T R Sreekrishnan

Indian Institute of Technology Delhi, New Dilli, NCT, India

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Publications (72)154.85 Total impact

  • S. M. Acharya, K. Kundu, T. R Sreekrishnan
    Journal of Environmental Engineering 01/2015; DOI:10.1061/(ASCE)EE.1943-7870.0000932 · 1.22 Impact Factor
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    ABSTRACT: The present study was undertaken to investigate the potential of enriched indigenous sulfur-and-iron-oxidizing microorganisms in the bioleaching of Cu, Ni, Zn and Fe from textile sludges by using elemental sulfur and ferrous sulfate (FS), respectively, as an energy source under batch conditions. The experiments were performed with three different textile sludges (S1, S2 and S3) at initial neutral pH of the sludges procured from different parts of the country i.e., UP, Haryana and Punjab. The three sludges used were not only procured from different parts of the country but also differ in physiochemical characteristics. The extent of heavy metals solubilization in each sludge was found to be different using sulfur- and iron-oxidizing microorganisms. The results of the study indicate that sulfur-oxidizing microorganisms were found more efficient in the bioleaching process, irrespective of any sludge. The use of sulfur-oxidizing microorganisms led to higher solubilization of heavy metals and after 7 days of bioleaching about 84–96% Cu, 64–78% Ni, 81–92% Zn and 74–88% Fe were removed compared to 62–73% Cu, 62–66% Ni, 74–78% Zn and 70–78% Fe using iron-oxidizing microorganisms. This study had shown the feasibility of applying the bioleaching process to textile sludge contaminated with heavy metals. The results of the present study indicate that the bioleached sludge would be safer for land application.
    Geomicrobiology 11/2014; 31(10). DOI:10.1080/01490451.2013.876467 · 1.80 Impact Factor
  • Kapil Kumar, M.G. Dastidar, T.R. Sreekrishnan
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    ABSTRACT: In search for a cheaper energy source, this study was undertaken to investigate the potential of mixed culture for the decolorization of Methylene blue (MB) and Remazol black B (RBB) using glucose, molasses, and cheese whey as an energy source for microbial growth in aerobic batch reactor. The experiments were performed with synthetic solutions of both the dyes ranging from 25 to 300 mg l−1. The results show that the decolorization and microbial growth was affected by the increase in concentration of dyes leading to the decreased decolorization of dyes. The presence of glucose was found to be more efficient as compared to molasses and cheese whey. After 36 h, mixed culture was able to decolorize MB up to 83, 59, and 54% and RBB up to 80, 58, and 52% in the presence of glucose, molasses, and cheese whey, respectively, at 300 mg l−1 initial dye concentration. The maximum specific uptake was 57, 51, and 52 mg g−1 in presence of glucose, molasses, and cheese whey, respectively, at 300 mg l−1 initial dye concentration of RBB. The maximum specific uptake was 58, 51, and 53 mg g−1 in the presence of glucose, molasses, and cheese whey, respectively, at 300 mg l−1 initial dye concentration of MB. The results of this study shall be useful to develop a suitable decolorization process for the treatment of dye-contaminated wastewater or wastewater contaminated with a variety of dyes.
    Desalination and water treatment 10/2014; 52(34-36). DOI:10.1080/19443994.2013.822333 · 0.99 Impact Factor
  • Arpita Ghosh, Manisha Ghosh Dastidar, T. R. Sreekrishnan
    Journal of Hazardous, Toxic, and Radioactive Waste 10/2014; 18(4):04014022. DOI:10.1061/(ASCE)HZ.2153-5515.0000230
  • Kapil Kumar, M. G. Dastidar, T. R. Sreekrishnan
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    ABSTRACT: The present study was undertaken to investigate the tolerance levels of indigenous sulfur-oxidizing micro-organisms to Methylene blue (MB), Remazol black B (RBB), and mixture of both the dyes (DM) during bioleaching of heavy metals from sewage sludge. The experiments were performed with anaerobically digested sewage sludge at initial neutral pH of the sludge containing 0–35,000 mg/l of the MB, RBB, and DM. The results show that the bioleaching process was affected by the increase in concentration of MB, which decreased the growth of indigenous sulfur-oxidizing micro-organisms leading to the slow rate of decrease in pH and hence decreased solubilization of metals. Similar effects were observed on the activity of indigenous sulfur-oxidizing micro-organisms using RBB and a mixture (DM) of MB and RBB. The presence of RBB and DM were found to be more toxic as compared to MB at the same initial concentration of the dyes. At initial concentration of 30,000 mg/l, a drastic reduction in pH drop was observed with decreased solubilization of metals, irrespective of any dye. The results of the present study shall be useful to develop a suitable bioleaching process for the sludges contaminated with a variety of dyes.
