Tadashi Hano

Recovery of boric acid from wastewater by solvent extraction

An extraction system for the recovery of boric acid using 2-butyl-2-ethyl-1,3-propanediol (BEPD) as an extractant was studied. Loss of the extractant to the aqueous solution was lowered by using 2-ethylhexanol as a diluent. The extraction equilibrium of boric acid with BEPD was clarified, and the equilibrium constants for various diluents were determined. Furthermore, continuous operation for the recovery of boric acid using mixer-settlers for extraction and stripping was successfully conducted during 100 hours.

Extraction of lactic acid from fermented broth with microporous hollow fiber membranes

Non-dispersive solvent extraction of lactic acid based on anion-exchange reaction with tri-n-octylmethylammonium chloride dissolved in oleyl alcohol, the optimum extraction reagents selected for extractive fermentation of lactic acid with Lactobacillus rhamnosus, was attempted in a microporous hollow fiber membrane device. A satisfactory recovery of lactic acid from both aqueous solution and actual fermented broth was accomplished, signifying the great potential of integrating the membrane extraction with fermentation process. A theoretical model which took into account the mass transfer resistances across organic and aqueous films and membrane was developed to analyze and predict the extraction behavior. The model prediction was found to be in good agreement with the experimentally observed results.

Extraction kinetics of rare earth metals with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester using a hollow fiber membrane extractor

A kinetic study concerning chemical complexation-based solvent extraction of rare earth metals with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester dissolved as an extractant in n-heptane was carried out using a microporous hydrophobic hollow fiber membrane extractor. The effects of concentration of chemical species in aqueous and organic feed solutions on the apparent permeabilities of metal species for extraction and stripping, respectively, were investigated to clarify the permeation mechanism. From the experimental results it was predicted that the permeation rate is controlled by diffusion of the chemical species in aqueous and organic phases and by interfacial chemical reaction. The experimental data were analyzed by the diffusion model accompanied with an interfacial reaction, taking into account the velocity distributions of the aqueous and organic phases through the inner and outer sides of the hollow fiber.

Combination of adsorption and biodegradation processes for textile effluent treatment using a granular activated carbon-bioflm confgured packed column system

The objective of this study was to investigate the feasibility of using a granular activated carbon-biofilm configured packed column system in the decolorization of azo dye Acid Orange 7-containing wastewater. The Acid Orange 7-degrading microbial from anaerobic sequencing batch reactor which treating the azo dye-containing wastewater for more than 200 d was immobilized on spent granular activated carbon (GAC) through attachment. The GAC-biofilm configured packed column system showed the ability to decolorize 100% of the azo dye when working at high loading rate of Acid Orange 7 at 2.1 g/(L x d) with treatment time of 24 h. It was observed that the decolorization rate increased along with the increasing of initial Acid Orange 7 concentrations, until it reached an optimum point at about 0.38 g/h with initial Acid Orange 7 concentrations of 1,150 mg/L and the decolorization rate tend to be declined beyond this concentration.

Decolorization of Orange II using an anaerobic sequencing batch reactor with and without co-substrates

We investigated the decolorization of Orange II with and without the addition of co-substrates and nutrients under an anaerobic sequencing batch reactor (ASBR). The increase in COD concentrations from 900 to 1750 to 3730 mg/L in the system treating 100 mg/L of Orange II-containing wastewater enhanced color removal from 27% to 81% to 89%, respectively. In the absence of co-substrates and nutrients, more than 95% of decolorization was achieved by the acclimatized anaerobic microbes in the bioreactor treating 600 mg/L of Orange II. The decrease in mixed liquor suspended solids concentration by endogenous lysis of biomass preserved a high reducing environment in the ASBR, which was important for the reduction of the Orange II azo bond that caused decolorization. The maximum decolorization rate in the ASBR was approximately 0.17 g/hr in the absence of co-substrates and nutrients.

Biological nitrogen removal in a bubble column with a draught tube

Abstract A bubble column with a draught tube was applied as a small scale treatment unit of anaerobic-aerobic activated sludge processes in which nitrogen and phosphorus compounds were removed together with BOD sources. The inside of a draught tube was used as an aerobic zone and the annulus as an anaerobic zone. The circulation flow rate of the mixed liquor between these two zones was varied by changing the air flow rate into the draught tube. There existed the optimum values for volume ratio of aerobic/anaerobic zones, air flow rate and liquid circulation flow rate between two zones depending on the activities of nitrification and denitrification . The performance of the treatment unit was simulated by using the model of the liquid flow in the reactor and the kinetics of simultaneous nitrification and denitrification in the activated sludge floc. It became clear that the consumption of BOD source inside the floc should be considered to explain the drop of nitrogen removal at high aeration rate and long residence time.

