Higher Initial pH Research Articles

Kinetic growth parameters of different amylolytic and non-amylolytic Lactobacillus strains under various salt and pH conditions

Four Lactobacillus species were studied for their ability to grow at high NaCl concentrations and different initial pH values. Lactobacillus plantarum 541 and A6 could ferment glucose and produce lactic acid in the presence of 8% salt in the medium. For strain 541, the specific rate of lactate production ( q lac) and the yield of lactic acid relative to substrate ( Y p/ s ) remained constant, whereas the yield of biomass relative to substrate ( Y x/ s ) decreased up to 6% salt. In contrast, for strain A6, Y p/ s decreased up to 6% salt whereas Y x/ s did not vary markedly. Combined effects of salt and pH studied through a factorial design did not show significant interaction between salt and pH. The pH was the dominant factor in glucose fermentation for both the strains. Considering overall performance, 4% salt and pH between 6.0 and 6.6 can be taken as appropriate conditions, for the use of both strains as starters in processes where higher salt concentrations are required.

Sedimentary dolomite: a reality check

Abstract The failure to precipitate dolomite experimentally at low temperatures or from seawater in which it is both supersaturated and the most thermodynamically favoured carbonate phase, together with its unequal distribution through geological time relative to limestone, are all aspects of the ‘dolomite problem’, a subject of continuing controversy. A plethora of physicochemical models has been invoked to explain sedimentary dolomite formation, none of which satisfactorily addresses the basic problem of how kinetic barriers are overcome. These barriers are related to the disproportionate distribution of the component ions of dolomite, cation hydration and ion complexing in seawater. Competing claims for the effectiveness of sulphate as an inhibitor to dolomite formation further confuse the debate, although there are many reports of modern dolomite associated with bacterial sulphate reduction. The uppermost sediments in some lakes of the Coorong region of South Australia comprise almost 100% dolomite, and afford an ideal opportunity to study this association. Samples of lake waters taken during late evaporative stages of several shallow hypersaline dolomitic lakes showed high initial sulphate concentrations, high pH and high carbonate alkalinities. Pore waters from unlithified lake sediment cores directly below the lake-water sample sites showed a substantial and progressive decrease in sulphate concentrations with depth, coupled with an exponential increase in carbonate concentrations, through the sulphate-reduction zone. By the end of the evaporative cycle, sulphate was entirely removed. High bacterial counts on cultures from the sediment cores, and sulphur isotope values consistent with ‘bacterial’ fractionation in lake waters, indicate that the chemical changes in ambient water chemistry can be related to active bacterial sulphate reduction. Laboratory experiments using sulphate reducers cultured from the lake sediments and simulating the anoxic microbiogeochemical environment of the lakes, have resulted in the precipitation of dolomite, demonstrating that bacterial sulphate reduction in the Coorong lakes modifies lake-water and pore-water chemistry so that dolomite precipitation is kinetically favoured. Given the wide spatial and temporal distribution of sulphate-reducing bacteria, and their frequent association, both past and present, with cyanobacteria, it is likely that this process was more widespread in the geological past when dolomite was found in far greater abundance than limestone. Bacterial sulphate reduction may thus have played an important role in dolomite formation throughout the geological record.

Biological hydrogen production: effects of pH and intermediate products

A series of batch tests were conducted to investigate the effects of pH and intermediate products on biological hydrogen production. The tests were run in serum bottles to determine the optimal operating conditions to maximize hydrogen production using sucrose and starch as organic substrates. Apart from hydrogen, variations in pH, volatile fatty acids, and solvent concentrations were also monitored. Initial pH was found to have a profound effect on both hydrogen production potential and hydrogen production rate. A mixed microbial culture was involved in the fermentation process with H 2, propionate, acetate, butyrate, and CO 2 as major products. The lowest initial pH of 4.5 gave the highest specific hydrogen production potentials of 214.0 ml H 2/g chemical oxygen demand (COD) and 125.0 ml H 2/g COD for sucrose and starch respectively, but with the lowest specific hydrogen production rate. Although hydrogen production started earlier with the high production rate at a higher initial pH, the duration of the production was shorter. The rapid pH depletion could have caused a metabolic alteration of the microorganisms involved in hydrogen production, thereby resulting in the shift of intermediates production pathway [variation of the acetate/butyrate (HAc/HBu) ratio] and a consequent decrease in hydrogen production. The specific hydrogen production rate was highest for the pH range of 5.5–5.7. For the optimum pH range, the HAc/HBu ratio was in the range of 3–4 for both sucrose and starch. The findings of this study can be applied in the design of a high rate hydrogen bioreactor.

