Maximum Chemical Oxygen Demand Reduction Research Articles

Electrochemical removal of crystal violet dye from simulated wastewater by stainless steel rotating cylinder anode: COD reduction and decolorization

Crystal violet dye is a harmful organic pollutant when it exists in wastewater. It may potentially cause renal failure and respiratory issues in humans, while it is considered carcinogenic and mutagenic in aqua life. In this study, crystal violet dye was electrochemically removed from simulated wastewater using a stainless-steel rotating cylinder anode. Effects of anode rotation rate (250–500 rpm), applied current (400–750 mA), concentration of supporting electrolyte (0.3–0.6 M), and time (30–70 min) on chemical oxygen demand (COD) reduction and colour removal were studied. The experimental results were correlated by two quadratic regression models: one for COD reduction with R2 equals to 0.859, and one for colour removal with R2 equals to 0.934. Process optimization was conducted using the response surface methodology (RSM) with a rotatable central composite design CCD. The results showed that the optimum conditions for maximum COD reduction (86.89 %) and maximum colour removal (88 %) are as follows: anode rotation rate = 625 rpm, applied current = 658.568 mA, supporting electrolyte = 0.422 M and treatment time = 90 min. Generally, all the studied factors have a potential effect on the process efficiency.

Adsorptive removal of biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) from greywater using activated carbon prepared from tropical almond and palm kernel shells

This study assesses the reduction of 5-day biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) of household greywater using palm kernel activated carbon (PKAC) and tropical almond activated carbon (TAAC) produced from locally available materials in a kiln at 800oC and activated using steam at a flowrate of 120 mL hr-1. Brunauer-Emmet-Teller (BET) surface area determination revealed that PKAC had a larger surface area than TAAC. Scanning electron microscope (SEM) imagery of the carbons also revealed amorphous and large internal shapes for TAAC while crystalline and closed packed shapes for PKAC. X-ray diffraction (XRD) analysis indicated that the major component present in the PKAC and TAAC was carbon and other allotropes of carbon. Batch results showed that reduction of BOD5 and COD was affected by particle size. The maximum percentage reduction of BOD5 and COD by PKAC was 76% and 65% respectively while reduction by TAAC was 62% and 52% respectively. The adsorption process was well described by the Freundlich adsorption isotherm. The studies showed that PKAC is a better adsorbent for reducing BOD5 and COD from domestic greywater as compared with TAAC. The PKAC is a potential low-cost adsorbent for BOD5 and COD removal from domestic greywater.

Optimization of human urine to synthetic wastewater ratio for pollutants removal, power generation in a bioelectrochemical system

When the human urine is mixed with the domestic wastewater, it leads to 70 % increase in nitrate level and 50 % increase in phosphorus level in the domestic sewage. So, the treatment of municipal sewage becomes more expensive and energy-intensive. Human urine is a waste and contributes to only 1 % (v) of domestic municipal wastewater, but yet it contributes 75 % nitrogen, 50 % phosphorus and 10 % chemical oxygen demand (COD) in the entire municipal wastewater. In this study, the optimization studies of human urine to synthetic wastewater ratio for power generation and pollutant removal in a dual chamber microbial fuel cell (MFC) is investigated. As diluted human urine has shown promising results in terms of power generation, current studies carried out the investigation by feeding the MFC with raw human urine diluted by synthetic wastewater in various ratios. Over the course of 336 h, the MFC were operated in batch mode. Along with bioelectricity generation and COD removal, certain physic-chemical parameters like pH, electrical conductivity, and dissolved oxygen levels were also assessed on a regular basis. A maximal power production of 7.74 W/m2 was achieved in the final batch scale with human urine and synthetic wastewater of 2:7 ratio, whereas a quite lower power generation, i.e., 1.64 W/m2, was reported in the first batch scale with urine and synthetic wastewater in a 1:8 ratio. The initial batch scale, which used synthetic wastewater and urine in a 1:8 ratio as feed, attained a maximum COD reduction of 50 %.

