Initial Concentration Of Organic Matter Research Articles

Effect of the Fe0/PMS advanced oxidation system on the removal of aromatic organic compounds

The aromatic organic compounds present in groundwater environments have low contents, high toxicity, long half-lives and stable chemical properties, which increase the difficulty of degradation under natural conditions. In this study, an zero-valent iron activated peroxymonosulfate system (Fe0/PMS) was constructed to remove common aromatic organic compounds in groundwater. The results showed that at an initial pH of 7.0, Fe0=0.3 g/L, PMS= 0.5 mM, and initial concentration of organic matter (C0) =0.1 mM, the removal efficiency of the seven aromatic organic compounds by the Fe0/PMS system reached more than 70 %, which shows good removal ability. Alcohol quenching tests and liquid chromatography time-of-flight mass spectrometry tests showed that the main active oxygen species in the system were SO4•─ and OH•, which could efficiently degrade aromatic organic compounds through electrophilic substitution, hydroxylation, carbonylation and decarboxylation reactions and reduce the biological toxicity of organic compounds in wastewater to a certain extent. In the long-term dynamic reaction process, the removal rate of aromatic organic compounds in actual groundwater by the Fe0/PMS system can be maintained above 75 %, and the complex structure can be effectively destroyed. This research can provide a theoretical basis for the efficient treatment of aromatic organic compounds in groundwater.

Biohydrogen production by co-digestion of food waste and corn industry wastewater

Food waste (FW) and corn industry wastewater (cornWW) are residues with a high potential for hydrogen production in the dark fermentation process. The study aimed to identify the co-digestion of FW and cornWW ratios for improving hydrogen production and evaluating the synergistic effect on biohydrogen production potential (BHP) in batch test. The inoculum consisted of a mixed culture plus the native microbiota of each substrate. The adjustment of the initial pH to 7.5 was compared to the co-digestion without control of the initial pH of the experiments. The highest hydrogen and metabolites production were obtained with a co-digestion FW:cornWW ratio. When no pH adjustment is applied, pH values above 10 completely inhibit the metabolic activity of bacteria in the process. The cornWW not only provided alkalinity to the system but also can be applied to adjust the organic matter content of FW, adjusting the initial concentration of organic matter. The growth of microbial communities was formed mainly by Clostridium sp. The co-digestion of FW:cornWW can be technically feasible to improve the production of H2 through the dark fermentation process.

Removal of BTEX from water system by synergistic flocculation of biosurfactant and iron salt

The adsorption micelle flocculation (AMF) effect of biosurfactants (rhamnolipids, RL) and polymerized ferric sulfate (PFS) on the removal of low molecular weight benzoic acid (benzoic acid and p-methyl benzoic acid) and phenol (2,4-dichlorophenol and bisphenol A) organics was investigated. The coexistence system of RL and organic matter was constructed, and the effects of pH, Fe concentration, RL concentration and initial concentration of organic matter on the removal effect were discussed. For benzoic acid and p-methyl benzoic acid, the increase of Fe and RL concentrations was beneficial to their removal rates under weak acidic conditions, and the removal rate of the coexistence system was higher for methyl benzoic acid (87.7 %) than for benzoic acid (78.6 %), which might be attributed to the stronger hydrophobicity of the coexistence system for methyl benzoic acid; while for 2,4-dichlorophenol and bisphenol A, pH and Fe concentration changes had less effect on the removal rate, but the increase in RL concentration was favorable to the removal rate, which was 93.1 % and 86.7 % for BPA and 2,4-dichlorophenol, respectively. These findings provide feasible ideas and directions for the removal of organics by AMF using biosurfactants.

Analysis of the Supercritical Water Gasification of Cellulose in a Continuous System Using Short Residence Times

Supercritical Water Gasification (SCWG) has the capacity to generate fuel gas effluent from wet biomass without previously having to dry the biomass. However, substantial efforts are still required to make it a feasible and competitive technology for hydrogen production. Biomass contains cellulose, hemicellulose and lignin, so it is essential to understand their behavior in high-pressure systems in order to optimize hydrogen production. As the main component of biomass, cellulose has been extensively studied, and its decomposition has been carried out at both subcritical and supercritical conditions. Most previous works of this model compound were carried out in batch reactors, where reaction times normally take place in a few minutes. However, the present study demonstrates that gasification reactions can achieve efficiency levels of up to 100% in less than ten seconds. The effect of temperature (450–560 °C), the amount of oxidant (from no addition of oxidant to an excess over stoichiometric of 10%, n = 1.1), the initial concentration of organic matter (0.25–2 wt.%) and the addition of a catalyst on the SCWG of cellulose in a continuous tubular reactor at short residence times (from 6 to 10 s) have been studied in this work. Hydrogen yields close to 100% in the gas phase were obtained when operating under optimal conditions. Moreover, a validation of the experimental data has been conducted based on the theoretical data obtained from its kinetics.