Air stripping of ammonia from pig slurry: characterisation and feasibility as a pre- or post-treatment to mesophilic anaerobic digestion

The objective of the present paper has been to study the effect of pig slurry waste type, fresh or anaerobically digested, and the effect of initial pH on ammonia air stripping from pig slurry waste at high temperature (80 °C). Stripping process as pre- or post-treatment to anaerobic digestion has been also evaluated. Treatment performances differ according to pig slurry type. When fresh pig slurry is used, despite working at 80 °C, a high initial pH (11.5) is required for complete ammonia removal. On the other hand, for digested pig slurry, complete ammonia removal without pH modification is possible and organic matter significantly less contaminates recovered ammonia salt. Batch anaerobic tests showed that ammonia air stripping is not an advisable pre-treatment to pig slurry anaerobic digestion.

Regulation of Cl--HCO3- exchangers by cAMP-dependent protein kinase in adult rat hippocampal CA1 neurons.

The contributions of HCO(3)(-)-dependent, DIDS-sensitive mechanisms to the maintenance of steady-state pH(i), and the regulation of their activities by cAMP-dependent protein kinase (PKA), were investigated in CA1 neurons with the H(+)-sensitive fluorophore, BCECF. The addition of HCO(3)(-)/CO(2) to neurons with "low" (pH(i) < or = 7.20) and "high" (pH(i) > 7.20) initial pH(i) values under Hepes-buffered conditions, increased and decreased steady-state pH(i), respectively. Conversely, under HCO(3)(-)/CO(2)-buffered conditions, DIDS caused pH(i) to decrease and increase in neurons with low and high initial pH(i) values, respectively. In the presence, but not the absence, of HCO(3)(-), the PKA inhibitor Rp-adenosine-3',5'-cyclic monophosphorothioate (Rp-cAMPS; 50 microM) evoked DIDS-sensitive increases and decreases in pH(i) in neurons with low and high initial pH(i) values, respectively. In contrast, in neurons with low initial pH(i) values, activation of PKA with the Sp isomer of cAMPS (Sp-cAMPS; 25 microM) elicited increases in pH(i) that were smaller in the presence than in the absence of HCO(3)(-), whereas in neurons with high initial pH(i) values, Sp-cAMPS-evoked rises in pH(i) were larger in the presence than in the absence of HCO(3)(-); the differences between the effects of Sp-cAMPS on pH(i) under the different buffering conditions were attenuated by DIDS. Consistent with the possibility that changes in the activities of HCO(3)(-)-dependent, DIDS-sensitive mechanisms contribute to the steady-state pH(i) changes evoked by the PKA modulators, in neurons with initial pH(i) values < or = 7.20, Rp-cAMPS concurrently inhibited Na(+)-independent Cl(-)-HCO(3)(-) exchange and stimulated Na(+)-dependent Cl(-)-HCO(3)(-) exchange; in contrast, Sp-cAMPS concurrently stimulated Na(+)-independent Cl(-)-HCO(3)(-) exchange and inhibited Na(+)-dependent Cl(-)-HCO(3)(-) exchange. Data from a limited number of neurons with initial pH(i) values > 7.20 suggested that the directions of the reciprocal changes in anion exchange activities (inhibition or stimulation) evoked by Rp- and Sp-cAMPS may be opposite in cells with low vs. high resting pH(i) values. Taken together, the results indicate that the effects of modulating PKA activity on steady-state pH(i) in rat CA1 neurons under HCO(3)(-)/CO(2)-buffered conditions reflect not only changes in Na(+)-H(+) exchange activity but also changes in Na(+)-dependent and Na(+)-independent Cl(-)-HCO(3)(-) exchange activity that, in turn, may be dependent upon the initial pH(i).