A comparative analysis of degradation efficiencies using alum and orange peel waste for the treatment of tannery wastewater

The tannery wastewater effluent consists of complex compounds requiring a series of treatment processes to meet the desirable effluent discharge standards. The current study deals with the comparison of degradation efficiencies obtained in terms of turbidity, total suspended solids (TSS) and chemical oxygen demand (COD) removal by using alum as a chemical coagulant, orange peel powder (OPP) and activated orange peel powder (AOPP) as naturally obtained adsorbents respectively. The experimental analysis showed that the maximum COD reduction of 49 % approx. was obtained using AOPP at optimum coagulant dosage of 2 g/L, at pH 4 and flocculation time of 30 min. Scanning Electron Microscope (SEM) showed that the AOPP consists of porous structure that leads to adsorption of pollutants over the surface. Brunauer–Emmett–Teller (BET) analysis resulted in surface area reduction of AOPP from 11.663 m2/g to 1.289 m2/g before and after adsorption correlating the experimental results of the study. Moreover, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Total organic carbon (TOC) proved that the chemical properties also play an important role in degrading the pollutants present in TWE. It can be concluded that the AOPP can be used as a cost-efficient alternative for pre-treatment of TWE.

Using Ti/Ti0.7Ru0.3O2 anode-type with a Flow Cell System for the Electrochemical Treatment of a Tannery Wastewater

ABSTRACT The electrochemical oxidation of a real wastewater discharged by the baths of “Dar Dbagh” tannery (DDT) in Fez city (Morocco) was performed using Ti/Ti0.7Ru0.3O2 anode (a dimensionally stable anode (DSA)-type electrode) underflow condition. The effect of different operational parameters, namely chloride ions concentration, electrolysis time, current density, initial pH, and temperature has been studied in detail. The discoloration and chemical oxygen demand (COD) removal have been taken as the key experimental indicators to monitor the electrochemical treatment process of DDT wastewater. The obtained results have shown that the best degradation rates (i.e., 100% and 56% of de-colorization and COD removal, respectively) were accomplished under acidic conditions at 20 mA cm−2 as a current density in the presence of 0.033 M Na2SO4 + 0.800 M NaCl as supporting electrolyte at room temperature. The maximum reduction of the effluent COD attained using Ti/Ti0.7Ru0.3O2 anode consuming 39.24 kWh per m3 clearly shows that DSA electrodes could be a good alternative for the remediation of DDT effluents.

Acoustic and hydrodynamic cavitation-based combined treatment techniques for the treatment of industrial real effluent containing mainly pharmaceutical compounds

The current work investigates the effectiveness of hybrid treatment techniques involving cavitation combined with AOPs for treating real industrial effluent obtained from common effluent treatment plant (CETP), which contains dominantly recalcitrant pharmaceutical pollutants. A laboratory scale study was performed initially using ultrasonic horn to optimize the operating parameters to be used for combination schemes as AC/H2O2, AC/Fe(II)/H2O2, AC/KPS and AC/O3. The maximum extent of Chemical Oxygen Demand (COD) reduction was observed as 83.53% for AC/Fe(II)/H2O2 system at 1:5 ratio of Fe(II) and H2O2 under the best operating conditions of 125 W ultrasonic power, 22 kHz frequency, pH of 3 and time of 60 min. The scaleup possibility of AC has been explored by utilizing a novel US reactor for the treatment of 4000 mL of effluent at the optimized conditions. Large scale US reactor also showed the best results for AC/ Fe(II)/H2O2 system yielding 81.47% COD reduction. A comparison of the efficacy of HC and AC has also been established by performing a set of experiments using the combinations as HC/ H2O2, HC/Fe(II)/ H2O2, HC/KPS, and HC/O3 at same capacity. A maximum COD reduction of 87.4% was achieved for the HC/Fe(II)/ H2O2 system at pH 3 and inlet pressure of 4 bar. The study also established the comparison of kinetic rate constants and treatment costs for different approaches. Overall, the large scale potential for the treatment of real industrial effluent involving the pharmaceutical pollutants using combination of cavitation and AOPs has been demonstrated.

