Efficiency of removing low-concentration molybdenum from wastewater
by coagulating sedimentation method and adding the aggregate of CaMoO4
Mitsuru INOUE, Kazuo OKAMURA, Atsuko HIDEHIRA
(Environmental Technology Division)
Bulletin of Kanagawa Environmental Research Center No.27,60-66(2004)
The efficiency of removing low-concentration molybdenum from wastewater was examined by the coagulating sedimentation method and adding the aggregate of molybdic acid calcium (CaMoO4).
In order to select the optimum processing experiment, a laboratory test by batch processing was carried out for pH adjustment, mixing, settling and discharging of supernatant water after placing the aggregate of CaMoO4 made beforehand, wastewater containing molybdenum, and calcium chloride in a reactor.
The aggregate of CaMoO4 was made by adding calcium chloride to molybdenum solution. With the aggregate of CaMoO4 which had been made with solution containing 10000 mg l-1 of molybdenum, sedimentation and separation of the supernatant water and the aggregate of CaMoO4 were successfully achieved.
The optimum processing condition was calcium addition to give a Ca/Mo ratio (Ca concentration in the solution/Mo concentration in the solution) of 1 or more, processing time of about ten minutes or more, and mixing speed such that CaMoO4 did not precipitate. Moreover, in removal efficiency tests using a control system without the aggregate of CaMoO4, almost no molybdenum was removed.
The molybdic removal efficiency of sequencing batch processing was 90% or more with a Ca/Mo ratio of 5 or more and processing time of six hours or more.
It was thought that part of the crystal sodium chloride, etc. bonded on the aggregate of CaMoO4 as the coagulating reaction progressed.
When the molybdic removal efficiency was examined with actual industrial wastewater, the removal efficiency was 92-98%.
Improvement of nitrogen removal efficiency
of an anaerobic filter-aerobic biological filtration process
by using nitrifying bacteria immobilized pellets
Mitsuru INOUE, Yasuhiro YAMAMOTO*, Osamu NISHIMURA**, Yuhei INAMORI***, Ryuichi SUDO****
(Environmental Technology Division, *Agricultural Sciences University of Tsukuba, **Graduate School of Engineering, Tohoku University,***National Institute for Environmental Studies,****Tohoku Institute of Technology)
Japanese J. Wat. Treat. Biol. , 39 (3) , 99-107 (2003)
In order to improve nitrogen removal efficiency, an anaerobic filter-aerobic biological filtration process was modified by filling with nitrifying bacteria immobilized carrier made of polyethylene-alcohol (immobilized pellets) as a media for biological filtration tank. The effect of water temperature on T-N removal efficiency was investigated.
When aeration was performed so that the immobilized pellets were fluidized above the ceramic carrier filled in the biological filtration tank, T-N was successfully removed. T-N removal efficiency was increased by increasing the filled ratio of immobilized pellets by replacing a portion of the ceramic carrier at the water temperature of 10 deg C. Conversely, the removal efficiency was lower when the filled ratio of immobilized pellets was 60%, due to the increase of suspended solids in the effluent. Therefore, a proper filled ratio of immobilized pellets was thought to be about 50%.
The nitrification rate at the water temperature of 5 deg C was 17 mg l-1 h-1 for the immobilized pellets and 3.9 mg l-1h-1 for the ceramic carrier, thus the nitrification rate of the former was 4.4 times that of the latter. Removal rates of the inflow carbon and nitrogen were 72% as carbon dioxide and 65% as nitrogen gas, respectively.
The molybdenum removal efficiency of the coagulating sedimentation
with calcium addition method used to treat wastewater containing molybdenum
Shigenori SHOJI , Kazuo OKAMURA , Mitsuru INOUE
(Water Quality Division)
Bulletin of Kanagawa Environmental Research Center No.25,47-52(2002)
The molybdenum removal efficiency of the coagulating sedimentation method
that generates calcium molybdate when it is used to treat wastewater containing
molybdenum was examined.
