SEARCH · Search PubMed

Results for “Biomass”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources

PubMedDate not supplied

Hydrodynamic alterations during cyanobacteria (Arthrospira platensis) growth from low to high biomass concentration inside tubular photobioreactors.

The rheological behavior of an Arthrospira culture was studied from low to high biomass concentration. Two tubular undulating row photobioreactors (TURP-5r and TURP-10r), with a very short light path of 1.0 cm, were used during batch growth. In TURP-5r, the biomass concentration increased to 14.5 g(dw) L(-1), and alterations of the physical properties and hydrodynamic behavior occurred as a result. In the past, the rheological characteristics of photosynthetic-microbe cultures were rarely investigated because of the low biomass concentration attained in the systems. Developing closed photobioreactor technologies, the optimum biomass concentration rises and the viscosity, the generalized Reynolds number (N'(Re)), and the power required for culture recycling are also subject to alteration. Starting from a biomass concentration of 4.1 g(dw) L(-1), the Arthrospira culture already exhibits the characteristics of a non-Newtonian fluid. As a result of culture recycling from 2.0 to 20.5 g(dw) L(-1) and an available power of 1.67 W row(-1), we demonstrated that N'(Re) is reduced from 6265 to 1148. Our experimental results showed that N'(Re) of 2345 can be reached only at a cell concentration below 11.1 g(dw) L(-1), while at a cell concentration below 4.1 g(dw) L(-1) N'(Re) = 4080 was reached. The power consumption (P(c)) for culture recycling increased noticeably when the cell concentration rose; the highest P(c) increase attained was from 2.0 to 4.1 g(dw) L(-1). This is the range within which the Arthrospira culture changes from a Newtonian to a non-Newtonian fluid.

Bioreactors↗

PubMed2006

Relationship between metabolism and biomass of medically important zygomycetes.

Little is known about the relationships between metabolic activity and fungal biomass or time of incubation for medically important fungal pathogens. Understanding these relationships may be especially relevant for rapidly growing organisms, such as zygomycetes. A range of inocula of five clinical isolates of zygomycetes (one each of Rhizopus oryzae,Rhizopus microsporus, Cunninghamella bertholletiae, Mucor circinelloides and Absidia corymbifera) were incubated for 6, 8, 12, 24 and 48 h, after which hyphal mass was assessed spectrophotometrically and metabolic activity was measured using various concentrations of XTT and menadione. Both linear regression and the Boltzmann sigmoid model were used and compared for description of relationships between metabolic activity, biomass and time of incubation. Modeling was further applied to eleven additional zygomycete isolates. The relationships of biomass or metabolic activity as a function of time of incubation were well described with the Boltzmann sigmoid model. The latter was superior to linear regression in describing the relationship between metabolic activity and fungal biomass. For all isolates of zygomycetes, increases in metabolic activity preceded increases in biomass. Inter-species differences in growth patterns were observed, with Rhizopus microsporus and Mucor spp. reaching the plateau of growth earlier compared to other species. These findings on the temporal relationship and inter-species differences of hyphal growth and metabolic activity for zygomycetes may be useful in the design and interpretation of in vitro studies of these emerging pathogens.

Humans↗

PubMedDate not supplied

Offsetting changes in biomass allocation and photosynthesis in ponderosa pine (Pinus ponderosa) in response to climate change.

We examined the effect of climate on aboveground biomass allocation of ponderosa pine (Pinus ponderosa) by measuring trees in disjunct forest stands growing on the same substrate at high-elevation montane sites and low-elevation desert sites. Climatic differences between the sites were comparable to the difference between present and future climates of interior North America that is expected to result from a doubling of atmospheric CO(2) concentration. Relative to the montane populations, the desert populations allocated a greater proportion of biomass to sapwood (functional xylem) at the expense of foliage. The leaf/sapwood area ratio and percent of aboveground biomass in sapwood for trees of the same height were 0.201 m(2) cm(-2) and 58% for montane trees and 0.104 m(2) cm(-2) and 71% for desert trees. In a phytotron experiment, increases in net photosynthesis and net assimilation rate for seedlings grown under future conditions of high CO(2) and temperature were offset by a decrease in leaf area ratio. As was observed for large trees at different elevations, increased temperatures caused an increase in biomass allocation to stem in the phytotron seedlings. Thus, CO(2)- and temperature-driven shifts in biomass allocation negated the effect on growth of the CO(2)-driven increase in carbon assimilation rate. Our data from the controlled growth chamber and field experiments suggest that future climate conditions, including elevated atmospheric CO(2), may not stimulate growth and productivity of ponderosa pine.

