Amruta Morone | National Environmental Engineering Research Institute (original) (raw)

Papers by Amruta Morone

Pharmaceuticals and Personal Care Products: Waste Management and Treatment Technology

Abstract Recently, pharmaceuticals and personal care products (PPCPs) have attracted much attenti... more Abstract Recently, pharmaceuticals and personal care products (PPCPs) have attracted much attention because of their requirement in everyday life and huge production/consumption worldwide. India’s pharmaceutical industry has emerged as the world’s third largest in terms of volume of production. As a leading science-based industry, the pharmaceutical industry contributes to the tune of 1% of India’s total GDP. Ever increasing international demand of these products drives continued rapid expansion of the pharmaceutical industry. India becomes a preferred manufacturing location for PPCPs, which is obvious from the export of PPCPs to over 65 countries. This is primarily because of the manufacturing cost advantage. Nevertheless, the major concern of these PPCPs is their nonpassive nature. They are not benign travelers in the environment but rather they are bioaccumulative and their retention becomes toxic to wildlife and human beings. It is reported that residual PPCPs may cause endocrine disruptions that can change hormonal actions, although the adverse impact of PPCPs on human health and the environment is still not fully understood. Therefore, there is an urgent need to protect our limited water resources and the available aquatic species from deterioration due to residual PPCPs. A variety of technologies, including physical, biological, and chemical processes, have been extensively investigated for the removal of PPCPs from wastewater. Recently, advanced oxidation processes (AOPs) and advanced materials have shown great promise as an efficient alternative for mineralization of such refractory species. Therefore, a critical review of the recent advances in PPCP removal is imperative to gauge their performance. In this chapter, we briefly summarize the advances made in the technologies for PPCPs removal, followed by an in-depth review of the removal of PPCPs by advanced materials and AOPs.

Journal of Environmental Science & Engineering

Korean Journal of Chemical Engineering

The manufacturing of the antiepileptics, carbamazepine (CBZ) and oxcarbazepine (oxCBZ), results i... more The manufacturing of the antiepileptics, carbamazepine (CBZ) and oxcarbazepine (oxCBZ), results in generation of wastewater containing these micropollutants which exhibit toxicity even at trace levels. Therefore, we focused on monitoring their fate and removal in various units of a full-scale wastewater treatment plant (WWTP) using mass balance approach. An apparent CBZ removal of 50±3% was observed by conventional activated sludge process in the biological treatment unit, whereas oxCBZ still persisted after the biological treatment and showed negative mass balance. However, reverse osmosis resulted in 91% oxCBZ removal, whereas CBZ still continued to persist as a result of lower solubility of CBZ as compared to oxCBZ. Only 3% CBZ exhibited sorption onto the suspended solids and sludge, which was negligible for oxCBZ, thus demonstrating their tendency to remain in aqueous phase. Additionally, we attempted to understand the fundamental mechanism behind the removal of these pharmaceuticals and it was apparently the collective effect of sorption, mineralization, biotransformation, biodegradation, phototransformation/photodegradation, etc. Thus, the integrative data presented in the present study on productivity of these pharmaceuticals, their mass loading in influent and effluents allied with their removal efficiency will be significantly constructive in benchmarking the operational effectiveness through operational optimization and design improvement of the current conventional treatment plant.

Korean Journal of Chemical Engineering

The present study was aimed at evaluating the effect of variable sodium carbonate (Na2CO3) loadin... more The present study was aimed at evaluating the effect of variable sodium carbonate (Na2CO3) loading during wet air oxidation (WAO) pretreatment of rice straw in reducing biomass recalcitrance. The research study was intended to increase the cellulose recovery, hemicellulose solubilization, lignin removal in the solid fraction and limiting the generation of inhibitors in the liquid fraction while reducing the chemical input. The operating condition of 169 °C, 4 bar, 18 min and 6.5 g/L Na2CO3 loading resulted in maximum cellulose recovery of 82.07% and hemicellulose solubilization and lignin removal of 85.43% and 65.42%, respectively, with a total phenolic content of 0.36 g/L in the liquid fraction. The crystallinity index increased from 47.69 to 51.25 along with enzymatic digestibility with an increase in Na2CO3 loading from 0 to 6.5 g/L as a result of removal of barriers for saccharification via effective cleavage of ether and ester bonds cross-linking the carbohydrates and lignin as indicated by FT-IR spectroscopy. A further increase in the Na2CO3 loading to 9.5 g/L did not significantly increase the sugar release. Thus, it was concluded that 6.5 g/L Na2CO3 during WAO is sufficient to increase the delignification and deacetylation, leading to significant changes in apparent cellulose crystallinity inter alia improvement in cellulose accessibility and digestibility of rice straw.

