COD Analysis Research Articles

Pediatric liver transplantation for primary malignant liver tumors with a focus on hepatic epithelioid hemangioendothelioma: The UNOS experience

Treatment for HEH does not follow a standardized algorithm. From clinical experience, it is assumed that pediatric patients with HEH will fare as well as other common pediatric liver tumors post-OLT. The UNOS dataset was examined for patients with pediatric OLT between 1987 and 2007. Patients were grouped into non-tumors, HB, HCC, HEH, and rare liver tumors. COD analysis was calculated using Fisher's exact test. Patient, allograft, and recurrence-free survival were compared using Kaplan-Meier curves and log-rank tests. A total of 366 patients with pediatric OLT were identified with primary liver tumors (HB - 237, HCC - 58, HEH - 35, other - 36). HEH patient survival (five yr: 60.6%) was poorer than non-tumor OLTpatient survival (five yr: 84.4%). Survival was worse when compared to HB (five yr: 72%) and rare liver tumors (five yr: 78.9%), but better than HCC (five yr: 53.5%). Allograft survival in HEH (five yr: 50.1%) lies between HB (five yr: 63.6%) and HCC (five yr: 42.8%). COD analysis demonstrates recurrence as a major cause in HB and HCC, but not for HEH or other liver tumors. The data suggest that patient survival may not be as high as previously believed and further investigation is warranted.

Modeling a bench-scale alternating aerobic/anoxic activated sludge system for nitrogen removal using a modified ASM1

The Activated Sludge Model No. 1 (ASM1), developed by The International Association of Water Pollution Research and Control, was applied to model dynamics of NH4 +, and NO3 − in a bench scale alternating aerobic-anoxic (AAA) activated sludge system for nitrogen removal. The model was modified by eliminating inert soluble COD (SI) and inert particulate COD (XI) from the model's state variables as these two variables are not involved in any biological reaction and are not readily measurable with conventional routine COD analysis. It was assumed that the soluble COD and particulate COD of wastewater represent readily biodegradable COD (SS) and slowly biodegradable (XS) in the model, respectively. In addition, alkalinity was also removed from the model, since alkalinity of an AAA system remains stable due to the cyclic modes of the system. Even with the elimination of the three state variables and the assumption made, the model could reasonably predict the NH4 + and NO3 − dynamics of the AAA system, and effluent NH4 + and NO3 − concentrations with adjustment of only a few kinetic parameters. Compared to the original ASM1, it is expected that the modified ASM1 presented in this study can be more easily utilized by engineers in designing or operating an AAA system in practice, since it requires simple characterization of wastewater COD.

Comparison of and uncertainties in raw sewage COD measurements by laboratory techniques and field UV-visible spectrometry

A comprehensive investigation of the uncertainty of different COD analysis methods (DIN, small tube tests (STT) and UV-visible spectrometry methods) has been carried out on potassium hydrogen phthalate standard solutions and raw sewage samples from a large wastewater treatment plant. The UV-visible method allows estimating COD equivalent concentration from the measured absorption spectra by means of site specific regression and correlation functions. CODdin and CODstt methods showed equivalent global results but specific calibration relationships are necessary when high accuracy is required. The CODstt method is suitable for immediate COD analysis in the field. Sub-sampling is the main source of uncertainty. Spectrometry is able to estimate CODeq with an uncertainty of the same order of magnitude as the uncertainty in CODdin.

Practical pulp washing implications of Donnan equilibria in the fiber line

The washing of dissolved lignin residues from fibers is significantly favored at low ionic strengths. This is shown to affect the standard procedures for COD analysis of pulp, and evaluations of wa ...

Photocatalytic degradation of Direct Yellow 12 dye using UV/TiO 2 in a shallow pond slurry reactor

The adsorption and photocatalytic degradation of diazo Direct Yellow 12 (Chrysophenine G), commonly used as a cotton, paper and leather dye has been investigated in aqueous suspension of semiconductor oxide TiO 2 as photocatalyst in a non-concentrating shallow pond slurry type reactor under UV light. The adsorption of dye on the semiconductor shows a strong dependence on the pH and follows a Langmuir adsorption model. The studies include dark adsorption experiments at different pH conditions and their effect on initial rate of photodegradation. The effect of initial concentration of dye, catalyst loading, pH, addition of oxidant on the reaction rate was ascertained and optimum conditions for maximum degradation was determined. The disappearance of the organic molecule follows approximately a pseudo-first kinetic order according to the Langmuir–Hinshelwood model. COD analysis of the dye under optimum conditions showed 94% reduction in COD after 2.5 h and complete decolourisation as determined by UV–vis analysis was achieved in 1.5 h.

Detection of dioxygenase genes present in various activated sludge.