Skeletal repair in rabbits with calcium phosphate cements incorporated phosphorylated chitin

The effects of phosphorylated chitin (P-chitin) on the tissue responses to two kinds of calcium phosphate cements (CPCs) were investigated using experimental rabbits. One of them consisting of monocalcium phosphate monohydrate, calcium oxide, 1 m phosphate buffer (pH: 7.4) and different amounts of P-chitin (CPC-I or P-CPC-I) with relatively neutral initial pH was filled as paste into tibial defects of the rabbits for 1, 4, 12 and 22 weeks. The other kind of cement made from dicacium phosphate dihydrate/calcium hydroxide/1 m Na 2HPO 4/different amounts of P-chitin (CPC-II or P-CPC-II) with relatively higher initial pH was implanted as prehardened cylinders into the radial defects of the rabbits for the same periods. Pure CPC-I and CPC-II were used as controls. Histological and histomorphological studies were performed on thin un-decalcified and decalcified sections. Three different bone formation types in the resorption lacuna of the P-CPCs were found during this study. The biodegradation rate of the P-CPCs had a negative relationship with the P-chitin content. Most of the low P-chitin-containing samples were bioabsorbed in 16 weeks, while the high P-chitin-containing samples disappeared in 22 weeks. The newly formed bone was identified with back scattered scanning electron microscopy and X-ray energy-dispersive spectrometry. The results show that with P-chitin component in a certain range, the P-CPCs are biocompatible, bioabsorbable and osteoinductive and could be used as promising candidates of bone repair materials.

Synergistic effect of cationic surfactants on perchloroethylene degradation by zero-valent iron.

Zero-valent iron (ZVI) as a permeable barrier material for degradation of chlorinated organic compounds has been extensively studied recently. One of the focal areas in ZVI studies is to increase the contaminant reduction rate. In this research, batch tests were performed to evaluate the synergistic effect of sorbed cationic surfactants on degradation of perchloroethylene (PCE). Sorption of cationic surfactants on ZVI was a function of hydrophobic chain length of the surfactanttail group. Minimal counterion sorption indicated that the sorbed surfactant molecules form a patchy monolayer on ZVI. Both PCE and trichloroethylene (TCE) degradation by ZVI with and without sorbed surfactant followed pseudo-first-order reaction kinetics. In general, the PCE degradation rate increases as the chain length of sorbed surfactant increases. Compared to unmodified ZVI, both apparent rate constants of PCE degradation and TCE accumulation increased by an order of magnitude when ZVI was modified by hexadecyltrimethylammonium. The rate of PCE degradation by ZVI modified to lower surfactant loading was relatively higher than that by ZVI modified to higher surfactant loading. It was speculated that longer chain length will result in better admicelle formations, and thus, promote PCE partition and increase PCE surface concentration or surface admicelle catalysis, while low surfactant loading makes significant amounts of surface reduction sites still available. The PCE reduction rate constants were not affected by solution ionic strength, but high initial solution pH, buffered by sodium carbonate and sodium bicarbonate, significantly reduced the PCE degradation rate.

Continuous Process for Photodegradation of Industrial Bayer Liquor

Photodegradation of spent Bayer liquor has been carried out in an 18-L pilot-scale continuous annular photoreactor. The performance of the reactor was studied with respect to various process parameters such as the gas flow rate, liquid flow rate, initial solution pH, initial substrate concentration, light intensity, and catalyst loading. The average reaction rate and overall conversion of Bayer liquor, in terms of total organic carbon, have been found to be strongly dependent on all of these parameters. Despite the very dark color and high initial pH (ca. 12) of the reaction mixture, significant conversion (25-35%) was achieved within about 2 h of operation, showing a considerable improvement over the existing industrial oxalate removal methods. Notwithstanding the complex composition of the spent Bayer liquor, the rate data could adequately be analyzed in terms of simple linear or hyperbolic-type kinetic expressions.

