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The results of studies on producing the biocatalyst based on catalase immobilized in the fibers from triacetate are presented. The catalase producer is Penicillium fungus. Catalase was produced by precipitation with the use of ethyl alcohol from the cultural fluid with separate and unseparate mycelium. The highest activity of catalase in the cultural fluid is seen on the nutrient medium containing 4% of carbon source. For immobilization the water solution of enzyme was concentrated in the vacuum-rotor evaporator at temperature of 25 degrees C. The enzyme was included in the structure of fibers during the process of their formation. Of the fiber-producing polymers (cellulose triacetate, chlorine, polysulphone) the most enzymatic activity has the catalase-containing fibers derived from the cellulose triacetate, in this case, the fine fibers of biocatalyst have the higher specific activity. It is established that the fibers obtained by using catalase of microbiological origin possess high stability and their activity does not practically change in the aqueous environment. The unpurified catalase is one and a half higher than at purified catalase. Under laboratory conditions there turned out the experimental batches of fibers and there conducted their endurance tests. Catalase included in cellulase triacetate has effectively functioned during a period of 2 years purifying the distilled water containing 50 mg/l of hydrogen peroxide.
Photocatalytic processes in the presence of titanium dioxide provide an interesting route to destroy hazardous organic contaminants, being operational in the UV-A domain with a potential use of solar radiation. In this paper, some specific contaminant classes of interest such as ethylbenzene, gamma-lindane and EPTC have been tested at laboratory scale and in the field to determine the feasibility of the photocatalytic oxidation of organic contaminants in water. Our preliminary results at laboratory scale with these chemicals have provided a better understanding of the photocatalytic process which seems to be efficient and not selective. The application of these processes in removal of gamma-lindane from water operating in a parabolic trough concentrator has demonstrated to be effective, being possible to reduce 99.9% of gamma-lindane levels in water in acceptable times.
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Enzymatic removal of various phenol compounds from artificial wastewater was undertaken by the combined use of mushroom tyrosinase (EC 1.14.18.1) and chitosan beads as function of pH value, temperature, tyrosinase dose, and hydrogen peroxide-to-substrate ratio. Chitosan film incubated in a p-crersol+tyrosinase mixture had the main peaks at 400-470 nm assigned to chemically adsorbed quinone derivatives, which increased over the immersion time. These results indicate that removal of phenol compounds is caused by their tyrosinase-catalyzed oxidation to the corresponding quinone derivatives and the subsequent chemical adsorption on the chitosan film. The optimum conditions for quinone adsorption were determined to be pH 7 and 45 degrees C for p-cresol. Some alkyl-substituted phenol compounds were removed by adsorption of quinone derivatives enzymatically generated on the chitosan beads, and the % removal for p-cresol, 4-ethylphenol, 4-n-propylphenol, 4-n-butylphenol, and p-chlorophenol went up to 93%. In addition, 4-tert-butylphenol underwent tyrosinase-catalyzed oxidation in the presence of hydrogen peroxide. This procedure was applicable to removal of chlorophenols and alkyl-substituted phenols.
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We have analyzed the dissolved activity of various radionuclides of natural origin (226Ra and (234,235,235)U) and artificial origins (90Sr and (239+240)Pu), together with other non-radioactive physico-chemical parameters (pH, conductivity, dry residue, [Ca2+], [Mg2+], [K+] and [Fe(2+,3+)], in both pre-potable and potable water from 17 treatment plants in Extremadura (Spain). We have established a series of criteria and complementary techniques to the traditional methods of purification, aimed at the quantitative elimination of the presence in solution of the mentioned radionuclides. We highlight: (a) the increment of the mineral content of the water in its treatment succeeds in eliminating 226Ra, until reaching values close to 70%; (b) the increment of the mineralization of the water by addition of chemical reagents, conducted within the pH values 7.1 and 7.8, succeeds in eliminating up to 90% of the total uranium in dissolution; (c) the elimination of 90Sr during the purification is poor, in general, reaching average levels of only 15% when the purification process is practiced within concrete ranges for potable water (pH > 7, conductivity > 150 microS/cm, dry residue > 150 mg/l, [Ca2+] > 10 mg/l and [Mg2+] > 1.2 mg/l), and finally, (d) the decrease of the solubility of the iron, as low as it can get during the purification process, together with an increase of the conductivity associated, in principle, to parallel increments of other variables not analyzed in this work, such as SO4(2-), CO3(2-), etc., the activity of dissolved (239+240)Pu decreases to 90%. The application of the traditional processes of water purification outside the ranges and criteria formulated can increase the presence in dissolution up to 400%, for some radionuclides, largely the consequence of its redissolution from the non-soluble fraction of the water.