Journal Article↗

PubMed1997

Branch growth and biomass allocation in Abies amabilis saplings in contrasting light environments.

Aboveground biomass allocation, and height and branch growth were studied in saplings of the shade-tolerant conifer, Abies amabilis Dougl. ex Forbes growing in large openings and in the understory of an old-growth forest in western Oregon. The presence of annual overwintering budscale scars was used to infer extension growth histories; annual growth rings in branches and stems were used in combination with extension histories to compute partitioning of new biomass among leaves, branches and stems. Saplings growing in large gaps had conical crowns, whereas understory saplings had umbrella shaped crowns as a result of much greater rates of branch extension than stem extension. Understory saplings grew slowly in height because of low rates of biomass production and low allocation of biomass to stem extension. About 40% of new biomass was allocated to foliage in both groups, but understory saplings allocated more of the remaining growth increment to branches and less to stem than did saplings growing in large gaps. These results differ from the patterns observed in shade-tolerant saplings of tropical forests, where allocation to foliage increases with shading and branch allocation is much lower than observed here. This difference in allocation may reflect mechanical constraints imposed by snow loads on the evergreen A. amabilis crowns, particularly on flat-crowned understory saplings.

Journal Article↗

PubMed1999

Fine root biomass of Scots pine stands differing in age and soil fertility in southern Finland.

The biomass of small and large fine roots (</= 2 mm and 2-5 mm in diameter, respectively) in mineral soils of southern Finland was compared with estimated foliage biomass in the same stands. Study material was collected from stands differing in site fertility and age. The humus layer was deeper at the more fertile sites than at the less fertile sites. Fine root density was greater in humus than in mineral soil, and the fine root density in mineral and humus layers was greater at the less fertile sites than at the more fertile sites. Although the amount of fine root biomass was not correlated with any commonly recorded stand characteristic, small fine root biomass was proportional to foliage biomass for both site types. The coefficient of proportionality was larger for the less fertile sites than for the more fertile sites, supporting the theory of functional balance. A similar relationship could not be established for the large fine roots. A trend of increasing fine root:needle mass ratio with stand age was observed for stands on the less fertile sites.

Journal Article↗

PubMed2000

Effect of elevated [CO(2)] and varying nutrient application rates on physiology and biomass accumulation of Sitka spruce (Picea sitchensis).

Sitka spruce (Picea sitchensis (Bong.) Carr.) seedlings were supplied with solutions containing nitrogen (N) at 0.1 x or 2 x the optimum rate (low-N and high-N supply, respectively) and grown either outside in a control plot or inside open-top chambers and exposed to ambient (355 &mgr;mol mol(-1)) or elevated (700 &mgr;mol mol(-1)) CO(2) concentration ([CO(2)]). Gas exchange measurements, chlorophyll determinations and nutrient analysis were made on current-year (< 1-year-old) shoots of the upper whorl after the seedlings had been growing in the [CO(2)] treatments for 17 months and the nutrient treatments for 6 months. Total seedling biomass and biomass allocation were assessed at the end of the experiment. Nutrient treatment had a significant effect on the light response curves, irrespective of [CO(2)] or chamber treatment; seedlings supplied with high-N rates had higher net photosynthetic rates than seedlings supplied with low-N rates. The degree of photosynthetic stimulation in response to elevated [CO(2)] was larger in seedlings receiving high-N rates than in seedlings receiving low-N rates. Light-saturated net photosynthesis of seedlings grown and measured in elevated [CO(2)] was 26% higher than that of seedlings grown and measured in ambient [CO(2)]. There was no significant effect of [CO(2)] or chamber treatment on the CO(2) response curves of seedlings receiving High-N supply rates. In contrast, analysis of the CO(2) response curves of seedlings receiving Low-N supply rates showed acclimation to elevated [CO(2)]. Both maximum rate of carboxylation (V(cmax)) and maximum electron transport capacity (J(max)) were lower and J(max)/V(cmax) higher in seedlings in the elevated [CO(2)] treatment. There was no effect of elevated [CO(2)] on stomatal conductance, although it was highly dependent on foliar [N], ranging from ~60 mmol m(-2) s(-1) at ~1.5 g N m(-2) to 200 mmol m(-2) s(-1) at ~5 g N m(-2). In the high-N and low-N treatments, foliar N concentration was 10 and 28% lower in seedlings grown in elevated [CO(2)] than in seedlings grown in ambient [CO(2)], respectively. There was no [CO(2)] effect on foliar phosphorus concentration ([P]). Chlorophyll concentration increased with increasing N supply in all treatments. There was no significant effect of elevated [CO(2)] on specific leaf area. Chlorophyll concentration expressed either on an area or dry mass basis for a given foliar [N] was higher in seedlings grown in elevated [CO(2)] than in seedings grown in ambient [CO(2)]. Elevated [CO(2)] increased total biomass accumulation by 37% in seedlings in the high-N treatment but had no effect in seedlings in the low-N treatment. There was a proportionally bigger allocation of biomass to roots of seedlings in the elevated [CO(2)] + low-N supply rate treatment compared with seedlings in other treatments. This resulted in a reduction in aboveground biomass compared with corresponding seedlings grown in ambient [CO(2)].

