Chemical Oxygen Demand Concentration Of Wastewater Research Articles

Performance evaluation of novel Mica@reduced graphene oxide fixed rotating disk reactor in treatment of anaerobically reduced textile dyeing wastewater containing aromatic amines

AbstractBACKGROUNDAnaerobically reduced textile dyeing wastewater containing aromatic amines can cause serious environmental problems as a consequence of their toxicity.RESULTSThe performance of a novel design, laboratory‐scale mica@reduced graphene oxide (rGO) reactor fixed on three rotating disks was evaluated for the removal of anaerobically reduced textile dyeing wastewater containing aromatic amines. Fourier‐transform infrared and UV–visible spectroscopy analyses of wastewater after anaerobic treatment revealed that it contained high aromatic compound concentrations. Scanning electron microscope images confirmed that the rGO nanosheets were deposited on the mica surface by the spin‐coating method aromatic amines adsorbent. The effects of wastewater initial chemical oxygen demand (COD) concentration (100, 500 and 1500 mg L–1), pH (5, 7 and 9) and processing temperature (293, 303 and 313 K) on the aromatic compounds and COD removal using the designed reactor were investigated. The results indicated that aromatic molecule adsorption occurred faster with higher wastewater COD concentration. Also, increase in pH improved the mica@rGO adsorption. Likewise, the increase in temperature caused swelling in the stacked graphene layers, resulting in new surfaces for adsorption, leading to an increase in reactor efficiency. The experimental results indicated that the adsorption process fitted well with the Langmuir isotherm model and pseudo‐second‐order reaction kinetics. The thermodynamic study revealed that the adsorption was spontaneous.CONCLUSIONThe improvement in the removal of aromatic molecules by Mica@rGO indicates that the novel designed reactor has a great potential for the treatment of textile wastewater. © 2021 Society of Chemical Industry (SCI).

Reduction of Chemical Oxygen Demand (COD) Effluent of Plastic Recycling Processing Plant using LD Slag

In wastewater plastic recycling processing plant, commonly contain high chemical oxygen demand (COD) concentration. Coagulation-flocculation, adsorption and foam fractionation are the examples of treatment processes that can reduce COD concentration in wastewater. Steel slag can be used as an alternative to remove COD concentration of wastewater adsorption process. Linz-Donawitz (LD) slag can be obtained from steel manufacturing plant. LD slag also contains alkali oxides, porous characteristic, large surface area and contain an easy solid-liquid separation. This research is to study the percentage reduction of COD in wastewater using LD slag as adsorbent. This research will investigate the effect of particle size, dosage amount and contact time between LD slag and COD reduction. From the experiment, the highest percentage COD removal for particle size is 0.2mm, the dosage amount is 6 gram and the contact time is at 60 min. Comparison of COD removal by using coagulation -flocculation, adsorption using activated carbon and adsorption using LD slag processes was done. LD slag can reduce 2% higher of COD compared to activated carbon. LD slag should be invested more in wastewater treatment process.

Enhancement Student Understanding Through The Development Of Lab Module Based On Constructivistic

Experimental focuses learning on developing the skills of student in the process of knowledge, discover and develop their own fact, concept, and values required. The way to make it is by doing modification to the practical guidance module had been given. Nowadays, practical guidance tend to emphasize on the explanation, so its use both practical and follow the path that has been presented. The practical guidance module should be modified based on constructivism. The module is an experimental guidance to environmental laboratory subject. The test material consists of water and wastewater sample with parameter of chemical oxygen demand (COD), total dissolved solid (TDS), and nitrate. The results showed progress in the cognitive aspects such students' ability to predict the concentration of COD sample. The greater COD concentration of wastewater make the color of mixture is blue-green. The student could communicate the calibration curves correctly. Hypothesis skills presented at TDS testing. The greater of the sediment, the greater the concentration of its. The same thing happened on COD testing, COD levels can be estimated earlier. The skills show an increasing such as the skill to ask questions, experiment planning skills, skills in using tools/materials, accuracy in data retrieval, seriousness and cooperation in conducting the experiment.