Synthesis of Calcium Carbonate Nanoparticles and its Application in Grey Water Treatment

Nanotechnology is one of the emerging technologies with unique functionalities and great potential in the removal of pollutants from waste water. Nanoparticle mediated waste water treatment is a promising alternative to traditional water treatment techniques. Considerable amount of grey water is thrown out of the household activities on a daily basis, which in turn lead to environmental pollution in the long run and hence results in increased fresh water consumption. The present study focused on the synthesis of calcium carbonate nanoparticles using homogenisation process for the treatment of grey water. The nanoparticles were characterised using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and X-Ray Diffraction (XRD). The synthesised nanoparticles were employed in the batch treatment of grey water by varying the solution pH, stirring time; stirring speed and dosage of calcium carbonate nanoparticles. The pollutant removal efficiency of the nanoparticles were assessed by measuring the Chemical Oxygen demand (COD), Total Suspended solids (TDS), Total dissolved solids (TDS), Dissolved oxygen (DO) and turbidity. The study demonstrates that the optimum pollutant removal efficiency was obtained at pH 8.0, stirring speed of 100 rpm, mixing time of 75 minutes and 0.7 g dosage of calcium carbonate nanoparticles. The maximum reduction in COD at optimum processing condition was 78%. The outcome of the study suggests that calcium carbonate nanoparticle could effectively remove pollutants from grey water. This research is in line with the United Nations Sustainable Development Goals (UNSD), which is clean water and sanitation. This community engagement project will serve the society by saving the water and to produce a clean environment.

Hydrodynamic Cavitation: Its optimization and potential application in treatment of Pigment Industry Wastewater

Paper presents the application of Hydrodynamic Cavitation technique in reduction of Chemical Oxygen Demand (of Chemical Oxygen Demand (COD) and its various fractions from the Pigment Industry wastewater. Orifice plate with dimension of single hole of 1.5 mm is used in this study. The sample were analyzed at different pressures of 2 bar, 3 bar, 4 bar, 5 bar and 6 bar at different time intervals of 30 min, 60 min, 90 min, 120 min and 180 min. The optimum time and inlet pressure for maximum COD reduction is obtained at 5 bar and 120 min. The samples are analyzed in two stages. In stage first stage, samples are treated with hydrodynamic cavitation only and filtered thereafter. Both the unfiltered and filtered samples were analyzed for various parameters such as COD (filtered and unfiltered), BOD (filtered and unfiltered), TDS and pH. In stage two, the samples are treated with aeration for optimum time followed by Hydrodynamic Cavitation. The optimum time of aeration was obtained at 36 hrs. Response Surface Methodology was used to check the sensitivity of the Hydrodynamic Cavitation set up. Optimization using RSM provided optimum results with desirability 0.798 when pressure was at 5 bar and time of reaction was 120 min.

Coupling of acoustic/hydrodynamic cavitation with ozone (O3), hydrogen peroxide (H2O2), magnesium oxide (MgO) and manganese dioxide (MnO2) for the effective treatment of CETP effluent

In the current work, chemical oxygen demand (COD) reduction of Common Effluent Treatment Plant (CETP) effluent was investigated using acoustic (AC) or hydrodynamic cavitation (HC) coupled with ozone, O3/H2O2, O3/MnO2 and O3/MgO. AC was based on a dual-stepped ultrasonic horn whereas HC was based on an orifice applied as cavitating device. Maximum COD reduction of 88.66% was obtained for the approach of AC/O3/MgO followed by 85.13%, 67.12%, 56.28% and 52.23% for AC/O3/MnO2, AC/O3/H2O2, AC/O3 and only ozone respectively within 60 min at natural pH of 9. For HC, maximum COD reduction of 88.36% was achieved for HC/O3/MgO followed by 83.11%, 64.77%, 54.61% and 51.12% for HC/O3/MnO2, HC/O3/H2O2, HC/O3 and ozone operated in recirculation mode without HC respectively. The influence of ̇OH radical scavengers as Cl¯, CO32¯ and HCO3¯, and ozone scavenger as S2O32¯ on the efficacy of different approaches has also been demonstrated to establish the controlling mechanisms. The experimental data was fitted to the Generalized Kinetic Model (GKM) considering the formation of intermediates along with the determination of volumetric mass transfer coefficients on the basis of dissolved ozone concentration. The cost estimation for various approaches have also been performed. Overall it has been clearly demonstrated that HC based catalytic ozonation offers promise for treatment of effluents in the CETP.

