Wet oxidation: a pre-treatment procedure for sludge

Wet oxidation process is specially effective for wastes with a high organic matter which can not be removed by conventional treatment methods. The digested and raw activated sludges of PAKMAYA yeast factory are treated by wet oxidation process. The liquid-phase organic matter concentration [as total organic carbon (TOC)] was increased by 16.5% in 10 min during the wet oxidation in the presence of Cu as catalyst and H2O2. Lenghtening the period of the wet oxidation, the TOC-concentration was increased by 66% in 120 min. The biodegradability of the sludge after wet oxidation process was also examined. A very little development in the biodegradability was observed, when wet oxidation was applied as pre-treatment to the digested sludge (5% decrease as TOC, in the presence of Cu catalyst and H2O2). However, in the case of digestion of the raw sludge after the application of wet oxidation, the biodegradability increased significantly (approximately 75%, as TOC). Moreover, wet oxidation improved the ability of settling of sludge solids, as well as enhancing the treatment efficiency. Finally, the volume of settled solids was decreased by 80% in the presence of Cu and H2O2. NH3+-N, NO2(-)-N and NO3(-)-N concentrations in the supernatant decreased with the wet oxidation. pH value of the sludge increased from 6.6 to 7.8-8.0. Since stable sludge was taken from the digester where the nitrification process was progressing, a decrease in the nitrite concentration, with an increase in nitrate was observed in the digestion continuing after the wet oxidation pre-treatment. However, in the raw activated sludge, there was a nitrite formation only in the non-pretreated sludge.     

Upflow column reactor design for dechlorination of chlorinated pulping wastes by Penicillium camemberti

A Penicillium camemberti strain isolated in our laboratory has been studied for its ability to degrade chlorinated pulping wastes, presumably containing a variety of chlorinated polyphenols. In batch tests, the highest removals (76% AOX, 61% color and 65% TOC) were obtained with 0.2 g/l feed acetate concentration. The tendency of the fungus to dechlorinate bleachery effluents better under non-shaking conditions and to attach onto surfaces suggested the use of immobilized cells rather than freely suspended ones in further exploitation of the process. An upflow glass wool packed column reactor established with this fungus could be operated for nearly two years in the laboratory. At best around 70% AOX could be removed from chlorinated pulping wastes in 7.3 h of contact with no aeration and with a minimal amount of carbon supplement (0.2 g/l). Finally, an asymptotic mathematical formula for determining Michaelis-Menten kinetic rates has been derived. The kinetic rates K(m) (the Michaelis constant or saturation constant for the substrate) and V(m) (the product of maximum rate for the enzymatic reaction and biomass concentration) were then calculated as 126.386 mg/l and 2.83017 mg/lh, respectively.     

Confined placental mosaicism in term placentae: Analysis of 125 cases

In order to determine the incidence of confined placental mosaicism (CPM) in term placentae and to show the presence of specific sites and the effect on fetal development, 125 placentae from uneventful pregnancies were analysed by cytogenetic methods. The incidence was at least 4.8 per cent and there were no specific sites on the placenta. Although the number of cases is still too small, we found CPM to be associated with intrauterine growth retardation in six cases.     

Determination of cytotoxic,genotoxic, and oxidative damage from deltamethrin on primary hepatocyte culture of Lake Van fish,Alburnus tarichi

ABSTRACT

Deltamethrin is a widely used pyrethroits worldwide. Although the chemical is used to combat insects, it has effects on other non-target organisms. Deltamethrin is extensively used in agriculture, animal husbandry, and domestic areas in the Lake Van basin. The aim of this study was to determine the cytotoxic, genotoxic, and oxidative damage from deltamethrin on the primary hepatocyte culture of Lake Van fish (Alburnus tarichi). In this study, the toxic effects of different concentrations (0.01, 0.1, 1, and 10?µM) of deltamethrin in the primary hepatocyte culture of Lake Van fish were investigated via liver enzymes aspartase aminotransferase (AST) and alanine aminotransferase (ALT), and the total antioxidant status (TAS), total oxidant status (TOS), lipid peroxidation (MDA), and DNA damage (8-OHdG).

