Characterization and control of foulants occurring from RO disc-tube-type, membrane treating, fluorine manufacturing, process wastewater

This study was carried out to find a way to limit fouling of disc-tube-type reverse osmosis membranes in the treatment of acid rinse wastewater from the fluorine manufacturing process as well as to pretreat the wastewater before it entered the membrane process. Experiments showed that the scale consisted of Ca²⁺, SO₄⁻² and F⁻. Complex scales were removed in a subsequent procedure where the membrane was rinsed with NaOH followed by citric acid which could consequently recover its flux up to 86%. Cleaning chemicals had to be used regularly for efficient recovery of permeate flux. Ultrasonic cleaning could also improve the recovery of permeate flux up to 83%. Calcium salts were used to remove fluoride ions. CaCl₂ removed fluoride ions up to 11% more than Ca(OH)₂ at 0.5 [Ca²⁺]/[F⁻]. At acidic pH 4-7 or alkaline pH 7 and above, residual fluoride ions increased as Ca²⁺ reacted more efficiently with Cl⁻, OH⁻ and SO₄⁻² rather than F⁻. On the other hand, fluoride ions were best removed at pH 7. Adding Ca²⁺ salt above pH 7 caused an increase of residual Ca²⁺ salt in the effluent, even if fluoride ions can be ideally removed in the form of CaF₂ at a pH over 11.     

Anaerobic co‐digestion of food waste leachate and piggery wastewater for methane production: statistical optimization of key process parameters

BACKGROUND: Anaerobic co‐digestion of refractory liquid organic wastes is an alternative environmental management strategy with economic benefits arising out of biogas production. Laboratory‐scale experimental investigations were carried out on the anaerobic co‐digestion of two liquid organic wastes, food waste leachate (FWL) and piggery wastewater (PWW). Three important parameters affecting methane yield were chosen for this study, namely, mixing ratio, alkalinity and salinity, which were optimized using response surface methodology. RESULTS: The results were analyzed statistically and the optimum conditions identified as: mixing ratio (FWL: PWW) 33 (in terms of volatile solid, w/w) (2 on v/v), alkalinity 2850 mg CaCO₃ L^?1, and salinity 3.4 g NaCl L^?1. Under the optimum conditions, a cumulative methane yield (CMY) of 310 mL CH₄ g^?1 VS_added and VS reduction (VSR) of 54% were predicted. Mixing ratio and alkalinity showed the greatest individual and interactive effects on CMY and VSR (P < 0.05). A confirmation experiment under optimum conditions showed a CMY and VSR of 323 mL CH₄ g^?1 VS_added and 50%, respectively. This was only 1.04% and 1.1%, respectively, different from the predicted values. CONCLUSION: Anaerobic co‐digestion of FWL and PWW carried out under the optimum condition may be a feasible and efficient treatment option for methane production. Copyright © 2012 Society of Chemical Industry     

氨氮和林可霉素对有机物厌氧消化的抑制效应

以含高蛋白质和抗生素的林可霉素生产残渣产沼利用为背景,通过中温厌氧消化批式实验,研究不同的氨氮浓度(300～4500 mg·L<'-1>)和林可霉素浓度(0～100 mg·L<'-1>)对含氮含抗生素类生物质废物的厌氧消化产甲烷能力的抑制作用.结果表明,氨氮和林可霉素浓度均与累积产甲烷量显著负相关.经过240 h的培养...     

Study of the Δ12-desaturase system ofLipomyces starkeyi

The specific activity of the microsomal Δ12-desaturase system, which transforms oleic acid into linoleic acid, was about 16 pmol/min/mg protein. However, most of the total activity was nonsedimentable even after a 200000×g centrifugation for 100 min. The study of various physicochemical parameters showed that this enzymatic complex, functioning optimally between pH 7 and 8, had low thermal stability. Ca²⁺, which may cause an aggregation of the microsomes, and Hg²⁺ completely inhibited the activity, whereas Mg²⁺, Mn²⁺, and Zn²⁺ were activators. The Δ12-desaturase system was relatively specific toward oleic acid, though isomers of this fatty acid also had an action, either as substrates or as competitive inhibitors, on the activity of the system. The study of the effect of the exogenous oleoyl-CoA and elaidoyl-CoA on the specific activity of the Δ12-desaturase system showed a preference toward oleoyl-CoA.     

