Interactive Effects Of pH Research Articles

An investigation into the performance and perikinetics of Brassica nigra meal in the treatment of real vegetable oil refinery condensate effluent.

In this study, the treatment of vegetable oil refinery plant condensate effluent (VORCE) having high total suspended solids (TSS) and chemical oxygen demand (COD) generated from acid oil unit was focused. The utilization of waste Brassica nigra meal (BNM) as protein flocculant in treating VORCE was explored. The B. nigra meal flocculant (BNMF) exhibited a crystalline nature, with the presence of amino and carboxyl functional groups, rendering it highly efficient (89.69% efficiency) in floc formation. Zeta potential and particle size (-5.6mV and 240.68 nm, respectively) indicate BNMF's effectiveness in initiating floc formation. The interactive effects of pH, dosage, settling time on COD, and TSS removal were investigated using the Box-Behnken design. At an optimal pH of 6.9 and BNMF dosage of 0.77 g/L, a maximum removal of 85.38% COD and 72.56% TSS was obtained. The perikinetic theory for the coagulation-flocculation followed a second-order rate reaction with high Kc (0.0001 L/mg min), low settling time (37.04 min), and high collision efficiency (2.703 × 1017), indicating the model's significance in achieving maximum COD and TSS removal. These findings highlight the potential use of BNMF in the treatment of VORCE, leading to circular economy by valorizing waste from mustard oil extraction and zero discharge. PRACTITIONER POINTS: Valorization of waste Brassica nigra meal (BNM) as a potent protein flocculant Optimization for vegetable oil refinery condensate effluent (VORCE) treatment was done. Interactive effects of the process parameters were analyzed using Design expert. Perikinetic theory for VORCE treatment follows second-order reaction rate with high Kc.

Morphological and physiological responses of the cosmopolitan marine diatom Thalassiosira rotula to acidification

We investigated the effect of decreased pH on the morphology and nutrient physiology of the cosmopolitan marine diatom Thalassiosira rotula (CCMP3362) by acclimating unialgal cultures to two different CO2 gas concentrations under optimal light, temperature and nutrient conditions. At lower pH (higher CO2), T. rotula exhibited a reduction in cell diameter (7%), surface area (13%), and volume (20%), and an increase in surface area-to-volume ratio (7%). All measures of silicification in T. rotula, i.e., silica (SiO2) quota, rate of silicic acid (Si(OH)4) utilization, and elemental ratios of SiO2:C and SiO2:N, remained unchanged. Similarly, carbon (C) and nitrogen (N) quotas, ratios and utilization rates were mostly unaffected by pH. In contrast, the utilization rate of nitrate (ρNO3) was significantly lower at decreased pH when the rate was normalized by cell number instead of by cell volume. The changes in cell morphology found in this study under low pH were likely not large enough to significantly impact physiological processes and the role of this species in marine food webs and biogeochemical cycles. It is possible that the interactive effects of pH, temperature, light, and nutrient availability characteristic of different regions of the world ocean could result in stronger physiological and morphological responses in this widespread diatom. However, under constant optimal growth conditions, T. rotula was only mildly affected by changes in pH, and in particular the physiology and elemental stoichiometry of C, N and Si were not sensitive to acidification.

Interaction effects of pH and land cover on soil microbial diversity are climate-dependent.

Factors regulating the diversity and composition of soil microbial communities include soil properties, land cover and climate. How these factors interact at large scale remains poorly investigated. Here, we used an extensive dataset including 715 locations from 24 European countries to investigate the interactive effects of climatic region, land cover and pH on soil bacteria and fungi. We found that differences in microbial diversity and community composition between land cover types depended on the climatic region. In Atlantic, Boreal and Continental regions, microbial richness was higher in croplands and grasslands than woodlands while richness in Mediterranean areas did not vary significantly among land cover types. These differences were further related to soil pH, as a driver of bacterial and fungal richness in most climatic regions, but the interaction of pH with land cover depended on the region. Microbial community composition differed the most between croplands and woodlands in all regions, mainly due to differences in pH. In the Mediterranean region, bacterial communities in woodlands and grasslands were the most similar, whereas in other regions, grassland and cropland-associated bacteria showed more similarity. Overall, we showed that key factors interact in shaping soil microbial communities in a climate-dependent way at large scale.