Uptake of calcium and magnesium by human scalp hair from waters of different geographic locations

The uptake of Ca 2+ and Mg 2+ by human scalp hair from waters of 24 different locations throughout the world was determined. The uptake was found to vary markedly depending on the initial total hardness and pH of the water. Water of high initial total hardness and/or high initial pH were found, in general, to result in more hair adsorption of these alkaline earth cations. When hair is washed with these differing waters, varying effects are then found in the eventual coiffure.

Electrokinetic remediation of heavy metal-contaminated soils under reducing environments

This paper describes the migration of hexavalent chromium, Cr(VI), nickel, Ni(II), and cadmium, Cd(II), in clayey soils that contain different reducing agents under an induced electric potential. Bench-scale electrokinetic experiments were conducted using two different clays, kaolin and glacial till, both with and without a reducing agent. The reducing agent used was either humic acid, ferrous iron, or sulfide, in a concentration of 1000 mg/kg. These soils were then spiked with Cr(VI), Ni(II), and Cd(II) in concentrations of 1000, 500 and 250 mg/kg, respectively, and tested under an induced electric potential of 1 VDC/cm for a duration of over 200 h. The reduction of chromium from Cr(VI) to Cr(III) occurred prior to electrokinetic treatment. The extent of this Cr(VI) reduction was found to be dependent on the type and amount of reducing agents present in the soil. The maximum reduction occurred in the presence of sulfides, while the minimum reduction occurred in the presence of humic acid. The concentration profiles in both soils following electrokinetic treatment showed that Cr(VI) migration was retarded significantly in the presence of sulfides due both to the reduction of Cr(VI) to Cr(III) as well as an increase in soil pH. This low migration of chromium is attributed to: (1) migration of Cr(VI) and the reduced Cr(III) fraction in opposite directions, (2) low Cr(III) migration due to adsorption and precipitation in high pH regions near the cathode in kaolin and throughout the glacial till, and (3) low Cr(VI) migration due to adsorption in low pH regions near the anode in both soils. Ni(II) and Cd(II) migrated towards the cathode in kaolin; however, the migration was significantly retarded in the presence of sulfides due to increased pH through most of the soil. Initial high pH conditions within the glacial till resulted in Ni(II) and Cd(II) precipitation, so the effects of reducing agenets were inconsequential. Overall, this study demonstrated that the reducing agents, particularly sulfides, in soils may affect redox chemistry and soil pH, ultimately affecting the electrokinetic remediation process.

PH gradients in immobilized amidases and their influence on rates and yields of ?-lactam hydrolysis

The pH gradients developing within immobilized biocatalysts during hydrolysis of penicillin G and glutaryl-7-aminocephalosporanic acid have been estimated both theoretically and experimentally. For the latter a fluorimetric method for the direct measurement of the average pH value within the carrier during reaction has been developed using the pH-dependent fluorescence intensity of an enzyme-bound fluorophore determined with a fiber bundle. The theoretical calculations were based on a model for the hydrolysis with immobilized enzymes using a kinetic expression with five pH-dependent, measurable kinetic and equilibrium constants. The transport reaction differential equation which considers the laminar boundary layer has been solved numerically for the key component. The calculated values agreed well with the experimental data. Under the typical reaction conditions of penicillin G hydrolysis the average pH value in the carrier was 1 and 2.5 pH units below the bulk pH (=8) with and without buffer, respectively. The corresponding changes for the hydrolysis of glutaryl-7-aminocephalosporanic acid at bulk pH 8 in the presence of buffer was 0.5. This demonstrates the existence of considerable pH gradients in carriers during hydrolytic reactions, even in buffered systems with negligible mass transfer resistance. The low pH value causes suboptimal reaction rates, reduced equilibrium conversion, and reduced enzyme stability. These pH gradients can be minimised by using buffers with pK values approximately equal to the bulk pH used for the hydrolysis. The prediction quality of the model has been tested applying it to fixed bed reactor design. The reduction in rate and yield due to concentration and pH gradients can be overcome with simple measures such as high initial pH value and pH adjustments in segmented or recycling fixed bed reactors. Thus, enzymatic conversions with high yield and high operational effectiveness are achieved.

