An alternative for pre‐treatment of high‐strength raw whey wastewaters: submerged membrane bioreactors

The direct treatment of whey wastewater at various sludge ages (10–75 days) and high biomass concentration (above 50 g mixed liquor suspended solid (MLSS) dm^?3) in a submerged membrane bioreactor (sMBR) is described. The chemical oxygen demand (COD) of raw whey varied in the range of 60 and 90 g dm^?3. After feeding the sMBR with raw whey, effluent COD reduced to about 20 g dm^?3. The effluent was free of suspended solids and total coliform bacteria. Total phosphorus (TP) and orthophosphate (Ortho‐P) in the influent varied between 204 and 880 mg dm^?3 and between 180 and 620 mg dm^?3, and effluent TP and Ortho‐P reduced to 113 and 109 mg dm^?3, respectively. The ammonium and nitrate concentrations in the influent were in the ranges of 3.4 and 120 mg dm^?3 and 10 and 503 mg dm^?3, respectively. The effluent ammonium concentration varied between 17.6 and 198 mg dm^?3 and nitrate concentrations varied between 0.9 and 69 mg dm^?3. Effluent turbidity varied between 23 and 111 FAU (Formazin Attenuation Unit). The results show that sMBR is an effective pre‐treatment system for high‐strength agro‐wastewaters because of its ability to reduce the pollution load. Copyright © 2004 Society of Chemical Industry     

Impact of the presence of solids on peroxidase‐catalyzed treatment of aqueous phenol

The impact of the presence of solids on the treatment of aqueous solutions of phenol using horseradish peroxidase (HRP) and hydrogen peroxide was investigated. The solids studied were silica gel, kaolin, bentonite, cellulose and peat moss. Kaolin, bentonite, cellulose and peat moss enhanced phenol transformation at pH 5.0 and 7.0 starting at concentrations of 100, 1000 or 10 000 mg dm^?3. At pH 9.0, bentonite and kaolin had negative impacts when present at 10 000 mg dm^?3 and peat moss when present at 1000 mg dm^?3 and 10 000 mg dm^?3. In the case of bentonite and peat moss, the enhancing effects at pH 7.0 were associated with the dissolved or colloidal constituents, while in the case of kaolin, the enhancing effects were due to the solid material. Freshly made bentonite suspensions inactivated the peroxidase enzyme; however aged bentonite suspensions and their supernatants did not affect enzyme stability. H₂O₂ was unstable in solutions containing peat moss constituents. Phenolic solutions treated in the presence of bentonite, kaolin and peat moss were significantly less toxic than the controls, indicating that these materials were able to interact with and partially neutralize precursors of toxic reaction products. Copyright © 2003 Society of Chemical Industry     

Effect of microbial treatment on brightness and heat‐induced brightness reversion of high‐yield pulps

BACKGROUND: The manufacture of high‐yield pulps is attractive due to its efficient utilization of lignocellulosic material. However, their rapid brightness reversion when exposed to heat and light restricts their more widespread use in high‐quality papers. This study investigated the potential of bio‐treatment with more than 30 species of fungi and yeasts to inhibit heat‐induced yellowing of high‐yield pulps. RESULTS: Treatment with Penicillium sp. ZCF34, Saccharomyces cerevisiae INVS2 and 724 reduced the brightness reversion and increased the brightness of wheat straw semi‐chemical pulp after 4 days incubation (postcolor number decreased by 33.96%, 66.42% and 57.09%, and brightness increased by 0.84%ISO, 0.48%ISO and 0.89%ISO, respectively). Phanerochaete chrysosporium W14 treatment was best for depressing yellowing of bleached aspen CTMP (chemi‐thermo‐mechanical pulp) and Saccharomyces cerevisiae AH22 treatment gave the highest brightness and a lower postcolor number. For unbleached aspen CTMP, treatment with Fusarium concolor X4 and Saccharomyces cerevisiae H158 was effective in improving brightness and brightness stability after 2 and 4 days incubation, respectively. CONCLUSION: Treatment with some microorganisms increased pulp brightness and strongly suppressed heat‐induced yellowing. It offers an option for improving the brightness stability of high yield pulps and some valuable information for bio‐pulping and bio‐bleaching with microbial treatment. Copyright © 2009 Society of Chemical Industry     

Surface modification of polypropylene membrane by low‐temperature plasma treatment