Review of techniques for biohydrogen production from palm oil mill effluent

Due to rapid growth in population and societal development, the demand for energy is on the increase. The production of palm oil as one of the major edible oils consumed in the world has increased tremendously. Palm oil mill effluent (POME), a wastewater from the most significant agricultural industry is produced in tremendous amounts that requires proper management to mitigate its negative environmental effects. Studies have shown that Palm oil mill effluent (POME) possesses the properties of a good carbon feedstock for hydrogen generation in fermentation processes. In this study, several methods for biohydrogen production from Palm oil mill effluent (POME) were discussed. An apprehension into the different pre-treatment methods on POME including physicochemical, chemical and biological and their effects on the characteristics of POME including pH, temperature, sugar content, solid content, viscosity, nutrients and by-product toxicity on the biohydrogen production and effluent quality were reviewed. Various bioreactor designs were used for biohydrogen from POME, the modifications applied on the system design to increase the stability and productivity of POME treatment have been examined. The individual and interactive effects of pH, different temperatures of heat treatment, different inoculum sizes and substrate concentrations on biohydrogen production were discussed. Moreover, higher biohydrogen productivity could be obtained with the addition of nanoparticle nutrients and introducing genetically modified H2-producing bacteria. Finally, further investigation in the future shall focus on the development of a more inclusive and efficient POME treatment via DF process that favours biohydrogen production, environmental benign and economically viable.

The combined effect of pH and dissolved inorganic carbon concentrations on the physiology of plastidic ciliate Mesodinium rubrum and its cryptophyte prey

Ocean acidification is caused by rising atmospheric partial pressure of CO2 (pCO2) and involves a lowering of pH combined with increased concentrations of CO2 and dissolved in organic carbon in ocean waters. Many studies investigated the consequences of these combined changes on marine phytoplankton, yet only few attempted to separate the effects of decreased pH and increased pCO2. Moreover, studies typically target photoautotrophic phytoplankton, while little is known of plastidic protists that depend on the ingestion of plastids from their prey. Therefore, we studied the separate and interactive effects of pH and DIC levels on the plastidic ciliate Mesodinium rubrum, which is known to form red tides in coastal waters worldwide. Also, we tested the effects on their prey, which typically are cryptophytes belonging to the Teleaulax/Plagioslemis/Geminigera species complex. These cryptophytes not only serve as food for the ciliate, but also as a supplier of chloroplasts and prey nuclei. We exposed M. rubrum and the two cryptophyte species, T. acuta, T. amphioxeia to different pH (6.8 - 8) and DIC levels (∼ 6.5 - 26 mg C L-1) and assessed their growth and photosynthetic rates, and cellular chlorophyll a and elemental contents. Our findings did not show consistent significant effects across the ranges in pH and/or DIC, except for M. rubrum, for which growth was negatively affected only by the lowest pH of 6.8 combined with lower DIC concentrations. It thus seems that M. rubrum is largely resilient to changes in pH and DIC, and its blooms may not be strongly impacted by the changes in ocean carbonate chemistry projected for the end of the 21st century.

Feasibility of fluoride removal using calcined Mactra veneriformis shells: Adsorption mechanism and optimization study using RSM and ANN