The processing experiment was carried out by placing the wastewater containing molybdenum and the calcium chloride solution in a reactor, then adjusting the pH, mixing and letting them stand, and analyzing the molybdenum concentration of the filtered supernatant water.
The proper processing conditions such as the amount of calcium added, the pH value, the mixing speed, and the processing time were examined. It was found that the optimum pH value is 7.5, the proper processing time is about 12 hours or more, and the proper mixing speed is that which prevents the precipitation of the calcium molybdate.
When the influence of the coexisting material and the initial molybdenum concentration at the start of the experiment were examined under these proper processing conditions, the removal efficiency decreased when about 5000mg/l of sulphate ion coexisted. Moreover, as the initial molybdenum concentration increased, a higher removal rate was obtained but, the lower the initial molybdenum concentration, the lower the removal rate.
When the reactor was enlarged and removal efficiency from actual industrial wastewater was examined, the removal efficiency was improved when more calcium chloride was added, though the removal efficiency was decreased by the coexisting sulphate ion.
A research on the method of estimating the amount of PRTR chemical substances
in the agricultural chemicals on each city
Takahiro IKEGAI, Keiichi OKA
(Environmental Information Division)
Bulletin of Kanagawa Environmental Research Center No.26,45-51(2003)
We examined the method of estimating the amount of discharge of the PRTR substances in the agricultural chemicals on each city in Kanagawa prefecture, using the cultivation area and the amount of spraying by crops. And we examined the method of estimating the discharge rate of PRTR substances on each phase in every city, using the fugacity model (level 1). Then following results were obtained.
The demand rate by each agricultural chemicals derived this method reflected actual usage of the agricultural chemicals in Kanagawa prefecture. This method is superior to the method using the national demand rate.
As a result of calculating the discharge rate of PRTR chemicals on each phase in every city, it became obvious that many substances distribute into soil. And the substances used together in a rice field and a field had large regional difference of discharge rate. These regional difference reflected actual usage of the agricultural chemicals in Kanagawa prefecture.
Effect of non-covalent interactions between organic compounds
and humic substances on analytical pervaporation
Satoko MISHIMA,Tutomu NAKAGAWA*
(Environmental Conservation Division,*Department of Industrial Chemistry, Meiji University)
Journal of Membrane Science, 228, 1-4(2004)
In analyzing the compounds in environmental samples, recovery is decreased by the effect of humic substances. The non-covalent interaction between the organic compounds and humic substances should be considered in analytical pervaporation. Analytical pervaporation through a PDMS membrane for environmental samples was investigated and evaluated by comparison to the pervaporation results for the model solution with added humic acids to clarify the non-covalent interaction. At pH 8.5, polar compounds, were prevented from permeating into the membrane by the interactions, also, the flux decreased with increasing humic acid concentration. At pH 4, the non-covalent interactions of pai-pai interactions are predominant between solute compounds and humic acids. Fluorobenzene and 4-bromofluorobenzene, with a benzene ring, interacted with humic substances and the flux decreased.
