Showing papers on "Bioreactor published in 1981"

A horizontal packed-bed bioreactor to reduce CO2 gas holdup in the continuous production of ethanol by immobilized yeast cells

Abstract: CO2 gas, evolved during alcohol fermentation using immobilized yeast, causes several undesirable problems in a packed-bed bioreactor installed vertically as it increases the dead space and causes hydrostatic pressure. In order to reduce this “CO2 gas phase effect” which lowers the efficiency of ethanol production, a shallow, horizontal packed-bed bioreactor has been developed with a free space above the gel bed. The horizontal packed-bed bioreactor was 1.5 times more productive than the vertical packed-bed bioreactor when operated continuously. Yeast cells immobilized in calcium alginate gel reached a steady state much quicker than those immobilized in polyacrylamide gels. In the horizontal packed-bed bioreactors, calcium alginate gel was also superior to polyacrylamide gel with respect to ethanol productivity. The profiles of both glucose and ethanol concentrations against axial sampling sites suggested that the horizontal packed-bed bioreactor was similar to a plug flow reactor. The mean gel size gradually increased upstream (1.9 mm to 3.3 mm). With the economic production of ethanol in view, the published data on different continuous alcohol production processes have been compared by plotting their productivities (y-coordinate) against the ethanol concentrations in the effluents (x-coordinate) for the dilution rate or space velocity at which the yield of ethanol from glucose was 95%. The horizontal packed-bed bioreactor has a very high performance which makes this bioreactor promising for the economic production of ethanol.

Anaerobic activated carbon filter for the treatment of phenol-bearing wastewater

Abstract: An experiment using an activated carbon filter for the treatment of phenol-bearing wasterwater from coal gasification processes is discussed. Two granular-activated-carbon-packed anaerobic filter systems were constructed for use in the study. Both phenol and glucose of phenol-fed reactor systems were operated under continuous feeding for a period of 735 days. The glucose-fed reactor was very effective in reducing the organic content of the feed substrate. The performance of the phenol-fed reactor was tested at three different phenol concentration levels: (1) 200 mg/l; (2) 400 mg/l; and (3) 1000 mg/l. Using the 200 mg/l concentration of phenol an average 79% of the feed chemical oxygen demand (COD) was accounted for in the aqueous and gaseous phases of the final effluent. Using 400 mg/l the COD accounted for the aqueous and gaseous phases of the effluent rose to an average of 92%, and using 1000 mg/l, the COD removal efficiencies from the three columns fell to an average of 90%, respectively. Despite the differences in removal efficiencies between the different phases of the experiment, the granular-activated-carbon-packed anaerobic bioreactor proved to be an effective process in the reduction of phenol from a synthetically prepared wastewater. In addition to phenol reduction, there was alsomore » a consistent and effective reduction of the chemical oxygen demand and the total organic carbon content of the waste at a time when a methane-rich gaseous by-product was being produced simultaneously.« less

A bio reactor for continuous treatment of waste waters with immobilized cells of photosynthetic bacteria

Abstract: A bioreactor for assaying immobilized cells of photosynthetic bacteria for hydrogen production under optimal operating conditions was made. High and lasting H2-photoevolutions were obtained using waste waters as substrates.

Bioconversion of gitoxigenin by immobilized plant cells in a column bioreactor

Abstract: Daucuscarota cells immobilized in a Ca-alginate performed the bioconversion of gitoxigenin to 5β-hydroxygitoxigenin in a column bioreactor. The smooth spherical shape of the alginate beads was preserved for more than three weeks. The bioreactor was functional for more than thirty days as detected by the bioconversion activity. The rate of bioconversion was influenced by means of aeration.

Chemostat studies on the assimilation of hexadecane by the yeastCandida tropicalis

Abstract: The yeastCandida tropicalis was grown in a chemostat with hexadecane as the sole carbon source. The influence of the dilution rate, oxygen and ammonium limitation on s, x, Ys, QO2, QCO2, and Qs was investigated. When the extracellular hexadecane concentration exceeded 120 mg l−1 (at dilution rates close to Dc, at pO2 below 2.54 kPa and at ammonium limited growth) Ys decreased and QO2, QCO2, and Qs increased. It was concluded that uncoupling of the mitochondrial respiratory chain occurred under these conditions. The QO2 was determined by two different methods: first in situ, with a gasanalyzer directly connected to the bioreactor to analyze the outcoming gas, and second, with a sample from the bioreactor transferred to a Clark-type oxygen electrode. When cell growth was not oxygen limited in the chemostat (pO2 above 2.54 kPa), no apparent difference between the in situ and the dynamically determined QO2 was observed. In contrast, when cell growth was oxygen limited in the chemostat, the QO2 measured in the Clark-type oxygen electrode was remarkably higher than the in situ QO2. This indicates that the electron transport chains are limited bythe oxidases, when the cells lack oxygen.