Renewable Energy

Abstract Rice straw, a renewable feedstock, is recalcitrant and its degree of polymerization make... more Abstract Rice straw, a renewable feedstock, is recalcitrant and its degree of polymerization makes pretreatment obligatory for subsequent bioconversion. The present study explores an advanced oxidation process i.e. Alkaline Wet Air Oxidation (AWAO) as a pretreatment for rice straw and scrutinizes the effect of operation parameters on cellulose recovery, hemicellulose solubilization and lignin removal through Response Surface Methodology (RSM). AWAO resulted in 68–90% cellulose recovery, 67–87% hemicellulose solubilization and 32–66% lignin removal while generating limited inhibitors. AWAO caused oxidative delignification, hemicellulose deacetylation and cleavage of carbohydrate-lignin linkages as revealed by FT-IR, thereby improving cellulose accessibility indicated by 42–89% enzymatic cellulose convertibility (%ECC) or % cellulose conversion. The findings of the present study indicate minimization of chemical input and absence of potent inhibitors in the liquor which collectively implies reduction in freshwater requirements, minimization of waste generation and its treatment cost.

Journal of Environmental Chemical Engineering

Abstract The bulk manufacturing of carbamazepine (CBZ) by pharmaceutical manufacturing industries... more Abstract The bulk manufacturing of carbamazepine (CBZ) by pharmaceutical manufacturing industries leads to generation of huge amount of wastewater containing this recalcitrant compound. This necessitates the application of advanced oxidation processes (AOPs) as a pretreatment strategy for the treatment of such complex industrial wastewaters. Therefore, in the present study, effect of Fenton treatment was investigated for removal of CBZ from real wastewater containing higher CBZ concentrations. The preliminary studies were conducted to assess the significant factors in Fenton treatment and pH, Fenton dose and time were found to be statistically significant parameters affecting the Fenton process. Based on these results, further experimental trials were designed statistically using Central Composite Design in MINITAB 16 software. The process conditions were optimized using Response Surface Optimizer Tool in MINITAB 16 and pH = 3.5 and H2O2 concentration of 8.5 g/L was obtained as optimum condition leading to 49.39 ± 0.93% CBZ removal from pharmaceutical wastewater containing higher CBZ concentrations. The detoxification of Fenton-treated wastewater through granulated activated carbon (GAC) column resulted in an overall CBZ removal of 99.51 ± 0.02%. The detoxification was further corroborated through seed germination test which demonstrated a potential reduction in toxicity post-detoxification using GACs.

Journal of Environmental Chemical Engineering

Abstract The rising demand of liquid transportation fuels and increased global energy consumption... more Abstract The rising demand of liquid transportation fuels and increased global energy consumption has compelled a switch from petroleum- to lignocellulosic biomass-based (LCB) biofuels. However, the foremost hindrance in bioconversion of LCB to fuels is the biomass recalcitrance, coercing pretreatment for enhancing the LCB hydrolysis efficiency via increased cellulose accessibility. In the present study, rice straw was used as feedstock owing to its renewability & abundance and was pretreated with wet air oxidation (WAO), alkaline wet air oxidation (AWAO), alkaline peroxide-assisted wet air oxidation (APWAO) and Organocat pretreatment to enhance the cellulose accessibility. The efficiency was examined in terms of enhancement in cellulose recovery, hemicellulose solubilisation, lignin removal and limited generation of sugar and lignin degradation products. The structural and surface changes occurring post- pretreatment and enzymatic hydrolysis were scrutinized through FT-IR and SEM which corroborated the removal of lignin and hemicellulose, thereby, increasing the cellulose accessibility. The comparative evaluation demonstrated that AWAO was advantageous owing to the increased cellulose accessibility, energy-efficiency, generation of limited carbohydrate & lignin degradation products and minimum waste generation.