In this study, Mactra veneriformis shells (MVS), a seafood by-product with high Ca content, was assessed as an adsorbent for fluoride removal from contaminated water. MVS was calcined at various temperatures (100–900 °C), and MVS calcined at 800 and 900 °C (MVS-800 and MVS-900) had the highest adsorption capacity. The high fluoride adsorption of MVS-800 and MVS-900 originated from the conversion of CaCO3 present in the raw MVS to CaO and Ca(OH)2 by calcination at high temperatures. The kinetic and equilibrium adsorption of fluoride by MVS-800 were accurately described by the pseudo-second-order and Langmuir models, respectively. The maximum fluoride adsorption capacity was 244.61 mg/g, which is comparable to that of other adsorbents reported in the literature. The enthalpy and entropy of adsorption were 7.42 kJ/mol and 56.48 J/mol‧K, respectively, and the Gibbs free energy was negative at all reaction temperatures. The interactive effects of pH, reaction time, dosage, and temperature and the optimal values for fluoride removal by MVS-800 were explored using response surface methodology (RSM) and artificial neural networks (ANN). The RSM results demonstrated that reaction time, dosage, and temperature significantly influenced fluoride removal; however, pH was an insignificant term. The accuracy of the ANN model (R2 = 0.9932) for predicting fluoride removal was higher than that of RSM (R2 = 0.9347). The optimal fluoride removal at a dosage of 3.3 g/L under optimized conditions (pH 5; reaction time 9 h; temperature 35 °C) was predicted to be 98.5% by the ANN model.

Biodegradation of Azo Dye Methyl Red by Pseudomonas aeruginosa: Optimization of Process Conditions.

Water pollution due to textile dyes is a serious threat to every life form. Bacteria can degrade and detoxify toxic dyes present in textile effluents and wastewater. The present study aimed to evaluate the degradation potential of eleven bacterial strains for azo dye methyl red. The optimum degradation efficiency was obtained using P. aeruginosa. It was found from initial screening results that P. aeruginosa is the most potent strain with 81.49% degradation activity and hence it was subsequently used in other degradation experiments. To optimize the degradation conditions, a number of experiments were conducted where only one variable was varied at a time and where maximum degradation was observed at 20 ppm dye concentration, 1666.67 mg/L glucose concentration, 666.66 mg/L sodium chloride concentration, pH 9, temperature 40 °C, 1000 mg/L urea concentration, 3 days incubation period, and 66.66 mg/L hydroquinone (redox mediator). The interactive effect of pH, incubation time, temperature, and dye concentration in a second-order quadratic optimization of process conditions was found to further enhance the biodegradation efficiency of P. aeruginosa by 88.37%. The metabolites of the aliquot mixture of the optimized conditions were analyzed using Fourier transform infrared (FTIR), GC-MS, proton, and carbon 13 Nuclear Magnetic Resonance (NMR) spectroscopic techniques. FTIR results confirmed the reduction of the azo bond of methyl red. The Gas Chromatography–Mass Spectrometry (GC-MS) results revealed that the degraded dye contains benzoic acid and o-xylene as the predominant constituents. Even benzoic acid was isolated from the silica gel column and identified by 1H and 13C NMR spectroscopy. These results indicated that P. aeruginosa can be utilized as an efficient strain for the detoxification and remediation of industrial wastewater containing methyl red and other azo dyes.

Cellulase production by Aspergillus niger using urban lignocellulosic waste as substrate: Evaluation of different cultivation strategies

Cellulases are used in various industries, acting efficiently and sustainably in the degradation of cellulose contained in different raw materials and recovering high value products. It is the third largest group of enzymes consumed industrially, as they are required in processes linked to the food, biofuel, textile, cleaning products, among others. However, the main disadvantage in the use of commercial cellulases is the high cost. In this context, the objective of this work was to determine conditions for obtaining more efficient and economical cellulases. For this, the efficiency in obtaining the extracellular cellulases endoglucanase (CMCase) and exoglucanase (FPase) by a fungus Aspergillus niger was investigated using an urban lignocellulosic waste as substrate characterized by tree leaves collected from squares and avenues in urban areas. As urban lignocellulosic waste is an innovative raw material, its chemical composition was determined. This substrate contains 20.36% cellulose and induced the production of cellulases in all fermentation methods, proving to be a promising and sustainable source. The influence of the nutrient medium on CMCase and FPase activities was evaluated for three different sequential fermentation (SF) configurations. Medium 2 provided an increase of up to 100 U/L of CMCase and FPase in relation to medium 1. The interactive effect of pH and moisture content on CMCase e FPase production under SF was studied in a central composite design (CCD). Also, different fermentation methods (solid state, submerged and sequential) were evaluated. The use of SF increased the enzymatic activities of both cellulases by 140% compared to other conventional methods and also stood out in the production of proteins (270.05 μg/mL) and reducing sugars (1.19 mg/mL). The desirability function determined the optimal activities of CMCase and FPase as 413.49 U/L and 230.68 U/L, respectively, obtained from the optimal variables of pH 5.5 and 75% moisture content under SF. The effect of pH and moisture content on the activity of each cellulase was analyzed using the Pareto chart and response surface methodology (RSM). These results revealed favorable strategies for cellulase production, such as the use of urban lignocellulosic waste, SF and ideal operational conditions.

