climate change mitigation. The development of HSAD is facing several challenges such as low biogas and methane yields, low reaction rates, and ease of process inhibition due to low mass diffusion and mixing limitations of the process. The...

Fossil-derived products contribute significantly to greenhouse gas emissions. Transitioning from fossil-based to bio-based products is an effective solution to this problem. There has been substantial research on how biorefinery systems can help achieve such an aim. Marine shell-based biorefinery systems have been proposed in the past, but their en...

Socioeconomic and environmental factors have led scientific community to find alternative approaches for management of agro-industrial wastes. An integrated approach, i.e., clean biotechnology, could be used for the conversion of agro-industrial wastes into industrial important and less toxic end products. Bacterial cellulose (BC) is an incredibly...

Plastics have become an essential part of life. When it enters the environment, it migrates and breaks down to form smaller size fragments, which are called microplastics (MPs). Compared with plastics, MPs are detrimental to the environment and pose a severe threat to human health. Bioremediation is being recognized as the most environmentally frie...

Due to their widespread occurrence and the inadequate removal efficiencies by conventional wastewater treatment plants, emerging contaminants (ECs) have recently become an issue of great concern. Current ongoing studies have focused on different physical, chemical, and biological methods as strategies to avoid exposing ecosystems to significant lon...

Food matrices contain bioactive compounds that have health benefits beyond nutritional value. The bulk of bioactive chemicals are still present in agro-industrial by-products as food matrices. Throughout the food production chain, there is a lot of agro-industrial waste that, if not managed effectively, could harm the environment, company, and how...

Astaxanthin (3,3-dihydroxy-β, β-carotene-4,4-dione) is a ketocarotenoid synthesized by Haematococcus pluvialis/lacustris, Chromochloris zofingiensis, Chlorococcum, Bracteacoccus aggregatus, Coelastrella rubescence, Phaffia rhodozyma, some bacteria (Paracoccus carotinifaciens), yeasts, and lobsters, among others However, it is majorly synthesized by...

The World Health Organization recognised variant B.1.1.529 of the Severe Acute Respiratory Syndrome Coronavirus 2 as a variant of concern, termed "Omicron", on November 26, 2021. Its diffusion was attributed to its several mutations, which allow promoting its ability to diffuse worldwide and its capability in immune evasion. As a consequence, some...

Using the aerobic granular sludge (AGS) to improve tetracycline (TET) removal in the treatment of mariculture wastewater was investigated in the present study. The AGS rapidly adapted to and was sustained in seawater matrices with a robust granule strength (k = 0.0014) and a more stable sludge yield than the activated sludge (AS) (0.14 vs. 0.11 g-V...

Anaerobic digestion (AD) has emerged as a promising technology for diverting the organic waste from the landfills along with the production of clean energy. AD is a microbial-driven biochemical process wherein the plethora of microbial communities participate in converting the putrescible organic matter into biogas. Nevertheless, the AD process is...

As indicated in the call for papers posted for this Special Issue, Soil Science deals with various environmental compartments, so it is closely related to Environmental Research. It is clear that synergisms and collaboration are keys to reach the most fruitful relations among different sciences and scientists, and especially in all that focused on...

Wastewater management has emerged as an uprising concern that demands immediate attention from environmentalists worldwide. Indiscriminate and irrational release of industrial and poultry wastes, sewage, pharmaceuticals, mining, pesticides, fertilizers, dyes and radioactive wastes, contribute immensely to water pollution. This has led to the aggrav...

Machine learning techniques were employed to evaluate the effect of process parameters viz. microwave power (100 W, 300 W, 600 W); pH (1, 1.5, 2); and microwave time (the 60 s, 120 s, 180 s) on the pectin yield from Citrus limetta peel. A fourth-order polynomial function of 66.60 scales was used by the Support Vector Regression (SVR) model at an ep...

"Save Soil Save Earth" is not just a catchphrase; it is a necessity to protect our soil ecosystem from the unwanted and unregulated level of xenobiotic contamination. Numerous challenges such as type, lifespan, nature of pollutants and high cost of treatment has been associated with the treatment or remediation of contaminated soil, whether it be e...

The current world energy crisis and increasing greenhouse gas emissions demand a shift from fossil-based fuels to alternative and sustainable biofuels. The innate potential of microalgae over traditional terrestrial feedstocks to provide a high-quality and sustainable fuel portfolio has been recognized. Microalgae are known to mitigate atmospheric...

The pinnacle of all the efforts of nutrient removal is practically put-down the moment biological cells are lysed, hydrolyzed or digested causing subsequent reappearance of assimilated nitrogen and phosphorus in any biological process. While sludge reduction requires high SRT, the enhanced phosphorus assimilative uptake demands low SRT. A novel rea...