Industrial Crops and Products

Abstract Rice straw is deemed as an attractive feedstock for biofuel and platform chemical produc... more Abstract Rice straw is deemed as an attractive feedstock for biofuel and platform chemical production owing to its renewability and availability on regional as well as global scale. However, the recalcitrance of rice straw compels an ancillary pretreatment step in the bioconversion process that effectively fractionates the lignocellulosic components. The present article evaluates the OrganoCat process as a pretreatment for rice straw and its effect on the subsequent enzymatic hydrolysis owing to the novel application of OrganoCat pretreatment to rice straw. The maximum cellulose recovery of 98.99%, hemicellulose solubilization and lignin removal of 88.79% and 71.46% respectively was achieved during the OrganoCat pretreatment of rice straw along with improved cellulose accessibility leading to maximum glucose release of 160.57 ± 2.7 g/kg untreated rice straw at different pretreatment conditions included under the range of operating conditions examined in the present study. OrganoCat pretreatment also led to effective fractionation and cell wall breakdown, thereby, enhancing the cellulose accessibility as distinctly evident from the adsorption studies and indirectly deduced from SEM and FT-IR analysis. The material balance of the input & output streams indicated an efficient one-step fractionation with 50% catalyst recovery and 80% solvent recovery. The significance of the obtained results are reported and discussed to gain an insight into the overall potential of the process.

Pretreatment of rice husk by the Alkaline Peroxide Assisted Wet Air Oxidation (APAWAO) approach e... more Pretreatment of rice husk by the Alkaline Peroxide Assisted Wet Air Oxidation (APAWAO) approach enhanced the enzymatic convertibility of cellulose in APAWAO-pretreated rice husk. The present work describes the structural changes in rice husk brought about by APAWAO pretreatment by means of Scanning Electron Microscopy (SEM). The SEM images illustrate the extensive loss of biomass integrity following APAWAO pretreatment. X-ray diffraction (XRD) studies indicated the loss of amorphous lignin following APAWAO to be a factor contributing to the enhanced enzymatic digestibility of pre-treated rice husk.

Cellulose

Biomass recalcitrance is considered to be one of the impediments in bioconversion of lignocellulo... more Biomass recalcitrance is considered to be one of the impediments in bioconversion of lignocellulosic biomass (LCB) to sugars. Rice straw, a potential lignocellulosic waste, owing to the surplus availability, renewability and high carbohydrate content was used as a model LCB in the present study. The alkaline hydrogen peroxide-assisted wet air oxidation (APWAO) was evaluated as plausible pretreatment for rice straw based on the 23—factorial experimental design with a goal to reduce biomass recalcitrance by enhancing the cellulose recovery, hemicellulose solubilization, lignin removal and concomitantly generating limited degradation products. APWAO resulted in an overall cellulose recovery ranging from 80.54 to 93.02%, hemicellulose solubilization of 36.44–82.08% and lignin removal of 65.95–81.11% (all on w/w basis) respectively and absence of potent inhibitors viz. furfural and 5-hydroxymethylfurfural. The statistically significant pretreatment factors that affected each of these responses were assessed and optimum pretreatment conditions were determined to be biomass soaking in 0.5% H2O2 for 14 h succeeded by wet air oxidation (WAO) at 190 °C, 6 bar, 20 min by multi-objective numerical optimization. Further, the morphological and structural changes occurring as a result of pretreatment were scrutinized using SEM and FT-IR. APWAO further ensued in enhanced cellulose accessibility during enzymatic saccharification indicated by the glucose yield ranging from 113.97 to 200.34 g/kg untreated rice straw. Thus, the combined pretreatment (APWAO) i.e. pre-soaking in alkaline H2O2 followed by WAO was shown to enhance glucose yields owing to significant delignification.

Renewable and Sustainable Energy Reviews, Jun 17, 2015

The rise in fuel and oil prices has driven the hunt for alternative renewable resources for produ... more The rise in fuel and oil prices has driven the hunt for alternative renewable resources for production of chemical intermediates or biofuels since they provide a sustainable solution to an increasing demand. Levulinic acid (LA), one of the platform chemicals, can be produced chemically using renewable resources such as starch waste and lignocellulosic biomass which sounds to be an attractive alternative owing to its abundance and environmentally benign nature. The presence of acidic carboxyl and ketone carbonyl groups in LA impart a remarkable pattern of reactivity to levulinic acid and allow it to form several derivatives having significant applications in various fields, thereby making it a versatile green chemical. The present review deals with the current status of the technologies available for levulinic acid production, its recovery and the array of applications in several areas along with the gridlocks involved at each step of conversion process and suggest some possible remedies. Further, it not only throws light on the recent advancements in LA production approaches along with the avant-garde biotechnological approach for its biosynthesis but also depicts the current market scenario of commercial LA industry. The review also discusses the future R&D scope with an aim to enhance the yield of levulinic acid production and to make the process energy-efficient and cost-effective.