Formation of 1,3-, 2,4-, 1,2-, 1,6-, 1,8- and 1,7-Dinitropyrenes
in Metallic Oxides as Soil Components in the Presence of Indoor Air
with 1-Nitropyrene and Sodium Chloride Under Xenon Lamp Irradiation
Hidetoshi SUGIYAMA, Tetsushi WATANABE*, Tsuyoshi MURAHASHI*, Teruhisa HIRAYAMA*
(Environmental Conservation Division,*Kyoto Pharmaceutical University )
Journal of Health Science,50(1), 66-74(2004)
The reaction products obtained from the mixture of 1-nitropyrene (1-NP) and sodium chloride were investigated on three metallic oxides as soil components under xenon lamp irradiation in the presence of indoor air. These chemicals including 1-NP were extracted with benzene/ethanol (4/1, v/v) and analyzed by gas chromatography/mass spectrometry (GC/MS). The amounts of 1-NP gradually decreased as irradiation time elapsed on all three metallic oxides (TiO2: titanium dioxide, anatase form; SiO2: silicon dioxide, silicic anhydride form; and Al2O3: aluminum oxide). In TiO2 in particular, 1-NP showed a greater decrease than the other two metallic oxides for all irradiation times. Six types of dinitropyrenes (DNPs) were detected from the reaction products (1,3-, 2,4-, 1,2-, 1,6-, 1,8- and 1,7- DNP). In both TiO2 and Al2O3, all 6 DNPs were detected, while in SiO2, 5 DNPs were confirmed except for 2,4-DNP. In TiO2, 1,7-DNP was formed in especially rich amounts for all irradiation times in comparison with the other metallic oxides. We presumed that 4- and 2-NPs were generated from 1-NP by the photochemical reaction of OH radical, and that 2,4-, 1,2- and 1,7-DNPs were formed continuously by the nitration of these isomers. The formation of 2,4-, 1,2- and 1,7-DNPs was confirmed for the first time on the metallic oxides by the photochemical reaction system of the 1-NP-NOx-Cl ion. NOx in the indoor air was shown to be a source of nitrogen used in forming DNPs in these metallic oxides. The yields and formation patterns of DNPs differed in the 3 metallic oxides as the irradiation time was extended. Hence, the nature of the photochemical reaction in the formation of DNPs differed depending on the type of metallic oxide in question. In SiO2, mutagenicity increased gradually up to 6 hrs of irradiation when mutagenic potency showed 2.6 million revertants/sample, and then decreased to 1.5 million revertants/sample at 12 hrs. In Al2O3, mutagenicity increased gradually as irradiation time elapsed to a maximum of 1.64 million revertants/sample. In TiO2, mutagenicity decreased rapidly to 60 % at 10 min and thereafter decreased gradually to 22 % at 12 hrs.
A Revision of the Genus Cincticostella (Insecta: Ephemeroptera: Ephemerellidae)
(Environmental Conservation Division)
The Japanese mayfly genus Cincticostella is taxonomically revised. The four currently recognized species are Cincticostella (Cincticostella) elongatula (McLachlan, 1875) (=okumai Gose, 1980, syn. nov.), C. (C.) levanidovae (Tshernova, 1952), C. (C.) nigra (Ueno, 1928), and C. (C.) orientalis (Tshernova,1952) ( = tshernovae (Bajkova, 1962). The lectotype and paralectotypes of Ephemerella nigra are designated from the syntypes of Ueno. Specimens treated as C. (C.) nigra by many authors are identified with C. (C.) elongatula. All species are redescribed based on examined types and newly collected specimens. Keys are given to all stages: imagoes, subimagoes, nymphs, and eggs. Illustrations, complete synonymies, and distributional records are included for all the species, and the life histories of two species, C. (C.) elongatula and C. (C.) nigra, are presented.
Simultaneous sampling in multisite of benzene and 8 chlorinated organic compounds
by passive sampler and estimate of upper-bound lifetime cancer risks
Yoichi KATO, Hidetoshi SUGIYAMA, Mitimasa TAKAHASHI,Atuko HASEGAWA,Yoshiaki SUYAMA
(Air Quality Division)
Bulletin of Kanagawa Environmental Research Center No.24,50-55(2001)
In order to estimate the upper-bound lifetime cancer risks, we measured
benzene and 8 chlorinated organic compounds at 37 sampling sites in Kanagawa
Prefecture. These chemicals were collected by "passive sampler"
method at simultaneous sampling in multisite.
The "passive sampler", as monitoring sampler for organic solvent fume in working environment was applied to the estimation of atmospheric concentrations of these chemicals. The upper-bound lifetime cancer risks by these chemicals were estimated from cancer unit risk factors. The average of estimated risk was 3.8*10-5(between 2.1*10-5 and 8.0*10-5), and significant difference was not found according to the areas.