EFFECT OF COPPER AND CADMIUM BINDING ON FLOCCULATION OF FERRIC OXIDE PARTICLES

ABSTRACT The sorption of copper and cadmium ions from aqueous solutions by ferric oxide particles was studied using batch equilibrium and kinetic experiments. The sorption process was found to be pH dependent, with the uptake increasing at high pH values. An increase in equilibrium pH was observed when the initial pH was in the acidic range, and a decrease from initial values was observed in the basic range, in the case of both copper and cadmium sorption. The former phenomenon is due to competition between metal and proton binding, and the latter is due to precipitation mechanisms at high initial pH values. A large increase in the zeta potential of the particles from baseline values was observed during equilibrium sorption. This increase occurs as a result of surface charge neutralization due to metal ion uptake. Particle destabilization appears to occur as a result of metal ion sorption. Kinetic experiments indicate that the uptake of copper by ferric oxide particles is a slow process. The pH histories were similar to those obtained in the sorption equilibrium experiments. Changes in the size distribution of the ferric oxide particles due to aggregate formation during uptake of ions were observed in the kinetic studies. These findings indicate a potential role of metal ion uptake in particle flocculation kinetics through alteration of the surface electrostatic potential.

Digestibility by mink and storage stability of feedstuffs made from raw ground, acid-treated or fermented dogfish (Squalus acanthias)

Dogfish was evaluated in a 3 × 4 factorial design experiment conducted to determine digestibility coefficients (DC) of dry matter (DM), crude protein (CP), crude fat (CF), gross energy (GE) and amino acids (AA) in raw ground dogfish (RGD), acid (ASD) and fermented (FSD) dogfish silages for mink. The ASD was prepared with the addition of 2.5% (wt:wt) formic acid (conc. 85%) and 200 mg kg−1 antioxidant (ethoxyquin) to the raw ground fish. The FSD was produced with the addition of the commercial biopreservative Marisil®, (Finn Sugar) (1%) and extruded wheat (15%) to the raw ground fish. In the digestibility trial, consisting of three, 11-d periods, each having a 6-d adjustment followed by a 5-d collection, 12 mature standard type mink were confined to metabolism cages. Using the total collection (TC) method, where graded levels (0, 15, 30 and 45%) of the test feedstuff were substituted into a basal diet, an extrapolation using regression analysis was done to estimate digestibility of each test feedstuff. The AD of DM, CP, CF and GE was RGD: 81.8, 92.2, 96.2 and 89.6%; ASD: 87.1, 92.6, 100.0 and 93.2%; FSD: 86.0, 93.3, 98.1 and 90.4%, respectively. The AD of AAs was generally highest in the fermented dogfish feedstuff. A quality evaluation of the silages was conducted in a completely randomized design with four replications (two replications for AAs), to determine storage stability of the silages, on 10 different sampling days (days 1, 3, 6, 9, 15, 30, 90, 180, 270 and 360), (three sampling days for AAs) post-manufacture. The ASD was stable up to 180 d, after this storage time it underwent increases in pH and total volatile nitrogen (TVN) and decreases in N and AA content. The preservation of dogfish with a fermentation method (FSD) was judged to be unsuccessful with this feedstuff having a high initial pH (6.4) and large increases in TVN content early in storage. It was concluded that feedstuffs made from dogfish would provide a source of highly digestible nutrients for mink; however, more research is required before a fermented dogfish feedstuff can be incorporated into practical mink diets. Key words: Apparent digestibility, dogfish, fish by-products, mink, silage, silage quality