Journal Article↗

PubMed1994

Advances in biosorption of metals: selection of biomass types.

Within the past decade, the potential of metal biosorption has been well established. For economic reasons, of particular interest are abundant biomass types either generated as a waste by-product of large-scale industrial fermentations or certain metal-binding algae found in large quantities in the sea. Some of these high metal-sorbing biomass types serve as a basis for newly developed metal biosorption processes foreseen particularly as a very competitive means for detoxification of metal-bearing industrial effluents. Ions of lead and cadmium, for instance, have been found to be bound very efficiently from very dilute solutions by the dried biomass of some ubiquitous brown marine algae such as Ascophyllum and Sargassum which accumulate more than 30% of biomass dry weight in the metal. Mycelia of industrially steroid-transforming fungi Rhizopus and Absidia are excellent biosorbents for lead, cadmium, copper, zinc, and uranium, binding also other heavy metals up to 25% of the biomass dry weight. The common yeast Saccharomyces cerevisiae is a 'mediocre' metal biosorbent. Construction of biosorption isotherm curves serves as a basic technique assisting in evaluation of the metal uptake by different biosorbents. The methodology is based on batch equilibrium sorption experiments extensively used for screening and quantitative comparison of new biosorbent materials. Experimental methodologies used in the study of biosorption and selected recent research results demonstrate the route to novel biosorbent materials some of which can even be repeatedly regenerated for re-use.

Absorption↗

PubMed1993

Impact of bacterial biomass on contaminant sorption and transport in a subsurface soil.

The objective of this study was to investigate the impact of bacterial biomass on the sorption and transport of three solutes (quinoline, naphthalene, and Ca) in a subsurface soil. Miscible displacement techniques were employed to measure sorption and transport of the above compounds during steady, saturated water flow in sterile and/or bacterium-inoculated soil columns. The soil was inoculated with either a quinoline-degrading bacterium, Pseudomonas sp. 3N3A isolate, or its mutant isolate, B53, which does not degrade quinoline. In soil columns inoculated with the B53 and 3N3A isolates, quinoline sorption was reduced by about 60 and 20%, respectively. In contrast, Ca sorption was minimally reduced, which indicated that biomass did not significantly alter the cation-exchange capacity of the soil. Biomass impacts on sorption were solute specific, even when the sorption mechanism for both quinoline and Ca was similar. Thus, the differential response is attributed to biomass-induced changes in quinoline speciation; an increase in pH at the sorbent-water interface would result in a larger proportion of the neutral species and a decrease in sorption. Sorption of naphthalene was reduced by about 30%, which was attributed to accessibility of hydrophobic regions. Minimal biosorption of all solutes indicated negligible biofacilitated transport. Alteration of the soil surfaces upon addition of bacterial biomass reduced sorption of quinoline and naphthalene, thereby enhancing transport.

Journal Article↗

PubMed1995

Comparison of biomass dry weights and radial growth rates of fungal colonies on media solidified with different gelling compounds.