Agro-residues having lignocellulosic biomass are considered the most effective source (heating value 16 MJ/kg) for energy production through anaerobic digestion (AD). However, complex lignocellulosic fraction in agro-residue obstructs its biotransformation and is a rate-limiting step of the AD process. This study presents a novel free nitrous acid...

Over the decades, water contamination has increased substantially and has become a severe global issue. Degradation of natural resources is taking place at an alarming rate as a result of the use of chemicals like dyes, heavy metals, fertilizers, pesticides, and many more, necessitating the development of long-term pollution remediation methods/tec...

Anaerobic digestion is considered an environmentally benign process for the recycling of food waste into biogas. However, unscientific disposal of ammonium-rich food waste digestate (FWD), a by-product of anaerobic digestion induces environmental issues such as odor nuisances, water pollution, phytotoxicity and pathogen transformations in soil, etc...

This study investigates the effect of acidic pretreatment (HT-ACPT), enzymatic pretreatment (ENZ-PT), and microwave laser-hydrogen peroxide-Fe-nanoparticle pretreatment (Mv-H2O2-Fe-PT) on the production of bioethanol (bio-eth.) and biopolymer (bio-p) from residual algal biomass (RAB). The effectiveness of these pretreatments is based on using the e...

Chinese medicinal herbal residues (CMHRs) are known for their antipathogenic properties due to the presence of bioactive compounds. Hence, CMHRs could be used as a potential resource to produce biofertilizer with antipathogenic properties for agricultural applications. In this study, a novel approach was used by utilizing the waste-derived bioferti...

Hydrothermal liquefaction (HTL) is identified as a promising thermochemical technique to recover biofuels and bioenergy from waste biomass containing low energy and high moisture content. The wastewater generated during the HTL process (HTWW) are rich in nutrients and organics. The release of the nutrients and organics enriched HTWW would not only...

Biofilter (BF) has been regarded as a versatile gas treatment technology for removing volatile organic compounds (VOCs) from contaminated gas streams. In order for BF to be utilized in the industrial setting, it is essential to conduct research aimed at removing VOC mixtures under different inlet loading conditions, i.e. as a function of the gas fl...

Landfilling is the most widely used disposal method for municipal solid waste around the world. The main disadvantage of this strategy is the formation of leachate, among other aspects. Landfill leachate contains highly toxic and bio-refractory substances that are detrimental to the environment and human health. Hence, the risk of discharging poten...

Fungi is a diverse group of microorganisms with over 1.5 million species worldwide. It lives in a variety of environments and develops a variety of survival mechanisms that allow it to manufacture a wide variety of chemicals, i.e., biomolecules. Organic acids, enzymes and secondary metabolites have been shown to be useful in the production of biomo...

Space missions are expanding their horizons towards green energy. At the same time humans are expanding their invasion beyond the earth’s orbit and envisage to have a habitat on other planets like Mars. This is possible only when there is a continuous efflux of human biowaste and influx of vital and breathable air, food and water for the habitants....

Biofuels have gained much attention as a potentially sustainable alternative to fossil fuels to tackle climate change and energy scarcity. Hence, the increasing global interest in contributing to the biofuel supply chain (BSC), from biomass feedstock to biofuel production, has led to a huge amount of scientific production in recent years. In this v...

Selenium is targeted as a priority pollutant to be removed due to its high toxicity level and lethal effects. In this research, a novel nano sorbent was fabricated using ionic liquid on multiwalled carbon nanotubes (IL-MCNT) and employed for Selenium remediation from aqueous media. Besides solution pH, nanocomposite dosage, the initial selenium con...

The rigid lignocellulosic structure of Lantana camara impedes the hydrolysis phase and reduces the biogas production during anaerobic digestion of Lantana camara. Hence, the current study focuses on the impact of various heating pretreatment techniques, viz., hot air oven (HAO), autoclave (ATC), hot water bath (HWB), and microwave (MCW) on L. camar...

Microalgae and cyanobacteria are photosynthetic microorganisms’ sources of renewable biomass that can be used for bioplastic production. These microorganisms have high growth rates, and contrary to other feedstocks, such as land crops, they do not require arable land. In addition, they can be used as feedstock for bioplastic production while not co...

Novel phycosphere associated bacteria processes are being regarded as a potential and cost-effective strategy for controlling anthropogenic contaminants in wastewater treatment. However, the underlying concern with the process is its vulnerability to improper organic or nutrient intake. This study established a synergistic interaction between micro...

