@article { ISI:000371228200017, title = {Differentiating process performance of various coagulants in removal of congo red and orange G dyes}, journal = {International Journal of Chemical Reactor Engineering}, volume = {14}, number = {1}, year = {2016}, month = {FEB}, pages = {195-211}, publisher = {WALTER DE GRUYTER GMBH}, address = {GENTHINER STRASSE 13, D-10785 BERLIN, GERMANY}, abstract = {

Two refractory azo dyes-Congo red and Orange G, especially at high concentrations were subjected to coagulation with different conventional coagulants and newer formulations developed from Aluminum sulfate, Iron (III) chloride, Aluminium chloride, Poly diallydimethylammonium chloride (Poly DADMAC) and Poly Aluminium Chloride (PAC). The highest COD reduction of 99 \% was obtained with PAC SAB 18 (Powder Grade PAC) for Congo red at pH 4.5 while the color removal of 99 \% was achieved with almost all the coagulants in the present study at specific pH within 3-8. The optimum dose for the iron-based coagulant is 200 mg/L while that of aluminum-based coagulants and PAC is 150-200 mg/L. Results showed that Orange G was more difficult to remove with a maximum COD removal of 65 \% and 35 \% color removal using various formulations. The combinational formulations of inorganic-inorganic and inorganic- organic produced a substantial enhancement in COD and color removal and reduced sludge. PAC-Fe30/70 produces the minimum sludge of 50 mL/g on Congo red. pH in the range 3-9 showed high reductions in COD and color (90-99 \%) for Congo red while jerky rise in COD and color reduction was observed in the case of Orange G after pH 9. An attempt to understand the dye coagulation mechanism has been made based on the specific difference in dye structure and cation speciation.

}, keywords = {coagulation, Congo red, dye removal, Orange G, Wastewater treatment}, issn = {2194-5748}, doi = {10.1515/ijcre-2015-0083}, author = {Prajapati, Kavita and Sorokhaibam, Laxmi Gayatri and Bhandari, Vinay M. and Killedar, D. J. and Ranade, Vivek V.} } @article {46060, title = {Hydrodynamic cavitation using vortex diode: an efficient approach for elimination of pathogenic bacteria from water}, journal = {Journal of Environmental Management}, volume = {242}, year = {2019}, month = {JUL }, pages = {210-219}, type = {Article}, abstract = {

The present study successfully demonstrates greener methodology of hydrodynamic cavitation using rotational flows for disinfection of water. Disinfection of two model microbial strains-gram-negative (Escherichia colt) and gram-positive (Staphylococcus aureus) using vortex diode was evaluated. The removal efficacy was quantified for two different cavitation reactors. Practically complete elimination of E. coli was achieved (99\%) after 1 h of cavitation at a pressure drop of only 0.5 bar. However, elimination of S. aureus using vortex diode was observed to be lower in comparison to the removal of E. coli and only 60\% disinfection could be achieved under similar conditions, which can be subsequently enhanced up to 98\% by increasing pressure drop. The results were compared with another cavitating device that employs linear flow for cavitation, orifice. The reactor geometry has significant impact on the disinfection process and orifice was found to require significantly higher pressure drop (10 bar) conditions for disinfection and for eliminating grain-positive bacteria with high efficiency. A plausible mechanism for disinfection was proposed to elucidate the role of cavitation in cell destruction leading to death of cells through the rupture of cell wall, oxidative damage and possible DNA denaturation. Also, a cavitation model using per pass disinfection was developed that can provide meaningful physical description of the disinfection process as against the conventional first order reaction rate model. This study would provide meaningful insight into cavitation process based on hydrodynamic cavitation for the destruction of both gram-negative and gram-positive bacteria from various water sources, including industrial wastewaters.

