Shailey Singhal

Exploration of upstream and downstream process for microwave assisted sustainable biodiesel production from microalgae Chlorella vulgaris

The present study explores the integrated approach for the sustainable production of biodiesel from Chlorella vulgaris microalgae. The microalgae were cultivated in 10m(2) open raceway pond at semi-continuous mode with optimum volumetric and areal production of 28.105kg/L/y and 71.51t/h/y, respectively. Alum was used as flocculent for harvesting the microalgae and optimized at different pH. Lipid was extracted using chloroform: methanol (2:1) and having 12.39% of FFA. Effect of various reaction conditions such as effect of catalyst, methanol:lipid ratio, reaction temperature and time on biodiesel yields were studied under microwave irradiation; and 84.01% of biodiesel yield was obtained under optimized reaction conditions. A comparison was also made between the biodiesel productions under conventional heating and microwave irradiation. The synthesized biodiesel was characterized by (1)H NMR, (13)C NMR, FTIR and GC; however, fuel properties of biodiesel were also studied using specified test methods as per ASTM and EN standards.

Impact of various media and organic carbon sources on biofuel production potential from Chlorella spp.

In this study, five Chlorella species (Chlorella vulgaris, Chlorella minutissima, Chlorella pyrenoidosa, Chlorella sp.1 and Chlorella sp.2) were grown in various nutrient medium including BG-11, BBM, Fog’s medium and M4N medium for the evolution of biomass and lipid production potential. Among the tested medium, BG-11 was found most economical and efficient medium for all Chlorella species. To see the impact of organic carbon sources on lipid production potential, all microalgae species were also cultured in selected medium (BG-11) with different organic carbon sources like glucose, glycerol, sodium acetate, and sucrose under mixotrophic condition. The results showed that all Chlorella species performs better under mixotrophic condition, but Chlorella vulgaris achieved maximum lipid productivity (3.5 folds higher) in glycerol supplemented culture medium than control medium among all species.

A green route for copper ions removal from textile industry effluent.

The adsorption of copper(II) on tea waste has been studied in batch mode using flame atomic absorption spectroscopy for metal estimation. Important process parameters like adsorbent dose, pH, contact time, reaction temperature, shaking speed and particle size were investigated. Adsorption was found to be in accordance with Freundlich and Langmuir isotherms. The maximum amount of copper(II) adsorbed (qm), as evaluated by Langmuir isotherm, was approximately 1.33 mg per gram of powder of tea waste per litre of solution. The optimized process parameters were observed to be 3 g adsorbent, pH 5, 40°C temperature, 120 rpm shaking speed and 150 μm particle size. The effectiveness of tea waste for copper removal from industrial effluent was observed to be around 95.345%. The used tea waste after adsorption produced 51.76% methane as biofuel.

Environmental Implications of Rice and Wheat Stubble Burning in North-Western States of India

The paddy and wheat cropping pattern (PWS) is one of the extensive farming systems in north-western zones of India mainly the river plains of Haryana, Punjab, Rajasthan and western Uttar Pradesh. These river plains famous for extensive agricultural fields are equally defamed for burning of rice and wheat straw and stubbles by peasants after the reaping season. In India, it is reckoned that 22,289 Gg of paddy stubble biomass is generated annually and out of this, 13,915 Gg is blazed in the agricultural fields as calculated. Haryana and Punjab alone produce 48% of the whole straw production which is openly burnt in situ. The flaming of paddy stubbles causes soil nutrient loss of organic carbon (3850 million Kg), nitrogen (59 million Kg), phosphorus (20 million Kg) and potassium (34 million Kg), aside from deteriorating the ambient air quality. Burning of agricultural residue discharges various trace gases like COX, CH4, NOX, SOX and huge quantity of particulates matters (PM10 and PM2.5) which cause adverse impacts on human health. The major problems faced by the local people are eye irritation, dryness of eyes and chest congestion. It also led to chronic obstructive pulmonary disease (COPD), pneumoconiosis, pulmonary tuberculosis, bronchitis, cataract, corneal opacity and blindness. The cases of road accidents also enhance during the period of stubble burning due to poor visibility. It also contributes to haze, greenhouse effect and environmental changes thereto. In India, National Green Tribunal (NGT) prohibited this ancient agricultural practice of straw burning in pollution-wrecked city New Delhi and the adjacent four states viz. Punjab, Haryana, Rajasthan and Uttar Pradesh. One suitable method to reduce this menace is incorporation of straw into soil which eventually enhances soil fertility. The crop residue material can also be used for compost formation as a traditional approach. Alternate energy resources can also be generated from this agro-biomass. The most prominent method to prevent this threat is to generate biomass energy. Further, in past decades, many conversion processes have been developed to produce alternate biofuels under different forms (pellets, briquettes) from crop residues. An integrated crop residue management approach is need of the hour to combat this anthropogenic disaster.