With the ever-increasing size of anaerobic digesters (AD), the management and disposal of digestate have become a challenging task for AD operators. Anaerobic digestate is rich in nutrients and contaminants; thus, a suitable treatment is required to meet environmental legislation and protect the receiving environment. There has been a thrust among...

There is an immediate global requirement for an ingenious strategy for food waste conversion to biofuel in order to replace fossil fuels with renewable resources. Food waste conversion to bioethanol could lead to a sustainable process having the dual advantage of resolving the issue of food waste disposal as well as meeting the energy requirements...

In everyday life, plastic plays a big role in people's daily lives as well as in society's life as a whole. In the environment, plastics are accumulating, and their biodegradability is very low, so this problem will likely persist for decades. Research on the degradation of synthetic plastics by enzymes or microorganisms has become a prominent topi...

Biocatalysts, including live microbial cells/enzymes, have been considered a predominant and advantageous tool for effectively transforming biomass into biofuels and valued biochemicals. However, high production costs, separation, and reusability limit its practical application. Immobilization of single and multi-enzymes by employing different nano...

CO2 sequestration carried by biological methodologies shows enhanced potential and has the advantage that biomass produced from the captured CO2 can be used for different applications. Bio-mitigation of carbons through a micro-algal system addresses a promising and feasible option. This review mostly focused on the role of algae, particular mechani...

Due to the nutritional values and functional bioactivities of mushrooms, the global market value of the edible mushroom industry has been growing steadily. However, the production of 1 kg of fresh mushroom generates about 5 kg of wet byproducts (known as spent mushroom substrate; SMS). This necessitates proper waste management to mitigate potential...

Membrane bioreactor (MBR) process has been recognized as the promising technology for wastewater treatment/reuse in the 21st century. Thus this chapter is introduced to provide a comprehensive review of the MBR process, covering not only the principle of MBR but also the aspect of the practice of wastewater treatment, fouling, economic of MBR. Here...

In this “plastic era” with the increased use of plastic in day today's life the accumulation of its degraded products like microplastics or plastic additives such as Bisphenol A(BPA) is also increasing. BPA is an endocrine-disrupting chemical used as a plasticizing agent in clear plastic, building materials, coatings, and epoxy resin. Several enzym...

Current experimental evidence has revealed that pomegranate peel is a significant source of essential bio compounds, and many of them can be transformed into valorized products. Pomegranate peel can also be used as feedstock to produce fuels and biochemicals. We herein review this pomegranate peel conversion technology and the prospective valorized...

The kingdom Fungi includes ubiquitous and adaptable microorganisms playing a predominant role in our life and has benefits in the fields of biotechnology, genetics, biochemistry, food industry, bioremediation, medical and plant mycology, environmental ecology, soil biology, and taxonomical studies. Fundamental information is required on how a fungu...

The coronavirus pandemic of 2019 has already exerted an enormous impact. For over a year, the worldwide pandemic has ravaged the whole globe, with approximately 250 million verified human infection cases and a mortality rate surpassing 4 million. While the genetic makeup of the related pathogen (SARS-CoV-2) was identified, many unknown facets remai...

Proper waste disposal is a key towards sustainable development. Wastewater treatment is delineated by the application of efficient, economic and novel catalysts. Biochar is derived from the thermochemical conversion of biomass or any carbonaceous materials and is considered as one of the most eco-friendly substitute for activated carbon. Owing to i...

Food waste digestate (FWD) is an organic waste characterized by high NH4⁺-N content and its composting is challenging due to the higher NH3 emission and nitrogen loss. In the present study, FWD was co-composted with sawdust and mature compost, and zeolite was used as a physical additive for nitrogen conservation. The results demonstrated that amend...

Organic-rich wastewater is a feasible feedstock for biohydrogen production. Numerous review on the performance of microorganisms and the diversity of their communities during a biohydrogen process were published. However, there is still no in-depth overview of enzymes for biohydrogen production from wastewater and their scale-up applications. This...

This work reported a new waste functionalization and utilization method, which use digestate to prepare hydrochar to improve methane production from food waste (FW) and sewage sludge (SS). Experimental results presented that 10 g/L hydrochar obtained the cumulative methane production of 133.11 ± 1.18 mL/g volatile solids added, 26.99% higher than t...

This study examined the effects of nitrogen species (NH4+-N/NO3−-N ratio) and biomass retention time (BRT) on nutrient uptake and biomass productivity in Chlorella sp. In batch photobioreactors (PBR), microalgae were cultivated with varied nitrogen species ratios (100% NH4+-N, 50% NH4+-N:50% NO3−-N, and 100% NO3−-N). It was observed that a medium c...

