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Diagnosis of Treatment Efficiency in Industrial Wastewater Treatment Plants: A Case Study at a Refinery ETP
No full textMany industries employ the activated sludge process for
biological removal of pollutants present in wastewater. Yet,
treatmentplantsdonotfunctionatoptimumpotential.Thebiological
component of such systems remains a black box, and reasons responsible for poor performance have not been identified. We have used genomic and physiological tools to understand the process and propose that analysis of catabolic signatures and nutrient levels, are crucial parameters in
assessing and monitoring the performance of an effluent
treatment plant. In this study, we use activated sludge collected from a refinery running at a capacity of 8 million metric tonnes of wastewater as a model. The presence of hydroxylases, oxygenases,anddioxygenasesin thebiomasswasdemonstrated by polymerase chain reaction and sequence analysis of aromatic-ring hydroxylating dioxygenase clones extracted from the metagenome, suggests the presence of hitherto unreported enzymes. The actual degradative state of the biomass was demonstrated by respirometric analysis using 11 substrates expected in refinery wastewater. Nutrient-levels required for the microbial population were estimated by onsite analysis. Diagnosis of the degradative potential of activated sludge can be carried out by incorporating these tools in regular monitoring procedures and can set the rules for improving
the efficiency of treatment
Catalytic Hydrogenation of Aqueous Phase Nitrate Over Fe/C Catalysts
No full textAbstract Catalytic hydrogenation of nitrate in water has been carried out over Fe/C catalysts at ambient temperature using batch and continuous reactors. In batch reaction nitrate reduction activity of 2.9 mmol g-metal1 min-1 with nearly 100% selectivity towards nitrogen was obtained. Column study shows nitrate reduction below 5 ppm for an initial concentration of 100 ppm. Break through capacity, to reach concentration of 45 mg L-1, is more than 530 bed volumes. The catalysts were characterized using XRD, SEM–EDAX and XPS. With high selectivity and activity the catalytic system in present study could be a potential option for nitrate removal from water.
Keywords Catalytic hydrogenation _ Fe/C catalyst _ Water treatment _ Nitrat
Spatial distribution of metals in ground/surface waters in the Chandrapur district (Central India) and their plausible sources
No full textThis study addresses a framework to evaluate
and map environmental hazard with reference to spatial
distribution of major and trace metal contamination and its
relationship with lithology in Chandrapur district of
Maharashtra, India using geospatial, statistical and GIS
tools. In all, 208 ground water and 35 surface water samples
were collected using global positioning system (GPS)
synoptically with satellite imagery IRS P6 LISS III and
were analyzed in ICP-AES. Analytical results reflect the
presence of major and trace metals in ground water in
terms of % as Fe (48%), Mn (12%), Zn (9%), Al (8%), Pb
(7%), Cu (6%), Ni (4%), Cd (3%) and Cr (3%) of the total
average concentration. The contamination is attributed to
weathering of rocks and also to mining activities. Similarly,
surface water contribution of major and trace metals
was found as Al (47.8%), Fe (42.8%), Mn (5.5%), Zn
(2.3%), Pb (0.56%), Ni (0.42%), Cu (0.16%), Cr (0.16%)
and Cd (0.10%) of the total average concentration.
Ordinary kriging interpolation method was adopted to
assess the spatial distribution of different major and trace
metals in groundwater samples with their best model fit
variogram Classical statistical method like principal component
analysis (PCA) was carried out in order to establish
correlation between spatial pattern of metal contamination
and geology of the area in GIS environment. Various surface
and subsurface aspects like landuse/land cover,
structural features, hydrogeology, topography etc were also
considered to ascertain their impact to supplement the
inference of the study
Visible light induced photoreduction of methyl orange by N-doped mesoporous titania
No full textN-doped mesoporous titania was synthesized using templating method. Biopolymer chitosan was used
as a template and also as a nitrogen source along with ammonium hydroxide. Three different types of Ndoped
mesoporous titania were synthesized by varying composition of chitosan and titania precursor.