Benchmarking of energy consumption in municipal wastewater treatment plants - a survey of over 200 plants in Italy.

One of the largest surveys in Europe about energy consumption in Italian wastewater treatment plants (WWTPs) is presented, based on 241 WWTPs and a total population equivalent (PE) of more than 9,000,000 PE. The study contributes towards standardised resilient data and benchmarking and to identify potentials for energy savings. In the energy benchmark, three indicators were used: specific energy consumption expressed per population equivalents (kWh PE-1 year-1), per cubic meter (kWh/m3), and per unit of chemical oxygen demand (COD) removed (kWh/kgCOD). The indicator kWh/m3, even though widely applied, resulted in a biased benchmark, because highly influenced by stormwater and infiltrations. Plants with combined networks (often used in Europe) showed an apparent better energy performance. Conversely, the indicator kWh PE-1 year-1 resulted in a more meaningful definition of a benchmark. High energy efficiency was associated with: (i) large capacity of the plant, (ii) higher COD concentration in wastewater, (iii) separate sewer systems, (iv) capacity utilisation over 80%, and (v) high organic loads, but without overloading. The 25th percentile was proposed as a benchmark for four size classes: 23 kWh PE-1 y-1 for large plants > 100,000 PE; 42 kWh PE-1 y-1 for capacity 10,000 < PE < 100,000, 48 kWh PE-1 y-1 for capacity 2,000 < PE < 10,000 and 76 kWh PE-1 y-1 for small plants < 2,000 PE.

The effect of flow modes and electrode combinations on the performance of a multiple module microbial fuel cell installed at wastewater treatment plant

A larger (6.1 L) MFC stack made in a scalable configuration was constructed with four anode modules and three (two-sided) cathode modules, and tested at a wastewater treatment plant for performance in terms of chemical oxygen demand (COD) removal and power generation. Domestic wastewater was fed either in parallel (raw wastewater to each individual anode module) or series (sequentially through the chambers), with the flow direction either alternated every one or two days or kept fixed in a single direction over time. The largest impact on performance was the wastewater COD concentration, which greatly impacted power production, but did not affect the percentage of COD removal. With higher COD concentrations (∼500 mg L−1) and alternating flow conditions, power generation was primarily limited by the cathode specific area. In alternating flow operation, anode modules connected to two cathodes produced an average maximum power density of 6.0 ± 0.4 W m−3, which was 1.9 ± 0.2 times that obtained for anodes connected to a single cathode. In fixed flow operation, a large subsequent decrease in COD influent concentration greatly reduced power production independent of reactor operation in parallel or serial flow modes. Anode modules connected to two cathodes did not consistently produce more power than the anodes connected to a single cathode, indicating power production became limited by restricted anode performance at low CODs. Cyclic voltammetry and electrochemical impedance spectroscopy data supported restricted anode performance with low COD. These results demonstrate that maintaining power production of MFC stack requires higher influent and effluent COD concentrations. However, overall performance of the MFC in terms of COD removal was not affected by operational modes.

Performance of microbial fuel cell using chemically synthesized activated carbon coated anode

The effect of chemically synthesized activated carbon (AC) on the performance of microbial fuel cell (MFC) was investigated in this study. Coconut fiber was used as a source material for synthesizing the AC. The AC with different ranges (5, 10, and 15 mg/cm2) was coated on the anode electrode surface to investigate and compare the performance of MFC with the control electrode (plain surface). The experimental results showed that the AC-5 (5 mg/cm2) coated electrode produced a peak power density (5.8 W/m3) which was higher than the control (plain) electrode (3.8 W/m3). The MFC performance in terms of power density and chemical oxygen demand (COD) removal efficiency was increased with increasing loading quantity of AC. When an AC-15 (15 mg/cm2) coated was electrode used in the MFC, the highest power density of 9.5 W/m3 with a COD removal efficiency of 74.8% was observed. Cyclic voltammetry analysis visualized the clear enhancement in electrochemical activity with an AC coated electrode. The effect of wastewater COD concentration on the performance was also investigated. The AC derived from coconut fibers can be considered as a biocompatible material to enhance MFC performance.