Renewable and Sustainable Energy Reviews, May 3, 2014

A spike in greenhouse gas emissions due to burning of fossil fuels and issues over energy securit... more A spike in greenhouse gas emissions due to burning of fossil fuels and issues over energy security and its cost have obligated to identify the alternatives to petroleum fuels currently reigning transportation sector. Butanol, one of the substitutes, is still produced via petrochemical means but the confluence of global issues like declining oil reserves and upsurge in oil prices has compelled to identify renewable biomass resources for butanol production and commercialize the process. Biobutanol is one of the second-generation biofuels, superior to bioethanol, due to higher energy content, lower Reid vapor pressure, easy blending with gasoline at any ratio and ease in transportation. Although bioethanol, a strong competitor of biobutanol, has acquired enough attention from the transportation industry as the current commercially available liquid fuel for transportation, biobutanol possesses the potential to leapfrog various barriers and emerge as an attractive alternative biofuel. Lignocellulosic butanol production faces challenges in various frontiers such as cost of raw material, pretreatment strategies, enzymatic hydrolysis, and low butanol tolerance of the fermenting strain leading to its low yield and productivity, downstream processing of butanol, production of undesired solvents and the production cost. This review discusses these gridlocks along with the possible pertinent solutions to deal with these problems. It also sheds light on recent advancements coupled with the newer approaches for butanol production that revitalize the hopes on having a cleaner, energy-efficient commercial process.

Applied Microbiology and Biotechnology, 2015

A bench scale system consisting of an up-flow packed bed bioreactor (UAPBR) made of polyurethane ... more A bench scale system consisting of an up-flow packed bed bioreactor (UAPBR) made of polyurethane foam was used for the treatment and regeneration of aqueous solution of ferrous-NTA scrubbed with nitric oxide (NO). The biomass in the UAPBR was sequentially acclimatized under denitrifying and iron reducing conditions using ethanol as electron donor, after which nitric oxide (NO) gas was loaded continuously to the system by absorption. The system was investigated for different parameters viz. pH, removal efficiency of nitric oxide, biological reduction efficiency of Fe(II)NTA-NO and COD utilization. The Fe(II)NTA-NO reduction efficiency reached 87.8 % at a loading rate of 0.24 mmol L(-1) h(-1), while the scrubber efficiency reached more than 75 % with 250 ppm NO. Stover-Kincannon and a Plug-flow kinetic model based on Michaelis-Menten equation were used to describe the UAPBR performance with respect to Fe(II)NTA-NO and COD removal. The Stover-Kincannon model was found capable of describing the Fe(II)NTA-NO reduction (R m = 8.92 mM h(-1) and K NO = 11.46 mM h(-1)) while plug-flow model provided better fit to the COD utilization (U m = 66.62 mg L(-1) h(-1), K COD = 7.28 mg L(-1)). Analyses for pH, Fe(III)NTA, ammonium, nitrite concentration, and FTIR analysis of the medium samples indicated degradation of NTA, which leads to ammonium and nitrite accumulation in the medium, and affect the regeneration process.

Bioresource Technology, 2013

Environmental Technology, 2013

An air-lift bioreactor (ALR) system, applied for the treatment of waste-gas-containing monochloro... more An air-lift bioreactor (ALR) system, applied for the treatment of waste-gas-containing monochlorobenzene (MCB) was seeded with pure culture of Acinetobacter calcoaceticus, isolated from soil as a starter seed. It was found that MCB was biologically converted to chloride as chloride was mineralized in the ALR. After the built up of the biomass in the ALR, the reactor parameters which have major influence on the removal efficiency and elimination capacity were studied using response surface methodology. The data generated by running the reactor for 150 days at varying conditions were fed to the model with a target to obtain the removal efficiency above 95% and the elimination capacity greater than 60%. The data analysis indicated that inlet loading was the major parameter affecting the elimination capacity and removal efficiency of >95%. The reactor when operated at optimized conditions resulted in enhanced performance of the reactor.