    Desalination and water treatment 09/2014; 52(31-33). DOI:10.1080/19443994.2013.817374 · 0.99 Impact Factor
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    Surajbhan Sevda, T R Sreekrishnan
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    ABSTRACT: In this study, a dual chamber MFC was constructed for simultaneous removal of organic matter and nitrogenous pollutants and bioelectricity generation from synthetic and complex industrial wastewaters and it was operated in batch and continuous mode. When the cell potential was stable after 16 days of batch mode operation, the MFC was converted to continuous mode (from batch mode) and operated for 125 days with different organic loading rates (OLR) and ammonia loading rates (ALR) and fixed hydraulic retention time (HRT) of 40 h. The OLR of 1.49 kg COD m(-3) d(-1) and ALR of 0.58 kg NH3(-) m(-3) d(-1), for anodic and cathodic chambers, respectively, gave the best results. The highest value of cell potential on these OLRs was 310 mV with current density of 85.11 mA m(-2), power density of 26.38 mW m(-2) and volumetric power density of 192.20 mW m(-3). During this period, COD reduction was 78-83% in the anodic chamber and the ammonia reduction was 36-38%. After stable operation with synthetic wastewater one case study was performed with complex industrial wastewater. Continuous mode operation was performed at two different OLR and HRT with a constant ALR. A stable power density and volumetric power density of 23.56 mW m(-2) and 112.50 mW m(-3), respectively were achieved after 24 days of continuous operation at an OLR of 0.35 kg COD/m(3) day with an ALR of 0.43 kg NH3(-) m(-3) day(-1) and corresponding HRT of 68 h. A maximum of 89% COD removal and 40% removal of ammonia was obtained after 50 days. A stable voltage of 300 mV was obtained across 1000 Ω resistance. These findings suggest that BMFC can be used for the treatment of industrial wastewater, with carbon removal in anodic chamber and electricity generation.
    Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 09/2014; 49(11):1265-1275. DOI:10.1080/10934529.2014.910064
  • Mohammad Zain Khan, Satyendra Singh, Trichur Ramaswamy Sreekrishnan, Shaikh Ziauddin Ahammad
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    ABSTRACT: Anaerobic digestion of textile azo-dyes is very effective and widely used since it is cost-effective and energy efficient. The present study deals with the anaerobic degradation of reactive orange 16 (RO 16, an azo-dye) using mixed microbial culture. 80 mL each of three different concentrations of RO 16 (100, 200 and 300 ppm) were taken in 150 mL serum vials containing 20 mL of mixed microbial culture and studied periodically. HPLC and UV data revealed that more than 90% of the color was removed within the very first week of the reactor start up. A high COD removal efficiency (≥80%) was achieved after the steady state. Methane and VFAs were produced, and monitored by Gas chromatography. The pH of the medium was slightly acidic favoring methanogenic activity. The diversity of the microbial community was studied by denaturing gradient gel electrophoresis (DGGE) of the polymerase chain reaction (PCR) amplified products of the bacterial and archeal 16S rRNA and the results showed the presence of significant population of acetogens as well as methanogens in the reactor. Quantitative real time PCR (qPCR) was used for the quantitative analysis of some major genera. This study showed that strategic operation of anaerobic digester can be a viable option for effective decolorization of complex substrate resulting into energy (biogas) generation.
    RSC Advances 09/2014; 4(87). DOI:10.1039/C4RA06716A · 3.71 Impact Factor
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    ABSTRACT: The present study evaluates the performance of air-cathode microbial fuel cells (MFCs) under alternating open circuit/closed circuit (OC/CC) modes and its effect on independent-electrode and full-cell potentials, power output (at different external resistances) and the polarization behaviour of the electrodes. Three different types of feeds were evaluated using this approach: (1) phosphorus buffer solution (PBS) with acetate as carbon source, (2) glucose-rich synthetic wastewater, and (3) sewage from wastewater treatment plant enriched with fermented molasses. When MFCs were suddenly switched to CC from CC and then again back to CC from CC, the behaviour of the anodes vs reference electrode (Ag/AgCl,3 M KCl) was monitored. When electric circuit of the MFCs was switched from open to closed circuit, for all cases: (a) the anode potential-shift (vs Ag/AgCI) reallocated in the positive direction in about 200-400 mV, (b) the air-cathode potential-shift (vs Ag/AgCI) reallocated in the negative direction in about 10-25 mV, and (c) the cell-potential difference started at around 0 mV and progressively increased as the MFC reached stability. This behaviour was consistently reproduced during different OC/CC cycles. The systems studied delivered good performance with both controlled media and industrial wastewater. Additionally, this study provides insightful characterization of the independent-electrode behaviours.