Experiments were conducted to measure communities of bacteria within operating ultrapure water treatment systems intended for laboratory use. Samples from various locations within Milli-Q Plus and Milli-Q UV Plus systems were analyzed for populations of planktonic bacteria at weekly intervals over 3 months of operation. Relatively high initial densities of planktonic bacteria (10(2) to 10(3) bacteria per ml) were seen within both units when they were challenged with source water of poor quality, although the product water continued to be acceptable with regard to bacterial numbers, resistivity, and endotoxin concentration. Under more normal operating conditions, significant differences were seen in planktonic populations throughout the systems with excellent product water quality. A great deal of variability was observed in biofilm populations analyzed from various system surfaces after 3 months of operation. The concentrations of planktonic bacteria and biofilm densities were much lower in the unit containing a UV lamp. These findings suggest that a range of microenvironmental conditions exist within purified water systems, leading to variable populations of bacteria. However, product water of excellent quality was obtained despite the bacterial communities.
Studies on PCB concentration and their distribution in waste water sludge of a municipal sewage plant are made. The incoming sewage has an average concentration of 813 ng/l, the effluent still contains 108 ng/l. The biggest part of the PCB is accumulated in the sludge. A comparison of the in- and output of PCB and the average PCB-patterns at the various sampling sites of the sewage plant shows that the PCB are not transformed or decomposed microbially.
Between 1968 and 1980 fractures occurred in 56 of 284 patients treated by home haemodialysis in the Sheffield area for longer than one year. Patients sustained four times as many fractures while using dialysate prepared with water containing more than 1.0 mumol aluminium per 1 (2.7 micrograms/100 ml) than while using water containing a smaller concentration. When aluminium was removed from water by deionisation the incidence of fractures diminished during the next year and no patient developed dialysis encephalopathy. These findings show that 1.0 mumol/l is a safe maximum concentration of aluminium in water for use in home haemodialysis. It can be detected by the colorimetric aluminium analyses used by many water authorities. When financial resources are limited it is expedient to reserve aluminium analyses by electrothermal atomic absorption for plasma from patients receiving regular haemodialysis. Ingestion of aluminium hydroxide contributes significantly to the increased plasma aluminium concentration of these patients.
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In order to select the method of water regeneration from air moisture condensate in a manned enclosed environment, the procedure of water decontamination from ethylene glycol was investigated. The process developed at t 20-22 degrees C and the following concentrations of C2H6O2 = 0.0125-0.5 mole/l, H2O2 = 1-5 mole/l, and catalyst = 1.7-50% wt. In the presence of 6.67 g/l of homogeneous catalyst FeSO4.7H2O, destructive oxidation of ethylene glycol to yield CO2 in the system 0.1 M C2H6O2 + 1M H2O2 proceeded effectively. However, the iron concentration in the decontaminated water exceeded significantly the maximally allowable concentration of iron in potable water as well as in industrial and non-industrial sewage. Heterogeneous MnO- and PbO-based catalysts provided no more than 20% ethylene glycol oxidation. Siderite, a natural mineral containing 33% wt. Fe2+, proved a more effective catalyst of ethylene glycol oxidation. When ethylene glycol and hydrogen peroxide were used at ratios of 1:30 and 1:80 with 5% wt. siderite, the degree of C2H6O2 to CO2 conversion was 99.2% and 99.8, respectively.