Media configuration and recirculation of upflow anaerobic floating filter for piggery wastewater treatment

An upflow anaerobic floating filter media (UAFF) reactor was applied to the treatment of synthetic and real piggery wastewater. The effect of media configuration and internal recirculation on the system performance was studied. In the first experiment, three-UAFF reactors filled with different media, i.e., polypropylene beads, sponge cubes and coconut fiber were continuously fed with synthetic wastewater at upflow velocity of 0.04 m h⁻¹. The COD removal efficiency in the reactor filled with sponge cubes was highest at 90%, whereas the others filled with polypropylene beads and coconut fibers with lower specific surface area were about 80%. In the second experiment, three-UAFF reactors with sponge were applied to treat real piggery wastewater. COD removal efficiencies were found to be about 80% and methane production rate of 0.26 l l _r ⁻¹d⁻¹. The system performance could be slightly improved by 10% when applying internal recirculation. A sludge blanket (60–70% of total biomass) plays an important role in the system when applied to the treatment of piggery wastewater containing high suspended solid concentration.     

Highly Efficient and Selective Transport of Cu(II) with a Cooperative Carrier Composed of Tetraaza-14-Crown-4 and Oleic Acid through a Bulk Liquid Membrane

Tetraaza-14-crown-4 and oleic acid was successfully applied for transport of Cu(II) in chloroform bulk liquid membrane. The uphill moving of Cu(II) during the liquid membrane transport process has occurred. The main effective variable such as the type of the metal ion acceptor in the receiving phase and its concentration, tetraaza-14-crown-4 and oleic acid concentration in the organic phase on the efficiency of the ion-transport system were examined. By using L-cysteine as a metal ion acceptor in the receiving phase, the maximum amount of copper (II) transported across the liquid membrane was achieved to 96 ± 1.5% after 140 minutes. The selectivity of copper ion transport from the aqueous solutions containing Pb²⁺, Tl⁺, Ag⁺, Co²⁺, Ni²⁺, Mg²⁺, Zn²⁺, Hg²⁺, Cd²⁺ and Ca²⁺ ions were investigated. In the presence of CH₃COONH₄ and Na₄P₂O₇ as suitable masking agents in the source phase, the interfering effects of Pb⁺² and Cd²⁺ were diminished drastically.     

Transfer of Monovalent and Divalent Cations in Salt Solutions by Electrodialysis

Abstract

The selectivity mechanism of transport of Na⁺, Ca²⁺ and Mg²⁺ through commercial monovalent‐cation permselective membranes is investigated in batch electrodialysis experiments with synthetic salt solutions containing monovalent and divalent cations. The role of hydration energy, steric effect, kinetic effect as well as effects of permselectivity of cation exchange membrane has been elucidated with electrodialysis of single solutions (NaCl, CaCl₂, MgCl₂). The mechanism of interferences is investigated in (Na⁺/Ca²⁺, Na⁺/Mg²⁺, Ca²⁺/Mg²⁺ and Na⁺/Ca²⁺/Mg²⁺) mixtures.     