Catalytic ozonation of organic contaminants in petrochemical wastewater with iron-nickel foam as catalyst

This work investigated the removal of organic contaminants in actual petrochemical wastewater by catalytic ozonation with iron-nickel foam as catalyst. Under different conditions, the DOC removal percentages ranged from 40% to 61%, the sCOD removals were from 73% to 96% in the reaction time of 120 min. Two thirds of the 66 detected organic compounds disappeared in the treated wastewater. The biodegradability of the petrochemical wastewater was greatly improved after catalytic ozonation. TP, TN, NO3-N, Cl− and some heavy metals in the petrochemical wastewater were also removed to some extent. The influence of pH and initial organic matter concentration on the performance of catalytic ozonation was limited. Increase of aqueous ozone concentration and catalyst dosage was advantageous for organic contaminants removal. The probable mechanism of catalytic ozonation was proposed as that the iron-nickel foam was oxidized by ozone into the mixture of oxides, hydroxides, and hydroxyoxides. On one hand, the hydroxyl groups on the catalyst surface motivated the formation of OH. On the other hand, the electrons transferred among different valences of transition metals facilitated the decomposition of ozone. The generated OH diffused into bulk solution, working together with ozone to degrade the organic contaminants. From theoretical modeling, the residue ozone in the off gas can be reduced from 98% to 11% by using iron-nickel foam as the catalyst.

Elimination of natural organic matter by electrocoagulation using bipolar and monopolar arrangements of iron and aluminum electrodes

The aim of this research was to evaluate the efficiency of electrocoagulation (EC) for the removal of natural organic matter (NOM) by using iron (Fe) and aluminum (Al) electrodes. The effects of several operational parameters such as initial pH (3–10), time of electrolysis (5–30 min), initial concentration of organic matter (10–50 mg NOM/L), current density (0.25–1.25 mA/cm2), type of electrode material (n = 4, 2 sides × 11 cm × 10 cm, wall thickness = 2 mm, distance between each electrode = 5 mm), and type of connection of electrodes (bipolar and monopolar configurations) were explored for the removal of NOM from synthetic humic acid solution in a 2 L laboratory-scale EC cells (A s/V = 0.110 cm−1). The optimum conditions for the process were identified as pH = 3 and 7, electrolysis time = 20 and 10 min for Fe and Al electrodes, respectively. Using both electrodes at current density = 0.25 mA/cm2 and initial concentration of organic matter = 50 mg/L, a NOM removal efficiency of almost 100% could be achieved in the bipolar mode. Based on the optimum conditions, specific reactor electrical energy consumptions were 14.90 kWh/kg Al (or 0.092 kWh/m3) and 2.88 kWh/kg Fe (or 0.11 kWh/m3). Specific electrode consumptions were obtained to be 0.0062 and 0.0382 kg/m3, and operating costs of the EC system were preliminary estimated at 0.057 and 0.119 $/m3 for Al and Fe electrodes, respectively.

Sequential Treatment of Tequila Industry Vinasses by Biopolymer-based Coagulation/Flocculation and Catalytic Ozonation

ABSTRACTThis article describes the study of the treatment of tequila industry vinasses based on the sequential application of coagulation-flocculation and heterogeneous catalytic ozonation. Coagulation-flocculation treatment used biopolymers to reduce the nondissolved organic matter and to reduce the degree of color units in effluent. Among six different substances, chitosan was the most efficient biopolymer to remove the highest chemical organic demand (COD) concentration (84.0%). The response surface technique was used to obtain the best attainable operation conditions of coagulation-flocculation process. The initial organic matter concentration, the reaction period and biopolymer concentration were selected as the independent variables. Two levels of analysis were performed: optimally and sensibility. The best reaction conditions were 3.23 × 104 mg L−1 of initial COD, 125.4 mg L−1 of chitosan concentration, and 60.0 min of reaction. Ozonation process was performed on the effluent of coagulation-flocculation treatment. A batch reaction with 30 mg L−1 of ozone in gaseous phase and a flow of 0.1 L min−1 was implemented. Nickel oxide (100 mg L−1) was used as the catalyst of the ozonation reaction. Twice larger COD concentration removal was obtained when the catalyst participated in the reaction compared to the so-called conventional ozonation (12.00% in conventional case vs 26.70% in catalyst presence). An ultraviolet-visible (UV-Vis) spectroscopy study was conducted to obtain a preliminary evaluation of organic compounds removal by effect of the sequential method proposed in this study. A significant total organics removal from the tequila industry wastewater (measured as the integral of UV-Vis spectrum) of 398.6 conditional units was obtained when the conventional ozonation was used after coagulation-flocculation, but that value was increased up to 1609.12 conditional units when the catalyst was inserted into the reaction.