Bioelectricity production from microbial fuel cell using mixed bacterial culture isolated from distillery wastewater

The effect of various system parameters such as wastewater Chemical Oxygen Demand (COD) concentration, pH, conductivity, membrane size and thickness on efficient energy production using mixed isolated culture from the distillery wastewater in the MFC was studied. The power density increased with increase in the anolyte pH from 6 to 8. The peak power density and COD removal efficiency was observed as 63.8±0.65mW/m2 and 63.5±1.5% at pH 8, respectively. The MFC performance increased with increasing COD concentration (800–3200mg/l), conductivity (1.1–9.7mS/cm) and membrane area (8–24cm2). The MFC operating with wastewater COD concentration of 3200mg/l and its conductivity of 9.7mS/cm produced the highest power density of 202±6mW/m2 with a corresponding current density of 412±12mA/m2. The results showed that the efficient electricity generation and simultaneous treatment of distillery wastewater can be attained in the MFC.

Performance and biomass kinetics of activated sludge system treating dairy wastewater

The performance and bio‐kinetic coefficients of the activated sludge process (ASP) treating synthesised dairy wastewater were evaluated in a lab‐scale setup. The step‐loading experiment showed that the chemical oxygen demand (COD) removal efficiency, in general, increased with increasing influent wastewater COD concentration from 180 to 1200 mg/L (correlation coefficient was 0.80). The COD removal efficiency ranged from almost 80–88.4% depending on the COD concentration of the influent wastewater. Also, it could be stated that the ASP was probably underfed with organics at COD concentrations &lt;725 mg/L. Monod, Moser, Contois and Chen &amp; Hashimoto substrate utilisation models, relating the growth of micro‐organisms to substrate utilisation, were employed to describe the bio‐kinetics of the ASP at an organic loading rate of 1200 mg/L. Amongst them, the Contois and Monod models predicted the bio‐kinetic reactions of the ASP very well with coefficient of determination (R2) values of 0.95 and 0.93, respectively. The estimated bio‐kinetic coefficients of the Contois model (on COD basis) were as follows: half‐velocity constant (0.20 mg/L), maximum substrate utilisation rate (3.13 per day), biomass yield coefficient (0.68), endogenous decay coefficient (0.07 per day) and maximum specific growth rate (2.13 per day).

Adsorption treatment of oxide chemical mechanical polishing wastewater from a semiconductor manufacturing plant by electrocoagulation

In this study, metal hydroxides generated during electrocoagulation (EC) were used to remove the chemical oxygen demand (COD) of oxide chemical mechanical polishing (oxide-CMP) wastewater from a semiconductor manufacturing plant by EC. Adsorption studies were conducted in a batch system for various current densities and temperatures. The COD concentration in the oxide-CMP wastewater was effectively removed and decreased by more than 90%, resulting in a final wastewater COD concentration that was below the Taiwan discharge standard (100 mg L −1). Since the processed wastewater quality exceeded the direct discharge standard, the effluent could be considered for reuse. The adsorption kinetic studies showed that the EC process was best described using the pseudo-second-order kinetic model at the various current densities and temperatures. The experimental data were also tested against different adsorption isotherm models to describe the EC process. The Freundlich adsorption isotherm model predictions matched satisfactorily with the experimental observations. Thermodynamic parameters, including the Gibbs free energy, enthalpy, and entropy, indicated that the COD adsorption of oxide-CMP wastewater on metal hydroxides was feasible, spontaneous and endothermic in the temperature range of 288–318 K.

