Chandrajit Balomajumder

Cyanide in industrial wastewaters and its removal: a review on biotreatment.

Cyanides are produced by certain bacteria, fungi, and algae, and may be found in plants and some foods, such as lima beans and almonds. Although cyanides are present in small concentrations in these plants and microorganisms, their large-scale presence in the environment is attributed to the human activities as cyanide compounds are extensively used in industries. Bulk of cyanide occurrence in environment is mainly due to metal finishing and mining industries. Although cyanide can be removed and recovered by several processes, it is still widely discussed and examined due to its potential toxicity and environmental impact. From an economic standpoint, the biological treatment method is cost-effective as compared to chemical and physical methods for cyanide removal. Several microbial species can effectively degrade cyanide into less toxic products. During metabolism, they use cyanide as a nitrogen and carbon source converting it to ammonia and carbonate, if appropriate conditions are maintained. Biological treatment of cyanide under anaerobic as well as aerobic conditions is possible. The present review describes the mechanism and advances in the use of biological treatment for the removal of cyanide compounds and its advantages over other treatment processes. It also includes various microbial pathways for their removal.

Enzymatic mechanism and biochemistry for cyanide degradation: A review

Cyanides are fast-acting poisons, can be lethal if exposed in excess. In spite of fact, cyanides are discharged as effluents in large scale from industries every year. Certain bacteria, fungi, algae and plants produce cyanides. It has been observed that microbes and plant systems can degrade cyanides to less toxic compounds. There are many enzymes, which are produced by microorganisms that utilize cyanides as substrate to make alanine, glutamic acid, alfa-amino-butyric acid, beta-cyanoalanine, etc. Present paper deals with different enzymes, their mechanisms and corresponding pathways with respect to the known biochemistry of enzyme and feasibility for the use in treatment of cyanides containing industrial effluents.

TREATMENT OF RESORCINOL AND PHENOL BEARING WASTE WATER BY SIMULTANEOUS ADSORPTION BIODEGRADATION (SAB): OPTIMIZATION OF PROCESS PARAMETERS

In the present paper the observations on the simultaneous adsorption biodegradation (SAB) of resorcinol and phenol from two separate synthetic wastewater samples have been reported. For SAB, immobilization of Pseudomonas putida MTCC 1194 on granular activated carbon (GAC) has been done. The optimum process parameters like adsorbent dose, particle size of GAC, and pH have been determined experimentally by calculating percentage removal. The optimum process parameters have also been verified by the theoretical model of Weber and Morris (1963). Under the experimental conditions at 28 degrees Celsius the optimum process parameters are noted as adsorbent dose = 10 g/l, GAC particle size = 2- 4 mm and pH = 6.24. The isotherm studies of these processes have been done. Adsorption studies have also been done separately for both the compounds for comparing the efficiency of SAB over adsorption.

Design and optimization of simultaneous biosorption and bioaccumulation (SBB) system: a potential method for removal of Zn(II) ion from liquid phase

Abstract This study has dealt with the design of simultaneous biosorption and bioaccumulation (SBB) batch system for Zn(II) ion removal from liquid phase. Cedrus deodara sawdust was used as carrier to immobilize Zinc sequestering bacteria “VMSDCM” accession number HQ108109. This methodology was adopted for SBB of metal ion zinc from liquid phase. The surface texture of the biomass was studied through scanning electron microscopy and Fourier transformation infra red spectrum analysis. Physico-chemical analysis of the biomass was performed through proximate carbon, hydrogen, nitrogen and sulphur analysis coupled with measurement of the surface area by Brunauer–Emmett–Teller (BET) method, obtained after the adsorption and desorption of nitrogen gas on the sample. Various isotherm models such as Langmuir (Type I to IV), Freundlich, and Temkin isotherm models have been used in the present work. A modified model was proposed to elucidate the better explanation of the sorption of Zn(II) on the surface of Zinc se...

Biological treatment and modeling aspect of BTEX abatement process in a biofilter

In the present work, a laboratory scale corn-cob based biofilter inoculated with Bacillus sphaericus (MTCC 8103) was used for degradation of BTEX for a period of 86 days. The overall performance of a biofilter evaluated in terms of its elimination capacity by using 3-D mesh technique. Maximum removal efficiency was found more than 96.43% for all four compounds in each phase of experiments. A maximum elimination capacity (EC) of 60.89 gm(-3)h(-1) of the biofilter was obtained at inlet BTEX load of 63.14 gm(-3)h(-1). The follow-up of carbon dioxide concentration profile through the biofilter revealed that the mass ratio of carbon dioxide produced to the BTEX removed was approximately 2.2, which confirms complete degradation of BTEX. Moreover, BTEX concentration profile along the biofilter depth bed also determined by convection-diffusion reactor (CDR) model.

Removal of metal cyanides from aqueous solutions by suspended and immobilized cells of Rhizopus oryzae (MTCC 2541).