Wastewater treatment using a natural coagulant (Moringa oleifera seeds): optimization through response surface methodology

The high expense of chemical coagulant-treated water forces most people in rural regions to rely on easily available sources, which are usually of poor quality, and expose them to waterborne infections. According to this statement, the purpose of this study was to confirm the efficiency of extracting powder Moringa oleifera seeds, which are widely available in rural regions. The experiment was done based on a random design load of 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 g/500 ml of powder extracted from Moringa seeds. Chemical oxygen demand (COD), color, and turbidity were determined for both acidic and basic characteristics of wastewater. The optimum dosage of Moringa oleifera was 0.4 g/500 ml in both characteristics of wastewater in the case of color and turbidity. Moringa oleifera maximum reduction in turbidity, color, and COD in acidic wastewater was 98 %, 90.76 %, and 65.8 % respectively; while, the maximum reduction of turbidity, color, and COD in basic wastewater were 99.5 %, 97.7 %, and 65.82 % respectively. The study was demonstrated that, the application of RSM for seeking optimum conditions in the coagulation process for the treatment of wastewater. Moringa seed powder works best with a 7–9 pH range. The study also investigated that, best adsorption equilibrium was observed when using 0.1 g of Moringa oleifera seed powder. All the results showed that Moringa oleifera seeds were very effective for the removal of impurities.

Enhancing Disinfection of Contaminated Natural Water Using 40 kHz Frequency Cavitational Reactor

Natural water quality is continuously diminishing with human intervention and poses a major threat to the ecosystem. The present work investigated the treatment of contaminated lake water using a 40 kHz frequency cavitational reactor. The total colony count present in raw water was 1,300 ± 150 CFU with initial chemical oxygen demand (COD) of 100 ± 30 mg/L. The synergy of cavitation with a catalyst (titanium dioxide [TiO2]) and ozonation was studied. The comparative performance was analyzed by comparing individual and synergic effects. The combined effects of a catalyst with cavitation have shown the maximum removal of the microbial count and COD. Techno-economic feasibility analysis confirmed that the synergy of a catalyst with cavitation results in the maximum reduction in microbial count and COD. The percentage removal of coliform such as Enterobacter, Salmonella, and Escherichia coli (catalyst concentration: 25.0 μM/L and treatment time: 20 min) was 90.8, 92.6, and 100, respectively, with COD removal of 71.6%. Enhanced results may be obtained due to an increase in the cavitational effect in the presence of a solid catalyst. The synergy of cavitation with TiO2 enhanced the microbial removal rate by 45.8% compared to the individual effect. Investigation confirms that synergy effects produced from ultrasound and catalyst were highly beneficial for reducing microbial count from raw water with a substantial COD reduction.

Hydrogen peroxide assisted electrocoagulation treatment of rice gain based biodigester effluent: mechanism, performance, and cost analysis

Abstract In the current scenario treatment of industrial waste water is big challenge especially waste water that contain high organic load. Hydrogen peroxide assisted electrocoagulation (EC) process provides better result to treat highly polluted wastewater as compared to EC alone. However, hydrogen peroxide is well known as a strong oxidant, which cast a potential threat to human health. To overcome this problem hydrogen peroxide has been used here for treatment of wastewater in small quantity, and that consume during the process. Therefore the harmful effect of hydrogen peroxide in human and aquatic life could be minimized. This work is an attempt to treat biodigester effluent (BDE) using H2O2 assisted EC processes with respect to chemical oxygen demand (COD) and color reductions. To perform this experiment both iron and aluminum electrodes are used as an electrode material in the presence of H2O2. In case of iron electrode the maximum COD and color reduction efficiency of 98.3 and 83.6% was achieved at the cost of 1.5 Wh/dm3 energy consumption while maximum COD and color removal efficiency of 96.8 and 77.1% with 1.7 Wh/dm3 of energy consumption was observed in the aluminum electrode based EC process. A part from this conventional biological process (i.e., activated sludge treatment, ponds, and lagoon etc.) and physiochemical treatment process (i.e., coagulation, adsorption) provided treatment efficiency of 40–80% hence hydrogen peroxide assisted EC process should a better choice to treat distillery effluent. Furthermore, hybrid EC process was also performed with iron used as anode and aluminum as cathode in the presence of H2O2. Iron electrode based peroxi-EC process provided better result at optimum operating conditions; current density of 114 A/m2, initial COD concentration of 12,000 mg/dm3, initial pH of 7.3, H2O2 concentration of 120 mg/dm3, stirring speed of 120 rpm and electrolysis time of 90 min. The cost estimated for operation is 1.56 US $/m3. Finally, sludge analysis and cost optimization are also incorporated in this article.