Activated sludge from refineries contains various microorganisms that could utilize aromatics under aerobic conditions due to the oxygenase enzymes. Dioxygenase enzymes are oxygenases, which are involved in the ring cleavage step of aromatic hydrocarbons. In this study, the selected catabolic loci involved in ring cleavage have been monitored in the activated sludge samples at different time intervals. The investigation of the dioxygenase genes in the Effluent Treatment Plants (ETPs) and evaluation of their presence at different time points provides a clue for the aromatic utilizing potential of the inherent microbial flora. The catabolic gene loci pheB, xylE, tod-isp, bed and nahG responsible for the enzymes catechol 1,2-dioxygenase, catechol 2,3-dioxygenase, toluene dioxygenase-iron-sulphur protein component, benzene dioxygenase and naphthalene dioxygenase were used respectively. The time dependent change in eubacterial population was demonstrated by the amplification of 16S rDNA product, followed by restriction digestion. The template DNA was obtained from the activated sludge collected from ETPs. The supporting physiological data for the overall performance of sludge was developed using respirometric analysis. The on-site COD and MLSS analysis for ETP was used in final evaluation. The study was carried out with samples collected from three different ETPs and also from a selected ETP at different time intervals. The respirometric studies were carried out with phenol, catechol, toluene, and naphthalene to arrive at the target genotypes for further study by PCR protocol. The respirometric analysis coupled with the COD and MLSS analysis represented the physiological capacity of the various sludges. Initially, the tracking protocol was optimized by using different sludge samples, which were collected from refineries. The selected genotypes were amplified and their presence has been confirmed using Southern analysis. The gene loci tod-isp, bed and xylE were commonly observed at various time intervals of the sludge from the same source. The gene loci pheB and nahG were found to be relatively rare. The 16S rDNA PCR products after restriction digestion produced different DNA fingerprint patterns, suggesting that the microbial community composition was diverse in the three sources. Similarly, the presence of the catechol 2,3-dioxygenase, benzene dioxygenase and toluene dioxygenase genes confirmed the aromatic degrading potential in the various sludges. The probes could not pick the nahG and pheB genes. However, the respirometeric assay suggested that the oxidative capacity to use naphthalene as a substrate exists. Our study of the diversity at various time points from the ETP provided an overview of the shifts of the catabolic composition of the sludge. This also depends on the influential parameters like the incoming pollutant level and the environmental conditions that are prevailing and often changing from time to time. The results of direct DNA extraction and PCR amplification do reflect the relative abundance of a particular catabolic genotype, which could be used to monitor the efficiency of treatment.

PHOTOCATALYTIC OXIDATION OF PESTICIDE RINSATE

Pesticide rinsate has been considered as one of the major threats for the environment. In this study, photocatalysts such as TiO2 and O3 were used to promote the efficiency of direct UV photolysis to prevent such wastewater pollution. Carbofuran (a carbamate pesticide) and mevinphos (an organophosphate pesticide) with a concentration of 100 mg/L were selected as the test pesticide rinsates. Parent pesticide compound, COD, and microtoxicity analysis were employed to investigate the effect of photocatalyst on the degradation efficiency of pesticide in rinsate. It was found that the photocatalytic oxidation process (UV/O3, UV/TiO2) showed much higher COD removal and microtoxicity reduction efficiency for pesticide rinsate than did direct UV photolysis under the imposed conditions, suggesting that photocatalytic oxidation processes such as UV/O3 and UV/TiO2 could be a better alternative to treat pesticide rinsate. In addition, it was noted that increasing the initial pH of mevinphos rinsate to a basic level was required to reach higher COD removal efficiency and positive microtoxicity reduction efficiency while it was not necessary for the treatment of carbofuran rinsate.

Multivariate approach to photocatalytic degradation of a cellulose bleaching effluent

TiO2-photocatalytic degradation of a cellulose ECF effluent was evaluated using multivariate experimental design. The effluent was characterised by general parameters such as AOX, TOC, COD, colour, total phenols, acute toxicity and by the analysis of chlorinated low molecular weight compounds using GC/MS. The pH, catalyst amount and hydrogen peroxide were simultaneously varied using multivariate analysis to establish the weight of each variable in the COD and AOX removal after 180min of reaction. The pH has a large effect in the AOX degradation at values below 5 and over 10, while COD removal is improved at low pH. The presence of hydrogen peroxide in the photocatalytic reaction has a small effect in degrading the AOX and COD. The optimal concentration of TiO2 was found to be around 1gl−1. In addition, the reaction was monitored for longer periods of irradiation by carrying out TOC, COD, AOX, acute toxicity and spectrophotometric analysis, concluding that the organic matter contained in the effluent was significantly degraded. After 30min of reaction more than 60% of the toxicity was removed and after 420min of reaction none of the initial chlorinated low molecular weight compounds were detected, suggesting an extensive mineralisation which was corroborated by 95 and 50% AOX and TOC removals, respectively. Colour and total phenols were also removed.

Batch tests for assessing decolourisation of azo dyes by methanogenic and mixed cultures

Most of the published studies on azo dye colour removal involve anaerobic mixed cultures and there is some interest in the knowledge of how dye reduction occurs, if by facultative, strictly anaerobic or both bacterial trophic groups present in classic anaerobic digestors. This paper describes the behaviour of methanogenic and mixed bacteria cultures on the colour removal in batch systems, of a commercial azo dye, C.I. Acid Orange 7, used in paper and textile industries. The aim of this study is to demonstrate, by analysing dye decolourisation, that it occurs with mixed cultures as well as with strictly anaerobic (methanogenic) cultures. Tests were performed with a range of dye concentrations between 60 and 300 mg l −1. The influence of dye concentration on the carbon source removal and decolourisation processes was studied. The effect of carbon source concentration on colour removal was also analysed for both cultures. The degradation rates in mixed and methanogenic cultures were compared. The consumption of carbon source was monitored by COD analysis and dye degradation by ultraviolet-visible spectrophotometry and thin layer chromatography.