Back extraction of lactic acid with microporous hollow fiber membrane

In this work, back extraction was considered a promising alternative to regenerate carboxylic acids of low-volatility into appropriate aqueous solution from organic phase. Identification of an efficient back extraction system for lactic acid recovery was focused on. Screening of back extraction reagents was first carried out by employing a wide variety of inorganic compounds. From the viewpoints of high stripping power, low cost and capability of simultaneously regenerating the extractant, aqueous sodium chloride solution was selected as the most suitable one for recovery of lactic acid from lactate–TOMAC (tri-n-octylmethylammonium chloride) complex. However, TOMAC and oleyl alcohol are likely to pose the troubling emulsion problem in conventional mixer–settler system. Therefore, non-dispersive back extraction of lactic acid from organic phase was attempted in a microporous hollow fiber (MHF) membrane device by aqueous NaCl solution. A satisfactory recovery was accomplished, signifying the great potential of integrating membrane back extraction with extractive fermentation process for lactic acid production.

Method for measuring mutagen formation potential (MFP) on chlorination as a new water quality index

A novel water quality index, the mutagen formation potential (MFP) is proposed for use in evaluation of the quality of drinking water which may contain pollutants capable of forming mutagens when chlorinated under the conditions used in water purification processes. A method for measuring MFP was established as follows. The water sample to be tested is diluted until the TOC reaches 3-4 mg l-1, the pH is adjusted to 7.0 +/- 0.2, sodium hypochlorite is added to obtain conditions where Cl/TOC = 3-4 mg Cl (mg C)-1, and the water sample is left standing for 24 +/- 2 h at room temperature. Thereafter, 21 of the chlorinated water sample at pH 2.0 +/- 0.1 is passed through a Sep-Pak Plus CSP-800 cartridge to adsorb any mutagens formed, and DMSO is applied to the cartridge to desorb the mutagens. Then, a 2 ml sample of the eluate is collected after the DMSO had begun to flow out of the cartridge and evaluated by the Ames Salmonella mutagenicity assay (preincubation method).

Extraction of rare earth metals by calix[4]arene solubilized in AOT reversed micellar solution

Abstract Extraction of rare earth metals (europium and yttrium) and their separation from zinc were investigated using a novel host compound, p - tert -octylcalix[4]arene carboxyl derivative as an extractant. Extraction behavior of the metals with a typical commercial extractant PC-88A or Versatic 10 was also examined. The cyclic ligand calixarene showed a high selectivity towards rare earth metals compared with PC-88A and Versatic 10. The addition of sodium ion into the feed aqueous solution enhanced the extractability of rare earth metals, and resultantly, improved the selectivity. The drawback of this promising extractant was the poor solubility in organic solvents, especially in nontoxic aliphatic solvents such as isooctane and kerosene. We attempted to solubilize the novel extractant calix[4]arene in isooctane by utilizing reversed micelles formed with an anionic surfactant AOT. p - tert -Butylcalix[4]arene could be dissolved in the AOT–isooctane reversed micellar solution by injecting an adequate amount of water. Furthermore, the extraction of metals from the aqueous solution dissolving sodium ion was conducted by the AOT–isooctane system containing p - tert -butylcalix[4]arene. The excellent extraction and separation of metals was achieved by using calixarene solubilized in the AOT-reversed micellar solution.

Application of a liquid surfactant membrane for the recovery of penicillin G

Abstract The extraction equilibria of penicillin G with di-n-octylamine, Amberlite LA-2 (lauryltrialkylmethylamine), or ECA 4360J were studied. The amines reacted with penicillin G to form 1:1 complex. The extraction of penicillin G by liquid surfactant membrane (LSM) was examined to develop a new recovery process from the fermented broth. Penicillin G could be rapidly separated and enriched by LSM where the oil phase of the emulsions was composed of ECA 4360J and the mixture of n-butyl acetate and kerosene. It was found that ECA 4360J played both roles of emulsifier and carrier. Nearly complete extraction was accomplished by adjusting the pH of both internal and external water phases to an optimum region.