This paper presents a study on biodegradation and simultaneous adsorption and biodegradation (SAB) of zinc and iron cyanides by Rhizopus oryzae (MTCC 2541), with a brief process review. Granular activated carbon was used for the immobilization of Rhizopus oryzae (MTCC 2541) for the SAB study. pH and temperature were optimized at an initial cyanide concentration of 100 mg/L for biodegradation and SAB. The microbes adapted to grow at maximum cyanide concentration were harvested and their ability to degrade cyanide was measured in both biodegradation and SAB. The removal efficiency of the SAB process was found to be better as compared to the biodegradation process. In the case of biodegradation, removal was found up to a maximum cyanide concentration of 250 mg CN−/L for zinc cyanide and 200 mg CN−/L for iron cyanide, whereas in the case of SAB, about 50% removal of cyanide at 400 mg CN−/L zinc cyanide and 300 mg CN–/L iron cyanide was possible. It was found that the SAB process is more effective than biodegradation.

Adsorption of Cu (II) on the Surface of Nonconventional Biomass: A Study on Forced Convective Mass Transfer in Packed Bed Column

The present investigation has dealt with the adsorption of Cu (II) across liquid phase on the nonconventional adsorbent. The nonconventional adsorbent used in the present work was Cedrus deodara sawdust obtained from local carpenters shop. The maximum uptake capacities of Copper (II) ions at saturation and breakthrough point were 55.63 mg/g and 53.18 mg/g for an initial concentration of 93 mg/L of copper, respectively. The fitting of the experimental data in Langmuir, Freundlich, and Temkin isotherm models indicated the suitability of Langmuir isotherm in terms of very low statistical error functions that is, and sum of square errors (SSE) and higher values of linear regression coefficient. The goodness of fit of the breakthrough curve in Bohardt-Adams, Wolborska, Modified dose response, and Thomas model indicated the suitability of Thomas model with higher linear regression coefficient and lower values of statistical error functions. The flow rate and bed height affected the hydrodynamic parameters of the packed bed reactor significantly.

Performance evaluation and model analysis of BTEX contaminated air in corn-cob biofilter system.

Biofiltration of BTEX with corn-cob packing material have been performed for a period of 68 days in five distinct phases. The overall performance of a biofilter has been evaluated in terms of its elimination capacity by using 3-D mesh techniques. Maximum removal efficiency was found more than 99.85% of all four compounds at an EBRT of 3.06 min in phase I for an inlet BTEX concentration of 0.0970, 0.0978, 0.0971 and 0.0968 g m(-3), respectively. Nearly 100% removal achieved at average BTEX loadings of 20.257 g m(-3) h(-1) to biofilter. A maximum elimination capacity (EC) of 20.239 g m(-3) h(-1) of the biofilter was obtained at inlet BTEX load of 20.391 g m(-3) h(-1). Moreover, using convection-diffusion reaction (CDR) model for biofilter depth shows good agreement with the experimental values for benzene, toluene and ethyl benzene, but for o-xylene the model results deviated from the experimental.

USE OF IRON-IMPREGNATED GRANULAR ACTIVATED CARBON FOR CO-ADSORPTIVE REMOVAL OF PHENOL AND CYANIDE: INSIGHT INTO EQUILIBRIUM AND KINETICS

In the present study, the effect of iron impregnation on granular activated carbon (GAC) for removal of multicomponents from synthetic wastewater was studied. It was observed that percentage removal of phenol and cyanide increased from 72.89% to 91.82% and from 75.99% to 95.57% respectively. A decrease in equilibrium time from 33 to 27 h and a decrease in optimum adsorbent dose from 30 to 10 g/L were also observed. Equilibrium modeling using two single-component isotherms and four multicomponent isotherms was performed, and it was found that extended Langmuir and extended Freundlich isotherm fits best to the adsorption of phenol and cyanide, respectively. Kinetic modeling using contact time studies was done to reveal the nature of adsorption and it was found that the rate-limiting step was a chemical adsorption process.

Biosurfactant as a Promoter of Methane Hydrate Formation: Thermodynamic and Kinetic Studies.

Natural gas hydrates (NGHs) are solid non-stoichiometric compounds often regarded as a next generation energy source. Successful commercialization of NGH is curtailed by lack of efficient and safe technology for generation, dissociation, storage and transportation. The present work studied the influence of environment compatible biosurfactant on gas hydrate formation. Biosurfactant was produced by Pseudomonas aeruginosa strain A11 and was characterized as rhamnolipids. Purified rhamnolipids reduced the surface tension of water from 72 mN/m to 36 mN/m with Critical Micelle Concentration (CMC) of 70 mg/l. Use of 1000 ppm rhamnolipids solution in C type silica gel bed system increased methane hydrate formation rate by 42.97% and reduced the induction time of hydrate formation by 22.63% as compared to water saturated C type silica gel. Presence of rhamnolipids also shifted methane hydrate formation temperature to higher values relative to the system without biosurfactant. Results from thermodynamic and kinetic studies suggest that rhamnolipids can be applied as environment friendly methane hydrate promoter.