Production of hydroxyl radicals by electrochemically assisted Fenton's reagent: Application to the mineralization of an organic micropollutant, pentachlorophenol

Hydroxyl radicals are very powerful oxidizing agents. They are involved in hydroxylation reactions, in biological and atmospheric phenomena. A recent application of these radicals is their use in decontamination of water polluted by toxic organic substances like pesticides. Chemically, these radicals are produced by the use of a mixture of (H 2O 2+Fe 2+), the so called Fenton's reagent. In this work Fenton's reagent is generated by electrochemistry in a catalytic way. The reaction of the hydroxyl radicals with pentachlorophenol (PCP) was studied. These radicals generated in situ in aqueous solution react with PCP and thus lead to its degradation. The evolution of the composition of the solution was followed by chromatographic analysis, COD analysis and the measurement of the total organic carbon (TOC) of the studied aqueous solution. Tetrachloro- o-benzoquinone and tetrachloro- p-benzoquinone (TCBQ) are the only aromatic intermediates identified. They result from the oxidation of the corresponding tetrachlorohydroquinones (TCHQ). Just like PCP, the TCBQs are degraded and disappear in their turn. The mineralization of the initial toxic substrate is confirmed on the one hand, by the regular decrease in quantity of the total organic carbon of the solution (TOC analysis) and on the other hand, by the quantitative release of chloride ions according to the electrical charge passed during electrolysis. The degradation of PCP appears relatively slow compared to that of the other organic pollutants studied by the electro-Fenton process and also to the degradation of other less substituted chlorophenols. The kinetic rate of the appearance of chloride ions is slower than that in the degradation of PCP. This phenomenon highlights the formation of chlorated aliphatic intermediates.

COD and TOC analysis of leachate from a solidified organic waste

Several combinations of binders and absorbent additives were utilized to solidify a typical organic waste, API Separator sludge. The effectiveness of the materials was based on the waste leachability from the solidified samples. COD and TOC analyses were used to determine the organic content of the leachate samples.The ability of the COD and TOC analyses to assess waste leachability was limited. The inability of the COD and TOC tests to differentiate between organic compounds made the results difficult to interpret. This was due to organic contaminants from the solidification materials contributing to the COD and TOC contents of the leachates. Also, the COD test may have be influenced by reduced inorganic compounds contained in the flyash binder and the sludge. Representative samples for the TOC analysis were difficult to obtain for the leachates containing oils or suspended particles. It is recommended that the COD and TOC tests only be used as a screening method for determining solidified organic waste leachability and other methods need to be employed to obtain more accurate results.

CJ90-03. A COD analysis of heterogeneous welded joints with a cracked transversely sandwiched hard layer : By Ma Weidian (Qinghua University, Beijing, China) et al. Chinese J. Mech. Engng26, No. 1 (Feb., 1990), pp. 14–18

CJ90-03. A COD analysis of heterogeneous welded joints with a cracked transversely sandwiched hard layer : By Ma Weidian (Qinghua University, Beijing, China) et al. Chinese J. Mech. Engng26, No. 1 (Feb., 1990), pp. 14–18

Rückdifferenzierung als Voraussetzung ontogenetischer Entwicklung.

The main purpose of this research is to synthesize porous ceramic membrane based on alkali-activated blast furnace slag and achieve optimal synthesis conditions for removing over 90% petroleum compounds and flux in the range of microfiltration (MF) and ultrafiltration (UF). The method applied for membrane synthesis is simple, environmentally friendly, and economical. The blast furnace slag as the main starting material was used to fabricate these free sintering and self-supported ceramic membranes. The L9 orthogonal array of the Taguchi method was employed to determine the optimum conditions of three controlling factors, i.e. hydraulic pressing pressure, alkali-activated blast furnace slag drying time, and pressing time in three levels. Morphology and filtration performance of the synthesized membranes were characterized via SEM images using Image-j software, total porosity determination, and pore size study using bubble point method. Cross-flow filtration of 75 ppm gas oil in water emulsion was performed and COD analysis of permeate was then monitored. Distribution of synthesis parameters and their influences on the membrane fabrication process were investigated using analysis of variance (ANOVA). According to the results, drying time and hydraulic pressing pressure were known as the most effective parameters on COD and permeation flux. Two optimal membranes for COD removal and permeation flux were identified in hydraulic pressing pressure, drying time and pressing time of (400 bar, 6 h, 5 min) and (225 bar, 8 h, 30 min), respectively. COD optimal UF membrane with an average pore size of 0.07 µm and 100% removal of gas oil and permeation flux optimal MF membrane with an average pore size of 0.66 µm and pure water permeation flux of 1960 kg/m2 h were introduced.