Penicillium commune, Aureobasidium pullulans, and Paecilomyces farinosus were grown on two different media solidified with agar, Pluronic F-127, Carrageenan X-4910, or Carrageenan X-4910 overlaid with cellophane. Growth on Carrageenan X-4910 was generally the same as that on agar, as was the visual appearance of the colonies, e.g., the pigmentation. The Carrageenan X-4910 gels had a melting point, depending on the medium, of 41 to 46(deg)C, and the dry weights of the colonies were readily determined at 60(deg)C. To determine the dry weights of the colonies grown on agar plates, the gels were boiled for 10 min to melt the agar. Comparison of these two procedures showed that the boiling procedure resulted in a 22% reduction of the biomass dry weight. Cellophane membranes did not affect the radial growth rate profoundly. The biomass density was almost halved for P. commune and P. farinosus grown with membranes, whereas the presence of the membrane did not affect the biomass density of A. pullulans. The biomass densities of the colonies grown on Pluronic F-127 were significantly reduced, while in most cases, the radial growth rates of colonies grown on Pluronic F-127 were significantly higher than those obtained on agar or Carrageenan X-4910. Furthermore, the morphology of the leading hyphae was altered, and the hyphal growth unit length was more than twice that obtained on agar and Carrageenan X-4910. Carrageenan X-4910 is a valuable gelling compound for the study of the growth of fungi, as the biomass dry weight is readily determined and growth is similar to that obtained on agar gels.

Journal Article↗

PubMed2000

Influence of high biomass concentrations on alkane solubilities.

Alkane solubilities were measured experimentally for high-density biomass. The resulting Henry's law constants for propane were found to decrease significantly for both dense yeast suspensions and an actual propane-degrading biofilm consortium. At the biomass densities of a typical biofilm, propane solubility was about an order of magnitude greater than that in pure water. For example, a dense biofilm had a propane Henry's law constant of 0.09+/-0.04 atm m(3) mol(-1) compared to 0.6+/-0.1 atm m(3) mol(-1) measured in pure water. The results were modeled with mixing rules and compared with octanol-water mixtures. Hydrogels (agar) and salts decreased the alkane solubility. By considering a theoretical solubility of propane in dry biomass, estimates were made of intrinsic Henry's law constants for propane in pure yeast and biomass, which were 13+/-2 and 5+/-2 atm kg biomass mol(-1) for yeast and biofilm consortium, respectively.

Agar↗

PubMed2000

Soluble polysaccharide and biomass of red microalga Porphyridium sp. alter intestinal morphology and reduce serum cholesterol in rats.

The present study investigated the effects of the red microalga Porphyridium sp. on gastrointestinal physiology and lipid metabolism in male Sprague-Dawley rats. Diets containing dietary fibre from pelleted red microalgal cells (biomass) or their sulfated polysaccharide, pectin or cellulose (control) were fed to rats for a period of 30 d. All three fibre-supplemented diets increased the length of both the small intestine and colon, with a significantly greater effect in rats fed the algal polysaccharide. The polysaccharide also increased mucosa and muscularis cross-sectional area of the jejunum, and caused hypertrophy in the muscularis layer. The algal biomass significantly lowered gastrointestinal transit time by 44% in comparison with the control rats. Serum and mucosal cholecystokinin levels were lower in rats on the pectin and polysaccharide diets, while cholecystokinin levels in rats fed algal biomass were not different from those in the control animals. In comparison with the control diet, all the experimental diets significantly lowered serum cholesterol levels (22-29%). Feeding of non-fermentable algal polysaccharide or biomass significantly increased faecal weight and bile acid excretion compared with pectin-fed or control rats. The algal polysaccharide and biomass were thus shown to be potent hypocholesterolaemic agents active at low concentrations in the diet. Both metabolic and morphological changes were observed following consumption of algae, suggesting several possible mechanisms by which the alga affects lipid metabolism. The results presented in the present study encourage the use of red microalga as a functional food.

Analysis of Variance↗

PubMed2001

Cooking with biomass stoves and tuberculosis: a case control study.

OBJECTIVE: To search for an association between tuberculosis and use of biomass stoves found recently in a cross sectional study. DESIGN: In a case-control study based in a chest referral hospital, the cases were 288 patients with active smear-positive or culture-positive tuberculosis, and the controls were 545 patients with ear nose and throat ailments with no evidence of chest disease studied at the same time as the cases. Exposure to present or previous biomass smoke by history of cooking with traditional wood stoves was assessed by positive or negative response. RESULTS: Exposure to biomass smoke was significantly higher in cases than in controls. Crude odds ratios for tuberculosis and biomass smoke exposure were 5.2 (95%CI 3.1-8.9) for current exposure, 3.4 (95%CI 2.4-5.0) for past or present exposure and 1.8 (95%CI 1.1-3.0) for past exposure. The association was observed only for patients living in Metropolitan Mexico City and urban or suburban areas in the center of Mexico providing most cases and controls. For rural areas, the power of the study was low and the origin of the patients heterogeneous. Odds ratio for Mexico City Metropolitan area and the center of Mexico was 2.4 (95%CI 1.04-5.6), adjusted for age, sex, level of education, crowding, smoking, socio-economic level, zone of residence and state of birth. In the same model smoking had an OR of 1.5 (95%CI 1.0-2.3) for tuberculosis. CONCLUSION: Our results support a causal role of current domestic biomass smoke exposure in tuberculosis.

