Pijush Kanti Mondal

Bioremediation of 2-chlorophenol containing wastewater by aerobic granules-kinetics and toxicity.

2-Chlorophenol (2-CP) degrading aerobic granules were cultivated in a sequencing batch reactor (SBR) in presence of glucose. The organic loading rate (OLR) was increased from 6.9 to 9.7 kg COD m(-3)d(-1) (1150-1617 mg L(-1)COD per cycle) during the experiment. The alkalinity (1000 mg L(-1) as CaCO(3)) was maintained throughout the experiment. The specific cell growth rate was found to be 0.013 d(-1). A COD removal efficiency of 94% was achieved after steady state at 8h HRT (hydraulic retention time). FTIR, UV, GC, GC/MS studies confirmed that the biodegradation of 2-CP occurs via chlorocatechol (modified ortho-cleavage) pathway. Biodegradation kinetics followed the Haldane model with kinetic parameters: V(max)=840 mg2-CPgMLVSS(-1)d(-1), K(s)=24.61 mg L(-1), K(i)=315.02 mg L(-1). Abiotic losses of 2-CP due to volatilization and photo degradation by sunlight were less than 3% and the results of genotoxicity showed that the degradation products are eco-friendly.

Hybrid UASFB-aerobic bioreactor for biodegradation of acid yellow-36 in wastewater

In this study, a combined anaerobic-aerobic treatment process based on mixed culture of bacteria was used to degrade azo dyes (AY-36). The experiment was integrated by exposing anaerobic granular sludge and aerobic aromatic amine degrading bacterial enrichment cultures. Under anaerobic conditions UASFB bioreactor using sodium acetate as a co-substrate, the AY-36 was reduced and resulting in a temporary accumulation of aromatic amines by the bacterial biomass. Hydraulic residence time (HRT) was fixed (24 h) through out the experiment. The two aromatic amine p-amino diphenylamine (p-ADPA) and 4-aminobenzenesulfonic acid (4-ABS) were detected from the reduction of AY-36. Subsequently, 4-ABS was degraded in the aerobic reactor which was earlier accumulated for 30days. But p-ADPA was not degraded in aerobic condition. The combined anaerobic-aerobic bioreactor was able to completely remove the AY-36 at a maximum loading rate of 100mg AY-36L(-1)d(-1).

Degradation pathway, toxicity and kinetics of 2,4,6-trichlorophenol with different co-substrate by aerobic granules in SBR.

The present study deals with cultivation of 2,4,6-trichlorophenol (TCP) degrading aerobic granules in two SBR systems based on glucose and acetate as co-substrate. Biodegradation of TCP containing wastewater starting from 10 to 360 mg L(-1) with more than 90% efficiency was achieved. Sludge volume index decreases as the operation proceeds to stabilize at 35 and 30 mL g(-1) while MLVSS increases from 4 to 6.5 and 6.2 g L(-1) for R1 (with glucose as co-substrate) and R2 (with sodium acetate as co-substrate), respectively. FTIR, GC and GC/MS spectral studies shows that the biodegradation occurred via chlorocatechol pathway and the cleavage may be at ortho-position. Haldane model for inhibitory substrate was applied to the system and it was observed that glucose fed granules have a high specific degradation rate and efficiency than acetate fed granules. Genotoxicity studies shows that effluent coming from SBRs was non-toxic.

Adsorption and Photodegradation of Methylene Blue by Using PAni/TiO2 Nanocomposite

In this study, polyaniline-titanium dioxide (PAni-TiO2) nanocomposite has been prepared and was utilized as an effective catalyst for photodegradation of methylene blue (MB) dyes from aqueous solution. Adsorption characteristic on the PAni-TiO2 surface and the aqueous solubility of the dyes also play an important role in the photodegradation of dye. Adsorption and photodegradation process occurs simultaneously on the surface of the catalyst at first adsorption occurs (21.5%) on the outer surface of the catalyst and then photodegrade the material up to (66.5%). In reaction mechanism OH· makes the vital role to the degradation of methylene blue and its intermediates. To know the surface and stability of the photocatalyst, it was characterized by FTIR, TEM, TGA–DTA, XRD, UV-vis spectrophotometer, and SEM analysis. Kinetic data indicate that up to 20 minutes photodegradation rates usually follows the pseudo-first-order reaction. After 20 minutes, it follows the Langmuir-Hinshelwood (LH) kinetics. Photo reactivity of PAni-TiO2 was studied with pH of solution, dosage of photocatalyst and concentration of dye. The reaction rate constant (r) and equilibrium binding constant (K) values were incredibly significant than other catalyst.