Deltamethrin caused an increase in the AST and ALT levels dependent on the dosage and time. The TAS and TOS levels increased at the end of 24?h and there was no difference at the end of 48?h. Deltamethrin did not affect the MDA level, but increased the 8-OHdG (P?<?0.05). In conclusion, it can be said that high doses of deltamethrin (1 and 10?µM) have a toxic effect on the primary hepatocyte culture of Lake Van fish.     

Observations on solid phase micro-extraction for MTBE analysis

In a recent study of aqueous phase methyl tertiary butyl ether (MTBE) adsorption onto hydrophobic molecular sieves, the solid phase micro-extraction gas chromatography analytical technique was used to measure MTBE concentrations in water. The method was especially beneficial in measuring MTBE concentrations in the microg/l range, but anomalies were observed that investigators should be aware of before employing this technique. Specifically, it was observed that the calibration of the extraction fiber with known MTBE concentrations was non-linear over all concentration ranges. The technique was not suited to higher concentrations, and dilutions were necessary to increase the working range of the technique. Lastly, the fiber was observed to extract increasingly less MTBE from known standard solutions over time, requiring repeated calibrations to obtain reliable concentrations of unknown samples.     

Investigation of acute toxicity of permethrin on guppies Poecilia reticulata

Permethrin, a synthetic pyrethroid pesticide and potential toxic pollutant contaminating aquatic ecosystems, was investigated in the present study for acute toxicity. Guppy fish (Poecilia reticulata) were selected for the bioassay experiments. The experiments were repeated 3 times and the 48-h LC(50) was determined for the guppies. The static test method of acute toxicity test was used. Water temperature was regulated at 20+/-1 degrees C. In addition, behavioral changes at each permethrin concentration were observed for the individual fish. Data obtained from the permethrin acute toxicity tests were evaluated using the probit analysis statistical method. The 48-h LC(50) value for guppy was estimated as 245.7 microg/l. Values in the range of 0.05-97.0 microg/l have been reported for various other fish species.     

Investigation of organic nitrogen and carbon removal in the aerobic digestion of various sludges

Nitrification and carbon removal are investigated in aerobicbatch digestion of various sludges. The experiments arecarried out with activated sludge (Test 1) and with amixture of activated and primary settling sludge (Test2). The nitrification rate was monitored, measuring theNO₂ ^- concentration. At the 3rd day of thedigestion 40.7 mg_NO2-N/l and 3.89 mg_NO2-N/l werefound in Tests 1 and 2 respectively. In a digestion process,the degradation of biomass indicates the beginning of theendogenous phase. Our measure for biomass content of thesludge was protein analysis. In Test 1, the first day valuesof 50.93 mg_TOC/ g_{dry matter}/day and 138.53mg_protein-C/g_{dry matter}/day for specific TOC andprotein-C removal rates showed, that the digestion processbegan in the endogenous phase. For Test 2, since theendogenous phase began after removal of raw organic matter inprimary settling sludge, specific TOC and protein-C removalrates were observed to be 60.12 mg_TOC/g_{dry matter}/dayand 26.72 mg_protein-C/g_{dry matter}/day,respectively.     

外浮顶原油储罐VOCs排放核算参数对排放量的影响

依据美国环保署颁布的储罐VOCs排放量核算公式,从环境参数、原油参数和储罐结构参数3个方面对外浮顶储罐VOCs排放的影响进行了研究,其中包括了边缘密封排放挂壁排放、浮盘附件排放和浮盘着陆期间排放等几个相关排放核算数学公式。结果表明:环境风速增大,环境温度升高或太阳辐射强度提高均导致排放量增大;原油温度升高或原油周转量增加也导致排放量增加;储罐直径增加,罐漆颜色浅,或者罐壁锈蚀情况好会降低VOCs排放量。