    Biochemical Engineering Journal 07/2014; 90:294-300. DOI:10.1016/j.bej.2014.06.024 · 2.37 Impact Factor
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    International Journal of Green Energy 05/2014; DOI:10.1080/15435075.2014.909363 · 2.07 Impact Factor
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    ABSTRACT: Adequate information is available on colour and organics removal in batch mode using pure microbial cultures from dye contaminated wastewater. There was a need to develop environment friendly and cost effective treatment technique for actual field conditions. Therefore, the present study was undertaken with an aim to evaluate the potential of acclimatized mixed microbial consortia for the removal of colour and organics from real textile wastewater. Experiments were performed in laboratory scale activated sludge process (ASP) unit under steady state condition varying mixed liquor volatile suspended solids (MLVSS) (2500, 3500 and 5000 mg/l) and hydraulic retention time (HRTs) (18, 24 and 36 h). The results showed that decolourization and chemical oxygen demand (COD) removal increased with increase in MLVSS and HRT. At 18 h HRT, decolourization was found to be 46%, 54% and 67%, which increased to 67, 75 and 90% (36 h HRT) at 2500, 3500 and 5000 mg/l MLVSS respectively. COD removal was found to be 62, 73 and 77% (at 18 h HRT) which increased to 77, 85 and 91% (36 h HRT) at 2000, 3500 and 5000 mg/L MLVSS respectively. On the basis of the results obtained in this study suitable treatment techniques can be developed for the treatment of wastewater contaminated with variety of dyes in continuous mode of operation. This shall have the advantage of treatment of larger quantity of wastewater in shorter duration.
    03/2014; DOI:10.1016/j.wri.2014.01.001
  • Kankana Kundu, Ingo Bergmann, Michael Klocke, Shilpi Sharma, Trichur Ramaswamy Sreekrishnan
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    ABSTRACT: BACKGROUND Hydrodynamic shear plays a major role in the formation, maintenance, structure, and metabolism of self-immobilized microbial communities in reactors. The study attempts to correlate the performance and microbial community structure of granular sludge in a mesophilic hybrid anaerobic reactor under different upflow velocities to fluidize the bed. The reactor was started with an initial upflow velocity of 4 m h-1, which was increased gradually till system deterioration to observe its effect on granule size, reactor performance, and microbial community structure. Monte Carlo method was used to quantify hydrodynamic shear range at different upflow velocities using a modified Ergun equation for the respective ranges of granule size. RESULTSUp to 6 m h-1 performance was positively affected, but beyond this upflow velocity, the system started showing reduced performance and completely deteriorated at 10 m h-1. Significant reduction in the abundance and diversity of both Archaea and Bacteria was observed. Among all methanogenic groups, Methanosaetaceae was most severely affected due to breakage and wash out of granules. CONCLUSION It can be concluded that hydrodynamic shear can be employed as a sensitive control parameter to improve reactor performance, and a specified range should be determined experimentally to avoid negative influences associated with this. © 2013 Society of Chemical Industry
    Journal of Chemical Technology & Biotechnology 03/2014; 89(3). DOI:10.1002/jctb.4194 · 2.50 Impact Factor
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    ABSTRACT: Antibiotic resistance (AR) is often rooted in inappropriate antibiotic use, but poor water quality and inadequate sanitation exacerbate the problem, especially in emerging countries. An example is increasing multi-AR due to mobile carbapenemases, such as NDM-1 protein (coded by blaNDM-1 genes), which can produce extreme drug-resistant phenotypes. In 2010, NDM-1 positive isolates and blaNDM-1 genes were detected in surface waters across Delhi and have since been detected across the urban world. However, little is known about blaNDM-1 levels in more pristine locations, such as the headwaters of the Upper Ganges River. This area is of particular interest because it receives massive numbers of visitors during seasonal pilgrimages in May/June, including visitors from urban India. Here we quantified blaNDM-1 abundances, other AR genes (ARG) and coliform bacteria in sediments and water column samples from seven sites in the Rishikesh-Haridwar region of the Upper Ganges and five sites on the Yamuna River in Delhi to contrast blaNDM-1 levels and water quality conditions between season and region. Water quality in the Yamuna was very poor (e.g., anoxia at all sites), and blaNDM-1 abundances were high across sites in water (5.4 ± 0.4 log(blaNDM-1·mL-1); 95% confidence interval) and sediment (6.3 ± 0.7 log(blaNDM-1·mg-1)) samples from both seasons. In contrast, water column blaNDM-1 abundances were very low across all sites (2.1 ± 0.6 log(blaNDM-1·mL-1)) in February in the Upper Ganges and water quality was good (e.g., near saturation oxygen). However, per capita blaNDM-1 levels were 20 times greater in June in the Ganges water column relative to February and blaNDM-1 levels significantly correlated with fecal coliform levels (r=0.61; p=0.007). Given waste management infrastructure is limited in Rishikesh-Haridwar; data imply blaNDM-1 levels are higher in visitor's wastes than local residents, which results in seasonally higher blaNDM-1 levels in the river. Pilgrimage areas without adequate waste treatment are possible "hot spots" for AR transmission, and waste treatment must be improved to reduce broader AR dissemination via exposed returning visitors.
