Wastewater generated from coke oven industries contains highly toxic organic and inorganic compounds. In the present study, biological reactors were integrated in sequence of anaerobic-aerobic-anoxic and tested with real coke oven wastewater obtained from a Steel Plant located in India. Among several pretreatment methods, coagulation of raw CWW was found to be effective. COD removal efficiency of 78.5% was achieved by the integrated bioreactor system after coagulation of CWW with 1000 mg/L of alum. The effluent COD, NH4-N and TCN concentration from the integrated bioreactors was 420, 152 and 20 mg/L, respectively. It was observed that 420 mg/L of COD present in the effluent after integrated bio treatment was degraded in less than 4 h to minimum COD concentration of 94 mg/L using UV-TiO2 photocatalysis. In absence of photocatalyst (TiO2), there was no COD reduction from the bio treated effluent. Similarly, there was insignificant reduction in COD from the raw CWW using photocatalysis without biological treatment. Considerable COD reduction (78.5%) was observed only in the wastewater subjected to integrated biological system. The overall COD removal efficiency of the combined treatment system was found to be 96.2%, which resulted in an effluent COD concentration less than 94 mg/L. © 2016 Elsevier B.V.

Ligy Philip

Department Of Civil Engineering

Bioreactors

catalysis

Coagulation

COKE OVENS

efficiency

Effluent treatment

Effluents

Inorganic compounds

Photocatalysis

STEELMAKING

Titanium dioxide

Wastewater treatment

Aerobic

Anaerobic

ANOXIC

COD REMOVAL EFFICIENCY

COMBINED TREATMENT SYSTEM

HYBRID TREATMENT

INTEGRATED BIOREACTORS

PHOTOCATALYTIC TREATMENT

Biological water treatment

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Chemical Engineering Journal

Studies were conducted on a mixture of pollutants commonly found in coke oven wastewater (CWW) to evaluate the biodegradation of various pollutants under anaerobic, aerobic, and anoxic conditions. The removal of the pollutants was monitored during individual bioreactor operation and using a combination of bioreactors operating in anaerobic–aerobic–anoxic sequence. While studying the performance of individual reactors, it was observed that cyanide removal (83.3 %) was predominant in the aerobic bioreactor, while much of the chemical oxygen demand (COD) (69 %) was consumed in the anoxic bioreactor. With the addition of cyanide, the COD removal efficiency was affected in all the bioreactors, and several intermediates were detected. While treating synthetic CWW using the combined bioreactor system, the overall COD removal efficiency was 86.79 % at an OLR of 2.4 g COD/L/day and an HRT of 96 h. The removal efficiency of 3,5-xylenol and cyanide, with inlet concentration of 150 and 10 mg/L, was found to be 91.8 and 93.6 % respectively. It was found that the impact of xylenol on the performance of the bioreactors was less than cyanide toxicity. Molecular analysis using T-RFLP revealed the dominance of strictly aerobic, mesophilic proteobacterium, Bosea minatitlanensis, in the aerobic bioreactor. The anoxic bioreactor was dominant with Rhodococcus pyridinivorans, known for its remarkable aromatic decomposing activity, while an unclassified Myxococcales bacterium was identified as the predominant bacterial species in the anaerobic bioreactor. © 2014, Springer Science+Business Media New York.

Applied Biochemistry and Biotechnology

Treatment of Phenolics, Aromatic Hydrocarbons, and Cyanide-Bearing Wastewater in Individual and Combined Anaerobic, Aerobic, and Anoxic Bioreactors

The objective of this study was to investigate the biodegradation of a mixture of pollutants commonly found in coke oven wastewater such as phenol, cresol, xylenol, quinoline, indole and cyanide under anaerobic and anoxic conditions. It was found that xylenol was highly recalcitrant under anaerobic and anoxic conditions. In presence of free cyanide (>2.5. mg/L), the organic compounds (100. mg/L) were degraded before the biodegradation of free cyanide under both the conditions. However, the biodegradation of pollutants prolonged under anaerobic conditions compared to anoxic conditions. All the organics, especially xylenol and indole, inhibited the degradation of cyanide. Experimental results highlighted the detrimental effects of the combined toxic influence of cyanide and organics on the anaerobic and anoxic microbes treating coking wastewater. The proposed mathematical model was able to simulate the biodegradation of organic compounds along with cyanide satisfactorily. © 2014 Elsevier B.V.

Effect of cyanide on phenolics and aromatic hydrocarbons biodegradation under anaerobic and anoxic conditions

Methyl parathion (O,O-dimethyl-O-4-nitrophenyl phosphorothioate) and dichlorvos (2,2-dichlorovinyl-O-O-dimethyl phosphate) are the most commonly used pesticides in India. These pesticides are often found in many surface and groundwater sources and their concentration levels often exceed the drinking water permissible limits recommended by Indian and European drinking water standards. In this study, doping of nitrogen on TiO 2 was carried out with different nitrogen containing organic compounds such as triethylamine, urea, ethylamine and ammonium hydroxide. Nitrogen (N) doped TiO 2 from triethylamine precursor showed better photocatalytic activity under visible and solar radiation for the degradation of methyl parathion and dichlorvos. Studies for the photodegradation of analytical and commercial grade methyl parathion and dichlorvos were carried out with N-doped TiO 2 and Degussa P-25 TiO 2 under UV, visible and solar radiation using batch reactor. N doped TiO 2 showed higher photocatalytic activity under solar radiation compared to UV and visible light. GC-MS analysis of commercial grade methyl parathion showed intermediates such as para-nitrophenol and O,O-dimethyl phosphonic ester in the middle of the photodegradation process. Similarly, commercial grade dichlorvos showed intermediates such as 2,2-dichlorvinyl-O-methyl phosphate and O,O,O-trimethyl phosphonic ester during the reaction. However, at the end of the reaction none of the intermediates were present in the system. Photodegradation of mixed pesticides showed that methyl parathion and dichlorvos were degrading simultaneously. However, the rates of reaction were different from single pesticide degradation. © 2011 Elsevier B.V.

Photodegradation of methyl parathion and dichlorvos from drinking water with N-doped TiO 2 under solar radiation

Nitrogen doped titanium photocatalysts with different nitrogen containing organic compounds were prepared by sol-gel method in acidic media. Among different nitrogen containing organic compounds, triethylamine doped TiO2 showed better photocatalytic activity under visible light. XRD, SEM and TEM analyses showed that the crystalline size of N-doped TiO2 was in the range of 20-24 nm. XRD and Raman spectrum showed that all peaks of N-doped TiO2 correspond to anatase crystalline structure. The formation of O-Ti-N bond in N-doped TiO2 does not lead to any new Raman band. XPS study confirmed that N replaces the O in the lattice of TiO2 and is present in the form of O-Ti-N. The photocatalytic activity of doped TiO2 was measured under UV and visible light using lindane as a target pollutant. The photocatalytic activity of anatase TiO2 and N-doped TiO2 was compared with commercially available Degussa P-25 TiO2. Intermediates formed during the degradation of lindane were monitored by GC-MS analysis. © 2010 Elsevier B.V.

Photocatalytic degradation of lindane under UV and visible light using N-doped TiO2

Journal of Hazardous Materials

Impact of oxidation and biodegradation on the most commonly used polycyclic aromatic hydrocarbon (PAH) diagnostic ratios: Implications for the source identifications

Combined biological and photocatalytic treatment of real coke oven wastewater

Journal	Data powered by TypesetChemical Engineering Journal
Publisher	Data powered by TypesetElsevier B.V.
ISSN	13858947
Open Access	No