Cupric ion-dependent inhibition of lysosomal acid cholesteryl ester hydrolase in the presence of hydroxylamine

In the presence of hydroxylamine or ascorbic acid, the inhibitory effects of Cu²⁺ on lysosomal acid cholesteryl ester hydrolase (acid CEH) partially purified from rat liver were studied. Hydroxylamine stimulated the inhibition of acid CEH activity by Cu²⁺ but not that by Zn²⁺, Fe²⁺, Co²⁺, Mn²⁺, Ca²⁺, Mg²⁺ and Hg²⁺. This Cu²⁺-dependent inhibition of acid cholesterol ester hydrolase (CEH) activity was completely prevented by ethylenediamine tetraacetic acid (EDTA), EGTA and o-phenanthroline, a chelator with a stability constant for Cu²⁺, and also by sulfhydryl agents and cytoplasmic reducing agents such as cysteine, glutathione and mercaptoethanol. In addition, the stimulative effects of hydroxylamine on Cu²⁺-dependent inhibition were maintained even after preincubation of Cu²⁺ with hydroxylamine. On the other hand, ascorbic acid was found to replace the stimulation by hydroxylamine of the Cu²⁺-dependent inhibition of acid CEH activity but the effects of ascorbic acid progressively became smaller with prolongation of the preincubation time. Moreover, addition of chemical radical scavengers to the reaction mixture did not prevent the Cu²⁺-dependent inhibition of acid CEH activity in the presence of ascorbic acid. These results suggest that Cu²⁺ causes inhibition of lysosomal acid CEH activity through the formation of Cu¹⁺ in a reductive medium.     

Fatty acid specificity of glyceride synthesis by homogenates of bovine mammary tissue

Fatty acid esterification by cell free preparations of bovine mammary tissue was investigated to determine if the type of long chain fatty acid supplied might influence the rate of triglyceride synthesis by that tissue. Homogenates of lactating bovine mammary tissue esterified¹⁴C-fatty acids into glycerides at rates dependent upon chain length and degree of unsaturation. Palmitic, stearic, oleic and linoleic acids were esterified at rates consistent with their concentration in milk fat. A comparison of free fatty acid concentrations of mammary tissue with levels saturating esterification suggested that supply of fatty acids does not limit glyceride synthesis. Certain combinations of fatty acids were facilitory, competitive or inhibitory to esterification. Stearic acid complimented esterification of palmitic and oleic acids. Unlabeledtrans-11-octadecenoic acid did not compete with¹⁴C-palmitate as efficiently in the esterification process as did unlabeledcis-9-octadecenoic acid, indicating that the mammary gland may preferentially esterify thecis-isomer of C-18∶1. Linoleic acid inhibited esterification of palmitic, stearic and oleic acids. Michigan Agricultural Experiment Station Journal Article No. 5100.     

A Novel Indirect Wollastonite Carbonation Route for CO2 Sequestration

A new CO₂ sequestration approach through indirect wollastonite carbonation is proposed to mitigate anthropogenic CO₂ emissions from fossil fuel combustion. The wollastonite carbonation process includes three steps: (1) dissolution of wollastonite in hydrochloric acid to leach Ca²⁺ from mineral matrix; (2) reaction of the resulting CaCl₂ solution with CO₂ in triisooctylamine (TIOA) at low temperature, producing CaCO₃ and an amino acid complex; (3) regeneration of the extractant and acid by backextraction through a temperature swing process and recycling to the dissolution and carbonation steps. It was found that the wollastonite dissolution rate was accelerated by hydrochloric acid and a maximum Ca²⁺ dissolution extent of 95 % was obtained.     

Humic acid fouling in the membrane distillation process

This work investigates the extent of humic acid fouling during the membrane distillation process for water treatment. The effects of pH, ionic strength, and divalent ion on fouling were studied. The experiments were performed with a 0.22-μm PVDF flat-sheet membrane in a direct contact membrane distillation unit. Flux declines were negligible (less than 6%) for the ranges of humic acid concentration, ionic strength, and pH studied. The examination of the membrane surface by SEM revealed a thin deposit layer. The addition of divalent cations (Ca²⁺) into the solution considerably reduced flux when Ca²⁺ concentration exceeded the critical coagulation concentration. Ca²⁺ affected flux by forming complexes with humic acids and resulted in coagulation on the membrane surface. The normalized flux, J/J₀, was 0.57 after 18 h of operation when the CaCl₂ concentration was 3.775 mM. However, the deposit of humic acid coagulate on the membrane surface was loosely packed, and was rather easily removed. Rinsing of the fouled membrane with clean water and a 0.1 M NaOH solution gave 100% of flux recovery.     