    Environmental Science & Technology 02/2014; 48(5). DOI:10.1021/es405348h · 5.48 Impact Factor
  • Shabana Abubakkar, Kankana Kundu, Trichur Ramaswamy Sreekrishnan
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    ABSTRACT: Background Process upset due to volatile fatty acid accumulation is one of the major drawbacks of anaerobic treatment of wastewater. The performance of an Anaerobic Rotating Biological Contactor (AnRBC) was studied under normal operating conditions as well as shock loadings of propionic acid, for its ability to enhance the conversion of hydrogen to methane. These results were compared with that of a reactor lacking the enhanced gas–liquid hydrogen transfer mechanism, a conventional anaerobic digester. ResultAnRBC exhibited lower concentrations of hydrogen in the headspace (300–600 ppm) under both normal and shock loading conditions, and also showed more number of hydrogenotrophic methanogens on the denaturing gradient gel electrophoresis (DGGE) profile of 16S rRNA gene amplicons, both in terms of intensity and band numbers (4 in AnRBC and 2 in anaerobic digester). Conclusion This study showed that AnRBC is able to maintain lower hydrogen partial pressure at both normal operating and shock loading conditions due to the abundance of hydrogenotrophic methanogens and good gas–liquid hydrogen transfer efficiency. This finding should encourage the commercial exploitation of AnRBC for the treatment of wastewaters, especially that containing easily acidifiable organic compounds, which causes instability in the operation through souring.
    Journal of Chemical Technology & Biotechnology 02/2014; 90(3). DOI:10.1002/jctb.4307 · 2.50 Impact Factor
  • K Kundu, I Bergmann, M Klocke, S Sharma, T R Sreekrishnan
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    ABSTRACT: This study aimed to analyse the effect of sudden temperature increases (in the range of 45-65°C) on the performance and the microbial community structure of a hybrid anaerobic reactor. The reactor recovered with time after every temperature shock up to the operating temperature of 55°C. At 55°C, a 10°C shock resulting in an operating temperature of 65°C, deteriorated the reactor's performance. At this condition, both, the diversity and the relative abundance of methanogenic groups, especially of Methanosaetaceae, were significantly affected as observed by DGGE fingerprinting and quantitative PCR. In contrast, at lower temperatures (i.e., 45 and 55°C), thermal shocks seemed to have less effect due to the presence and maintenance of thermophilic strains, which prevented system deterioration. At 65°C, the absence of any acetoclastic methanogen is assumed to be the cause of system failure.