Pharmaceuticals and Personal Care Products: Waste Management and Treatment Technology

Abstract Recently, pharmaceuticals and personal care products (PPCPs) have attracted much attenti... more Abstract Recently, pharmaceuticals and personal care products (PPCPs) have attracted much attention because of their requirement in everyday life and huge production/consumption worldwide. India’s pharmaceutical industry has emerged as the world’s third largest in terms of volume of production. As a leading science-based industry, the pharmaceutical industry contributes to the tune of 1% of India’s total GDP. Ever increasing international demand of these products drives continued rapid expansion of the pharmaceutical industry. India becomes a preferred manufacturing location for PPCPs, which is obvious from the export of PPCPs to over 65 countries. This is primarily because of the manufacturing cost advantage. Nevertheless, the major concern of these PPCPs is their nonpassive nature. They are not benign travelers in the environment but rather they are bioaccumulative and their retention becomes toxic to wildlife and human beings. It is reported that residual PPCPs may cause endocrine disruptions that can change hormonal actions, although the adverse impact of PPCPs on human health and the environment is still not fully understood. Therefore, there is an urgent need to protect our limited water resources and the available aquatic species from deterioration due to residual PPCPs. A variety of technologies, including physical, biological, and chemical processes, have been extensively investigated for the removal of PPCPs from wastewater. Recently, advanced oxidation processes (AOPs) and advanced materials have shown great promise as an efficient alternative for mineralization of such refractory species. Therefore, a critical review of the recent advances in PPCP removal is imperative to gauge their performance. In this chapter, we briefly summarize the advances made in the technologies for PPCPs removal, followed by an in-depth review of the removal of PPCPs by advanced materials and AOPs.

Journal of Environmental Science & Engineering

Korean Journal of Chemical Engineering

The manufacturing of the antiepileptics, carbamazepine (CBZ) and oxcarbazepine (oxCBZ), results i... more The manufacturing of the antiepileptics, carbamazepine (CBZ) and oxcarbazepine (oxCBZ), results in generation of wastewater containing these micropollutants which exhibit toxicity even at trace levels. Therefore, we focused on monitoring their fate and removal in various units of a full-scale wastewater treatment plant (WWTP) using mass balance approach. An apparent CBZ removal of 50±3% was observed by conventional activated sludge process in the biological treatment unit, whereas oxCBZ still persisted after the biological treatment and showed negative mass balance. However, reverse osmosis resulted in 91% oxCBZ removal, whereas CBZ still continued to persist as a result of lower solubility of CBZ as compared to oxCBZ. Only 3% CBZ exhibited sorption onto the suspended solids and sludge, which was negligible for oxCBZ, thus demonstrating their tendency to remain in aqueous phase. Additionally, we attempted to understand the fundamental mechanism behind the removal of these pharmaceuticals and it was apparently the collective effect of sorption, mineralization, biotransformation, biodegradation, phototransformation/photodegradation, etc. Thus, the integrative data presented in the present study on productivity of these pharmaceuticals, their mass loading in influent and effluents allied with their removal efficiency will be significantly constructive in benchmarking the operational effectiveness through operational optimization and design improvement of the current conventional treatment plant.

Korean Journal of Chemical Engineering

The present study was aimed at evaluating the effect of variable sodium carbonate (Na2CO3) loadin... more The present study was aimed at evaluating the effect of variable sodium carbonate (Na2CO3) loading during wet air oxidation (WAO) pretreatment of rice straw in reducing biomass recalcitrance. The research study was intended to increase the cellulose recovery, hemicellulose solubilization, lignin removal in the solid fraction and limiting the generation of inhibitors in the liquid fraction while reducing the chemical input. The operating condition of 169 °C, 4 bar, 18 min and 6.5 g/L Na2CO3 loading resulted in maximum cellulose recovery of 82.07% and hemicellulose solubilization and lignin removal of 85.43% and 65.42%, respectively, with a total phenolic content of 0.36 g/L in the liquid fraction. The crystallinity index increased from 47.69 to 51.25 along with enzymatic digestibility with an increase in Na2CO3 loading from 0 to 6.5 g/L as a result of removal of barriers for saccharification via effective cleavage of ether and ester bonds cross-linking the carbohydrates and lignin as indicated by FT-IR spectroscopy. A further increase in the Na2CO3 loading to 9.5 g/L did not significantly increase the sugar release. Thus, it was concluded that 6.5 g/L Na2CO3 during WAO is sufficient to increase the delignification and deacetylation, leading to significant changes in apparent cellulose crystallinity inter alia improvement in cellulose accessibility and digestibility of rice straw.