Statistical design and optimization of nutritional value production by an oleaginous yeast Yarrowia lipolytica cultured in industrial – waste molasses

Abundant by-products from sugar mills as industrial-waste molasses can be used as a carbon source in yeast culture media. Yarrowia lipolytica is an interesting yeast used as a candidate for cultivation in molasses medium. Here, we used response surface methodology to derive a statistical model for the individual and interactive effects of pH, temperature, and shaking speeds on the production of yeast cells. Cultivation conditions of yeast were optimized using Design Expert based on a 23 factorial central composite design (CCD) for maximum yeast cell production. Optimal conditions for maximum Y. lipolytica 5151 cell masses were as follows: pH, 6.45; temperature, 30°C; Shaking speed, 165 rpm. The Design Expert represented the maximal numerical solution with a predicted cell mass production level at 8.96 g/L. The experimental production of Y. lipolytica 5151 cell mass yielded 8.27 g/L that is 7.67% deviated from the model. Whereas, the model of TISTR 5621 was not adequate for prediction. Yeasts cultured under statistic prediction provide 55.94% and 51.25% of total protein. Amino acid content and vitamin B1 (1.06 mg and 1.47 mg per 100 g of dried Y. lipolytica 5151 and 5621, respectively) provided the relevant information for an alternative supplement in aquatic feed.

Enhanced biomass production and proximate composition of marine microalga Nannochloropsis oceanica by optimization of medium composition and culture conditions using response surface methodology

Nannochloropsis oceanica is a marine eustigmatophyte with high nutritional value, especially with high content of eicosapentaenoic acid that makes it an interesting aquaculture feed. The medium composition and culture conditions were optimized using response surface methodology for large scale culturing of this alga with improved productivity and nutritional value. Growth analysis of N.oceanica in five different meda (F/2; Walne’s; Miquel’s; L1 and K) showed the best growth in Walne’s medium in terms of cell count and specific growth rate. The effects of different concentrations of nutrients such as sodium nitrate, sodium dihydrogen phosphate and different temperature, pH, salinity and agitation speed on biomass concentration were analyzed using Plackett Burman experimental design, and the concentrations of significant medium components and culture conditions were further optimized for maximum biomass concentration and better proximate composition in terms of protein, lipid and carbohydrate using central composite design. The results showed that nitrate, temperature and pH had a positive effect on biomass production, protein concentration was significantly influenced by the interactions of pH and nitrate, and the carbohydrate and lipid concentrations were influenced by the interactive effects of pH, temperature and nitrate. The modified Walne’s medium with increased concentration of nitrate (160 mg/L) under optimum temperature 22 °C and pH 8, yielded a biomass of 760 ± 0.01 mg/L for a period of 10 days, or a 31 % increase compared to the yield under non-optimized conditions (580 ± 0.01 mg/L), and was accompanied by a significant change in the respective proximate composition of proteins, carbohydrates, and lipids. This work provides an efficient culture medium with appropriate nutrient concentrations and optimum culture conditions for the improved growth and proximate composition of N.oceanica.

Starch properties of high and low amylose proso millet (Panicum miliaceum L.) genotypes are differentially affected by varying salt and pH

Variation in salt content and in pH are common in starch-based foods and can affect starch properties and final product texture. Fifteen accessions of proso millet starch with diverse amylose content were selected to investigate single factor and interaction effects of pH and NaCl on thermal, pasting, and textural properties. Pasting properties and gelatinization temperatures were markedly altered by salt addition. Changes in pH only had substantial effects on ΔH, but other properties were generally stable under different pH conditions. From two-way ANOVA, interactive effects of salt and pH were found to affect ΔH. The response of starch of different genotypes in terms of thermal and pasting properties differed under the same pH and salinity conditions. The reason is likely that ions in the starch–water system performed the roles of both reducing water activity and building of hydrogen bonds, which will have opposite effects on starch gelatinization.