Biological reduction of nitrate wastewater using fluidized-bed bioreactors

Abstract: There are a number of nitrate-containing wastewater sources, as concentrated as 30 wt % NO/sub 3//sup -/ and as large as 2000 m/sup 3//d, in the nuclear fuel cycle as well as in many commercial processes such as fertilizer production, paper manufacturing, and metal finishing. These nitrate-containing wastewater sources can be successfully biologically denitrified to meet discharge standards in the range of 10 to 20 gN(NO/sub 3//sup -/)/m/sup 3/ by the use of a fluidized-bed bioreactor. The major strain of denitrification bacteria is Pseudomonas which was derived from garden soil. In the fluidized-bed bioreactor the bacteria are allowed to attach to 0.25 to 0.50-mm-diam coal particles, which are fluidized by the upward flow of influent wastewater. Maintaining the bacteria-to-coal weight ratio at approximately 1:10 results in a bioreactor bacteria loading of greater than 20,000 g/m/sup 3/. A description is given of the results of two biodenitrification R and D pilot plant programs based on the use of fluidized bioreactors capable of operating at nitrate levels up to 7000 g/m/sup 3/ and achieving denitrification rates as high as 80 gN(NO/sub 3//sup -/)/d per liter of empty bioreactor volume. The first of these pilot plant programs consisted of two 0.2-m-diam bioreactors, each more » with a height of 6.3 m and a volume of 208 liters, operating in series. The second pilot plant was used to determine the diameter dependence of the reactors by using a 0.5-m-diam reactor with a height of 6.3 m and a volume of 1200 liters. These pilot plants operated for a period of six months and two months respectively, while using both a synthetic waste and the actual waste from a gaseous diffusion plant operated by Goodyear Atomic Corporation. « less

Bio:reactor for methane gas prodn. from organic substances - pretreated with amylase, lipase and protease, comprising separate fermentation chambers with circulation of biomass under gas pressure

Abstract: In a new bioreactor for rotting down organic substances to produce methane gas, (a) before introducing into the bioreactor the biomass is prefermented with the enzymes amylase, lipase and the proteases trypsin, chymotrypsin, elastase and carboxypeptidase to break down cyclic hydrocarbon molecules to short, readily-degradable open-chain molecules; (b) methane bacteria of the desired mesophilic type are cultivated separately on nutrient solution in a separate process to avoid degenerative effects arising from inoculation of fresh sludge with old sludge; (c) the biomass is hygienized by basifying to pH 12 with CaO and exothermic heating at 70 deg.C for 30 mins; (d) the biomass is rotted separately for the entire duration of composting in 12 individual chambers so that the development of methane bacteria is not inhibited by continuous charging; (e) the biomass is cycled through the serially arranged rotting chambers using biogas at the operating temp. of 38 deg., the chambers being fitted at 1-day or 2-day intervals; (f) all the chambers are arranged in series, linked by a closed pipe system, but the pH of each chamber is individually automatically regulated to pH7 by addn. of lime water; and (g) the biomass reactor is fitted with a double mantle and biomass temp. is held constant throughout the process using a thermostatted heating system. The measures outlined above ensure that development of methane-generating bacteria is undisturbed. Gas yields are high, CO2 content is low, and reaction time for 80% gas yield is reduced to 6 days.

Volume reduction of solid waste by biological conversion of cellulosics

Abstract: It has been demonstrated that the types of cellulosic wastes generated at ORNL can be effectively degraded in an anaerboic bioreactor. The rate and extent of anaerobic microbial digestion of blotter paper, cloth, sanitary napkins, and pine sawdust in various types and sizes of bench-scale anaerobic bioreactors are described. Preliminary tests indicate that the resulting digests are amenable to incorporation into hydrofracture grouts.