Microporous polypropylene membranes were low temperature plasma treated with acrylic acid and allylamine. Parameters of plasma treatment were examined and optimized for the enhancement of membrane performance properties. Excess power damaged the membrane surface and excess monomer flow rate increased the reactor pressure to interfere with the glow discharge. Longer plasma treatment time resulted in even more plasma coating and micropore blocking. The contact angle with water decreased and wettabilities increased with the increase of plasma treatment time. Deposition of the plasma polymer on the membrane surface was confirmed by FTIR/ATR spectra of the treated surface. In determining the flux, the hydrophilicity of the surface played a role as important as that of the micropore size. Adequate plasma treatment could enhance both water flux and solute removal efficiency. Results from the BSA (bovine serum albumin) solution test confirmed that fouling was greatly reduced after the plasma treatment. The BSA solution flux through the plasma‐treated membranes depended on pH, whereas pH variation had no serious effects on the untreated membrane. Modification of the surface charge by the plasma treatment should exert a substantial influence on the adsorption and removal of BSA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1555–1566, 2001     

Solid‐state hydrolysis of postconsumer polyethylene terephthalate after plasma treatment

Plasma treatments were applied on the surface of postconsumer polyethylene terephthalate (PET) bottles to increase their wettability and hasten the subsequent hydrolysis process. Sixty‐four treatments were tested by varying plasma composition (oxygen and air), power (25–130 W), pressure (50–200 mTorr), and time (1 and 5 min). The best treatment was the one applied in air plasma at 130 W and 50 mTorr for 5 min, as it provided the lowest contact angle, 9.4°. Samples of PET before and after the optimized plasma condition were subjected to hydrolysis at 205°C. Although the treatment changed only a thin surface layer, its influence was evident up to relatively high conversion rates, as the treated samples presented more than 40% higher conversion rates than the untreated ones after 2 h of reaction. Infrared spectroscopy showed that the terephthalic acid obtained from 99% of depolymerization was similar to the commercial product used in PET synthesis. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The ultrasound‐based interfacial treatment of aramid fiber/epoxy composites

The quality of interfacial adhesion of aramid/epoxy composites affects the mechanical performance of the material, and thus there is a need to improve the condition by using the ultrasound‐based interfacial treatment. To do so, an ultrasonic transducer has been developed and evaluated under various operational conditions when it is installed in the winding system. It has demonstrated several key characteristics such as low power, high amplitude (more than 80 μm), and continuous working (more than 8 h) without water‐cooling. Subsequently, experiments were carried out to determine the mechanical performance of the polymer material with and without ultrasound treatment, showing that the ultrasonic treatment has improved the interfacial performance up to 10%, compared with those without any ultrasound‐treatment. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Thermal,chemical and thermo‐chemical pre‐treatment of waste activated sludge for anaerobic digestion

The influence of different pre‐treatments was studied in order to observe the effects of temperature, pH and treatment time on Waste Activated Sludge (WAS) solubilization, and anaerobic digestion of pre‐treated sludge. Results showed that thermo‐chemical pre‐treatments were the most efficient on Chemical Oxygen Demand (COD) solubilization, which could reach 83% at 170 °C with pH = 12. Yet, increase in COD solubilization in thermo‐chemical pre‐treatment was not linked to an increase in soluble Volatile Solids (VS) as optimal conditions were 170 °C, and 130 °C with pH = 10, for this criterion. So, temperature was found to be the most influential parameter on COD and VS solubilization. Biodegradability batch anaerobic tests confirmed results obtained on WAS solubilization, that is to say that 170 °C and 130 °C with pH = 10 were optimal conditions, with respectively 45% and 21% of anaerobic digestion enhancement. Thus these two conditions were chosen for sludge treatment before continuous anaerobic digestion. Results, after stabilization have shown a better efficiency of 170 °C compared with 130 °C with pH = 10 pre‐treatment, since after anaerobic digestion it led to 71% of COD degradation and 59% of Total Solids (TS) degradation, with an improvement of 54% in biogas production. The main differences between those two pre‐treatments could be due to the pre‐treatments themselves more than to an effect on anaerobic digestion, because the first one led to a partial loss of WAS COD (near 17% of initial COD) and the second one to an increase in TS due to addition of base. Copyright © 2004 Society of Chemical Industry     

