Jai Prakash Kushwaha

An overview of various technologies for the treatment of dairy wastewaters.

Dairy industries have shown tremendous growth in size and number in most countries of the world. These industries discharge wastewater which is characterized by high chemical oxygen demand, biological oxygen demand, nutrients, and organic and inorganic contents. Such wastewaters, if discharged without proper treatment, severely pollute receiving water bodies. In this article, the various recent advancements in the treatment of dairy wastewater have been discussed and the areas where further research is needed have been identified.

Treatment of dairy wastewater by commercial activated carbon and bagasse fly ash: Parametric, kinetic and equilibrium modelling, disposal studies.

Present study reports treatment of synthetic dairy wastewater (SDW) in terms of chemical oxygen demand (COD) removal by means of adsorption onto activated carbon-commercial grade (ACC) and bagasse fly ash (BFA). Optimum conditions for SDW treatment were found to be: initial pH approximately 4.8, adsorbent dose of 20g/l for ACC and 10g/l for BFA and contact time approximately 8h. Pseudo-second-order kinetic model was found to fit the kinetic data and Redlich-Peterson isotherm model was generally found to best represent the equilibrium data for SDW treatment by ACC and BFA. The change in entropy and enthalpy for SDW adsorption onto ACC and BFA were estimated as 125.85kJ/molK and 91.53kJ/mol; and 25.71kJ/molK and 17.26kJ/mol, respectively. The negative values of change in Gibbs free energy indicate the feasibility and spontaneous nature of the adsorptive treatment.

Electrocoagulation of Soluble Oil Wastewater: Parametric and Kinetic Study

Soluble oils (cutting oils) in aqueous solution are used extensively in the engineering and metal working industries, as coolants, metal forming fluids, and/or lubricants. Hysol-X is a general-purpose cutting oil used in 1–10% concentration in aqueous solution. This paper investigates demulsification of soluble-oil-water emulsion using electrocoagulation with aluminum electrodes. It examines the current efficiency and the pH variation of the system due to electrocoagulation and the effect of pH of the oil-water emulsion, current density, and temperature on the demulsification process. A simple first order kinetics fits the experimental data at a constant value of current density. The optimum pH and current density were found to be 6.50 and 138.8 A/m2, respectively. Apparent electrode current efficiency was found to be 115.5%. Temperature has significant effect on emulsion stability and solution pH. At a lower temperature of 20°C or a higher temperature of 60°C, the turbidity (or oil) removal is found to be very high. More than 99% oil separation is achieved in 3 h at 20°C. The residual aluminum concentration in the treated water at an initial pH 6.5 is found to be 0.001 mg/l, well below the statutory discharge standard value.

Modeling and evaluation of electro-oxidation of dye wastewater using artificial neural networks

Treatment of CBSOL LE red wool dye containing wastewater by an electro-oxidation (EO) method was investigated using Ti/RuO2 electrode. The performance of the EO system was evaluated in terms of % dye degradation (Y1) and % colour removal (Y2) along with important operating cost parameters such as energy consumed (Y3) at three EO process parameters: pH, current (i) and time (t). ANNs were applied for the modeling of the EO process, and optimization was performed by using multi response optimization by desirability function approach of Central composite Design (CCD) with stimulated data obtained from ANNs. Modeling for the treatment of CBSOL LE red wool dye wastewater by the EO process was done successfully by ANNs, and optimization by CCD vividly underscores interactions between variables and their effects for the degradation of CBSOL LE red wool dye by the EO process. At the optimum conditions, the actual % dye degradation (Y1), % color removal (Y2) and energy consumed (Y3) were 89.87%, 96.71%, 2.029 Wh respectively. The predictions agree well with the experimental results. It was found that both the mechanisms of EO treatment i.e. direct oxidation and indirect oxidation are responsible for the dye degradation/color removal. Color was found to be nearly completely removed, whereas 10.13% of dye is present in the treated wastewater.

A review on sugar industry wastewater: sources, treatment technologies, and reuse

AbstractSugar industries have an important place in the Indian economic development. However, the wastewater generated from these industries bear a high degree of pollution load. Sugar industries in India generate about 1,000 L of wastewater for one ton of sugar cane crushed. Wastewater from sugar industry, if discharged without treatment, poses pollution problems in both aquatic and terrestrial ecosystems. In this review, the sugar industry wastewater generation sources, characteristics, recent advancements in the aerobic, anaerobic, and physico-chemical treatment technologies, and the areas needing further research have been explored. Possibility of treated wastewater reuse was also investigated. Most of the research work for sugar industry wastewater treatments has been carried out by anaerobic treatment processes. However, oil and grease are not easily degraded by anaerobic processes. Also, an anaerobic process partly degrades nutrients whereas, aerobic processes consume higher energy. Anaerobic-aerob...