}, keywords = {Cavitation, Disinfection, kinetics, pollution, Wastewater treatment}, issn = {0301-4797}, doi = {10.1016/j.jenvman.2019.04.057}, author = {Jain, Pooja and Bhandari, Vinay M. and Balapure, Kshama and Jena, Jyotsnarani and Ranade, Vivek V. and Killedar, Deepak J.} } @article {46948, title = {Novel hybrid cavitation process for enhancing and altering rate of disinfection by use of natural oils derived from plants}, journal = {Ultrasonics Sonochemistry}, volume = {61}, year = {2020}, month = {MAR}, pages = {104820}, type = {Article}, abstract = {

The present study is an attempt to improvise the hydrodynamic cavitation methodology for effective disinfection of water and also to suggest prototype development for practical application. The enhancement in the disinfection efficiency was evaluated specifically for the effect of pressure, temperature, pH, microbial inoculum size and also on effect of different additives for the two model microbial strains, gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus). The efficacy of the hydrodynamic cavitation is evaluated for the two types of flows/cavitation devices - linear flow in the case of orifice and vortex flow for vortex diode. The vortex diode requires significantly lower pressures, 50\% lower as compared to orifice for the similar extent of disinfection. While the bacterial disinfection at high temperature is known, the usefulness of hydrodynamic cavitation is especially evident at ambient conditions and the process is effective even at very high concentrations of bacteria, not reported so far. The reactor geometry also has significant effect on the disinfection. The present study, for the first time, reports possible use of different natural oils such as castor oil, cinnamon oil, eucalyptus oil and clove oil in conjunction with hydrodynamic cavitation. The nature of oil modifies the cavitation behavior and an order of magnitude enhancement in the cavitation rate was observed for the two oils, eucalyptus and clove oil for a very small concentration of 0.1\%. The increased rates of disinfection, of the order of 2-4 folds, using oil can drastically reduce the time of operation and consequently reduce cost of disinfection. A possible mechanism is proposed for the effect of oil and hydrodynamic cavitation in cell destruction through the rupture of cell wall, oxidative damage and possible DNA denaturation. A cavitation model using per pass disinfection was used to correlate the data. The increased efficiency using oils and possible benefits of the developed process, where natural oils can be perceived as biocatalysts, can have significant advantages in practical applications.

}, keywords = {Antimicrobial, Cavitation, Disinfection, Oil, Wastewater treatment}, issn = {1350-4177}, doi = {10.1016/j.ultsonch.2019.104820}, author = {Mane, Maya B. and Bhandari, Vinay M. and Balapure, Kshama and Ranade, Vivek V.} } @article {47133, title = {Improving efficiency for removal of ammoniacal nitrogen from wastewaters using hydrodynamic cavitation}, journal = {Ultrasonics Sonochemistry}, volume = {70}, year = {2021}, month = {JAN}, pages = {105306}, type = {Article}, abstract = {

The present study reports significant improvements in the removal of ammoniacal nitrogen from wastewater which is an important problem for many industries such as dyes and pigment, distilleries and fisheries. Pilot plant studies (capacity, 1 m(3)/h) on synthetic wastewater using 4-amino phenol as model nitrogen containing organic compound and two real industrial effluents of high ammoniacal nitrogen content were carried out using hydrodynamic cavitation. Two reactor geometries were evaluated for increased efficiency in removal-orifice and vortex diode. Effect of initial concentration (100-500 mg/L), effect of pressure drop (0.5-5 bar) and nature of cavitating device (linear and vortex flow for cavitation) were evaluated along with effect of salt content, effect of hydrogen peroxide addition and aeration. Initial concentration was found to have significant impact on the extent of removal: similar to 5 g/m(3) removal for initial concentration of 100 mg/L and up to 12 g/m(3) removal at high concentration of 500 mg/L. Interestingly, significant improvement of the order of magnitude (up to 8 times) in removal of ammoniacal nitrogen could be obtained by sparging air or oxygen in hydrodynamic cavitation and a very high removal of above 80\% could be achieved. The removal of ammoniacal nitrogen by vortex diode was also found to be effective in the industrial wastewaters and results on two different effluent samples of distillery industry indicated up to 75\% removal, though with longer time of treatment compared to that of synthetic wastewater. The developed methodology of hydrodynamic cavitation technology with aeration and vortex diode as a cavitating device was found to be highly effective for improving the efficiency of the conventional cavitation methods and hence can be highly useful in industrial wastewater treatment, specifically for the removal of ammoniacal nitrogen.

}, keywords = {Amino phenol, Cavitation, Oxidation, pollution, Wastewater treatment}, issn = {1350-4177}, doi = {10.1016/j.ultsonch.2020.105306}, author = {Patil, Pravin B. and Bhandari, Vinay M. and Ranade, Vivek V.} }