    Bioresource Technology 01/2014; DOI:10.1016/j.biortech.2014.01.093 · 5.04 Impact Factor
  • Meenu Chhabra, Saroj Mishra, Trichur Ramaswamy Sreekrishnan
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    ABSTRACT: Textile effluent is characterized by high color, chemical oxygen demand and conductivity due to presence of a large number of recalcitrant compounds. The effluent is often discharged without an effective treatment leading to contamination of water bodies. In the present study, a combination of mediator assisted laccase and chemical treatment was used for decolorization of effluent from a local textile mill in a continuous enzyme membrane reactor (EMR). Treatment of the effluent first with laccase and ABTS (2, 2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) lead to about 60% decolorization but was accompanied by membrane fouling. Addition of alum further coagulated 90% of the residual color but the process was associated with dye sludge formation and ABTS could not be recovered from the treated effluent. Reversal of the treatment sequence was effective in that 85% decolorization was achieved in the EMR and the process could be operated for over a period of 15 days. No sludge formation was noticed and membrane fouling was negligible. Most importantly, about 60% ABTS could be recovered from the treated effluent. Analysis of the treated effluent by mass spectrometery indicated extensive breakdown of the dye molecules by laccase and ABTS and the breakdown products were neither toxic nor mutagenic as assessed by measurement of the oxygen consumption rate and the standard Ames test
    Biochemical Engineering Journal 01/2014; DOI:10.1016/j.bej.2014.09.007 · 2.37 Impact Factor
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    ABSTRACT: A comparative study was undertaken using indigenous sulfur-oxidizing microorganisms and iron-oxidizing microorganisms in separate 12 litre continuous stirred tank reactors (CSTRs) for solubilization of heavy metals from anaerobically digested sewage sludge. The CSTRs were operated at hydraulic retention times (HRTs) ranging from 4 to 10 days using sewage sludge feed having near neutral pH. The pH, oxidation-reduction potential (ORP) and solubilization efficiency of metals were found to be highly dependent on HRT and an increase in HRT led to higher solubilization of metals in both the CSTRs. In both the CSTRs, the CSTR operated with sulfur-oxidizing microorganisms at an HRT of 8 days was found to be optimum in solubilizing 58% Cu, 52% Ni, 72% Zn and 43% Cu from the sludge. The nutrient value, nitrogen and phosphorus of bioleached sludge was also conserved (<20% loss) at 8 days HRT. The metals fractionation study conducted using BCR sequential extraction procedure suggested that most of the metals remaining in the bioleached sludge were in the more stable fractions (F3 and F4) and, therefore, can be safely apply as a fertilizer on land.
    Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 01/2014; 49(1):93-100. DOI:10.1080/10934529.2013.824737
  • K Kundu, I Bergmann, S Hahnke, M Klocke, S Sharma, T R Sreekrishnan
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    ABSTRACT: Industrial effluents differ in their organic composition thereby providing different carbon sources to the microbial communities involved in its treatment. This study aimed to investigate the correlation of microbial community structure with wastewater composition and reactor's performance. Self-immobilized granules were developed in simulated wastewater based on different carbon sources (glucose, sugarcane molasses, and milk) in three hybrid anaerobic reactors operated at 37˚C. To study archaeal community structure, a polyphasic approach was used with both qualitative and quantitative analysis. While PCR-denaturing gradient gel electrophoresis of 16S rRNA gene did not reveal major shifts in diversity of archaea with change in substrate, quantification of different groups of methanogens and total bacteria by real-time PCR showed variations in relative abundances with dominance of Methanosaetaceae and Methanobacteriales. These data were supported by differences in the ratio of total counts of archaea and bacteria analyzed by catalyzed reporter deposition - fluorescence in situ hybridization. During hydraulic and organic shocks, the molasses-based reactor showed best performance followed by the milk- and the glucose-based reactor. The study indicates that carbon source shapes the microbial community structure more in terms of relative abundance with distinct metabolic capacities rather than its diversity itself.
    Journal of Biotechnology 08/2013; DOI:10.1016/j.jbiotec.2013.08.023 · 3.18 Impact Factor
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    ABSTRACT: Bioelectricity production from microbial fuel cell (MFC), fed with synthetic wastewater can achieve both wastewater treatment and energy production. Two different types of separators were used in this study to compare their performance in an air cathode MFC. Power generation and substrate utilization from the wastewater was compared for these membranes. The maximum power density obtained with Zirfon® was 424.50 mW/m2 and of 16.98 W/m3 (volumetric) while with Fumasep® was 38.03 mW/m2 and 1.52 W/m3 (volumetric). The internal resistance obtained with Zirfon® increased from initial 0.38 Ω cm2 to 1.72 Ω cm2 while with Fumasep® increased from 2.57 Ω cm2 to 10.92 Ω cm−2 at the end of the experiment. The results showed that the MFC with Zirfon® stabilized early and the anodic and cathodic cell potentials reached maximum earlier as compared to Fumasep®. Impedance spectra confirmed the lower resistance of the Zirfon® as compared to Fumasep® and this may be the reason for its better performance. Zirfon® might be a good option for the future scale up of MFCs because of its low cost and low internal resistance in comparison to other membranes.
    Chemical Engineering Journal 05/2013; 228:1-11. DOI:10.1016/j.cej.2013.05.014 · 4.06 Impact Factor