Benzene removal with vertical‐flow constructed treatment wetlands

BACKGROUND: Twelve vertical‐flow experimental wetlands have been constructed using different compositions, and were operated in batch‐flow mode to reduce pumping costs. Six wetlands were located indoors and six outdoors. Benzene was used as a representative example substance to assess the removal of low molecular weight petroleum compounds. RESULTS: Findings indicate that the constructed wetlands remove benzene (inflow of approximately 1.3 g L^?1) from hydrocarbon‐contaminated wastewater streams with better indoor (controlled environment) than outdoor treatment performances. Overall mean removal efficiencies for the experimental rig placed outside were as follows: benzene 85%, chemical oxygen demand (COD), 70%; ammonia‐nitrogen, 83%; nitrate‐nitrogen, 88%; ortho‐phosphate‐phosphorus, 58%. In comparison, removal efficiencies for the experimental rig placed indoors were higher: benzene 95%, COD, 80%; ammonia‐nitrogen, 90%; nitrate‐nitrogen, 94%; ortho‐phosphate‐phosphorus, 66%. Benzene removal was predominantly due to volatilization after 1 day of retention time. CONCLUSION: The use of aggregates (sand and gravel) and the presence of Phragmites australis (Cav.) Trin. ex Steud. resulted in no significant difference in terms of benzene, redox potential, dissolved oxygen, 5‐day at 20 °C N‐allylthiourea biochemical oxygen demand, COD and nutrients removal. Statistical differences were assessed by analysis of variance and Tukey HSD tests (P < 0.05). Copyright © 2007 Society of Chemical Industry     

Effect of thermal treatment on the tensile and in‐plane shear behavior of carbon fiber‐reinforced poly(phenylene sulfide) composite specimens

The effect of PPS matrix evolution occurring during thermal treatment of carbon fiber‐reinforced PPS plies prior to their consolidation to laminates on the mechanical behavior of the composite material has been investigated. The thermal treatments were performed at temperatures and times, which are relevant for processing PPS composites. All thermal treatments were carried out in an oven in air to facilitate the presence of oxygen, while the subsequent consolidation was performed in an autoclave. The tensile and in‐plane shear behavior of both, thermal‐treated and untreated materials, was investigated. Differential scanning calorimetry and microscopy analyses were made to evaluate the effect of the performed thermal treatments on degree of crystallinity and porosity of the laminates. The mechanical tests carried out have shown an appreciable degradation of the mechanical properties investigated. The observed degradation increases with increasing thermal treatment temperature and time when thermal treatments were carried out on each single composite ply prior to the consolidation. On the other hand, when, prior to the consolidation, the whole set of plies was subjected to thermal treatment, improved mechanical properties were observed. The results were discussed under the viewpoint of PPS matrix evolution during processing of the composite plies in the presence of oxygen. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A numerical‐indicator‐based method for design of distributed wastewater treatment systems with multiple contaminants

In the design of distributed wastewater treatment systems with multiple contaminants, it is very important to minimize unnecessary stream mixing to reduce total treatment flow rate as much as possible. A new numerical indicator, total mixing influence potential (TMIP), to reflect the influence of the stream mixing caused by performing a process on the total treatment flow rate of a distributed wastewater system is introduced. In design procedure, the TMIP value is calculated based on pinch principle. The process with the smallest TMIP value will be performed first. The results of a few literature examples show that designs with very low (even minimum) total treatment flow rates can be obtained with the method proposed. In addition, the method proposed is simple and of clear engineering insight. The calculation effort does not increase significantly when the number of streams, contaminants, and/or treatment units increases. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3223–3231, 2015     

Biological treatment of saline wastewaters from marine‐products processing factories by a fixed‐bed reactor

Wastewaters generated by a factory processing marine products are characterized by high concentrations of organic compounds and salt constituents (>30 g dm^?3). Biological treatment of these saline wastewaters in conventional systems usually results in low chemical oxygen demand (COD) removal efficiency, because of the plasmolysis of the organisms. In order to overcome this problem a specific flora was adapted to the wastewater from the fish‐processing industry by a gradual increase in salt concentrations. Biological treatment of this effluent was then studied in a continuous fixed biofilm reactor. Experiments were conducted at different organic loading rates (OLR), varying from 250 to 1000 mg COD dm^?3 day^?1. Under low OLR (250 mg COD dm^?3 day^?1), COD and total organic carbon (TOC) removal efficiencies were 92.5 and 95.4%, respectively. Thereafter, fluctuations in COD and TOC were observed during the experiment, provoked by the progressive increase of OLR and the nature of the wastewater introduced. High COD (87%) and TOC (99%) removal efficiencies were obtained at 1000 mg COD dm^?3 day^?1. © 2002 Society of Chemical Industry     