Renewable Energy

Abstract Rice straw, a renewable feedstock, is recalcitrant and its degree of polymerization make... more Abstract Rice straw, a renewable feedstock, is recalcitrant and its degree of polymerization makes pretreatment obligatory for subsequent bioconversion. The present study explores an advanced oxidation process i.e. Alkaline Wet Air Oxidation (AWAO) as a pretreatment for rice straw and scrutinizes the effect of operation parameters on cellulose recovery, hemicellulose solubilization and lignin removal through Response Surface Methodology (RSM). AWAO resulted in 68–90% cellulose recovery, 67–87% hemicellulose solubilization and 32–66% lignin removal while generating limited inhibitors. AWAO caused oxidative delignification, hemicellulose deacetylation and cleavage of carbohydrate-lignin linkages as revealed by FT-IR, thereby improving cellulose accessibility indicated by 42–89% enzymatic cellulose convertibility (%ECC) or % cellulose conversion. The findings of the present study indicate minimization of chemical input and absence of potent inhibitors in the liquor which collectively implies reduction in freshwater requirements, minimization of waste generation and its treatment cost.

Journal of Environmental Chemical Engineering

Abstract The bulk manufacturing of carbamazepine (CBZ) by pharmaceutical manufacturing industries... more Abstract The bulk manufacturing of carbamazepine (CBZ) by pharmaceutical manufacturing industries leads to generation of huge amount of wastewater containing this recalcitrant compound. This necessitates the application of advanced oxidation processes (AOPs) as a pretreatment strategy for the treatment of such complex industrial wastewaters. Therefore, in the present study, effect of Fenton treatment was investigated for removal of CBZ from real wastewater containing higher CBZ concentrations. The preliminary studies were conducted to assess the significant factors in Fenton treatment and pH, Fenton dose and time were found to be statistically significant parameters affecting the Fenton process. Based on these results, further experimental trials were designed statistically using Central Composite Design in MINITAB 16 software. The process conditions were optimized using Response Surface Optimizer Tool in MINITAB 16 and pH = 3.5 and H2O2 concentration of 8.5 g/L was obtained as optimum condition leading to 49.39 ± 0.93% CBZ removal from pharmaceutical wastewater containing higher CBZ concentrations. The detoxification of Fenton-treated wastewater through granulated activated carbon (GAC) column resulted in an overall CBZ removal of 99.51 ± 0.02%. The detoxification was further corroborated through seed germination test which demonstrated a potential reduction in toxicity post-detoxification using GACs.

Journal of Environmental Chemical Engineering

Abstract The rising demand of liquid transportation fuels and increased global energy consumption... more Abstract The rising demand of liquid transportation fuels and increased global energy consumption has compelled a switch from petroleum- to lignocellulosic biomass-based (LCB) biofuels. However, the foremost hindrance in bioconversion of LCB to fuels is the biomass recalcitrance, coercing pretreatment for enhancing the LCB hydrolysis efficiency via increased cellulose accessibility. In the present study, rice straw was used as feedstock owing to its renewability & abundance and was pretreated with wet air oxidation (WAO), alkaline wet air oxidation (AWAO), alkaline peroxide-assisted wet air oxidation (APWAO) and Organocat pretreatment to enhance the cellulose accessibility. The efficiency was examined in terms of enhancement in cellulose recovery, hemicellulose solubilisation, lignin removal and limited generation of sugar and lignin degradation products. The structural and surface changes occurring post- pretreatment and enzymatic hydrolysis were scrutinized through FT-IR and SEM which corroborated the removal of lignin and hemicellulose, thereby, increasing the cellulose accessibility. The comparative evaluation demonstrated that AWAO was advantageous owing to the increased cellulose accessibility, energy-efficiency, generation of limited carbohydrate & lignin degradation products and minimum waste generation.