Adult↗

PubMed2005

[Root biomass of different stand-age Pinus yunnanensis forests and its distribution pattern in different soil depths].

With average-tree-specific sampling method, the authors measured the root biomass of Pinus yunnanensis forests with different stand ages in Yongren County, Yunnan Province. The results indicated that total root biomass increased from 8.50 t x hm(-2) in young stand (15-17 yr) to 11.70 t x hm(-2) in middle-aged stand (30-32 yr), and to 18.91 t x hm(-2) in mature stand (60-130 yr). Among different stand age classes, the biomass of coarse roots (>10 mm) varied greatly (1.5-12.3 t x hm(-2)), whereas those of medium (5-10 mm) and fine (<5 mm) roots showed less variation (medium roots 1.4-1.6 t x hm(-2), fine roots 5.3-6.2 t x hm(-2)). The root biomass of mature stand decreased with soil depth, approximately 93% of total underground biomass being distributed in surface layer (0-30 cm), and only 7% in deeper layer (30-115 cm).

China↗

PubMedDate not supplied

[Short-term changes in the biomass of fungi and bacteria in soddy-podzolic soil].

Short-term (diurnal or daily) changes in fungal and bacterial biomass were studied using direct count. Diurnal changes in microbial biomass were found to be unreliable. Daily observations have shown that the length of fungal mycelium can change 3--4-fold within 10--30 days, and the number of bacteria, 2--3-fold, the frequency and amplitude of changes depending on the season. Fungal biomass was found to be greater than bacterial biomass by a factor of dozens; that is why, while estimating the biomass of soil fungi, other indices of the biological activity of soil (DNA content, enzymic activity, respiration, etc.) must be taken into account.

Bacteria↗

PubMed2026

Multistrategy metabolic engineering of Talaromyces pinophilus for α-amylase production from lignocellulosic biomass.

Filamentous fungi are important hosts for industrial enzyme production. Growing demand for α-amylase has increased reliance on food-derived carbon substrates, necessitating fungal strains that efficiently utilize nongrain biomass. In this study, Talaromyces pinophilus Y117 was metabolically engineered to produce α-amylase from lignocellulosic biomass. A strong cellobiohydrolase I gene (cbh1) promoter (Pcbh1Tru) was identified to drive expression. Multiple rounds of multilocus integration of the α-amylase gene were performed using homologous multicopy genomic sequences as recombination arms with a Cre/loxP-based recyclable selection system, yielding the multicopy strain Tp4, which achieved 4124.5 U/mL α-amylase activity in shake-flask fermentation with corncob powder as the sole carbon source. To minimize enzyme degradation, the protease gene 8538 was deleted using the Cre/lox2272 system, generating Tp4Δp. This strain showed a 50% increase in shake-flask α-amylase activity (6208.4 U/mL). In 3-L bioreactor cultivation, Tp4Δp exhibited excellent production performance, achieving 26 712.2 U/mL α-amylase activity. When corncob powder was used as the sole substrate, the cellulose and hemicellulose degradation rates reached 90.00% and 70.01%, respectively, and the enzyme yield reached 213 697.5 U per gram of corncob powder. This engineered strain demonstrates strong potential for industrial applications. The synthesis-degradation synergistic optimization strategy provides a practical approach for engineering filamentous fungal cell factories to produce enzymes directly from lignocellulosic biomass. One sentence summary Metabolic engineering of Talaromyces pinophilus through promoter optimization, multicopy integration, and protease deletion enables efficient α-amylase production from lignocellulosic biomass, achieving 26 712 U/mL in bioreactor fermentation.

Talaromyces↗

PubMed2001

Automatic inducer addition and harvesting of recombinant Escherichia coli cultures based on indirect on-line estimation of biomass concentration and specific growth rate.