Interactive effects of pH and aluminum on the secretion of organic acid anions by roots and related metabolic factors in Citrus sinensis roots and leaves

Low pH and aluminum (Al)-toxicity often coexist in acidic soils. Citrus sinensis seedlings were treated with nutrient solution at a pH of 2.5, 3.0, 3.5 or 4.0 and an Al concentration of 0 or 1 mM for 18 weeks. Thereafter, malate, citrate, isocitrate, acid-metabolizing enzymes, and nonstructural carbohydrates in roots and leaves, and release of malate and citrate from roots were measured. Al concentration in roots and leaves increased under Al-toxicity, but it declined with elevating nutrient solution pH. Al-toxicity increased the levels of glucose, fructose, sucrose and total soluble sugars in leaves and roots at each given pH except for a similar sucrose level at pH 2.5–3.0, but it reduced or did not alter the levels of starch and total nonstructural carbohydrates (TNC) in leaves and roots with the exception that Al improved TNC level in roots at pH 4.0. Levels of nonstructural carbohydrates in roots and leaves rose with reducing pH with a few exceptions with or without Al-toxicity. A potential model for the possible role of root organic acid (OA) metabolism (anions) in C. sinensis Al-tolerance was proposed. With Al-toxicity, the elevated pH upregulated the OA metabolism, and increased the flow of carbon to OA metabolism, and the accumulation of malate and citrate in roots and subsequent release of them, thus reducing root and leaf Al and hence eliminating Al-toxicity. Without Al-toxicity, low pH stimulated the exudation of malate and citrate, an adaptive response of Citrus to low pH. The interactive effects of pH and pH on OA metabolism were different between roots and leaves.

Interactive effect of pH and cation valence in background electrolyte solutions on simazine sorption to Miscanthus biochar produced at two different pyrolysis temperatures

Biochar has considerable sorption efficiency for organic pollutants; however, the effect of physicochemical characteristics and their alteration by environmental conditions on the sorption mechanism is still unknown. We investigated the pH-dependent sorption of simazine on Miscanthus biochar produced at two pyrolysis temperatures (400 and 700 °C; hereafter B-400 and B-700) under two different electrolytes and interpreted the sorption mechanism. The surface charge density (SCD) decreased more in B-400 than in B-700 at higher pH due to more deprotonation of acidic functional groups (AFGs), but greater decreases were observed in B-700 than in B-400 from pH 2 to pH 3 as a result of alkali salts deposition. The decrease in KF with increasing pH showed that simazine sorption decreased as van der Waals forces because the surface of biochar carried a greater negative SCD, which repulses simazine molecules due to the enhanced deprotonation of AFGs. At a given pH, KF was lower in CaCl2 than in NaCl due to the formation of larger metal-biochar complexes, resulting in enhanced blocking of pores available for simazine sorption. We believe that knowledge of the pH-dependence of SCD and accessibility of biochar pores could help better interpret the behavior of simazine-like pollutants in soil and aquatic environments.

Transcriptomic response to decreased pH in adult, larval and juvenile red king crab, Paralithodes camtschaticus, and interactive effects of pH and temperature on juveniles