Industrial Crops and Products

Abstract Rice straw is deemed as an attractive feedstock for biofuel and platform chemical produc... more Abstract Rice straw is deemed as an attractive feedstock for biofuel and platform chemical production owing to its renewability and availability on regional as well as global scale. However, the recalcitrance of rice straw compels an ancillary pretreatment step in the bioconversion process that effectively fractionates the lignocellulosic components. The present article evaluates the OrganoCat process as a pretreatment for rice straw and its effect on the subsequent enzymatic hydrolysis owing to the novel application of OrganoCat pretreatment to rice straw. The maximum cellulose recovery of 98.99%, hemicellulose solubilization and lignin removal of 88.79% and 71.46% respectively was achieved during the OrganoCat pretreatment of rice straw along with improved cellulose accessibility leading to maximum glucose release of 160.57 ± 2.7 g/kg untreated rice straw at different pretreatment conditions included under the range of operating conditions examined in the present study. OrganoCat pretreatment also led to effective fractionation and cell wall breakdown, thereby, enhancing the cellulose accessibility as distinctly evident from the adsorption studies and indirectly deduced from SEM and FT-IR analysis. The material balance of the input & output streams indicated an efficient one-step fractionation with 50% catalyst recovery and 80% solvent recovery. The significance of the obtained results are reported and discussed to gain an insight into the overall potential of the process.

Pretreatment of rice husk by the Alkaline Peroxide Assisted Wet Air Oxidation (APAWAO) approach e... more Pretreatment of rice husk by the Alkaline Peroxide Assisted Wet Air Oxidation (APAWAO) approach enhanced the enzymatic convertibility of cellulose in APAWAO-pretreated rice husk. The present work describes the structural changes in rice husk brought about by APAWAO pretreatment by means of Scanning Electron Microscopy (SEM). The SEM images illustrate the extensive loss of biomass integrity following APAWAO pretreatment. X-ray diffraction (XRD) studies indicated the loss of amorphous lignin following APAWAO to be a factor contributing to the enhanced enzymatic digestibility of pre-treated rice husk.

Cellulose

Biomass recalcitrance is considered to be one of the impediments in bioconversion of lignocellulo... more Biomass recalcitrance is considered to be one of the impediments in bioconversion of lignocellulosic biomass (LCB) to sugars. Rice straw, a potential lignocellulosic waste, owing to the surplus availability, renewability and high carbohydrate content was used as a model LCB in the present study. The alkaline hydrogen peroxide-assisted wet air oxidation (APWAO) was evaluated as plausible pretreatment for rice straw based on the 23—factorial experimental design with a goal to reduce biomass recalcitrance by enhancing the cellulose recovery, hemicellulose solubilization, lignin removal and concomitantly generating limited degradation products. APWAO resulted in an overall cellulose recovery ranging from 80.54 to 93.02%, hemicellulose solubilization of 36.44–82.08% and lignin removal of 65.95–81.11% (all on w/w basis) respectively and absence of potent inhibitors viz. furfural and 5-hydroxymethylfurfural. The statistically significant pretreatment factors that affected each of these responses were assessed and optimum pretreatment conditions were determined to be biomass soaking in 0.5% H2O2 for 14 h succeeded by wet air oxidation (WAO) at 190 °C, 6 bar, 20 min by multi-objective numerical optimization. Further, the morphological and structural changes occurring as a result of pretreatment were scrutinized using SEM and FT-IR. APWAO further ensued in enhanced cellulose accessibility during enzymatic saccharification indicated by the glucose yield ranging from 113.97 to 200.34 g/kg untreated rice straw. Thus, the combined pretreatment (APWAO) i.e. pre-soaking in alkaline H2O2 followed by WAO was shown to enhance glucose yields owing to significant delignification.

Renewable and Sustainable Energy Reviews, Jun 17, 2015

The rise in fuel and oil prices has driven the hunt for alternative renewable resources for produ... more The rise in fuel and oil prices has driven the hunt for alternative renewable resources for production of chemical intermediates or biofuels since they provide a sustainable solution to an increasing demand. Levulinic acid (LA), one of the platform chemicals, can be produced chemically using renewable resources such as starch waste and lignocellulosic biomass which sounds to be an attractive alternative owing to its abundance and environmentally benign nature. The presence of acidic carboxyl and ketone carbonyl groups in LA impart a remarkable pattern of reactivity to levulinic acid and allow it to form several derivatives having significant applications in various fields, thereby making it a versatile green chemical. The present review deals with the current status of the technologies available for levulinic acid production, its recovery and the array of applications in several areas along with the gridlocks involved at each step of conversion process and suggest some possible remedies. Further, it not only throws light on the recent advancements in LA production approaches along with the avant-garde biotechnological approach for its biosynthesis but also depicts the current market scenario of commercial LA industry. The review also discusses the future R&D scope with an aim to enhance the yield of levulinic acid production and to make the process energy-efficient and cost-effective.