Methodology to determine the specific hydrogenic activity (SHA) of waste sludges

Production of hydrogen is influenced by the pH, the concentration of organic matter, and the concentration of sludge. A short-term test is presented in which the specific hydrogenic activity of a waste sludge is calculated in order to quantify its hydrogen production capacity. To determine the ideal conditions for the measurement of SHA was used glucose in concentrations of 1000; 2000; 4000; 8000; 12,000; 16,000; and 20,000 mg O2 L−1; sludge in concentrations of 1250; 2500; 5000; and 7500 mg TVS L−1; and pH adjustments of 5.0; 5.5; 6.0; and 6.5. Given the initial concentration of soluble COD of 12,000 mg O2 L−1, sludge concentration of 2500 mg TVS L−1, and pH of 6.0, the highest SHA obtained was 483 mLH2 g TVS−1 h−1. As to volumetric measurements, given the initial concentration of organic matter of 8000 mg L−1, biomass concentration of 5.000 mg TVS L−1, and pH of 5.5, the volume of produced hydrogen per mass of soluble COD added reached a maximum of 38 mL gCOD−1.

Avaliação da produção de biogás de dejetos de suínos utilizando a metodologia de superfície de resposta

O presente estudo avaliou as condições operacionais que podem maximizar a produção do biogás a partir do uso de biodigestores. Os ensaios experimentais foram conduzidos utilizando dejetos de suínos em fase de terminação, com concentração de sólidos totais na coleta de 70,6% p/v. Os experimentos avaliaram, segundo a metodologia de superfície de resposta (MSR), a influência de cinco fatores: temperatura, concentração inicial de matéria orgânica e influência da adição de nutrientes inorgânicos (FeSO4×7H2O, NiSO4×6H2O e MnSO4×4H2O). Os melhores resultados foram obtidos para a concentração de biomassa inicial de 395 a 595 g.L-1 e a temperatura de 33,5 a 44ºC. Em relação ao uso de nutrientes no processo de biodigestão anaeróbia, os resultados permitiram concluir que houve significativa redução no tempo de retenção hidráulica (TRH) e maior produtividade de biogás.

Fish canning wastewater treatment by activated sludge: Application of factorial design optimization: Biological treatment by activated sludge of fish canning wastewater

The optimization of hydraulic retention time (HRT) and initial organic matter concentration for dissolved organic carbon (DOC) abatement of wastewater from a fish canning industry of northern Portugal by activated sludge was investigated using response surface methodology (RSM). The two parameters were chosen since it was found that the treatment efficiency is mainly influenced by them. The experimental data on DOC removal were fitted into a quadratic polynomial model using factorial design and RSM. The optimum process conditions were determined by analyzing the response surface of a three-dimensional plot and by solving the regression model equation. The obtained results showed a HRT of 6.4h and an initial DOC of 406.2mg/L as the best treatment conditions. Under these conditions, the maximum predicted DOC removal was 88.0%, confirming the feasibility and the reliability of fish canning wastewater treatment by activated sludge for organic content removal.

Influence of applied voltage and COD on the bioelectrochemical degradation of organic matter

Organic matter degradation was examined in an air cathode bioelectrochemical system (BES) operated in a fed-batch mode operation. The organic matter degradation rate in the air cathode BES was significantly affected by the initial concentration of organic matter with a chemical oxygen demand (COD) ranging from 25 to 600 mg/L, and by the applied voltage of 100 and 300 mV. When the initial COD concentration was less than 100 mg/L, the substrate affinity to bacteria at an applied voltage of 300 mV was slightly higher than that at 100 mV, but the substrate degradation potential that was evaluated by the ratio of maximum substrate degradation rate to saturation constant did not vary at 100 and 300 mV applied voltages. For initial COD concentrations higher than 300 mg/L, the substrate degradation potential at an applied voltage of 100 mV was higher than that at 300 mV. The anode and cathode potentials in the BES were affected by both the applied voltage and initial COD concentration, but the effect of applied voltage on the potential was increasingly important with decrease in COD concentration. The coulomb efficiency at an applied voltage of 100 mV was higher than that at 300 mV, but decreased with increase in initial COD concentration in the BES. The air cathode BES with applied voltage is an advanced wastewater treatment system for organic pollutants.