Sequential three-step process for the treatment of slaughter house wastewater and its optimization using response surface modeling studies

The rapid growth in the world population and fast developing industrialization have resulted in the acceleration of environmental pollution due to inadequate treatment methods accompanied by depletion of freshwater. The current research focused on the batch treatment of slaughter house wastewater (SWW) using the sequential three-step electro-coagulation (EC)–electro-oxidation (EO)–adsorption column (AC) processes and to compare the optimized values with the Omani National Standards for the application in irrigation purpose. The characterization of SWW before and after treatment was carried out by measuring chemical oxygen demand (COD), total organic carbon (TOC), total dissolved solids (TDS), turbidity, ammoniacal nitrogen (NH4–N) and conductivity. The optimization of the treatment processes was performed by response surface methodology (RSM) using central composite design. The maximum response obtained using EC unit was 99% with an operating cost of 2.78 USD/m3. The optimum treatment conditions in EC method were found to be 4.0 pH, electrolysis time of 30 min and electrolyte dosage of 5 g/L, with a current density of 18.11 mA/cm2. The maximum reduction in COD was 97% with an operating cost 0.32 USD/m3. The optimum COD reduction in EO method was 84.5% with an operating cost of 6.87 USD/m3. The optimum process parameters in the EO process were observed at 5.0 pH, 56.22 min electrolysis time with 5 g/L electrolyte dosage and a current density of 5 mA/cm2. The response shows 56.27% reduction in COD with an operating cost of 0.088 USD/m3. The study demonstrates that both EC and EO processes for the reduction of COD have a significant effect on the current density. Using adsorption column (AC) studies, the maximum reduction in COD was 76.8% with negligible operating cost. The optimum pH in the case of AC was 7.5, with an effluent flow rate of 8.63 mL/min, and the responses were found to be 76.067%, which indicates both pH and flow rate have significant effect on the % removal of COD.

Sono-assisted electrocoagulation treatment of rice grain based distillery biodigester effluent: Performance and cost analysis

Electrocoagulation process coupled with sonication is a type of advance oxidation process (AOP) to treat different type of waste waters. Biodigester effluent (BDE) generated from distillery industry contains very high chemical oxygen demand (COD=5500 mg/dm3) with high color (510 PCU) appearance. Organics reduction of biodigester effluent (BDE) in term of chemical oxygen demand (COD) and color have been investigated in a batch sono-electrocoagulation reactor with different electrode combinations such as Fe-Fe, Al-Al, Fe-Al, and Al-Fe at ultrasound frequency of 40 kHz. The impact of different operating parameters such as electrolyte concentration, electrode combination, pH and current density (CD) on COD and color removal are evaluated. The electrode combination of Fe-Fe has provided better results in sono-electrocoagulation process as compared to sonication and electrocoagulation alone. The maximum COD and color reduction efficiency of 99.1 % and 61.6 % was found at the electrode combination of Fe/Fe, CD 69.44 A/m2, pH 8, NaCl concentration 5 mg/dm3, and process time of 125 min. On the other hand the maximum COD and color removal efficiency of 98.3 % and 58.1 % was observed with the electrode combination of Al-Al at same operating conditions as described for Fe. Finally, sludge analysis and cost optimization are also incorporated in this article. It is found that at optimum condition (electrode combination of Fe/Fe, CD 69.44 A/m2, pH 8, NaCl concentration 5 mg/dm3, and process time of 125 min) the operating cost of the process is 1.39 $/m3. Sludge obtained after the treatment process contains anodic material (0.07 kg iron for the treatment 1 m3 of BDE) and also sludge had good heating value (5.5 MJ/kg). This work demonstrated that sono-electrocoagulation process is well applicable to treat BDE.

Application of Response Surface Methodology For Modeling and Optimization of A Bio Coagulation Process (Sewage Wastewater Treatment Plant).