Intraparticle cell growth and cell leakage in cultures of Nicotiana tabacum cells immobilized in calcium alginate gel beads

Immobilized Nicotiona tabacum cells in calcium alginate gel beads were prepared under various conditions and then were cultivated. The effects of different conditions of preparation, in relation to concentration of calcium ions (Ca²⁺), on intraparticle cell growth and cell leakage from beads were investigated experimentally. As the amount of Ca²⁺ incorporated into the beads increased, the numbers of cells leaked from the beads into the medium decreased. However, cell growth was inhibited by high Ca²⁺ concentrations in the beads. Optimal conditions existed, which prevented cell leakage without inhibiting intraparticle cell growth. The effect of adding CaCl₂ to the culture medium was also studied. The Ca²⁺, used for the alginate crosslinking, gradually leached from the beads with increasing cultivation time, such that the beads gradually became brittle and fragile. The addition of CaCl₂ was effective in preventing Ca²⁺ loss from the beads and cell leakage. © 2000 Society of Chemical Industry     

Modeling Kinetics of Anaerobic Co-Digestion of Poultry Litter and Wheat Straw Mixed with Municipal Wastewater in a Continuously Mixed Digester with Biological Solid Recycle Using Batch Experimental Data

The half-saturation rate coefficient and maximum rate constant in the Monod model, yield coefficient defined as the ratio of microbial mass to substrate mass, and endogenous decay coefficient are important kinetic parameters for design of anaerobic digestion. These parameters are usually determined from a continuous stable operation of anaerobic digestion, which is more difficult and complex than batch operation in laboratory scale. In this study, a novel method has been developed to determine those parameters from data of batch experiments. To verify this method, kinetics of batch anaerobic co-digestion of poultry litter and wheat straw mixed with municipal wastewater at three total solid (TS) levels (2, 4, and 8% TS) and 50% volatile solid (VS) of wheat straw (VSWS) were investigated. The results showed that the maximum specific methane volume (209?mL (initial g?VS)^?1)) was reached at 4% TS of 50% VSWS. Using the developed method, the kinetic parameters of endogenous decay coefficient, yield coefficient, maximum rate constant, and half-saturation coefficient were determined to be between 0.57?×?10^?3 and 1.2?×?10^?3?d^?1, 0.00938 and 0.0644?g volatile suspended solid (VSS) (VS)^?1, 1.394 and 13,797?d^?1, and 1.6?×?10^?8 and 99,996?g. The kinetic parameters obtained were used to simulate kinetic behaviors of a continuous mixed digester with biological solid recycle. The simulated results showed that the dilution rate was very significant for methane volume produced, VS and VSS concentrations in digestion operation. The maximum methane volume could be predicted to be 3071 and 4152?mL for 2 and 4% TS, respectively.     

Kinetic modelling of the anaerobic digestion of wastewater derived from the pressing of orange rind produced in orange juice manufacturing

A simplified kinetic model for studying the anaerobic digestion of wastewater derived from the pressing of orange rind as a result of orange juice production was proposed on the basis of the experimental results obtained. The process was conducted in a laboratory-scale completely stirred tank reactor operating in batch mode at mesophilic temperature (35 °C), with COD loads in the range of 2–5 g COD. The following simplified three-step reaction scheme was proposed: (1) hydrolysis and conversion of complex organic compounds into intermediate products of lower molecular weight; (2) conversion of these intermediates to volatile fatty acids (VFA); and (3) methanization of the VFA by methanogenic microorganisms. A mathematical model based on four segregated differential equations was formulated assuming that a fraction of this substrate is non-biodegradable and the above-mentioned steps follow first-order kinetics. It was found that the kinetic constants corresponding to these three stages (K₀, K₁ and K₂) decreased markedly with the load added to the reactor, showing the occurrence of an inhibition process. In addition, it was observed that the methanogenic step was the slowest in the overall anaerobic process. Finally, the model was validated by comparing the theoretical curves obtained with the corresponding experimental data of organic matter, VFA and methane. The deviations obtained (less than 20%) in most cases demonstrated the suitability of the mathematical model proposed and suggested that the parameters obtained represent and predict the activity of the microorganisms involved in the anaerobic digestion process of this wastewater.     