Electrocatalytic oxidative treatment of real textile wastewater in continuous reactor: Degradation pathway and disposability study

Electrocatalytic treatment of real textile wastewater was investigated in continuous electrochemical reactor using dimensionally stable Ti/RuO2 anode. Effects of various parameters such as: elapsed time, current, pH, retention time on the COD removal, color removal and specific energy consumed were evaluated. Central Composite Design under RSM was used for experimental design, data analysis, optimization, interaction analysis between the various electrochemical parameters and steady state time analysis. GC-MS and UV spectrophotometric analysis of the untreated and treated wastewater were conducted to identify the oxidized and transformed/degraded compounds during the oxidation process, and a suitable degradation mechanism was proposed. Treated wastewater may contain toxic chlorinated compounds due to mediated oxidation by various hydrolyzed chlorine species. Therefore, disposability of treated wastewater was assessed by conducting toxicity bioassay test. The optimal set of operating parameters were found to be elapsed time = 124 min, current = 1.37 A, pH = 5.54 and retention time = 157.6 min to simultaneously achieve COD removal, color removal and specific energy consumed as 86.22%, 94.74% and 0.012 kW h, respectively. GC-MS analysis showed presence of chlorinated compounds in the treated wastewater. The toxicity bioassay test resulted acute toxicity with 100% mortality rate within one minute and one hour exposure with untreated and treated textile wastewater, respectively.

Tannic acid adsorption/desorption study onto/from commercial activated carbon

AbstractThis study reports tannic acid adsorption onto commercial activated carbon (ACC) in a batch system. Adsorption process parameters namely pH, adsorbent dose (mad), temperature (T), initial tannic acid concentration (Co), and contact time (t) were studied and optimized. Optimum pH and adsorbent dose were found to be 3.0 and 15 g/l, respectively. Equilibrium contact time was found to be 7 h. Pseudo-second-order kinetic best fits the adsorption kinetic data. Three isotherms namely Langmuir, Temkin, and Redlich and Peterson (R–P) isotherms were studied and it was found that Langmuir and R–P isotherm generally fitted the experimental equilibrium adsorption data. Endothermic nature of the adsorption of tannic acid onto ACC was concluded, and heat of adsorption was found to be as 89.55 kJ/mol. On considering the cost of ACC, regeneration studies of Tannic acid (TA) loaded ACC have been performed using solvent and thermal desorption methods.

Adsorptive interaction of 4-aminobiphenyl with mesoporous MCM-41

ABSTRACT In this work, mesoporous silica-based MCM-41 was synthesised, and its adsorptive interaction with carcinogenic aromatic amine 4-aminobiphenyl (4-ABP) was studied. pH, MCM-41 dose, 4-ABP concentration, adsorption time and temperature were selected as process parameters for this purpose. Kinetic experimental data were fitted to pseudo-first-order and pseudo-second-order kinetic models to evaluate the adsorption kinetics. Further, adsorption rate controlling mechanism was investigated using intra-particle diffusion model. Langmuir, Freundlich, Temkin and D-R isotherm (Dubinin-Radushkevich) models were used to represent the adsorption equilibrium data. Gibbs free energy, entropy and enthalpy have also been determined to interpret the adsorption mechanism. MCM-41 exhibited 525 m2 g–1 BET surface area with pore volume of 0.85 cm3 g–1 and pore diameter of 3.21 nm. Kinetic data were best represented by the pseudo-second-order kinetic model. The adsorption equilibrium data were best fitted by Freundlich and Dubinin-Radushkevich (D-R) isotherms.

Transformation products and degradation pathway of textile industry wastewater pollutants in Electro-Fenton process

In this study, pollutants from textile industry wastewater were transformed/oxidized using Ti/RuO2 electrode by Electro-Fenton (EF) method in a continuous reactor. The performance was evaluated in terms of % COD removal, % color removal and energy consumed. Electrolysis time, retention time, current, and ferrous sulphate concentration as Fenton catalyst were selected as EF process parameters. To determine the optimum operating conditions multiple response optimization with desirability approach based on central composite design under response surface methodology was used. Spectrophotometric and GC-MS analysis were performed to identify the degraded/transformation compounds, and on this basis degradation mechanism during EF process as well as disposability of treated wastewater was analyzed. Further, bioassay test of treated textile wastewater was conducted for toxicity analysis in view of its disposal quality. Results showed that all the components of textile wastewater were totally eliminated/transformed in lower molecular weight compounds after EF treatment of textile effluent. Further, bioassay test analysis confirmed the nontoxic nature of treated wastewater.