Non-Chlorine Bleaching of Kraft Pulp. V. Participation of Radical Species in Ozonation of Methyl 4-O-Ethyl-β-D-Glucopyranoside

Methyl 4-O-ethyl-β-D-glucopyranoside was treated with ozone both in anhydrous CH 2 Cl 2 and in aqueous solutions, to investigate the participation of radical species in the degradation of the polysaccharide during ozone bleaching. The reactivity of C in the model compound during ozonation was compared with that during oxidation with Fenton's reagent. It was found that ozone itself brings about glycosidic bond cleavage with a high degree of selectivity. The degradation of the model compound during ozonation in distilled water is due in part to radical species, and in part to ozone itself. The contribution of radical species to the degradation in distilled water is estimated to be about 40-70 %. Initial high pH and Fe 2+ ions enhanced the degradation of the model compound, and the contribution of radical species increased. However, the degradation of the model compound with radical species generated by Fe 2+ ions can be inhibited by adjusting to pH 2 without the removal of Fe 2+ ions. Vanillyl alcohol also enhanced the degradation of the model compound during ozonation. Radical reactions initiated by vanillyl alcohol participate in the degradation of the model compound even at pH 2. although the additional degradation of the model compound was inhibited by the low pH. Inhibition of the degradation of carbohydrates by radical species is one of the keys to prevent the viscosity drop in ozone bleaching of pulp.

Non-Chlorine Bleaching of Kraft Pulp. IV. Oxidation of Methyl 4-O-Ethyl-β-D-Glucopyranoside with Fenton’s Reagent: Effects of pH and Oxygen

Article Non-Chlorine Bleaching of Kraft Pulp. IV. Oxidation of Methyl 4-O-Ethyl-β-D-Glucopyranoside with Fenton’s Reagent: Effects of pH and Oxygen was published on January 1, 1998 in the journal Holzforschung (volume 52, issue 2).

The pretreatment of acrylonitrile and styrene with the ozonation process

Acrylonitrile and styrene are used as the raw materials for manufacturing acrylic fiber, thus they are often found as pollutants in the petrochemical wastewater. This study utilizes ozone to decompose the organic nitrogen contained in acrylonitrile and styrene, and the oxidation process was monitored using on-line measurements of oxidation-reduction potential (ORP) and pH. The efficiency of organic nitrogen decomposition was also estimated based on the COD, organic nitrogen, TOC, ammonia-N, nitrite, and nitrate measurements. Both the initial pH and alkalinity are observed to affect the degradation rate of organic nitrogen. The acrylonitrile sample with the lowest initial pH value (i.e., 4.0) has a shorter t1/2 of 18.9 min and that for samples of the highest initial pH (i.e., 11) was 34 min. The alkalinity of one acrylonitrile sample was boosted by adding 500 mg/l CaCO3, to simulate the field ABS (Acrylonitrile-Butadiene-Styrene) wastewater effluent. It was observed that within a short ozone contact time, the acrylonitrile sample spiked with 500 mg/l CaCO3 had the highest COD decomposition rate of 0.411 min−1, or 1.3 times more than that for samples without addition of CaCO3. Results of the ozonation process can be fitted with a modified Nernst equation for the various pH conditions. Additionally, the ozone treated synthetic ABS sample shows a faster COD removal rate in the subsequent biological process than those samples without ozone treatment.