Prospects for the application of dielectric heating processes in the pre‐treatment of oilseeds

In some branches of industry dielectric heating processes are used in a wide range of different applications like drying of agricultural products and textiles or disinfection processes in the food processing and pharmaceutical industry. This report shows potential uses of this technology for thermal pre‐treatment of oilseeds. Therefore, the basic principles of the dielectric heating mechanism and some resulting characteristics are presented in comparison to conventional heating systems. Special aspects of the application of microwaves and high‐frequency energy for thermal pre‐treatment of oilseeds are also presented. Finally, some scenarios for imaginable applications of this technology in the European oil milling industry are discussed.     

Enhancement of biodegradability of industrial wastewaters by chemical oxidation pre‐treatment

Chemical oxidation technologies are often employed for the treatment of complex industrial effluents that are not amenable to conventional biological methods. The role of chemical oxidation depends on the treatment objectives and may vary from partial remediation to complete mineralization. In the case of partial treatment, chemical oxidation aims at the selective removal of the more bioresistant fractions and their conversion to readily biodegradable intermediates that can subsequently be treated biologically. Coupling chemical pre‐oxidation with biological post‐treatment is conceptually beneficial as it can lead to increased overall treatment efficiencies compared with the efficiency of each individual stage. This paper reviews recent developments and highlights some important aspects that need to be addressed when considering such integrated schemes. Copyright © 2004 Society of Chemical Industry     

Decrement of cellulose recalcitrance by treatment with ionic liquid (1‐ethyl‐3‐methylimidazolium acetate) as a strategy to enhance enzymatic hydrolysis

BACKGROUND: The high crystallinity of cellulose underlies the recalcitrance that this polymer presents in enzymatic degradation. Thus, a pre‐treatment step is applied in most bioconversion processes. Treatments with ionic liquids are considered an emerging pre‐treatment technology, owing to their high efficiency in solvating cellulose, over molecular solvent systems. RESULTS: Crystalline cellulose with and without ionic liquid (1‐ethyl‐3‐methylimidazolium acetate) treatment, both commercially available, were used as substrates in enzymatic hydrolysis reactions using the earlier evaluated cellulolytic system of Fusarium oxysporum. The in situ removal of the hydrolysate during reactions enhanced the reaction rate as well as the overall glucose production. Ionic liquid treatment significantly decreased cellulose crystallinity and enhanced bioconversion yields and rates. The effects of cellulose structural changes during treatment on hydrolysis rate were investigated and the recalcitrance constants were determined. CONCLUSION: The study showed that ionic liquid‐treated cellulose became more homogeneous and more easily degradable than the untreated cellulose, a conclusion that was expressed mathematically by the difference in the recalcitrance constants for the two substrates. It was concluded that glucose production from ionic liquid‐treated cellulose could achieve very high conversion yields in consolidated bioprocesses or during simultaneous saccharification and fermentation. Copyright © 2012 Society of Chemical Industry     

Effect of hypochlorite treatment on performance of hollow fiber membrane prepared from polyethersulfone/N‐methyl‐2‐pyrrolidone/tetronic 1307 solution

Polyethersulfone (PES) hollow fiber membrane was prepared by blending with nonionic surfactant Tetronic 1307 to improve its hydrophilicity. The membranes were posttreated by hypochlorite solution of 10, 100, 500, and 2000 ppm. The effect of hypochlorite treatment on the performance of PES membrane was investigated. Experimental results showed that the water permeability of treated membrane was two to three times higher than that of untreated membrane in case of blend membrane prepared from PES/N‐methyl‐2‐pyrrolidone (NMP)/Tetronic 1307 solution. On the other hand, hypochlorite treatment has no effect on water permeability of the membrane prepared from PES/NMP solution. Elemental analysis and ATR–FTIR measurement results indicated that hypochlorite treatment led to decomposition and leaching out of Tetronic 1307 component from the membrane. The change of membrane surface structure by the hypochlorite treatment was confirmed by atomic force microscopy measurement. The hypochlorite treatment brought about no significant impact on the mechanical property of the membranes. This indicated that the hypochlorite treatment of PES membrane prepared with surfactant was a useful way to improve the water permeability without the decrease of membrane strength. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008