Renewable and Sustainable Energy Reviews, May 3, 2014

A spike in greenhouse gas emissions due to burning of fossil fuels and issues over energy securit... more A spike in greenhouse gas emissions due to burning of fossil fuels and issues over energy security and its cost have obligated to identify the alternatives to petroleum fuels currently reigning transportation sector. Butanol, one of the substitutes, is still produced via petrochemical means but the confluence of global issues like declining oil reserves and upsurge in oil prices has compelled to identify renewable biomass resources for butanol production and commercialize the process. Biobutanol is one of the second-generation biofuels, superior to bioethanol, due to higher energy content, lower Reid vapor pressure, easy blending with gasoline at any ratio and ease in transportation. Although bioethanol, a strong competitor of biobutanol, has acquired enough attention from the transportation industry as the current commercially available liquid fuel for transportation, biobutanol possesses the potential to leapfrog various barriers and emerge as an attractive alternative biofuel. Lignocellulosic butanol production faces challenges in various frontiers such as cost of raw material, pretreatment strategies, enzymatic hydrolysis, and low butanol tolerance of the fermenting strain leading to its low yield and productivity, downstream processing of butanol, production of undesired solvents and the production cost. This review discusses these gridlocks along with the possible pertinent solutions to deal with these problems. It also sheds light on recent advancements coupled with the newer approaches for butanol production that revitalize the hopes on having a cleaner, energy-efficient commercial process.

Applied Microbiology and Biotechnology, 2015

A bench scale system consisting of an up-flow packed bed bioreactor (UAPBR) made of polyurethane ... more A bench scale system consisting of an up-flow packed bed bioreactor (UAPBR) made of polyurethane foam was used for the treatment and regeneration of aqueous solution of ferrous-NTA scrubbed with nitric oxide (NO). The biomass in the UAPBR was sequentially acclimatized under denitrifying and iron reducing conditions using ethanol as electron donor, after which nitric oxide (NO) gas was loaded continuously to the system by absorption. The system was investigated for different parameters viz. pH, removal efficiency of nitric oxide, biological reduction efficiency of Fe(II)NTA-NO and COD utilization. The Fe(II)NTA-NO reduction efficiency reached 87.8 % at a loading rate of 0.24 mmol L(-1) h(-1), while the scrubber efficiency reached more than 75 % with 250 ppm NO. Stover-Kincannon and a Plug-flow kinetic model based on Michaelis-Menten equation were used to describe the UAPBR performance with respect to Fe(II)NTA-NO and COD removal. The Stover-Kincannon model was found capable of describing the Fe(II)NTA-NO reduction (R m = 8.92 mM h(-1) and K NO = 11.46 mM h(-1)) while plug-flow model provided better fit to the COD utilization (U m = 66.62 mg L(-1) h(-1), K COD = 7.28 mg L(-1)). Analyses for pH, Fe(III)NTA, ammonium, nitrite concentration, and FTIR analysis of the medium samples indicated degradation of NTA, which leads to ammonium and nitrite accumulation in the medium, and affect the regeneration process.

Bioresource Technology, 2013

Environmental Technology, 2013

An air-lift bioreactor (ALR) system, applied for the treatment of waste-gas-containing monochloro... more An air-lift bioreactor (ALR) system, applied for the treatment of waste-gas-containing monochlorobenzene (MCB) was seeded with pure culture of Acinetobacter calcoaceticus, isolated from soil as a starter seed. It was found that MCB was biologically converted to chloride as chloride was mineralized in the ALR. After the built up of the biomass in the ALR, the reactor parameters which have major influence on the removal efficiency and elimination capacity were studied using response surface methodology. The data generated by running the reactor for 150 days at varying conditions were fed to the model with a target to obtain the removal efficiency above 95% and the elimination capacity greater than 60%. The data analysis indicated that inlet loading was the major parameter affecting the elimination capacity and removal efficiency of >95%. The reactor when operated at optimized conditions resulted in enhanced performance of the reactor.