This article describes a novel bioreactor configuration for production optimization of recombinant proteins in Escherichia coli. Inducer addition and harvesting are controlled on-line based on indirect estimation of biomass concentration and specific growth rate from addition of NaOH to maintain constant pH. When either a predetermined biomass concentration is reached or the cultures have obtained, a constant specific growth rate inducer is introduced automatically. The induction period is ended by automatic harvesting of the cultures either at a predetermined biomass concentration or when substrate (in this study glucose) is depleted, detected as an increase of pH, or dissolved oxygen tension. During harvesting, metabolic activities are quenched within 3 min by cooling of the cell suspension. The system has been used to optimize expression of glutathione S-transferase (GST) fusion protein of the ligand binding domain of mouse peroxisome proliferator-activated receptor, GST-PPARalpha LBD. Total yield of GST-PPARalpha LBD was independent of the time of inducer addition as long as the length of induction period corresponded to at least 0.25 cell divisions while the yield of soluble GST-PPARalpha LBD, the only active form, increased with the length of induction period. Highest yields were obtained when the inducer was added at low cell concentration as soon as constant specific growth rate was detected, resulting in induction periods corresponding to 3.4 +/- 0.4 cell divisions. The specific growth rate remained almost constant for one cell division after inducer addition, whereafter it decreased. No decrease of specific growth rate was observed when inducer was added in the lag-phase, and no soluble protein was produced. These results suggest that solely soluble GST-PPARalpha LBD acts as a growth inhibitor and that GST-PPARalpha LBD is expressed predominantly as inclusion bodies immediately after inducer addition whereas the proportion expressed as soluble protein is increased after 1 h of induction. Compared to the procedures, which are generally used for protein expression in the laboratory, this system is less labor intensive, it automatically provides recording of biomass concentration and specific growth rate, and it allows direct comparisons between expression of different proteins and performance of different constructs since the induction period is linked to growth.

Animals↗

PubMed2003

Microalgae cultivation in air-lift reactors: modeling biomass yield and growth rate as a function of mixing frequency.

The slow development of microalgal biotechnology stems from the failure in the design of large-scale photobioreactors where light energy is efficiently utilized. Due to the light gradient inside the reactor and depending on the mixing properties, algae are subjected to certain light/dark cycles where the light period is characterized by a light gradient. These light/dark cycles will determine productivity and biomass yield on light energy. Air-lift reactors can be used for microalgae cultivation and medium-frequency light/dark cycles will be found in these systems. Light/dark cycles are associated with two basic parameters: first, the light fraction, i.e., the ratio between the light period and the cycle time and second, the frequency of the light/dark cycle. In the present work, light/dark cycles found in air-lift reactors were simulated taking into account the light gradient during the light period. The effect of medium-frequency cycle time (10-100 s) and light fraction (0.1-1) on growth rate and biomass yield on light energy of the microalgae Dunaliella tertiolecta was studied. The biomass yield and growth rates were mainly affected by the light fraction, while cycle time had little influence. Response surface methodology was used and a statistical model describing the effect of light fraction and cycle time on growth rate and biomass yield on light energy was developed. The use of the model as a reactor design criterion is discussed.

Biomass↗

PubMed2005

Biomass characteristics and membrane aeration: toward a better understanding of membrane fouling in submerged membrane bioreactors (MBRs).

Fouling in submerged membrane bioreactors (MBRs) was studied under different operating conditions and with varying biomass characteristics. Fouling rates were determined using a flux-step method for seven biomass conditions with mixed liquor solids concentrations ranging from 4.3 to 13.5 g x l(-1), six permeate fluxes (5.5, 11.0, 16.5, 22.0, 27.5, and 33.0 l x m(-2) x h(-1)), and three membrane airflow velocities (0.07, 0.10, and 0.13 m x s(-1)). Statistical analysis was used to specify the degree of influence of each of the biomass characteristics (solids concentration, dewaterability, viscosity, particle size distribution, concentrations of protein and carbohydrate in the soluble microbial products, SMP, and extracellular polymer substances, EPS), the permeate flux and the membrane aeration velocity on the membrane fouling rate. Among all these variables, only the permeate flux, the solids concentration (correlated to the viscosity and the dewaterability), the carbohydrate concentration in the EPS, and the membrane aeration velocity were found to affect the fouling rate. The permeate flux had the greatest effect. A transitional permeate flux was observed between 16.5 and 33 l x m(-2) x h(-1), below which no significant fouling was observed regardless of the biomass characteristics, the permeate flux, and the membrane aeration velocity.

Bacteria, Aerobic↗