Performance of COD removal from oxide chemical mechanical polishing wastewater using iron electrocoagulation

This study investigated the feasibility of chemical oxygen demand (COD) abatement from oxide chemical mechanical polishing (oxide-CMP) wastewater. The process variables, including applied voltage, electrolyte concentration and temperature, were evaluated in terms of COD removal efficiency. In addition, the effects of applied voltage, supporting electrolyte, and temperature on electric energy consumption were evaluated. Under the optimum balance of variables, satisfactory COD removal efficiency and relatively low energy consumption were achieved. The optimum electrolyte concentration, applied voltage, and temperature were found to be 200 mg/L NaCl, 20 V, and 25°C, respectively. Under these conditions, the COD concentration in oxide-CMP wastewater decreased by more than 90%, resulting a final wastewater COD concentration that was below the Taiwan discharge standard (100 mg/L). Since the processed wastewater quality exceeded the direct discharge standard, the effluent could be considered for reuse. COD removal rates obtained during the electrocoagulation process can be described using a pseudo-kinetic model. The present study results show that the kinetic data fit the pseudo first-order kinetic model well. Finally, the morphology and composition of the sludge produced were characterized using scanning electron microscopy (SEM) and energy dispersion spectra (EDS).

Optimization of High-Strength Semiconductor Wastewater by Sequential Fenton Oxidation and Gas-Induced Ozonation

Treatment of organic-containing wastewater from a semiconductor plant treated by chemical oxidation was experimentally investigated. The wastewater was characterized by strong color, high chemical oxygen demand (COD) and low biodegradability. Treatment of this wastewater by traditional activated sludge method was essentially impossible. In the present work, advanced chemical oxidations by Fenton’s reagent and ozonation were utilized to tackle the problems of wastewater color and low biodegradability. To facilitate the particulate removal after Fenton oxidation, chemical coagulation using polyaluminum chloride and polymer was adopted as an integral part of the Fenton process. Experimental tests were conducted to determine the effectiveness and the optimum operating conditions of the chemical oxidation methods. Test results demonstrate that the two advanced oxidations were able to lower the wastewater COD concentration from as high as 15,000 mg/L to below 150 mg/L and completely eliminating the wastewater color, resulting in very good quality of the treated wastewater. A generalized kinetic model was employed to describe and elucidate the oxidation mechanisms of oxidation processes and the kinetic parameters of the models were appropriately identified using the test data.

Fenton oxidation and sequencing batch reactor (SBR) treatments of high-strength semiconductor wastewater

Treatment of a high-strength semiconductor wastewater was experimentally investigated in this study. The wastewater is characterized by a strong dark color, high chemical oxygen demand (COD) concentration, presence of refractory volatile organic compound and low biodegradability. Treatment of this wastewater by traditional activated sludge method is essentially impossible. In the present work, combined physical, chemical and biological methods were synergistically utilized to tackle the wastewater. The combined treatment consisted of air stripping, modified Fenton oxidation and sequencing batch reactor (SBR) method. Experimental tests were conducted to determine the effectiveness and the optimum operating conditions of the combined method. Test results clearly demonstrated the synergistic advantages of the combined treatments. The treatment train was capable of lowering the wastewater COD concentration from as high as 80,000 mg/l to below 100 mg/l and completely eliminating the wastewater color. The overall water quality of the final effluent exceeded the direct discharge standard and better yet, this effluent can even be considered for reuse.

Combined physical, chemical and biological treatments of wastewater containing organics from a semiconductor plant

Wastewater containing organics from a semiconductor plant was experimentally investigated in this study. The wastewater is characterized by strong color, high chemical oxygen demand (COD), a large amount of refractory volatile organic compounds and low biodegradability. Because of these characteristics, treatment of this wastewater by traditional activated sludge method is essentially impossible. In the present work, combined physical, chemical and biological methods were synergistically utilized to tackle the wastewater. The combined treatment consisted of air stripping, modified Fenton oxidation and sequencing batch reactor (SBR) method. Air stripping was employed to remove the majority of volatile organic components (notably isopropyl alcohol) from the wastewater, while the Fenton treatment decomposed the remaining refractory organics leading to simultaneous reductions of wastewater COD and color. After proper dilution with other low-strength, organics-containing wastewater stream, the wastewater effluent was finally treated by the SBR method. Experimental tests were conducted to determine the effectiveness and the optimum operating conditions of each treatment process. Test results clearly demonstrated the advantages of the combined treatments. The treatment train was found capable of lowering the wastewater COD concentration from as high as 80,000 mg/l to below 100 mg/l and completely eliminating the wastewater color. The overall water quality of the final effluent exceeded the direct discharge standard and the effluent can even be considered for reuse.