Application of Remote Sensing in the Monitoring of Biogas Production

Anaerobic digestion (AD) systems are extremely sensitive to changes in environmental variables. Correct design and control of the system’s parameters are essential to maximize process efficiency, increase stability, and prevent system failure. Automation systems can both raise plant availability and help meet the transparency requirements of the process. A fully automated continuous stirred tank reactor (CSTR) of 40 m3 capacity was designed for jatropha waste and installed at University of Petroleum and Energy Studies, Dehradun (India). This is first fully automated digestor at pilot scale which can be monitored by remote sensing all over the country. Parameters (pH, temp, feeding rate, energy consumption) were attained from a CSTR plant online by using remote monitoring system. Pilot scale CSTR was operated using cow dung:jatropha de-oiled cake (CD:JDOC) in a optimized ratio of 1:3. The reactor was run continuously for 120 days. Average biogas produced per day was 25 m3 per day.

Comparative evolution of biomass production and lipid accumulation potential of Chlorella species grown in a bubble column photobioreactor

ABSTRACT In the present study, biomass growth and lipid accumulation of five Chlorella species (Chlorella vulgaris, Chlorella minutissima, Chlorella pyrenoidosa, Chlorella sp.1 and Chlorella sp.2) were compared under different nitrogen concentration and sources. In addition, all microalgae species were also grown in a 10 L bubble column photobioreactor under outdoor conditions. The results revealed that Chlorella minutissima have maximum biomass production potential (1.65 g/L) at 35.30 mM nitrogen concentration. Maximum lipid content was recorded for Chlorella vulgaris (21.81%) at 2.21 mM nitrogen concentration. Among different nitrogen sources (NaNo3, KNO3, urea and DAP), urea was observed to be the most economical nitrogen source for large scale biodiesel production feasibility. All species grew well in a 10 L bubble column photo bioreactor under outdoor conditions, but Chlorella vulgaris showed maximum potential for biodiesel production.

Synthesis and characterization of zirconia-based catalyst for the isomerization of n-hexane

ABSTRACT Sulfated zirconia is a very strong solid acid catalyst which can be utilized for various reactions. The present study focuses on synthesis of zirconia-based catalyst with high acidity and high surface area, particularly for isomerization reaction. Sulfated zirconia has been obtained by sulfation of zirconia prepared by hydrothermal route. The catalyst was developed by impregnating tungstophosphoric acid on sulfated zirconia by wet incipient method. The catalyst was characterized through Brunauer–Emmett–Teller (BET) surface area, temperature-programmed desorption of ammonia, temperature program reduction of hydrogen, Fourier transmission infrared spectroscopy, and thermogravimetric analysis. The results revealed that the catalyst is crystalline in nature with surface area 190–225 m2 g−1 and acidity 0.135–0.558 mmol g−1. Twenty-five percent conversion was obtained (as confirmed by gas chromatography) at 225°C using n-hexane as model hydrocarbon in fixed-bed microreactor.

Solid acids: potential catalysts for alkene–isoalkane alkylation

Production of high-octane gasoline is important to improve upon the performance and hence economics of oil companies worldwide. Heterogeneous catalysis employing the use of solid acids plays a key role in accomplishing this target through various routes, including isomerization, alkylation, and reforming. Alkylation is an imperative means for this to be achieved in the presence of solid acid catalysts. The use of solid acids as catalysts has been considered as one of the foremost accomplishments in processes of industrial significance in the current century. The introductory part of this review describes the importance of alkylation as a route to obtain high-quality gasoline and the conventional catalysts applied to it globally. The main body of the article details the use of various solid acids as catalysts for alkylation including the concerns about it. It also includes the solution for the drawbacks associated with their use as catalysts for the process. The final section covers the mechanistic approach for alkylation to happen during the progression of the reaction and the recommendations. This review intends to provide a detailed insight into the significance of solid acid catalysts for such an important reaction for chemists, researchers and scientists of refineries.

Pretreatment Impact on Biomethanation of Lignocellulosic Waste

Lignocelluloses are often a major or sometimes the sole components of different waste streams from various industries, forestry, agriculture and municipalities. Hydrolysis of these materials is the first step for either digestion to biogas (methane) or fermentation to ethanol. However, enzymatic hydrolysis of lignocelluloses with no pre-treatment is usually not so effective because of high stability of the materials to enzymatic or bacterial attacks. Pre-treatment helps to improve the process of hydrolysis. In this work different methods of pre-treatment were studied. The present work illustrates the effect of acid, alkaline pre-treatment on different sizes of wheat straw and anaerobic digestion of treated biomass for the production of biogas in batch stirred tank bioreactor under particular parameters. The quality and quantity of biogas produced was analysed by gas chromatography and water displacement methods respectively. The Untreated wheat straw gave a biogas yield of 104 ml/g and methane content of 64%. Acid treated wheat straw gave biogas yield of 130, 140 and 134 ml/g and methane content of 68%, 72%, 75% for 1%, 2%, 5% acid concentration respectively. Similarly, for alkali treatment gave biogas yield of 124, 128, 126ml/g and methane content of 66%, 69%, 71% for 1%, 2%, 5% NaOH concentration respectively.