Cactus has shown great capabilities as a bio coagulant/flocculent in the treatment of wastewater and as a factor for sustainable development of the environment, due to its abundance and non-toxicity for human health. This has encouraged the present study based on the design of experiments to optimize the two operating factors: the bio coagulant dosage and initial pH. The effect of these considered factors on turbidity and chemical oxygen demand (COD) reduction performances was investigated to treat sewage wastewater from plants by the coagulation/flocculation process using the response surface methodology (RSM) based on a central composite faced design (CCFD). The effect of the pH on the supernatant turbidity removal and the COD reduction was very significant whereas that of the coagulant dosage was insignificant on the COD removal efficiency. Experimental results revealed that the maximum reduction of turbidity and COD could be reached at a coagulant dosage of 28 mg/l and a pH of 12. At these optimal conditions, the removal efficiency of turbidity and COD was 98.33% and 96.55% respectively. By the end of the treatment, final values of 0.84 NTU and 20.8 mg/l were obtained for turbidity and COD, respectively. A notable decrease of orthophosphate (O- PO4-2), nitrite (N-NO3-), ammonium (N-NH4+) and suspended matter (SM) was observed. The study also showed that the quadratic regression model could be used as a theoretical basis for the process based on a high coefficient of determination R2 value > 0.96, obtained from the analysis of variances (ANOVA).

Wastewater Treatment Using a Natural Coagulant (Moringa Oleifera Seeds): Optimization Through Response Surface Methodology

The high expense of chemical coagulant-treated water forces most people in rural regions rely on easily available sources, which are usually of poor quality and expose them to waterborne infections. According to this statement, the purpose of this study was to confirm the efficacy of extracting powder Moringa oleifera seeds, which are widely available in rural regions. The experiment was done based on random design load of 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6g/500ml of powder extracted from Moringa seeds. Chemical oxygen demand (COD), color and turbidity were determined for both acidic and basic characteristics of wastewater. The optimum dosage of Moringa oleifera was 0.4g/500ml in both characteristics of waste water in case of color and turbidity. Moringa airfare maximum reduction in turbidity, color and COD in acidic waste water was 98%, 90.76% and 65.8% respectively. And maximum reduction turbidity, color and COD in basic waste water were 99.5%, 97.7% and 65.82% respectively. The study was demonstrated that, the application of RSM for seeking optimum condition in the coagulation process for treatment of wastewater. Moringa seed powder works best with 7-9 pH range. All the results showed that, Moringa Oliver seeds were very effective for the removal of impurities. So, the researcher and the respective body give attention use of these trees in a wide application area.

An integrated approach of adsorption and membrane separation for treatment of sewage water and resource recovery

The traditional sewage treatment methods are facing several challenges and barriers necessitating the development of newer treatment approaches along with value addition and resource recovery. The present work demonstrates the integration of Carbon Capture Reactor (CCR) i.e. adsorption column and membrane separation for efficient treatment of wastewater collected from different sewage sources with resource recovery in terms of CCR-Oil which is a mixture of organic compounds having calorific value of 18−20 MJ/Kg. Detailed physicochemical characterization of sewage water was conducted for quantification of chemical oxygen demand (COD), total dissolved solids (TDS), and conductivity. The obtained CCR-Oil was also tested for its physicochemical properties by using attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), gas chromatography–mass spectroscopy (GC–MS), and elemental and calorific value analysis. In the adsorption studies, various hydrophobic, hydrophilic and ion exchange resins were tested for maximum COD reduction. Hydrophobic resin showed excellent performance with 50.0 ± 0.4 % COD reduction and maximum dynamic binding capacity of 0.0208 mg/L. The continuous CCR operation showed a 45.5 ± 1.5 % COD reduction with 1.5 bed volume (BV) per hour flow rate for up to 320 bed volume loading of sewage water. The integration of CCR with the reverse osmosis (RO) membrane showed an overall 85.0 ± 2.5 % COD reduction and 93.0 ± 0.5 % TDS reduction with the maximum flux of 34 L/hr/m2 (LMH) and no sign of membrane fouling, indicating very good performance for the combination approach. It was clearly demonstrated that the hybrid approach of adsorption followed by membrane separation provides a sustainable, efficient and economic alternative for the treatment of sewage water also yielding the benefits of resource recovery.