These photocatalysts were characterized using XRD, BET-SA, FTIR, UV-DRS, SEM–EDX and XPS analysis.
The photocatalytic activity of mesoporous titania was studied by methyl orange (MO) photoreduction
reaction. From the experimental results it was observed that the N-doped mesoporous titania (1:2) gives
the highest photocatalytic reduction of MO as compared to N-doped mesoporous titania prepared with
(1:1) and (1:3) stoichiometry. This could be due to the optimal level of ‘N’ incorporation in the N-doped
mesoporous titania (1:2).
Photocatalysts reduce theMO dye into derivative of hydrazine. Photoactivity of N-doped mesoporous
titania (1:2) is 1.0721 mg of MO reduced per g of TiO2 vis-a` -vis 0.508 mg of MO reduced per g of TiO2 for
Degussa P25 photocatalyst. The effect of various operating parameters like photocatalyst loading, initial
concentration and intensity of light also has been studied
A modified anaerobic baffled reactor for municipal wastewater treatment
No full textA nine-chambered modified anaerobic baffled reactor (MABR) was developed to evaluate its suitability for the treatment of municipal wastewater and to establish the understanding of the relationship between reactor design and operational parameters. The paper presents the configuration of the MABR, its start-up, effect of variation of hydraulic retention time (HRT) on treatment efficiency, and performance evaluation of the MABR while treating the municipal wastewater. To assess the self-inoculation
potential of the MABR, the start-up was carried out without seed sludge at a HRT of 6 d. An acclimatization curve was plotted and indicated that a start-up period of 90 d was required for the MABR. Reactor performance evaluation was carried out for 375 d at 11 different HRTs ranging from 6 d to 3 h. The HRT of 6 h was adjudged to be appropriate for this reactor configuration. At a HRT of 6 h, the efficiencies of reduction in suspended solids (SS), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) were found to be 86%, 87% and 84% respectively. Specific biogas yield and methane content were found to be 0.34 m3CH4/KgCODr and 67% respectively. The study has evaluated the performance pattern of the MABR and identified it as a suitable reactor technology for municipal
wastewater management in India.
Development of novel circular secondary clerifier for improving solid liquid seperation in wastewater treatment
No full textDetoxification of benzidine-based azo dye by E. gallinarum: time-course study.
No full textDirect black 38 (DB38) dye is a well-established toxic and carcinogenic compound. Present investigation reports isolation of an Enterococcus gallinarum strain capable of decolorizing and degrading it. Changes in toxicity and mutagenicity of DB38 and its metabolites were also determined using a battery of carefully selected tests (cytotoxicity, respiration inhibition test and Ames test). Toxicity assays were carried out on E. gallinarum itself as this also gave information about suitability of this strain for the dye decolorization operation. The strain was found to reduce both toxicity and mutagenicity of DB38 metabolites. Benzidine and 4-aminobiphenyl (4-ABP) were identified as the DB38 metabolites, responsible for its toxic and mutagenic properties, by HPLC-MS analysis. Further degradation of benzidine and 4-ABP was found to result in the decrease in toxicity and mutagenicity
pyridine biodegradation in a novel rotating rope bioreactor
No full textA novel immobilised bioreactor has been developed especially for the treatment of pollutants characterized by high volatility alongwith
high water solubility and low microbial yields. The new bioreactor referred to as the rotating rope bioreactor (RRB) provides higher
interfacial area (per unit reactor liquid volume) along with high oxygen mass transfer rate, greater microbial culture stability; and consequently
higher substrate loadings and removal rates in comparison to other conventional rectors for the treatment of volatile compounds.
Pyridine was used as a model compound to demonstrate the enhanced performance with RRB, when compared to that
reported with other conventional bioreactors. The experimental results indicate that the novel RRB system is able to degrade pyridine
with removal efficiency of more than 85% at higher pyridine concentration (up to 1000 mg/l) and loading [up to 400 mg/m2/h (66.86 g/
m3/h)], with a shorter hydraulic retention time (9–18 h). The reactor has been in operation for the past 15 months and no loss of activity
has been observed