Application of Modified Water Nut Carbon as a Sorbent in Congo Red and Malachite Green Dye Contaminated Wastewater Remediation

Batch and column adsorption experiments were conducted to investigate the removal of dyes from wastewater by water nut modified carbon (WNMC). Acidic pH was favorable for adsorption for Congo red dyes and basic pH was favorable for the adsorption for Malachite green dyes. The surface property of the sorbent was characterized by scanning electron microscopy and Fourier transform infrared techniques. The adsorption process was found to be endothermic and spontaneous. Different models of adsorption were used to describe the kinetics data and to calculate the corresponding rate constants of WNMC surfaces for dyes adsorption. A mechanism of dyes adsorption associating chemisorption processes is presented allowing the discussion of the variations in adsorption behavior of the material. These data suggested that WNMC are promising materials for dyes sorption. The data were in good agreement with bed depth service time model.

Application of Acid Treated Almond Peel for Removal and Recovery of Brilliant Green from Industrial Wastewater by Column Operation

Abstract The treated almond peels (TAP) have been employed as adsorbents for the removal of Brilliant green dye from waste water. The nature of possible adsorbent and dye interaction was examined by the FTIR and SEM technique. The adsorption of BG was found to be maximum (93%) at pH 8. The extent of removal of BG was found to be dependent on the adsorbent dose, the temperatures, and the times. The equilibrium data for adsorption was best represented by the Langmuir isotherm. Thermodynamic parameters (ΔH0 and ΔG0) suggest endothermic and spontaneous process. Kinetic studies show better applicability of second-order kinetic model. The practical utility of TAP was demonstrated by removing BG from pure solution and industrial effluent system by column process. It was found that the removal effficiency of TAP was better by pure solution. The breakthrough capacities of pure solution and industrial effluent systems on TAP are found to be 30 and 17 mg/g, respectively.

Biodegradation of Azo Dyes from Wastewater

Dyes are synthetic aromatic compounds with various functional groups. Colored dye effluents are highly toxic to the aquatic biota. They alter the symbiotic process by disturbing the natural equilibrium through reduced photosynthetic activity due to the coloration of the water in streams. The control of dyes containing water pollution has thus become of increasing importance in recent years. Amongst the synthetic dyes, azo dyes are the largest group, and account for more than half of the annually produced amounts of dyes. In recent years, several treatments have been proposed for efficient azo dye removal, most of them presenting some limitations such as poor capacity, generate waste products, incomplete mineralization or high operating cost. Nowadays combined anaerobic–aerobic treatments are considered as the most effective route. Removal of azo dyes is based on anaerobic-aerobic treatment for the reductive cleavage of the azo linkages of dyes and for the degradation of the aromatic amines from azo dye cleavage respectively. This chapter reviews the current technologies available for decolourisation of azo dyes and it suggests effective and economically attractive alternatives.

Aromatic amines sources, environmental impact and remediation

The authors thank the FCT exploratory EXPL/AAG-TEC/0898/2013 and Strategic Project of UID/BIO/04469/2013 unit. Acknowledgements also to the project RECI/BBBEBI/0179/2012 (FCOMP-01-0124-FEDER-027462)and the Project “BioEnv-Biotechnologyand Bioengineering for a sustainable world”, REF. NORTE-07-0124-FEDER-000048, co-funded by the Programa Operacional Regional do Norte (ON.2 – O Novo Norte), QREN, FEDER.

Microbial Degradation of Dye-Containing Wastewater

Rapid industrialization and urbanization cause environmental pollution and release several xenobiotic compounds into the environment. Many of them have been listed as priority pollutants by the United States Environment Protection Agency (http://www.epa.gov) due to their toxicity and persistence in nature. Dyes are used by a large number of industrial processes, most notably textile, leather, plastics, food, pharmaceuticals and paints manufacturing industries.