AbstractOcean warming and acidification are expected to influence the biology of the ecologically and economically important red king crab, Paralithodes camtschaticus. We investigated transcriptome responses of adult, larval and juvenile red king crab to assess sensitivity to reduced pH and elevated temperature. In adults, gill tissue (but not heart or cuticle) responded to reduced pH by differentially regulating many genes involved in metabolic, membrane and cuticular processes, but not ionic or acid/base regulation. In larval crabs, we found little evidence for a strong transcriptomic response to pH, but did observe large differences in the transcriptomes of newly hatched and one-week old larvae. In juvenile crabs, we found that there was a strong transcriptomic response to temperature across all pH conditions, but that only extreme low pH caused transcriptomic shifts. Most of the genes in juveniles that were differentially expressed were for cuticular and calcification processes. While inferences regarding the specific biological responses associated with changes in gene expression are likely to change as resources for red king crab genomics enabled studies continue to improve (i.e. better assemblies and annotation), our inferences about general sensitivities to temperature and pH across the life stages of red king crab are robust and unlikely to shift. Overall, our data suggest that red king crab are more sensitive to warming than acidification, and that responses to acidification at the transcriptomic level occur at different levels of pH across life stages, with juveniles being less pH sensitive than adults.

Interactive effects of pH and temperature on native and alien mussels from the west coast of South Africa

Global warming and ocean acidification influence marine calcifying organisms, particularly those with external shells. Among these, mussels may compensate for environmental changes by phenotypic plasticity, but this may entail trade-offs between shell deposition, growth and reproduction. We assessed main and interactive effects of pH and temperature on four mussel species on the west coast of South Africa (33°48′ S, 18°27′ E) in October 2012 by comparing shell dissolution, shell growth, shell breaking force and condition index of two native species, the ribbed mussel Aulacomya atra and the black mussel Choromytilus meridionalis, and two aliens, the Mediterranean mussel Mytilus galloprovincialis and the bisexual mussel Semimytilus algosus. Live mussels and dead shells were exposed for 42 days to seawater of pH 7.5 or 8.0, at 14 °C or 20 °C. Low pH, high temperature and their combination increased shell dissolution of the two aliens but their growth rates and condition indices remained unchanged. Aulacomya atra also experienced greater shell dissolution at a low pH and high temperature, but grew faster in low-pH treatments. For C. meridionalis, shell dissolution was unaffected by pH or temperature; it also grew faster in low-pH treatments, but had a lower condition index in the higher temperature treatment. Shell strength was not determined by thickness alone. In most respects, all four species proved to be robust to short-term reduction of pH and elevation of temperature, but the native species compensated for greater shell dissolution at low pH by increasing growth rate, whereas the aliens did not, so their invasive success cannot be ascribed to benefits accruing from climate change.

Effect of pH, temperature and time combinations on yield and degree of esterification of mango peel pectin: a box-behnken design based statistical modelling

A 3-factor-3-level Box-Behnken design was employed to determine the effect of conditions: pH, temperature and time on yield and degree of esterification (DE) of mango peel pectin obtained using acid extraction method. Fifteen experimental runs with different combinations of pH (1.3, 2.5 and 3.7), temperature (60, 75 and 900C) and time (45, 90 and 135 min) were performed on mango peel collected from fruit processing industry. Acid extraction method was used to extract pectin. Yield and the DE of mango peel pectin varied from 6.1 to 16.3% (dry weight basis) and 45.5 to 87.5%, respectively. Interactive effects of pH, temperature and time on the DE were significant at P 50 %) or low methoxyl pectin (DE

Pilot-scale formation of whey protein aggregates determine the stability of heat-treated whey protein solutions—Effect of pH and protein concentration

Denaturation and consequent aggregation in whey protein solutions is critical to product functionality during processing. Solutions of whey protein isolate (WPI) prepared at 1, 4, 8, and 12% (wt/wt) and pH 6.2, 6.7, or 7.2 were subjected to heat treatment (85°C × 30 s) using a pilot-scale heat exchanger. The effects of heat treatment on whey protein denaturation and aggregation were determined by chromatography, particle size, turbidity, and rheological analyses. The influence of pH and WPI concentration during heat treatment on the thermal stability of the resulting dispersions was also investigated. Whey protein isolate solutions heated at pH 6.2 were more extensively denatured, had a greater proportion of insoluble aggregates, higher particle size and turbidity, and were significantly less heat-stable than equivalent samples prepared at pH 6.7 and 7.2. The effects of WPI concentration on denaturation/aggregation behavior were more apparent at higher pH where the stabilizing effects of charge repulsion became increasingly influential. Solutions containing 12% (wt/wt) WPI had significantly higher apparent viscosities, at each pH, compared with lower protein concentrations, with solutions prepared at pH 6.2 forming a gel. Smaller average particle size and a higher proportion of soluble aggregates in WPI solutions, pre-heated at pH 6.7 and 7.2, resulted in improved thermal stability on subsequent heating. Higher pH during secondary heating also increased thermal stability. This study offers insight into the interactive effects of pH and whey protein concentration during pilot-scale processing and demonstrates how protein functionality can be controlled through manipulation of these factors.