Intensities of IR stretching bands as a criterion of the strength of Lewis acid sites in ZSM-5 zeolites with bivalent cations

The DFT calculations were applied to investigate the impact of the nature of bivalent cations M (M = Mg²⁺, Ca²⁺, Sr²⁺, Zn²⁺, Mn²⁺, Co²⁺, Ni²⁺) in cation-exchanged ZSM-5 zeolites on the Lewis acid site (LAS) strength. Intensities and shifts of IR stretching bands of adsorbed methane were calculated. Adsorption leads to a decrease in their frequencies and a marked increase in the intensities of the symmetric stretching band of methane. At the same time the intensities of the asymmetric stretching bands decrease. To characterize the strength of LAS, Fukui functions were computed. A good linear correlation between the intensity of methane vibrations and the LAS strengths (Fukui function f ⁺) was found.     

Adsorption mechanism of fulvic acid onto freeze dried poly(hydroxo aluminum) intercalated bentonites

Two poly(hydroxo aluminum) intercalated Wyoming bentonites were prepared starting from two different aluminum pillaring solutions. The sorption mechanism of Laurentian fulvic acid (FA) onto these poly(hydroxo aluminum) intercalated bentonites was investigated at different pH values and at different ionic strengths (NaCl or CaCl₂). Three mechanisms contribute to the FA adsorption, depending on the pH and the nature (NaCl or CaCl₂) and ionic strength of the background electrolyte. In the presence of NaCl the FA sorption onto poly(hydroxo aluminum) intercalated bentonites can be mainly ascribed to ligand exchange between the amphoteric poly(hydroxo aluminum) hydroxyl groups and the deprotonated carboxylic groups of the FA. The FA adsorption due to ligand exchange reactions decreases with increasing pH. In presence of Ca²⁺ ions the FA adsorption is enhanced, compared to the presence of Na⁺, due to Ca²⁺ bridging between negatively charged groups on the FA molecules and the poly(hydroxo aluminum) intercalated bentonite. The FA adsorption due to Ca²⁺ bridging increases with increasing pH. A third mechanism is enhanced FA adsorption ascribed to FA-Ca-FA bridging and was detected from the FA adsorption in presence of Ca²⁺ at the zero point of charge of the poly(hydroxo aluminum) bentonite (pH 5).     

Preparation and Application of Polymers as Inhibitors for Calcium Carbonate and Calcium Phosphate Scales

The scale inhibitor was prepared based on itaconic acid (IA), styrene p-sulfonic sodium (SSS), maleic anhydride (MA), and acrylamide (AM) as monomers, and ammonium persulfate as an initiator by the free-radical polymerization. The structure of the polymer was characterized by FT-IR and UV-Vis spectroscopy. Using the static experiment method, the scale inhibition efficiency to CaCO₃, the effects of some factors (concentration of polymer, time, concentration of Ca²⁺, pH value, concentration of HCO₃ ^?, and temperature) were investigated. Using the malachite green photometric method, the scale inhibition efficiency to Ca₃(PO₄)₂ and the effects of some factors (concentration of polymer, time, Ca²⁺, pH, temperature, and the concentration of PO₄ ^3?) were also investigated. The experimental results showed that the polymer had an excellent efficiency of scale inhibition and a resistance rate of calcium carbonate scale up to 96.67%, a resistance rate of calcium phosphate scale up to 92.5%, and could be used in the system of high-temperature and high-hardness water. The polymer had good dispersing ability with respect to iron.     