Physico-Chemical and Bacterial Characteristics of Groundwater and Surface Water Quality in the Lagbe Town: Treatment Essays with <i>Moringa oleifera</i> Seeds

The river water and groundwater from Lagbe town in Benin Republic were collected and analyzed for physical, chemical and microbiological parameters. The surface water samples were treated with alum, Moringa oleifera seeds powder and the combination of alum and Moringa oleifera seeds. The jar-test essays were carried out with two water samples at initial turbidities 7.2 NTU and 14.4 NTU. The water samples analyzed are fairly mineralized (conductivity varies between 166 and 687 μS/cm), enough soft and contain the nitrate (104 mg/L for W4 sample). They are greatly polluted by pathogenic microorganisms such as Escherichia coli, Klebsiella, Enterococcus, Vibrio, Serratia. The optimal dosages of Moringa are 96 mg/L and 80 mg/L respectively. We have observed a reduction of 60% of turbidity and a substantial remove of all pathogenic microorganisms after water treatment with Moringa oleifera seeds. For the combination treatment, 93% of initial turbidity and 92% of initial concentration of organic matter in the sample E2 were eliminated. The pH remained almost constant during the treatment.

Anaerobic degradation of organic waste: An experience in mathematical modeling

Some key aspects of organic waste degradation were analyzed by means of mathematical models using data obtained in laboratory reactors. It was shown that an essential condition of effective methane production is the balance between sequential and parallel stages not resulting in accumulation of intermediate products that are potential inhibitors of the process. Decreased initial concentration of organic matter (dilution) and the introduction of seed culture (a methanogenic microbial community) favor the balancing of the process. Decomposition of easily degradable organic substances may lead to excessive accumulation of volatile fatty acids and acidification of the medium, which, in turn, blocks the degradation of difficult-to-degrade compounds. If the process is unbalanced, agitation eliminates the initiation centers for methanogenesis by averaging the reagent concentrations, which results in complete cessation of methane production. Such centers may be multicellular aggregates of Methanosarcina sp.

The impact of different natural zeolite concentrations on the methane production in thermophilic anaerobic digestion of pig waste

The effect of natural zeolite on the thermophilic anaerobic decomposition of pig waste was investigated. In particular, the effect of adding different amounts of zeolite on the increase of methane production of waste was examined. Two sets of experiments were carried out in duplicate: one with a low initial concentration of organic matter and one with a high initial concentration of organic matter. These experiments were carried out in eight batch reactors at 55 °C. The doses of zeolite which were used for the experiments were 0, 4, 8, 12 g l−1 of waste. Methane production was significantly higher in treatments with natural zeolite at doses 8 and 12 g l−1 of wastes, compared to those without zeolite. Also in treatments with natural zeolite, the reduction of volatile solids and biological oxygen demand (BOD5) was statistically significant. The results appear to be caused by the addition of zeolite, which adsorbs ammonia, thus having an effect not only on the toxicity of ammonia and on the C/N proportion but also on the regulation of acidity (pH) of the pig wastes.

Degradation of Odontologic X-Ray Film Developing Wastewaters by Photo-Fenton Process

Effluents from radiographic X-ray film developing processes feature a high contaminant load (COD about 70000 mg/L and total phenols concentration about 16956 mg/L). Photo-Fenton's are potentially useful oxidation processes for destroying toxic organic compounds in water. In these reactions, hydrogen peroxide is combined with ferrous or ferric iron in the presence of light to generate hydroxyl radicals (·OH). The photo-Fenton process was explored as a photochemical treatment to degrade wastewater from radiographic X-ray film developing processes coming from odontologic clinics. A response surface methodology was applied to optimize the photo-Fenton oxidation process conditions using total phenol removal as the target parameter to be optimized, and the reagent concentrations, as related to the initial concentration of organic matter in the effluent, and time and pH as the control factors to be optimized. The best results in terms of maximal total phenol removal and economic process were achieved when wastewater samples were treated at pH 5 in the presence of hydrogen peroxide and iron in the ratios [total phenols]:[H2O2] 1:3 w/w and [Fe2+]:[H2O2] 1:18 w/w and time 1 h.