The rapid growth of the industrial sector has expedited the accumulation of heavy metal(loid)s in the environment at hazardous levels. The elements such as arsenic, lead, mercury, cadmium and chromium are lethal in terms of toxicity with severe health impacts. With issues like water scarcity, limitations in wastewater treatment, and costs pertainin...

The discharged saline wastewater has severely influenced the aquatic environment as the treatment performance of many wastewater treatment techniques is limited. In addition, the sources of saline wastewater are also plentiful from agricultural and various industrial fields such as food processing, tannery, pharmaceutical, etc. Although high salini...

In the present study, surface-active compounds (SAC) were extracted from biosolids using an alkaline treatment process. They were tested for its remediation efficiency of crude oil-contaminated sediment soil and compared with Triton x-100. The SAC exhibits a similar soil washing efficiency to that of the commercial Triton x-100, and under the optim...

Depleting fossil fuel resources such as crude oil and coal are responsible for greenhouse gas emissions and global warming. Hence, converting biogenic waste such as animal waste and agricultural and industrial residues to biogas (CH4 and CO2) using anaerobic digestion (AD) is a sustainable, renewable, and environmentally friendly way of producing f...

Increasing municipal solid waste (MSW) generation and environmental concerns have sparked global interest in waste valorization through various waste-to-energy (WtE) to generate renewable energy sources and reduce dependency on fossil-derived fuels and chemicals. These technologies are vital for implementing the envisioned global “bioeconomy” throu...

In recent years, biomass has been reported to obtain a wide range of value-added products. Biochar can be obtained by heating biomass, which aids in carbon sinks, soil amendments, resource recovery, and water retention. Microwave technology stands out among various biomass heating technologies not only for its effectiveness in biomass pyrolysis for...

Sustainable environmental management is one of the important aspects of sustainable development goals. Increasing amounts of WWs from exponential economic growth is a major challenge, and conventional treatment methods entail a huge carbon footprint in terms of energy use and GHG emissions. Microalgae-based WW treatment is a potential candidate for...

Ozone is a powerful oxidative gas widely used as a green pretreatment to enhance the delignification of cereal straws. Urea pretreatment can enrich straws with nitrogen to make them more accessible to anaerobic microorganisms. This study aimed to evaluate the effect of ozone-urea pretreatment on the digestibility of wheat straw (i.e., physicochemic...

Menstrual hygiene waste management has received lack of attention and hence it has been poorly investigated, mainly due to its association to social and cultural aspects of a natural process, that is often surrounded of entrenched stigma and taboos. Therefore, data about quantities and full lifecycle of the generated waste are often not available o...

A renewable tri-metallic spinel decorated biochar adsorbent (MZF-BC) was fabricated by a facile hydrothermal method and to remove tetracycline. The physicochemical properties of MZF-BC were well studied. MZF-BC with a hybrid pore structure of mesopores (~7.6 nm) and macropores (~50 nm) has the maximum tetracycline adsorption capacity reaching 142.4...

The enormous use of synthetic antibiotic and personal care products has impacted the natural microbiome and ecosystem. Overtime, treatment technologies developed suffered due to incomplete removal hence, a pilot dual-chambered microbial peroxide-producing cell that degrades ampicillin catalyzed by homogenous Fenton-reaction was designed. The system...

Leaching of cobalt and nickel into diverse water streams has become an environmental hazard and is continuously impacting human health through the food chain. Solvent extraction is the most widely accepted for separating these metals, but traditional extractants employed in conjunction with molecular diluents often lack selectivity and caused major...

This study evaluates the impact of biochar addition on the performance of anaerobic co-digestion of food waste (FW) and sewage sludge at different total solids (TS) contents (2.5%, 5.0%, and 7.5%). Biochar co-digestion improved hydrolysis and acidogenesis by neutralizing volatile fatty acids (VFAs) reducing its inhibitions (2.6-fold removal), which...

Food is an essential commodity for the survival of any form of life on earth. Yet generation of plethora of food waste has significantly elevated the global concern for food scarcity, human and environment deterioration. Also, increasing use of polymers derived from petroleum hydrocarbons has elevated the concerns towards the depletion of this non-...

The management of potato peel waste (PPW) has been a challenge faced by the potato industry. This investigation assessed the feasibility of PPW for volatile fatty acids (VFAs) production via anaerobic fermentation, and investigated the impact of Fe⁰ nanoparticles (Fe⁰ NPs) supplementation on the VFAs production. It is found that PPW is a potential...

Large-scale food waste (FW) disposal has resulted in severe environmental degradation and financial losses around the world. Although FW has a high biomass energy contents and a growing large number of national projects to recover energy from FW by anaerobic digestion (AD) are being developed. AD is a promising solution for FW management and energy...