Electrokinetic and rheological properties of Na-bentonite in some electrolyte solutions

Electrokinetic and rheological properties of Na-bentonite suspensions were investigated in the presence of various electrolyte solutions including LiCl, NaCl, KCl, NH₄Cl, NaClO₄, CH₃COONa, NaNO₃, Na₂SO₄, Na₃PO₄, CuCl₂, MnCl₂, CaCl₂, BaCl₂, NiCl₂ and AlCl₃. It was found that divalent cations (Cu²⁺, Mn²⁺, Ca²⁺, Ba²⁺ and Ni²⁺) and trivalent cation (Al³⁺) were potential determining cations for the Na-bentonite suspensions. Trivalent cation, Al³⁺, changed the surface charge of Na-bentonite from negative to positive. The zeta potential measurements showed that monovalent counter-cations and mono-, di- and tri-valent anions were indifferent ions for the Na-bentonite suspensions. The plastic viscosity and the Bingham yield stress values of the Na-bentonite suspensions were also determined in the presence of electrolyte solutions.     

Protective action of CLA against oxidative inactivation of paraoxonase 1, an antioxidant enzyme

The effect of CLA on paraoxonase 1 (PON1), one of the antioxidant proteins associated with HDL, was investigated for its protective action against oxidative inactivation as well as its stabilization activity. When cis-9 (c9),trans-11 (t11)-CLA and t10,c12-CLA were examined for their protective activity against ascorbate/Cu²⁻-induced inactivation of PON1 in the presence of Ca²⁺, two CLA isomers exhibited a remarkable protection (E _max, 71–74%) in a concentration-dependent manner (50% effective concentration, 3–4 μM), characterized by a saturation pattern. Such a protective action was also reproduced with oleic acid, but not linoleic acid. Rather, linoleic acid antagonized the protective action of CLA isomers in a noncompetitive fashion. Additionally, the two CLA isomers also protected PON1 from oxidative inactivation by H₂O₂ or cumene hydroperoxide. The concentration-dependent protective action of CLA against various oxidative inactivation systems suggests that the protective action of CLA isomers may be mediated through their selective binding to a specific binding site in a PON1 molecule. Separately, the inactivation of PON1 by p-hydroxymercuribenzoate (PHMB), a modifier of the cysteine residue, was also prevented by CLA isomers, suggesting the possible existence of the cysteine residue in the binding site of CLA. The c9,t11-CLA isomer seems to be somewhat more effective than t10,c12-CLA in protecting against the inactivation of PON1 by either peroxides or PHMB, in contrast to the similar efficacy of these two CLA isomers in preventing ascorbate/Cu²⁺-induced inactivation of PON1. Separately, CLA isomers successfully stabilized PON1, but not linoleic acid. These data suggest that the two CLA isomers may play a beneficial role in protecting PON1 from oxidative inactivation as well as in its stabilization.     

Influence of C18 long chain fatty acids on butyrate degradation by a mixed culture

Butyrate degradation in the presence of C₁₈ long chain fatty acids (LCFAs) was examined under anaerobic conditions at 21 °C. Butyrate degradation rates were a function of linoleic acid (LA) and oleic acid (OA) concentration but independent of the amount of stearic acid (SA) added. Within 2–4 h, butyrate reached undetectable levels in the control cultures. However, in cultures fed with LA, butyrate was removed within between 12 and 25 h and within 2–12 h for cultures inoculated with OA or SA. Propionate was detected in cultures fed with 50 mg dm^?3 LA and in cultures inoculated with OA and SA. LA exerted a greater inhibitory effect on butyrate‐degrading organisms than OA and SA with longer removal times observed in cultures fed with LA. The propionate and acetate removal times and quantity produced were not related to the type and concentration of LCFA. Copyright © 2004 Society of Chemical Industry