Books by Bipro Ranjan Dhar
Papers by Bipro Ranjan Dhar
Sulfide impact on biohydrogen production using dark fermentation of glucose at 37° C was investig... more Sulfide impact on biohydrogen production using dark fermentation of glucose at 37° C was investigated. Dissolved sulfide (S2−) at a low concentration (25mg/L) increased biohydrogen production by 54% relative to the control (without iron addition). Whereas on initial dissolved S2− concentration of 500mg/L significantly inhibited the biohydrogen production with total cumulative biohydrogen decreasing by 90% compared to the control (without iron addition).
Abstract: The impact of sono-thermal pretreatment combining ultrasound and conventional heating a... more Abstract: The impact of sono-thermal pretreatment combining ultrasound and conventional heating as a pretreatment process for municipal waste activated sludge prior to anaerobic digestion is evaluated in terms of sludge solubilization, solids reduction, biogas production, volatile sulfur compounds concentrations in biogas, dewaterability of digested sludge, and economic feasibility of the pretreatment process.
To enhance the anaerobic digestion of municipal waste-activated sludge (WAS), ultrasound, thermal... more To enhance the anaerobic digestion of municipal waste-activated sludge (WAS), ultrasound, thermal, and ultrasound + thermal (combined) pretreatments were conducted using three ultrasound specific energy inputs (1000, 5000, and 10,000 kJ/kg TSS) and three thermal pretreatment temperatures (50, 70 and 90 °C). Prior to anaerobic digestion, combined pretreatments significantly improved volatile suspended solid (VSS) reduction by 29–38%. The largest increase in methane production (30%) was observed after 30 min of 90 °C pretreatment followed by 10,000 kJ/kg TSS ultrasound pretreatment. Combined pretreatments improved the dimethyl sulfide (DMS) removal efficiency by 42–72% but did not show any further improvement in hydrogen sulfide (H2S) removal when compared with ultrasound and thermal pretreatments alone. Economic analysis showed that combined pretreatments with 1000 kJ/kg TSS specific energy and differing thermal pretreatments (50–90 °C) can reduce operating costs by $44–66/ton dry solid when compared to conventional anaerobic digestion without pretreatments.
Thermo-oxidative pretreatment of municipal waste activated sludge was conducted using thermal pre... more Thermo-oxidative pretreatment of municipal waste activated sludge was conducted using thermal pretreatment at 60 °C in presence of 0.6 mg H2O2 + 1.5 mg FeCl2/mg S2− as oxidants with the objective of achieving sludge disintegration for enhancing anaerobic digestion as well as to remove volatile sulfur compounds generation potential in biogas in continuous anaerobic digestion. For the pretreated feed digester, the hydrogen sulfide (H2S) and dimethyl sulfide (DMS) concentrations in biogas significantly decreased by an average of 75%, and 40%, respectively, while methanethiol (MT) removal efficiency was statistically insignificant compared to the control digester. Compared to the control, overall TSS and VSS removal efficiency were 10% and 11% higher for the pretreated feed digester operated at 10 days solid residence time (SRT), and methane production rate (L CH4/Day) increased by ∼20%. The simulation results using BioWin® suggest that the thermo-oxidative pretreatment has significantly increased the hydrolysis rate by 30% with higher methane production rate compared to the control digester.
Four individual pretreatment methods: ultrasonication, heat, acid, and base and three combined pr... more Four individual pretreatment methods: ultrasonication, heat, acid, and base and three combined pretreatment methods comprising ultrasonication with heat (UH), ultrasonication with acid (UA), and ultrasonication with base (UB) were applied on the food waste. The effect of the seven pretreatment methods on food waste solubilization was first evaluated, and then batch experiments were conducted for biohydrogen production without using extra seed. UB pretreatment achieved the highest increase in soluble chemical oxygen demand (SCOD) and soluble protein of 33% and 40%, respectively. The highest increase in soluble carbohydrate of 31% was observed for UA pretreatment. Among the four individual pretreatment methods, ultrasonic pretreatment produced the highest hydrogen yield (as mL hydrogen per g initial volatile solid) of 97 mL/g VSinitial, while the lowest hydrogen yield of 46 mL/g VSinitial was observed for base pretreatment. In case of combined pretreatment methods, UA pretreatment had a positive effect on hydrogen production reflected by the highest hydrogen yield of 118 mL/g VSinitial. While UH and UB pretreatments had a negative impact on hydrogen yield reducing it from 97 mL/g VSinitial for ultrasonic only to 78 mL/g VSinitial for UH pretreatment and to 67 mL/g VSinitial for UB pretreatment. A hydrogen yield of 42 mL/g VSinitial was observed for the untreated food waste. UA had the highest final volatile fatty acids (VFAs) concentrations of 16,900 mg COD/L as well as highest acetate to butyrate (HAc/HBu) molar ratio of 1.87, while base pretreatment had the lowest final VFAs of 9700 mg COD/L and the lowest HAc/HBu ratio of 0.61.
The effect of combination of mechanical and chemical pretreatment of municipal waste activated sl... more The effect of combination of mechanical and chemical pretreatment of municipal waste activated sludge (WAS) prior to anaerobic digestion was studied using a laboratory scale system with an objective to decrease volatile sulfur compounds in biogas and digested sludge. Mechanical pretreatment was conducted using depressurization of WAS through a valve from a batch pretreatment reactor pressurized at 75 ± 1 psi, while combined pretreatments were conducted using six different dosages of hydrogen peroxide (H2O2) and ferrous chloride (FeCl2) along with mechanical pretreatment. About 37–46% removal of H2S in biogas occurred for different combined pretreatment conditions. Sludge solubilization achieved due to the mechanical pretreatment increased total cumulative methane production by 8–10% after 30 days during the biochemical methane potential (BMP) test. The pretreatment also improved dewaterability in terms of time to filter (TTF), and decreased methyl mercaptan generation potential of the digested sludge.
Chemical Engineering Research Bulletin, Jan 1, 2010
This paper presents an ASPEN PLUSTM simulation study for excess methanol recovery in continuous b... more This paper presents an ASPEN PLUSTM simulation study for excess methanol recovery in continuous biodiesel production process using a distillation column. The feedstock used for biodiesel production was Triolein containing 15% free fatty acid (Oleic Acid). The special attention was devoted to the effect of different alcohol to oil ratio and important design and operating parameters of distillation column on excess methanol recovery from the product. The energy consumption is represented by reboiler heat duty of distillation column. Analysis of simulation results shows that for a certain distillation operating condition and reaction parameters it is possible to recover around 95-98% of excess methanol before phase separation of biodiesel and glycerol, although for high alcohol to oil ratio the energy requirement increases exponentially.
Talks by Bipro Ranjan Dhar
The abstracts in this book are reproduced verbatim from the submissions by the presenting authors... more The abstracts in this book are reproduced verbatim from the submissions by the presenting authors; no attempts were made to edit them. The contents of the abstracts and the presentations are entirely the responsibility of the presenters.
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Books by Bipro Ranjan Dhar
Papers by Bipro Ranjan Dhar
Talks by Bipro Ranjan Dhar