Investigation of flow dynamic characteristics of inverse fluidized bed biofilm reactor for degrading pharmaceutical based biomedical wastewater

The paper investigates the flow dynamic behaviour of inverse fluidized bed biofilm reactor (IFBBR) for the treatment of pharmaceutical based biomedical wastewater. The residence time distribution (RTD) study has been employed as a tool to investigate the flow dynamic behaviour of wastewater within the reactor. The biofilm reactor is operated using Pseudomonas fluorescens for various ratios of settled bed volume to reactor working volume (Vb/Vr) with different superficial air velocities and examined their impact on flow dynamics. The outcomes of this study demonstrate the presence of dead volume and short circuiting in the reactor were reduced for the optimized (Vb/Vr) ratio of 0.20 and optimum superficial air velocity (Ug)m of 0.220 m/s. The potential of IFBBR was experimentally validated by analysing the chemical oxygen demand (COD) removal efficiency, total dissolved solids (TDS) and total suspended solids (TSS) emanating from the wastewater. Findings of this study reveals that maximum COD reduction of about 92% was achieved when the reactor was operated with (Vb/Vr)m of 0.20 with superficial air velocity, Ugm of 0.220 m/s showing the optimal operating parameters for IFBBR which has good mixing and less back mixing condition inside the reactor.

Combined oxidation processes based on ultrasound, hydrodynamic cavitation and chemical oxidants for treatment of real industrial wastewater from cellulosic fiber manufacturing sector

The present work reports the application of cavitation for the real industrial effluent treatment, which was derived from the cellulosic fiber manufacturing sector, individually or in combination with advanced oxidation processes. Cavitation has been applied with the objective of reducing the chemical oxygen demand (COD) of the industrial effluent and to study its simultaneous effect on the total dissolved solids (TDS). A combination of cavitation with different additives/oxidants viz. hydrogen peroxide (H2O2), ozone (O3), sodium hypochlorite (NaCLO), and Fenton's reagent have been studied. Ultrasonic horn operating at an acoustic power of 120 W with a frequency of 20 kHz and duty cycle of 80% (8 sec ON, 2 sec OFF) was used for treatment based on ultrasound. Under optimized conditions, it was established that a combination of ultrasound (US) with Fenton’s reagent using an optimum mole ratio of H2O2/Fe2+ of 3 followed by lime coagulation gave a maximum COD reduction of 92% and also resulted in TDS reduction of 31%. Studies were also performed using a hydrodynamic cavitation (HC) reactor (10 L capacity) where slit venturi was used as a cavitating device. It has been observed that a combination of HC with Fenton's reagent at molar ratio of H2O2/Fe2+ as 3 gave the maximum COD reduction of 86% and a TDS reduction of 47%. It was also established that lime treatment played an important role in separating the sludge formed during the Fenton oxidation treatment and in converting brownish colored effluent to colorless effluent. Overall, it has been established that cavitation coupled with the Fenton oxidation was most the efficient among all studied combinations giving a good COD reduction as well as TDS reduction with a final colourless nature of effluent.

Catalytic thermolysis treatment of petroleum refinery wastewater collected from effluent treatment plant

AbstractCatalytic thermolysis of petroleum refinery wastewater was investigated as a pretreatment process. Effects of various parameters like temperature, pH, dose of catalyst and time were investigated for chemical oxygen demand (COD), turbidity, and element reduction. CuSO4, FeSO4, FeCl3, and 1:1 ratio (v:v) mixture of CuSO4 and FeCl3 were used as a catalyst. The maximum reduction of COD and turbidity were 90 and 98% by mixture (1:1) of CuSO4 and FeCl3 at 70 °C, 7 pH, 1.0 kg/m3 dose in 90 min reaction time. The removal of an element like Cr, Mn, Ni, and Pb was analyzed by ICP-OES. The sludge precipitated after catalytic thermolysis was characterized using scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), Fourier transform infrared (FTIR) and thermo-gravimetric analysis (TGA)/derivative thermal analysis (DTA) analyses. Sludge from CuSO4 and mixture of CuSO4 and FeCl3 treatment has a compact structure with irregular granule which favors adsorption.