Multivariate approach to the photo-Fenton process applied to the degradation of winery wastewaters

Winery wastewaters, being seasonal and experiencing substantial flow variations, are difficult to treat by conventional biological processes. This work proposes the photo-Fenton reaction in homogeneous phase as an alternative for their purification.Experimental design methodology has been used in order to study the main variables affecting the oxidation process as well as their most relevant interactions.Under energetic conditions the photo-Fenton treatment reached purification levels of up to 95% (measured as total organic carbon). The most influential factors behind organic matter removal are the Fe3+ and H2O2 dosage. The influence of the initial organic matter concentration and the reaction time is almost negligible for the confidence level selected (90%) in the results analysis.

Optimization of Fenton's oxidation of chemical laboratory wastewaters using the response surface methodology

Establishing a treatment process for practical and economic disposal of laboratory wastewaters has become an urgent environmental concern of the Department of Chemical Engineering of the Universidade Estadual de Maringá (State University of Maringá), Brazil. Fenton and related reactions are potentially useful oxidation processes for destroying toxic organic compounds in water. In these reactions, hydrogen peroxide is combined with ferrous or ferric iron in the presence or absence of light to generate hydroxyl radicals ( OH). The feasibility of Fenton's reagent to treat waste chemicals from an academic research laboratory was investigated in this study. A response surface methodology was applied to optimize the Fenton oxidation process conditions using chemical oxygen demand (COD) removal as the target parameter to optimize, and the reagent concentrations, as related to the initial concentration of organic matter in the effluent, and pH as the control factors to be optimized. Maximal COD removal (92.3%) was achieved when wastewater samples were treated at pH 4 in the presence of hydrogen peroxide and iron in the ratios [COD]:[H 2O 2]=1:9 and [H 2O 2]:[Fe 2+]=4.5:1. Under these conditions, it was possible to obtain simultaneously maximal COD removal and minimal chemical sludge after treatment, which is a residue that needs further processing.

Decomposition of Phytoplankton in Seawater. Part I: Kinetic Analysis of the Effect of Organic Matter Concentration

Decomposition experiments were conducted on cultured phytoplankton (Skeletonema costatum) in seawater containing decomposer and consumer of size less than 500 µm. We determined the decomposition rates of bulk particulate organic matter (POM), the ratio of labile to semi-refractory fractions in the POM, and the POM carbon/ nitrogen (C/N) ratio during decomposition. To identify the kinetic mechanisms involved in the reactions of different order (e.g., first- and second-order), we studied the sensitivity of reaction rates to the initial concentration of POM, ranging from 2.4 to 71 mg-C L−1. The results showed that decomposition consists of two first-order reactions: decomposition of labile and of semi-refractory particulate organic carbon (POC). The decomposition rate constants found for labile (0.13 day−1 at 20°C), and semi-refractory POC (0.008 day−1 at 20°C), and the carbon weight ratio of semi-refractory POC (13% at 20°C), were insensitive to the initial organic matter concentration. The time-dependence of the C/N ratio was also independent of this initial concentration. The decomposition rate constants and the content of semi-refractory POC did not change, regardless of the absence or presence of 25–500 µm organisms in natural seawater.

Effect of substrate concentration and temperature on the anaerobic digestion of piggery waste in a tropical climate

A study of the effect of substrate concentration and temperature variation on batch anaerobic digestion of piggery waste was carried out in laboratory-scale completely mixed reactors. The variation of chemical oxygen demand (COD), total volatile fatty acids (TVFA), alkalinity, pH and methane production with digestion time followed the same pattern at mesophilic (35 °C) and ambient temperatures (16.8–29.5 °C). The process was more stable at mesophilic than at ambient temperatures. The rate of COD removal correlated with the digestion time through an equation of the Grau kinetic model type. An increase in the initial concentration of organic matter caused a reduction of COD removal rate. In addition, COD removal rates at ambient temperatures were significantly lower than those obtained at mesophilic temperature.

Treatment of high organic-loaded industrial effluents

There are many treatment schemes for industrial wastewater in existence. Generally, the choice of bioprocess is determined with respect to efficiency and ease of operation. This choice is obviously dependent on the possibility for the wastewater to be readily biodegradable. This consideration leads to the use of more adapted process based on chemical operations or even incineration. Starting from the need of non transferring techniques (without production of sludge), UV/H2O2 photooxidation has been studied for the treatment of several chemical process- and waste-water containing dissolved organic carbon concentrations in the range of 5 to 30 g.L-1 were studied. More precisely, the effect of simple steps such as pH adjustment or coagulation have been studied before application of Advanced Oxidation Process schemes. Depending on the initial organic matter concentration (e.g. DOC) conversions higher than 80% can be achieved.