Biohydrogen production from mixtures of agro-industrial wastes: Chemometric analysis, optimization and scaling up

Cheese whey (CW) and wheat straw hydrolysate (WSH) were used to produce biohydrogen by anaerobic co-digestion of multiple substrates. In this work, the influence of pH, temperature, substrates concentrations on the biohydrogen production was explored with the application of the principal component analysis (PCA) and the hierarchical clustering analysis (HCA), allowing the identification of the main clusters and the uniqueness of some experiments. Response surface methodology (RSM) was used to evaluate the individual and interactive effects of pH, temperature, CW concentration and WSH concentration in the fermentation. Optimal operational conditions obtained by RMS were 5 g L−1 WSH, 25 g L−1 CW, 26.6 °C and pH 7.25. With these conditions was expected 5724.5 mL H2 L−1. When optimal conditions were tested using 0.11-L anaerobic serological bottles, 1-L and 4-L bioreactors the results obtained for biohydrogen production were 4554.5 ± 105, 3685 ± 305 and 4132.3 ± 151 mL H2 L−1, respectively; on the other hand, the biohydrogen production rate was improved from 66.6 to 89.5 mL H2 L−1 h−1. Results demonstrate that it is possible to use WSH and CW, both individually and in combination, as a substrate for the production of biohydrogen.

Biosorption of xenobiotic Reactive Black B onto metabolically inactive T. harzianum biomass: optimization and equilibrium studies

Biosorptive removal of Reactive Black B (RBB) from aqueous solution by metabolically inactive Trichoderma harzianum (T. harzianum) was examined in this study. The individual and interactive effects of pH (2.0–10.0), temperature (25–45 °C), initial dye concentration (100–300 mg/L) and adsorbent dosage (0.1–0.5 mg/L) on the biosorption of RBB were evaluated using central composite design (CCD), and the mathematical model describing the biosorption process was developed. Maximum removal percentage (97.42 ± 1.3%) of RBB was attained at pH 5.75, temperature 37.12 °C, initial dye concentration 210.92 mg/L and biosorbent dosage 0.28 g/L. Suitability of the isotherms were determined using Langmuir, Freundlich and Temkin in this study, among which Freundlich isotherm was found suitable to equilibrium data. Kinetic analysis revealed that the adsorption data correlated well with pseudo-second-order kinetic model. The obtained thermodynamic data revealed that the RBB adsorption onto T. harzianum was exothermic and spontaneous nature during the process.

Reprint of: Decomposition of PPCPs by ultrasound-assisted advanced Fenton reaction: A case study with salicylic acid

The study is about the degradation of a widely used pharmaceutical and personal care product-salicylic acid by sonocatalysis, and the experimental design of the reaction system. The first part of the study consists of sonication (572kHz) in the presence of zero-valent iron (ZVI) with or without H2O2 to select and optimize the operational parameters as frequency, time, initial solute concentration, dose of reagents and pH. The second part consists of the use of response surface methodology and multiple regression to develop an experimental design modeland to assess the individual and interactive effects of pH, power (Po), ZVI dose and H2O2. The results showed that the optimal conditions predicted by the model without defining any restrictions are: pH=2.0, Po=120W, ZVI=24mgL−1, which provide total salicyclic acid and 48% TOC decay. However, the prediction implies intensive consumption of energy and reagents, and must therefore be modified by restricting the value of TOC decay to a lower value and that of pH to a higher one. Cross-validation tests showed that the prediction accuracy of the model was considerably high with 5.0–9.4% deviation from the experimental data.