Wood Ash as an Amendment in Municipal Sludge And Yard Waste Composting Processes

Wood ash from a wood-fired, electrical generating plant was examined as a potential amendment in municipal biosolids and yard waste composting applications. The rate of composting and the final compost quality (chemical, physical, and plant growth characteristics) were examined. Yard waste (leaves, grass, and wood chips) and a municipal biosolids-chip mixture were either not amended or amended with wood ash at eight percent or five percent by weight, respectively, and then composted outdoors in insulated, 1700L, aerated reactors. Yard waste piles heated rapidly to 60°C within six to seven days, whereas biosolid piles heated more slowly to a maximum of 52 to 57°C within nine to 11 days. Ash had little, if any, effect on the time-temperature response. In general, ash-amended compost had higher pi I, plant nutrient, and salt contents. Tomato plants (Lycopersicum esculentum) produced 100 percent more shoot biomass in biosolids than in yard waste compost media. Poor plant growth in the yard waste compost was likely due to the high initial pH and salt content of the growth medium. In yard waste media, tomato plants germinated and produced more shoot biomass in the control compost than in the ash-amended compost.A pH neutralization study indicated that wood fly ash could be used as an economical substitute for lime which is commonly used to stabilize municipal biosolids prior to land filling or land application. Wood fly ash (pH = 13.2-13.4), when added to biosolids at a 2 to 1 ratio by weight, raised the pH of the mixture to 12.0.

The pretreatment of acrylonitrile and styrene with the ozonation process

Acrylonitrile and styrene are used as the raw materials for manufacturing acrylic fiber, thus they are often found as pollutants in the petrochemical wastewater. This study utilizes ozone to decompose the organic nitrogen contained in acrylonitrile and styrene, and the oxidation process was monitored using on-line measurements of oxidation-reduction potential (ORP) and pH. The efficiency of organic nitrogen decomposition was also estimated based on the COD, organic nitrogen, TOC, ammonia-N, nitrite, and nitrate measurements. Both the initial pH and alkalinity are observed to affect the degradation rate of organic nitrogen. The acrylonitrile sample with the lowest initial pH value (i.e., 4.0) has a shorter t1/2 of 18.9 min and that for samples of the highest initial pH (i.e., 11) was 34 min. The alkalinity of one acrylonitrile sample was boosted by adding 500 mg/l CaCO3, to simulate the field ABS (Acrylonltrde-Butadiene-Styrene) wastewater effluent. It was observed that within a short ozone contact time, the acrylonitrile sample spiked with 500 mg/l CaCO3 had the highest COD decomposition rate of 0.411 mm−1, or 1.3 times more than that for samples without addition of CaCO3. Results of the ozonation process can be fitted with a modified Nernst equation for the various pH conditions. Additionally, the ozone treated synthetic ABS sample shows a faster COD removal rate in the subsequent biological process than those samples without ozone treatment.

Salivacin 140, a novel bacteriocin from Lactobacillus salivarius subsp. salicinius T140 active against pathogenic bacteria

Fifteen of 353 environmental isolates of lactic acid bacteria consistently showed activity against Listeria monocytogenes, Streptococcus mutans, Actinomyces viscosus, and/or Propionibacterium acnes. Strain T140, isolated from the surface of Japanese pampas grass leaves and identified as Lactobacillus salivarius subsp. salicinius, also had activity against several Lactobacillus species, Staphylococcus aureus and Yersinia enterocolitica. Since the antagonistic factor(s) produced by T140 was sensitive to a proteolytic enzyme, it was concluded that a bacteriocin (named salivacin 140) was involved in the inhibition activity. Strain T140 required a high initial pH (7.5-8.5) in agar plates for bacteriocin production.

Effects of pH and substrate:inoculum ratio on batch methane fermentation

Batch digestion experiments were conducted to determine the effects of inoculum:substrate ratio and initial medium pH on methane production from glucose. A ratio between the chemical oxygen demands (COD) of the substrate and inoculum solids (SISR) was used to quantify the food to microorganisms (F/M) ratio. Two periods of active methane production, separated by a period of inactivity, characterized the fermentation. The duration of inactivity was affected by both SISR and the initial medium pH. It decreased as SISR was decreased or when a higher initial pH was used. With a SISR of 4.8 and a pH of 7.2 or 7.0, the inactive period was eliminated, indicating satisfactory coupling of the acid- and methane-forming phases. Ultimate methane yield at a SISR of 4.8 was higher than at a SISR of 38.5.