Chi Mei Lee

Removal of 2,4-dichlorophenol by suspended and immobilized Bacillus insolitus

In this experiment, Bacillus insolitus was isolated and selected from a mixed culture that have been acclimated to chlorophenols. Decomposition of chlorophenolic compounds will be studied using this pure culture in both suspended and immobilized form. The results are: at lower initial concentrations of 2,4-dichlorophenol (10-50 mg/l), immobilized Bacillus insolitus shows a higher removal of 2,4-dichlorophenol than Bacillus insolitus in suspended growth. When the 2,4-dichlorophenol concentration becomes higher (50-200 mg/l), both immobilized and suspended Bacillus insolitus have approximately the same efficiency for removal of 2,4-dichlorophenol. Higher concentrations of 2,4-dichlorophenol are inhibitive to the growth of either suspended or immobilized Bacillus insolitus. At lower concentrations of 2,4-dichlorophenol, immobilized mixed culture may have the same removal efficiency of 2,4-dichlorophenol as immobilized pure culture of Bacillus insolitus. But with regard to the overall 2,4-dichlorophenol removal efficiency, immobilized pure culture is considered to be superior to immobilized mixed culture.

Biodegradation of 2,4,6-trichlorophenol in the presence of primary substrate by immobilized pure culture bacteria

In this study, pure strains that are capable of utilizing 2,4,6-trichlorophenol have been isolated from the mixed culture grown on substrates containing chlorophenolic compounds. Studies have been carried out on the capability of these isolated pure strains in suspended and immobilized forms to decompose 2,4,6-trichlorophenol. Additionally, the influence of primary substrates (e.g., phenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol) on the decomposition of 2,4,6-trichlorophenol by the isolated pure strains grown in immobilized form is also investigated. The results are: Through bacterial isolation and identification, three pure strains have been obtained: Pseudomonas spp. strain 01, Pseudomonas spp. strain 02 and Agrobacterium spp. Whether in suspended or immobilized forms, all strains have poor removal efficiencies of 2,4,6-trichlorophenol. However, addition of 200 mg/l phenol will enable the immobilized Pseudomonas spp. strain 01, and Pseudomonas spp. strain 02 to achieve 65% and 48% removal of 2,4,6-trichlorophenol, respectively. Addition of phenol will assist the immobilized Pseudomonas spp. strain 02 in achieving removal of 2,4,6-trichlorophenol but the removal efficiency is not good if the phenol concentration is too low. The optimum phenol concentration should be between 200 and 400 mg/l.

Acrylic acid removal from synthetic wastewater and industrial wastewater using Ralstonia solanacearum and Acidovorax avenae isolated from a wastewater treatment system manufactured with polyacrylonitrile fiber

Ralstonia solanacearum and Acidovorax avenae were isolated from a wastewater treatment system manufactured with polyacrylonitrile fiber. The investigation goal is to elucidate the effectiveness of Ralstonia solanacearum and Acidovorax avenae in treating acrylic acid from synthetic wastewater and industrial wastewater. The results reveal that Ralstonia solanacearum and Acidovorax avenae could utilize acrylic acid from synthetic wastewater for growth, when the initial acrylic acid concentration was below 1,009.1 mg/l and 1,383.4 mg/l, respectively. When the acrylic acid concentration was below 606.8 mg/l, the acrylic acid removal ability reached 96.7% and 100%, respectively. Both strains could tolerate acrylamide toxicity, but only Ralstonia solanacearum could tolerate acrylonitrile toxicity. Ralstonia solanacearum and Acidovorax avenae could utilize acrylic acid from industrial wastewater for growth, when the initial acrylic acid concentration was below 1,741.1 mg/l and 1,431.2 mg/l, respectively. When the acrylic acid concentration was below 690.8 mg/l, the acrylic acid removal efficiency reached 83.5% and 62.2%, respectively. Whether the acrylic acid existed in synthetic wastewater or in industrial wastewater, the removal efficiency of acrylic acid by Ralstonia solanacearum exceeded that by Acidovorax avena.

Removal of nitrogenous compounds from wastewaters using immobilized cyanobacteria Anabaena CH3

The removal of nitrogenous compounds from wastewaters using calcium-alginate entrapped cyanobacteria Anabaena CH3 was studied in batch as well as semicontinuous cultures. Results of the batch cultivation showed that the removal rates of nitrate and ammonium nitrogen were between 15 - 23 and 17 - 30 mg N L -1 d -1 g -1 Anabaena CH3 while the observed specific growth rates of Anabaena CH3 for different initial nitrate and ammonium concentrations were between 0.35 - 0.65 and 0.2 - 0.56 d -1 , respectively. Results of the semicontinuous cultivation gave the average growth rate of Anabaena CH3 and ammonium removal rate of 83 mg L -1 d -1 and 86 mg N L -1 d -1 g -1 Anabaena CH3. The factors which influence the mass transfer limitations of substrate and the cultivation conditions of immobilized Anabaena CH3 were evaluated and quantitatively determined. The optimal growth conditions for immobilized Anabaena CH3 were derived as : pH 7 - 9, 30 -40°C, 2500 - 4000 lux, above 10 mg L -1 NO 3 -N or 10 - 100 mg L -1 NH 4 -N.

Denitrification with acrylonitrile as a substrate using pure bacteria cultures isolated from acrylonitrile-butadiene-styrene wastewater

This study attempted to isolate and identify the denitrifying bacteria that utilize acrylonitrile as a substrate from acrylonitrile-butadiene-styrene (ABS) resin wastewater. The performance of the denitrifying bacteria for treating different initial acrylonitrile concentrations was also investigated under anoxic conditions. The results showed that seven strains of denitrifying bacteria that can use acrylonitrile or acrylic acid as a substrate were isolated from the denitrification tank of a wastewater treatment plant in a ABS resin manufacturing plant and a lab-scale anoxic granular activated carbon-fluidized bed. The bacteria strains Acidovorax facilis B and Pseudomonas nautica could utilize acrylonitrile up to 279 mg/l as a substrate for denitrification. For complete nitrate removal, an adequate supply of acrylonitrile was necessary. Under the assumption that the acrylic acid would be completely removed, the removal of 1 mg/l nitrate by A. facilis B or P. nautica, about 0.64-0.74 mg/l acrylonitrile or 0.87-1 mg/l acrylic acid was needed. Because strains A. facilis B and P. nautica could utilize acrylonitrile for denitrification, they are expected to play an important role in the treatment of acrylonitrile in the wastewater treatment plant (denitrification and nitrification processes) and lab-scale granular activated carbon-fluidized bed.

A model of nitrogen removal in waste-waters using alginate-entrapped cyabobacteria Anabaena Ch3

Abstract A mathematical model accounting for the mass transfer process and the growth kinetics of alginate-entrapped cyanobacteria Anabaena CH3 in a batch reactor is presented to predict the removal of nitrogenous compounds in wastewaters. The governing equations were cast in dimensionless form and solved by the method of explicit finite difference. The mass transfer behaviour around a spherical bead and diffusion process within the cell-containing gel were drawm from the literature. The biological kinetic parameters of Anabaena CH3 in the nitrogenous medium were determined by a series of batch experiments. Good agreement between model predictions and experimental data was obtained by comparing dimensionless concentration profiles of ammonia and nitrate in the bulk liquid phase. The effects of dimensionless groups on the model performance were carried out in the sensitivity analysis. The Thiele modulus (φ2) and the total volume of the cell-containing gel beads available for liquid-phase mass transfer (α) were identified to strongly influence the ammonia removal rate in wastewaters.